Recent wrc items

River Seepage Investigation

Thu, 12 May 2011 00:00:00 +0000

Seepage from rivers and natural channels is a serious problem in the Sacramento Valley of California. Impairment of land use occurs along the Sacramento, Feather, Yuba and Bear Rivers as a result of intermittent periods of high ground water or ponded surface water. When channel levels exceed the adjacent ground surface elevation, water moves through and under the confining levels into adjacent lands. If drainage facilities are inadequate, the soil becomes saturated and water often ponds on the surface. The water damages orchards and perennial and annual crops, and prevents working of land, resulting in delays in or prevention of normal planting of annual crops.

From High Rise to Coast: Revitalizing Riveira da Barcarena

Wed, 25 Aug 2010 00:00:00 +0000

The Lisbon metropolitan region has grown rapidly in population since 1970, due largely to the immigration of people from former Portuguese colonies in Africa and from rural areas of the country in pursuit of higher living standards. Much of this population growth was accommodated clustered high-rise apartment blocks (many unpermitted) in the region west of Lisbon, in the municipalities Oeiras, Cascais, Sintra, and Amadora. These developments were largely unplanned, often did not provide for sewage treatment, and lack adequate mass transit or urban amenities such as parks and other open spaces. Moreover, because the main transport axes run east-west, it is difficult for residents of these apartment blocks to go the relatively short distance southward to the coast (e.g., only 10 km from Cacém to the coast).

This region is drained by a set of subparallel streams (each draining about 20-50 km2), flowing roughly north-south through deeply incised valleys to debouch into the...

Determining factors for Eurasian watermilfoil (M. spicatum) spread in and around Lake Tahoe, CA-NV

Wed, 21 Jul 2010 00:00:00 +0000

Humans play a critical role in the dispersal of exotic invasive species. Estimating pathways for non‐native species by human vectors is a major challenge to invasion biologists, as well as federal, state and regional resource managers. Focusing on dispersal pathways that are available to not just one, but a number of species, allows for the efficient inspection and possible reduction of many exotic species introductions. Transient recreational boating has been used as an estimate of invasion pressure to inland freshwater bodies, and used to predict prior and future species invasions. Specifically, recreational boating traffic is used to predict human-mediated aquatic invasion in the Midwestern United States through the use of spatial interaction models called gravity models. California and Nevada contain some of the largest and most recreationally utilized lakes, rivers and reservoirs in the Western United States. These waterways attract millions of visitor days by boaters...

Climate Variability of the Sierra Nevada Over the Last Millennium: Reconstructions from Annually Laminated Sediments in Swamp Lake, Yosemite National Park, CA

Tue, 16 Mar 2010 00:00:00 +0000

Persistent drought presents one of the greatest risks of climate change faced by the western United States. Highlighting this risk is from paleo hydrological evidence that during the medieval period (~900-1400 AD) this region experienced two extensive droughts of greater duration than any experienced in recorded history. However, much remains to be learned about these “mega droughts,” including the severity of deficit in precipitation and snowpack in California’s Sierra Nevada Mountain range, which currently serve as a crucial source of fresh water to California agriculture, industry and domestic users. To possibly extract a record of the hydrological conditions in the Sierra Nevada during this era, cores of annually laminated sediment from Swamp Lake, in the northwest portion of Yosemite Park were collected. Stable hydrogen isotope (δD) ratios of plant leaf-wax lipid compounds preserved in the lake sediments and the thickness of the annual sedimentary laminations (varves)...

Simulating and understanding variability in runoff from the Sierra Nevada

Tue, 2 Mar 2010 00:00:00 +0000

We have conducted a study of Sierra Nevada runoff by analyzing the onset of snowmelt (or peak snowmass timing) from observations and conducting model simulations of snowpack. For our observation study, monthly snow water equivalent (“SWE”) measurements were combined from two data sets to provide sufficient data from 1930 to 2008. The monthly snapshots are used to calculate peak snow mass timing for each snow season. Since 1930, there has been an overall trend towards earlier snow mass peak timing by 0.6 days per decade. The trend towards earlier timing also occurs at nearly all individual stations. Even stations showing an increase in April 1st SWE exhibit the trend toward earlier timing, indicating that enhanced melting is occurring at nearly all stations. Analysis of individual years and stations reveals that warm daily maximum temperatures averaged over March and April are associated with earlier snow mass peak timing for all spatial and temporal scales included in the data...

Enforcement-driven financing of water quality in California: The case of supplemental environmental projects

Tue, 2 Mar 2010 00:00:00 +0000

In this report, we compile empirical evidence regarding federal and state trends in the use of Supplemental Environmental Projects (SEPs). Our primary interest is in SEPs associated with enforcement of the federal Clean Water Act (CWA). We move from briefly examining the broadest trends—federal and state use of SEPs—to more particular emphasis on the experience of California’s State Water Resources Control Board (SWRCB) and Regional Water Quality Control Boards (RWQCB) with SEPs. Drawing on state and regional enforcement databases as well as extensive interviews with agency enforcement personnel, we evaluate the use of SEPs by the regional boards in California and offer recommendations for improving the use of this important policy tool.

Pyrethroid pesticide transport into Monterey Bay through riverine suspended solids

Fri, 8 Jan 2010 00:00:00 +0000

The three largest coastal rivers discharging to Monterey Bay, the Salinas, Pajaro, and San Lorenzo Rivers potentially serve as a route of transport of pyrethroids and other pesticides into the shelf waters of Monterey Bay and deeper areas within Monterey Canyon. Suspended sediment samples from the lower reaches of the rivers were collected over several rain events in the winters of 2007/2008 and 2008/2009, and analyzed for pyrethroids and one organophosphate pesticide. Bed sediments from Elkhorn Slough, Monterey Bay, and Monterey Canyon were also analyzed for these same substances. Nearly all suspended sediments contained measurable pyrethroids, with the pyrethroids bifenthrin and permethrin being the most commonly detected. The differences in pyrethroid composition between the rivers, some with predominantly an agricultural watershed and some with substantial urban influence, were relatively minor reflecting the broad uses for many of the insecticides within this class. While...

Consensus Building as a Policy Making Strategy for Water Resources Management

Fri, 8 Jan 2010 00:00:00 +0000

Collaborative processes offer possible means to resolve public policy disputes that administrative, regulatory and/or judicial processes have failed to solve, thus breaking the gridlock that results when governmental agencies don’t work effectively. The use of collaborative processes and collaborative policy making have produced important results in natural resources management in California, as illustrated by three cases.

Control of mercury methylation in wetlands through iron addition

Fri, 8 Jan 2010 00:00:00 +0000

The San Francisco Bay-Delta System lost an estimated 85-95% of its historical tidal marshes to urban development, agriculture, and commercial salt production since the middle of the nineteenth century. Fortunately, there are many recent initiatives underway throughout the estuary to re-establish the important ecosystem functions and critical wildlife habitat that these tidal wetlands offer. However, there is a significant potential drawback to these restorations, as wetlands have been shown to play a major role in the production and export of methylmercury (MeHg), which is a potent neurotoxin that affects both humans and wildlife. While mercury pollution is a global problem, it is of special concern in the San Francisco Bay-Delta, where substantial additional inputs of inorganic mercury from historical mining activities have resulted in increased mercury levels in ecosystem. The potential exacerbation of MeHg health effects due to wetland restoration and construction is a serious...

Inter-relationships between the spawning migration of Eagle Lake rainbow trout, streamflow, snowpack, and air temperature

Fri, 8 Jan 2010 00:00:00 +0000

Pine Creek has historically provided critical spawning and rearing habitat for Eagle Lake rainbow trout (ELRT, Oncorhynchus mykiss aquilarum). Over the past 100+ years modifications of Pine Creek watershed (e.g., overgrazing, timber harvest, passage barriers, culverts) decoupled the ELRT from its stream habitat. Introduced brook trout (Salvelinus fontinalis) now dominate historic rearing areas in the upper watershed. Passage barriers were constructed on Eagle Lake tributaries to prevent ELRT from spawning in degraded habitat, denying the ELRT access beyond the first kilometer of stream. Since 1950 the lake fishery has been maintained by artificial spawning. Offspring are reared in hatcheries and released into Eagle Lake. Since 1987 changes in grazing management, reconstruction of culverts, and other conservation projects have resulted in marked improvement of habitat, although ELRT have been not allowed to attempt their natural spawning migration. Their ability to migrate has...

Integrated regional water management: Collaboration or water politics as usual?

Fri, 8 Jan 2010 00:00:00 +0000

This report analyzes the effectiveness of integrated regional water management (IRWM) in the San Francisco Bay-Area of California for decreasing fragmentation and increasing collaboration among water management stakeholders. The theory identifies the elements of traditional water management politics that lead to fragmentation and conflict. The water-politics-as-usual model is then compared to the collaborative model of integrated water management. The evolution of IRWM in California is briefly described. A survey of Bay Area stakeholders is used to assess whether participation in the Bay Area IRWM achieves the goals of collaboration and integration. The basic results suggest the Bay Area has made only incremental progress away from the fragmentation and conflict seen in the past.

Evaluating the use of marine-derived nitrogen in riparian tree rings as an indicator of historical nutrient flux and salmon abundance

Mon, 14 Dec 2009 00:00:00 +0000

We examined the potential for using riparian conifer trees (coast redwood and Douglasfir) to assess historical nutrient flux and salmon escapement (fish that escape capture by commercial fisheries in the open ocean and are able to return to their natal stream to spawn) to a pair of coastal California watersheds (Mill Creek and Waddell Creek). In each basin, periods of known annual salmon escapement were compared with data on tree-ring growth, nitrogen content [N] and stable nitrogen isotope ratios (δ15N). All tree-ring variables (lagged by +1 year) were positively correlated with Mill Creek salmon escapement, but relationships were inconsistent at Waddell Creek and highly dependent on the time lag applied (0 to 7 years). Annual ring δ15N was especially variable among individual trees growing at the same location with differences as high as 4.8‰ at spawning sites and 6.8‰ at salmon-free control sites. Linear regression-based models were used to reconstruct historical escapement...

Investigation of Groundwater Flow in Foothill and Mountain regions using Heat Flow measurements

Mon, 14 Dec 2009 00:00:00 +0000

A field and model investigation has been performed to assess the potential of

subsurface temperature (T) measurements for tracing groundwater flow in montane areas.

Field measurements included monitoring of soil T at numerous sites and measurement of

T-profiles in many wells and boreholes. Field data collection for thermal tracing of

groundwater flow is inexpensive and easy to perform relative to standard geophysical

techniques for groundwater flow characterization, given wells that are accessible for Tprofile

measurement. Modeling investigations include development of a novel,

conceptually simple ‘black box’ subsurface thermal energy balance approach. This robust

model approach can be used together with T-profile data to bracket the rate of mountainfront

groundwater recharge.

Results of the soil T monitoring investigation show a wide range in summer and

mean annual soil T between different soil sites. Factors...

Predicting the Impacts of Urbanization on Basin-scale Runoff and Infiltration in Semi-arid Regions

Mon, 14 Dec 2009 00:00:00 +0000

The current study was undertaken to improve the understanding of the long-term impacts of urbanization on hydrologic behavior and water supply in semi-arid regions. The study focuses on the Upper Santa Clara River basin in northern Los Angeles County which is undergoing rapid and extensive development. The Hydrologic Simulation Program- Fortran (HSPF) model is parameterized with land use, soil, and channel characteristics of the study watershed. Model parameters related to hydrologic processes are calibrated at the daily timestep using various spatial configurations of precipitation and parameters. Results indicate that the HSPF performs best with distributed precipitation forcing and parameters (distributed scenario), however the model performs fairly well under all scenarios. The model also shows slightly better performance during wetter seasons and years than during drier periods. Potential urbanization scenarios are generated on the basis of a regional development plan....

Assessment of Seawater Intrusion Potential From Sea-level Rise in Coastal Aquifers of California

Mon, 14 Dec 2009 00:00:00 +0000

The California Department of Water Resources (2006) estimated a rise in mean sea level along California’s coastline ranging from 10 to 90 cm over the 21st century due to rising global mean surface temperature. This range of sea-level rise is consistent with the Intergovernmental Panel for Climate Change (2007) estimates. The rise in sea level threatens coastal aquifers by exacerbating the risk of saline intrusion. This study simulated the effect of sea-level rise on the Seaside Area sub-basin near the City of Monterey, California. The simulation was carried out with a state-of-art, finite-element, variable-density, numerical model that accounts for the effects of salinity on groundwater density and viscosity. Seawater intrusion was simulated for various scenarios of sea-level rise, varying from 0 m to 1 m assuming a linear increase of sea level through the 21st century. Each scenario contemplated the same level of predicted groundwater extraction through the 21st century in...

Impacts of Delayed Drawdown on Aquatic Biota and Water Quality in Seasonally Managed Wetlands of the Grasslands Ecological Area

Mon, 14 Dec 2009 00:00:00 +0000

The 178,000-acre Grassland Ecological Area in California’s San Joaquin Valley is managed to provide overwintering habitat to waterfowl on the Pacific Flyway. The major management activity is the fall flooding and spring drawdown of wetlands, timed to optimize the availability of forage vegetation and invertebrates for ducks and shorebirds. Wetland drainage contains salt, boron, and trace elements that are largely derived from imported surface water but concentrate during storage in the wetland impoundments and contribute to occasional water quality violations in the San Joaquin River (SJR) during dry years. Compliance with water quality objectives may be improved by timing wetland drawdown to coincide with high SJR salt assimilative capacity during mid-March to mid-April when reservoir releases are increased to aid salmon migration.

The experimental sites chosen were three pairs of matched wetland basins (20-100 acres each) that are part of the larger Modified Hydrology...

Sustainable Eco-Systems under Land Retirement

Mon, 14 Dec 2009 00:00:00 +0000

This study uses five years of field data from the Land Retirement Demonstration Project located in western Fresno County of California to develop a comprehensive theoretical and numerical modeling framework to evaluate the specific site conditions required for a sustainable land retirement ecosystem outcome based on natural drainage. Using field data, principles of mass balance in a control volume, the HYDRUS-1D Software Package for simulating one-dimensional movement of water, heat, and multiple solutes in variably-saturated media, and PEST, a modelindependent parameter optimizer, the processes of soil water and solute movement in root zone and the deep vadose zone were investigated. The optimization of unsaturated soil hydraulic parameters and downward flux (natural drainage) from the control volume against observed vadose zone salinity levels and shallow groundwater levels yield difficult to obtain natural drainage rate as a function of water table height within the control...

Maintenance and Dissemination of a Water Transfer Data Base for 12 Western States, 1987-2008

Tue, 8 Dec 2009 00:00:00 +0000

The project involves collaborate work between Gary Libecap and a graduate student, Zachary Donohew, to compile and maintain a comprehensive, publiclyavailable data set on water transfers and water markets for researchers and policy analysts. The data are drawn from the Water Strategist for 12 western states (Washington, Oregon, California, Arizona, Nevada, Utah, Idaho, Montana, Wyoming, Colorado, New Mexico and Texas) from January 1987-December 2008. There are 4,175 observations of water transfers that include amount of water, contract type (short-term lease, long-term lease, and sale), parties involved, origination use, destination use, and price (2,728 observations). The methodology is described and data categories are presented in a Word document along with an excel file of the trades placed on the Bren School Website and linked to the Bren website at http://www.bren.ucsb.edu/news/water_transfers.htm and the WRRC website at http://www.lib.berkeley.edu/WRCA/WRC/research_sp.html.

Irrigation Management Improvements for San Joaquin Valley Pima Cotton Systems

Fri, 2 Oct 2009 00:00:00 +0000

California Pima cotton production has and been particularly hard hit resulting in acreage declines caused by water supply reductions in the western San Joaquin Valley. Water management methods that improve water use efficiency while maintaining high agronomic yield are of value to the cotton producers that face water supply limitations. We tested structured and predictive approaches to water management and collected field water management information that evaluated our ability to match varying water supply amounts in a way that maximized production and limited economic losses due to reductions in crop quality. Evaluations at four separate sites conducted during the 2005 and 2006 cropping seasons confirmed Pima cotton’s ability to respond favorably to irrigation guidelines recently developed by the UCCE and to modest deficit irrigation approaches that have been developed for Acala type Upland cottons. Variations in soil water storage at each site were large and played a critical...

Investigating the Role of Nitrogen Fixation and Denitrification in Ameliorating Deteriorating Water Quality in a Highly Eutrophic Southern California Estuary

Tue, 2 Jun 2009 00:00:00 +0000

Estuaries are highly productive ecosystems that support many endangered and commercially important species. In most estuaries, nitrogen limits primary productivity. However, if present in excess, nitrogen leads to eutrophic conditions, which adversely affects water and habitat quality. Southern California’s estuaries have highly developed watersheds resulting in high loads of nitrogen from anthropogenic sources and eutrophication. Our overall goal was to understand the role of two biogeochemical processes, N-fixation and denitrification, that affect processing of N in estuaries and to investigate their response to increased N loads from the watershed. Nitrogen fixation transforms elemental nitrogen (N2) into ammonium ions (NH4+) that can be used by primary producers, and therefore is a “new” source of nitrogen. Denitrification transforms nitrate (NO3-) into atmospheric nitrous oxide (N2O) or nitrogen gas (N2), and is therefore a loss of nitrogen from aquatic ecosystems. As...

Impact of Climate Change on Irrigation Water Availability, Crop Water Requirements and Soil Salinity in the SJV, CA

Tue, 2 Jun 2009 00:00:00 +0000

We examine potential regional-scale impacts of global climate change on sustainability of irrigated agriculture, focusing on the western San Joaquin Valley in California. We consider potential changes in irrigation water demand and supply, and quantify impacts on cropping patterns, groundwater pumping, groundwater levels, soil salinity, and crop yields. Our analysis is based on archived output from General Circulation Model (GCM) climate projections through 2100, which are downscaled here to the scale of the study area (~30 km across). We account for uncertainty in GCM climate projections by considering output from two different GCM’s, each using three greenhouse gas emission scenarios. Significant uncertainty in projected precipitation translates into uncertainty of future water supply, ranging from an increase of 10% to a decrease of 30% in 2100. On the other hand, temperature projections are much less variable, resulting in consistent projections of crop water demand for...

Plant Water Use in Owens Valley, CA: Understanding the Influence of Climate and Depth to Groundwater

Thu, 23 Apr 2009 00:00:00 +0000

There is a long-standing controversy in Owens Valley, California about the potential impacts of water exports on the local ecosystem. It is currently extremely difficult to attribute changes in plant cover and community composition to hydrologic change, as the interactions between ecological and hydrologic processes are relatively poorly understood. Underlying predictions about losses of grasslands and expansion of shrublands in response to declining water tables in Owens Valley are assumptions about the differential access of grasses versus shrubs to groundwater and their physiological respones to water stress. We sought to test these assumptions with measurements of natural abundance isotope tracers in plants, soils, and groundwater, and with physiological measurements. We found that the grass species Distichlis spicata did use shallower water sources than co-occuring shrub species, particularly in late summer. However, at sites with watertable depths < 3 m we did not...

Monitoring and Modeling Non-Point Source Contributions of Host-Specific Fecal Contamination in San Pablo Bay

Thu, 23 Apr 2009 00:00:00 +0000

Fecal contamination from non-point sources in coastal and estuarine water bodies is a problem of increasing concern. Water monitoring alone is sometimes insufficient in providing a clear picture of the fecal contamination of a water body. Well-formulated and developed mathematical and numerical transport models, on the contrary, predict continuous concentrations of microbial indicators under diverse scenarios of interest, and they can quantify fecal source contributions on a land use basis (human versus livestock or wildlife).

The present project has demonstrated the utility of quantitative analyses of fecal contamination in water bodies via new experimental measurement techniques as well as mathematical/numerical modeling of the fate and transport of biological contaminants. San Pablo Bay was selected because there is abundant knowledge about the estuarine system and its tributaries and because of the availability of an existing 3-dimensional model. Environmental monitoring...

Large-Scale Utilization of Saline Groundwater for Irrigation of Pistachios Interplanted with Cotton

Thu, 23 Apr 2009 00:00:00 +0000

Twelve, 19.5 acre test plots arranged in a randomized complete block design are set within two 155 acre fields to provide a realistic production environment. These blocks of welldrained Panoche clay loam were formerly irrigated with California Aqueduct water and sprinklers for the last 30 years. Overall the field electrical conductivity (EC) ranged from 0.5 to 4.5, averaging 1.57 dS/m to a 3-foot depth. Saturation extract boron was 0.6 ppm. The area is underlain by a semi-saline aquifer that has been made worse over the decades by contamination from oilfield leachate water. Several production wells were drilled in fall 2003 to begin using this water. A drip tape irrigation system was set up to allow the planting of 6 rows of cotton every 22 feet the first year of the project (2004) followed with the planting of 1 year old pistachio seedling rootstocks March 2005 in 22 foot rows interplanted with 4, 38 inch rows of pima cotton. Salinity of the shallow groundwater for the test...

Investigating the Role of Large Woody Materials to Aid River Rehabilitation in a Regulated California River

Thu, 23 Apr 2009 00:00:00 +0000

To determine whether large wood (LW, ≥1-m length, ≥10-cm diameter) plays a role in Chinook salmon redd (i.e. egg nests) placements in a regulated, medium-sized, Mediterranean-climate river, characteristics of 542 large wood pieces, locations of 650 redds, and habitat unit delineations (riffle, run, glide, pool) were collected during a spawning season along a 7.7 km reach directly below Camanche Dam on the Mokelumne River (average width 31 m). Large wood was regularly distributed across the study reach with an average of 70 LW pieces km-1. Some LW clustering was evident at islands. Chinook spawners built 75% of observed redds at spawning habitat rehabilitation sites, and 85% of redds were within one average channel width of large wood. At the hydraulic scale of ~10-1 channel widths, redds were within a 10 m radius of large wood 36% of the time. These results suggest that spawners had the opportunity to utilize large wood as cover and refugia. In the lower 4.7 km where marginal...

Assessing the Effectiveness of California's Underground Storage Tank Annual Inspection Rate Requirements

Thu, 23 Apr 2009 00:00:00 +0000

Several states have experimented with varying degrees of local government implementation of hazardous substances (including waste) regulation. Local implementation allows more coordination of hazardous substances inspections with other local business regulation activities. However, there is the danger that some local governments may not pursue vigorous enforcement because of concerns over business and tax competition. California has instituted the most thorough system of local control over hazardous substances regulation in the nation. It has also gradually put in place a series of measures to attempt to hold local governments to minimum regulatory effort standards and to encourage enforcement actions when violations occur. These minimum standards and enforcement incentives appear to be successful as a whole and offer tools for other states considering local control over various environmental regulations. This report analyzes the minimum standards and enforcement incentives...

Numerical Simulation of Land Subsidence in the Los Banos-Kettleman City Area, California

Tue, 24 Mar 2009 00:00:00 +0000

Land subsidence caused by the excessive use of groundwater resources has traditionally caused serious and costly damage to the Los Banos-Kettleman City area of California's San Joaquin Valley. Although the arrival of surface water from the Central Valley Project has reduced subsidence in recent decades, the growing instability of surface water supplies has refocused attention on the future of land subsidence in the region. This report develops a three-dimenslonal, numerical simulation model for both groundwater flow and land subsidence. The simulation model is calibrated using observed data from 1972 to 1998. A probable future drought scenario is used to consider the effect on land subsidence of three management alternatives over the next thirty years. Maintaining present practices virtually eliminates unrecoverable land subsidence, but with a growing urban population to the south and concern over the ecological implications of water exportation from the north, it does not...

Assessment of Intraseasonal Variations in California Rainfall and the Role of the Madden and Julian Oscillation

Wed, 18 Mar 2009 00:00:00 +0000

California receives most of its annual precipitation during the winter season, with large spatial contrasts and temporal variations being observed in the total rainfall amounts. Currently there is widespread understanding of the implications of large atmospheric and oceanic anomalies to the economy and society of the state of California. Typical of this awareness, is the high level of public and government concern at the onset of El Nino conditions in 1997. Therefore, thorough documentation and understanding of the spatial and temporal variability of precipitation in California is a key element in developing efficient and successful programs of water resources management and emergency awareness.

Quantitative Assessment of the Response to Changing Sediment Supply, North Fork, American River, California

Wed, 18 Mar 2009 00:00:00 +0000

Changes in sediment supply relative to transport capacity In .e,ravel-bed streams lead to adjustments in stream geomorphology. Dietrich et al. (1989) propose that when sediment supply is low relative to transport capacity, bed surface coarsening develops due to selective erosion of fines. They developed a dimensionless bedload transport rate (q*), which is the ratio between the sediment transport rate of the surface layer and the transport rate of material as fine as the subsurface or bedload. Flume experiments show that q* approaches unity when supply meets or exceeds capacity, and decreases in value when supply decreases. Longitudinal profiles and crosssection surveys on 7 km of the North Fork American River, CA show a downstream increase in supply relative to transport capacity. Q* values calculated from 15 sediment samples show corresponding increases downstream, indicating that the q* method may be useful for detecting trends in the supply-capacity relationship. Strong...

Numerical Simulation of Land Subsidence in the Los Banos-Kettleman City Area, California

Wed, 18 Mar 2009 00:00:00 +0000

Land subsidence caused by the excessive use of ground water resources has traditionally caused serious and costly damage to the Los Banos-Kettleman City area of California's San Joaquin Valley. Although the arrival of surface water from the Central Valley Project has reduced subsidence in recent decades, the growing instability of surface water supplies has refocused attention on the future of land subsidence in the region. This report develops a three dimensional, numerical simulation model for both ground water flow and land subsidence. The simulation model is calibrated using observed data from 1972 to 1998. A probable future drought scenario is used to consider the effect on land subsidence of three management alternatives over the next thirty years. Maintaining present practices virtually eliminates unrecoverable land subsidence, but with a growing urban population to the south and concern over the ecological implications of water exportation from the north, it does not...

Optimal Nonpoint Source Monitoring: An Application to Redwood Creek

Wed, 18 Mar 2009 00:00:00 +0000

The research summarized in this report involves three interrelated analyses. First, we construct a theoretical nonpoint source (NPS) pollution control model and derive the optimal budget tradeoff between direct treatment of polluting sources versus data collection, which facilitates information acquisition and learning about the relative pollution loading among the sources. Second, we develop a sequential entropy filter to statistically update estimated NPS pollution loading parameters, as new data becomes available. We apply the entropy method to stream flow and ambient sediment loading data for Redwood Creek, which flows into and through Redwood National Park. Third, the theoretical and methodological results are incorporated into a sediment control model for Redwood Creek. We simulate the sediment control management program to provide policy analysis by comparing a uniform treatment policy where no data is collected against high and low-intensity data collection policies,...

Are Paleoclimate Reconstructions of Past Severe Drought in the Colorado Basin Accurate Enough to Warrant Changing the Current "Law of the River"?

Wed, 18 Mar 2009 00:00:00 +0000

The research problem addressed during this study focused on assessing and improving the accuracy of climate reconstructions from tree-ring width records in the Upper Colorado River Basin. The impact of severe sustained droughts (SSD) is a major concern for water availability in the face of increasing population growth in the southwestern United States. This concern is acute in the case of the Colorado River Basin, which includes Wyoming, Colorado, Nevada, Utah, Arizona, New Mexico and California. These states withdraw significant proportions of water for drinking and irrigation from the Colorado River. Since long-term records of hydrologic variability may influence the allocation of water resources, this research has focused on the following question: Are Paleoclimate Reconstructions of Past Severe Drought in the Colorado Basin Accurate Enough to Warrant Changing the Current "Law of the River"?

Spatial and temporal ecology of native and introduced fish larvae in Lower Putah Creek, California

Tue, 17 Mar 2009 00:00:00 +0000

For two years we studied the distribution and abundance of native and introduced fish larvae in Putah Creek (Yolo County, CA); a low elevation regulated stream. We used light traps and conical drift nets to sample the fish larvae at two spatially separated sites from March through July 1997 and at four sites from February through August 1998. Native larvae occurred both earlier in the year and in higher abundance than those of introduced species. Both native larvae and overall numbers of larvae were more abundant at upstream sites in both years. Larval sampling appeared to be sensitive to the detection ofrare species. Drift nets and light traps collected similar numbers of larvae, but each method tended to select for different taxa. There were significant trends in diel patterns of abundance, with more fish larvae being found during the hours of darkness. We suggest that differences between the sites were due to habitat changes resulting from an upstream dam that has created...

Pharmaceutically-Active Compounds in Alternative Water Supplies

Tue, 17 Mar 2009 00:00:00 +0000

Pharamceutically active compounds (PhACs) are a group of compounds that include hormones, antibiotics and painkillers. Results of several recent studies suggest that these compounds are present in wastewater effluents and in polluted surface waters. The possible presence of these compounds is especially significant to populated arid regions where wastewater effluents are used as drinking water and to augment freshwater habitats. To assess implications of PhACs in polluted waters, we have studied the fate and transport of several hormones. In the initial phase of the investigation, new analytical techniques were developed that are capable of detecting the hormones 17~-estradiol, ethinyl estradiol and testosterone under the conditions encountered in polluted natural waters. Analysis of hormones in wastewater effluents from conventional treatment plants indicates that estrogenic hormones are present at concentrations comparable to those that cause endocrine disruption in fish...

Institutional Arrangements for Conjunctive Water Management in California and Analysis of Legal Reform Alternatives

Tue, 17 Mar 2009 00:00:00 +0000

This project analyzes the legal and institutional opportunities and constraints on conjunctive management of groundwater and surface water in California. Conjunctive water use involves the coordination of groundwater and surface water management, usually by recharging the groundwater basin with surface water during times of hydrologic surplus and withdrawing the stored water during times of drought. The goals of conjunctive management include: (1) augmentation of total usable water supplies; (2) recharge of overdrafted aquifers; (3) increase in total available water supplies at less economic, political, and environmental cost than through construction of additional surface storage; (4) improvement of water quality; and (5) enhanced reliability of water supplies during times of drought.

There are a number of examples of conjunctive water management in California, particularly in adjudicated groundwater basins in Southern California. These management arrangements generally...

Stochastic Conjunctive Management of Water Resources in Yolo County

Mon, 16 Mar 2009 00:00:00 +0000

Two management models are developed to determine the optimal operating policies for hydraulically connected time-variant surface and ground water supplies in a hypothetical system. The system involves a multipurpose reservoir, a hydraulically connected stream and aquifer, agricultural plot, water supply and observation wells, and an artificial recharge zone so as to address various hydrologic components experienced in Yolo County in the management models. The first model minimizes deviations from a set of rule curves defined for storage in the reservoir and along stream course so as to consider possibilities for storage excess water in wet periods and its distribution in subsequent dry periods. The second model, in addition to the objective of the first model, minimizes total operational costs of surface and subsurface water storages (pricing) while meeting the target storage levels in the surface water supplies. The first model is formulated as a linear programming model whereas...

Microbial utilization of particulate organic carbon in northern San Francisco Bay and links to higher trophic levels

Mon, 16 Mar 2009 00:00:00 +0000

We examined bacterioplankton abundance and metabolic characteristics in northern San Francisco Bay, California during spring and summer 1996 at three sites: Central Bay, Suisun Bay and the Sacramento River. These sites spanned a salinity gradient from marine to freshwater, and sampling occurred during a period of seasonally declining river flow. The microbial measures included radio-labeled amino acid uptake (L-leucine, L-proline, L-serine), ectoenzyme activity (aminopeptidase and 13-D-glucosidase), and bacterial abundance using lum filters to separate free from particle-associated bacteria. We observed a seasonal decline in all bacterial metabolic measures at all stations, suggesting that a system-wide variable may be important in controlling bacterial activity. One such variable is freshwater flow into the Bay (as a proxy for organic matter flux), which positively covaried with all metabolic measures. We also observed a sharp decline in particle-associated bacteria in Suisun...

A Living Mediterranean River: Restoration and Management of the Rio Real in Portugal to Achieve Good Ecological Condition

Mon, 16 Mar 2009 00:00:00 +0000

In Mediterranean climates, mild year-round temperatures support comfortable human settlement with rich agricultural regions. The climate’s long summer drought, seasonal river flow, high inter-annual variability in precipitation, and episodic floods threaten these settlements, leading to highly manipulated hydrologic systems.

The degree of hydrological alteration and consequent ecological change is typically much greater in Mediterranean-climate rivers than humid-climate systems. Dams, diversions, irrigation channels, storage and distribution facilities simultaneously restrict flow regimes, support economic development and destroy the native biological communities in Mediterranean drainage basins. Overcoming the complex relationships among climate, economy and our entangled legal and political institutions challenge the restoration potential of Mediterranean-climate river systems worldwide.

The Role of Photochemistry the Transport and Transformation of Arsenic

Mon, 16 Mar 2009 00:00:00 +0000

Arsenic, a toxic trace element, enters surface waters from abandoned mines and geothermal springs. Once arsenic is discharged to surface waters, photochemical reactions can alter the oxidation state of the metal or cause the dissolution of the mineral phases onto which it could adsorb. To assess the role of these photochemical reactions arsenic fate and transport, we conducted laboratory studies and collected samples from arseniccontaminated surface waters. Results of laboratory studies indicate that hydroxyl radical (OH)is the only photo-produced transient in sunlit surface waters that is capable of oxidizing As(III) at significant rates. A field study conducted at a geothermal spring (Hot Creek) indicated As(III) is oxidized by photo-produced hydroxyl radical with a half-life of approximately minutes. Photochemical oxidation of As(III) is likely to be faster in acid mine drainage streams, where hydroxyl radical concentrations are much higher. Results of laboratory studies...

Will Releasing Treated Wastewater Stimulate Algal Blooms in Southern California Estuaries?

Mon, 16 Mar 2009 00:00:00 +0000

Quarterly monitoring of Upper Newport Bay, a highly eutrophic southern California estuary, has provided conflicting indicators of nutrient limitation for the seasonal macroalgal blooms in this system. Water column N:P ratios were high, up to 370:1, suggesting phosphorous limitation, while sediment N:P ratios were low, (<4:1), suggesting nitrogen limitation. A microcosm experiment was conducted to test whether macroalgal biomass was nitrogen or phosphorous limited in this system. Results indicate that even at high nutrient levels (300uM N/30uM P) macroalgal growth was nitrogen limited. Despite high N loading over the course of the experiment, water column N remained low as it was removed by the increasing algal biomass. The data also indicate that macroalgae used N fluxing from sediments for growth. Nitrogen accumulated in algal tissue while decreasing in microcosm sediments.

These results have important management implications. Winter releases of treated wastewater...

The Redox Transformation and Mobilization of Arsenate and Arsenite at Water - Sediment Interfaces

Fri, 13 Mar 2009 00:00:00 +0000

Arsenic toxicity, mobility, and bioavailability In sediment-water systems are highly depended on its oxidation states and chemical species. Arsenite (As(III)) and arsenate (As(V)) are two main species of arsenic in water ecosystem. As(III) is more toxic and mobile than As(V). In this research both wet chemistry and spectroscopic techniques were applied to study the adsorption and redox transformation of As(III) and As(V) on Fe and Mn iron minerals as well as on soil and sediment. The results indicate that the Fe mineral (goethite) can strongly adsorb both As(V) and As(III) while the Mn mineral Birnessite can effectively oxide As(III) to As(V) both in solution phase and on mineral surfaces. Mn and Fe are closely related in chemical properties and often occur together in soils and sediments. The interaction between of arsenite (As(III) and Mn-substituted goethite was investigated by both solution chemistry and XANES spectroscopy. This study suggests that the adsorption-oxidation...

Effects of Perennial Grass Buffer Strips on Movement of NPS Pollutants from Cropland to Wetland

Fri, 13 Mar 2009 00:00:00 +0000

Previous research has shown that vegetative buffer strips are effective at protecting water quality. Most of the research has been conducted on the east coast. Our research goals are to determine whether native perennial grasses serve to restore native biodiversity while simultaneously capturing both sediment and nutrients from adjacent conventional row-cropped agriculture. In particular, we are evaluating the efficacy of buffer strips in Mediterranean climate. Buffer strips bordering Elkhorn Slough, draining into the Monterey Bay National Marine Sanctuary, have received one of three treatments: annual non-native grasses, perennial native grasses, and an unseeded treatment of weedy volunteers. We measured sediment movement as part of an erosion study and quantifying nitrogen and phosphorus pools in soil, surface water, soil water, groundwater and vegetation. In addition, we have looked at the mechanisms and processes involved in nitrogen transformation to understand the fate...

Mobilization, Fate, and Transport of Iron in the Anoxic Zone of a Sewage Contaminated Aquifer

Fri, 13 Mar 2009 00:00:00 +0000

The work reported here is the first part of a larger effort focused on efficient numerical simulation of redox zone development in contaminated aquifers. The sequential use of various electron acceptors, which is governed by the energy yield of each reaction, gives rise to redox zones. The large difference in energy yields between the various redox reactions leads to systems of equations that are extremely ill-conditioned. These equations are very difficult to solve, especially in the context of coupled fluid flow, solute transport, and geochemical simulations. We have developed a general, rational method to solve such systems where we focus on the dominant reactions, compartmentalizing them, in a manner that is analogous to the redox zones that are often observed in the field. The compartmentalized approach allows us to easily solve a complex geochemical system as a function of time and energy yield, laying the foundation for our ongoing work in which we couple the reaction...

Multidimenstional Models for Macroscopic Virus Transport in Porous Media

Fri, 13 Mar 2009 00:00:00 +0000

Analytical models for virus transport in saturated, homogeneous porous media are developed. The models account for three-dimensional dispersion in a uniform flow field, and first-order inactivation of suspended and deposited viruses with different inactivation rate coefficients. Virus deposition onto solid particles is described by two different processes: nonequilibrium adsorption which is applicable to viruses behaving as solutes; and colloid filtration which is applicable to viruses behaving as colloids. The governing virus transport equations are solved analytically by employing Laplace, Fourier, and finite Fourier cosine transform techniques. Instantaneous and continuous/periodic virus loadings from either a point or an elliptic source geometry are examined. Furthermore, porous media with either infinite, semi-infinite, or finite thickness are considered. The effects of virus loading conditions, aquifer boundary conditions, and virus source geometry on virus migration...

Bioavailability and Toxicity of Heavy Metals in Urban Runoff in Simulated Natural Conditions

Fri, 13 Mar 2009 00:00:00 +0000

Copper is so ubiquitous in urban streams that it has been labeled a priority pollutant by the Nationwide Urban Runoff Program. Regulations and monitoring programs that have been developed in response to this problem concentrate on only total or total and dissolved copper concentrations. Our research has focused on measuring the partitioning of copper into its labile and non-labile fractions in urban storm water from the San Francisco Bay Area and its implications to toxicity. We found dissolved copper levels in runoff varied from 5 to 40 ug/L, but labile copper comprised only 10% to 25 % of the total dissolved copper levels. In experiments with runoff spiked with additional copper, we found that labile copper concentrations predicted toxicity better than dissolved copper concentration.

A Two-Step Nonlinear Programming Approach to the Optimization of Conjunctive Use of Surface Water and Ground Water

Fri, 13 Mar 2009 00:00:00 +0000

This report develops a systematic approach for solving the problem of conjunctive use of surface water and ground water in which both supply water quality and ground water quality are of major concern. The new approach utilizes a two-step nonlinear optimization. A test problem typical of a semiarid river basin with a seasonal agricultural demand and an increasing municipal and industrial demand is presented. Seasonal variations in demand, precipitation and recharge are handled by dividing each modeling year into a wet season and a dry season in the management model. Sustainable pumping and injection rates that would satisfy both the head and water quality constraints are obtained in the management model for each demand-supply scenario. An iterative technique is then used to solve the optimal pumping and injection rates within the planning horizon using the sustainable rates as upper bounds. Nonlinear programming solver MINOS is used to solve the management problem. MODFLOWand...

Application of Artificially Immobilized Microorganisms to Nitrate Removal from Drinking Water

Fri, 13 Mar 2009 00:00:00 +0000

For biological treatment of drinking water, several crucial issues need to be addressed: firstly, microorganisms used in the treatment must be confined and free from leaking into the bulk water; secondly, certain nutrients, particularly, organic carbon source must be provided for optimal microbial growth; finally, the end products of biological conversions must be non-toxic to humans and animals. These objectives are difficult to attain in a typical water treatment plant, as a result, most water treatment technologies employed in America have not been out of scope of physical-chemical treatment. In this study, however, application of artificially-immobilized microorganisms in alginate gel beads to drinking water treatment has proved to be a viable technology in solving these problems associated with the removal of high concentrations of soluble pollutants, such as nitrate in raw water sources. Naturally-derived alginate beads were used as support materials for immobilized microorganisms...

Potential of Long-lead Streamflow and Drought Forecasting in California

Fri, 13 Mar 2009 00:00:00 +0000

We investigated the roles of three tall emergent macrophytes (Scirpus acutus, S. californicus and Typha domingensisi in carbon cycling at a local wetland constructed for wastewater treatment and at an adjacent stream fed freshwater marsh. Combined above ground standing biomass ranged from 1125 g/m2 in freshwater to 3192 g/m2 in wastewater. Scirpus acutus (SA) densities ranged from 86 plants/m- in freshwater to 206 plants/m2 in wastewater. A combination of T. doming ens is and T. latifolia (TS) densities ranged from zero plants/m2 in wastewater and freshwater to 19 plants/m2 in wastewater. Growth rates of SA were highest for plants between 50 to 100 em and the average maximum rate was 6 cm/day. For TS the highest rates were recorded for plants between 0 and 50 ern and the average maximum rate was 4.5 ern/day. Growth for both SA and TS slows at heights between 2.5 and 3 m. Both SA and TS are subjected to grazing, TS more so than SA and there is no difference if they are in freshwater...

Optimal Operation of a Multiple Reservoir System

Wed, 11 Mar 2009 00:00:00 +0000

This report presents a methodology to obtain optimal reservoir operation policies for a large-scale reservoir system. The model maximizes the system annual energy generation while satisfying constraints imposed on the operation of the reservoir network. The model incorporates the stochasticity of river flows and keeps future operating schedules up-to-date with the actual realization of those random variables. It yields medium-term (one-year ahead) optimal release policies that allow the planning of activities within the current water year, with the possibility of updating preplanned activities to account for uncertain events that affect the state of the system. The solution approach is a sequential dynamic decomposition algorithm that keeps computational requirements and dimensionality problems at low levels. The model is applied to a nine-reservoir portion of the California Central Valley Project and the results are compared with those from conventional operation methods currently...

Effect of Stream Flow Regulation and Absence of Scouring Floods on Trophic Transfer of Biomass to Fish in Northern California Rivers

Wed, 11 Mar 2009 00:00:00 +0000

Scouring winter floods strongly influence the structure and dynamics of food webs in rivers with winter flood, summer drought hydrographs. Reduction or elimination of scouring floods, in addtition to altering physical conditions within rivers, may negatively affect salmonid populations by reducing energy flow to them from lower trophic levels. We compared food webs of two northern California rivers with drastically different flow regimes to assess the effects of differences in food web structure on the distribution and growth of juvenile steelhead trout. The upper Mad River has a highly regulated flow regime and rarely experiences scouring winter floods, while the upper Van Duzen River is free-flowing and experiences frequent scouring floods. Thrroughout spring and summer 1994 densities of the large, grazing caddisfly Dicosmoecus gilvipes exceeded 801m2 in the Mad River, but were < 21m2 in the Van Duzen. Consequently, filamentous green algae was nearly absent in the Mad...

Developing a Model System for Assessing the Effects of Conversion to Sustainable Agricultural Practices in a Sensitive Estuarine Watershed, Elkhorn Slough, California

Wed, 11 Mar 2009 00:00:00 +0000

The Elkhorn Slough is located in the Central Monterey Bay area and is considered one of the most ecologically important estuarine systems in California. Over 1400 acres of the slough are in the National Estuarine Research Reserve System. Non-point source pollutants from farm use of chemical fertilizers and pesticides have been identified as a primary cause of water quality degradation in Elkhorn Slough. Erosion of sediments from cultivated slopes surrounding the slough is likewise a serious problem. In spite of this, there nave been few studies addressing the relationship between cultivation practices, inputs to the estuary, and ecological effects of these inputs.

This paper reports preliminary, first-year results of a long term project to examine the effects of agricultural production on an adjacent wetland on a 137 acre ranch in the Elkhorn Slough. In two to four years, the organizations involved in the project intend to begin converting management of the land to more...

Anaerobic Degradation of Chlorinated Hydrocarbons in Groundwater Aquifers or "Chlorinated Hydrocarbon Degradation"

Wed, 11 Mar 2009 00:00:00 +0000

Groundwater contamination by chlorinated hydrocarbons, such as tetrachloroethene (PCE) or trichloroethene (TCE), is a major concern throughout the United States. A developing strategy for the remediation of PCE and TCE contaminated aquifers is anaerobic biodegradation. From a TCE contaminated groundwater site, microorganisms were enriched with the ability to anaerobically convert PCE and TCE completely to ethene. Kinetic studies performed with this culture showed that degradation of PCE, TCE, and vinyl chloride (VC) was first order with respect to substrate concentration up to their solubility. It was also shown that, although VC inhibited TCE degradation, a finite degradation rate could be achieved in the presence of high VC concentrations.

PCE and TCE form dense-nonaqueous-phase liquids (DNAPLs) which can provide a persistent groundwater contamination source. Under saturating PCE and TCE conditions, these chlorinated ethenes were rapidly converted to ethene with little...

Developments in vadose zone soil solution extraction

Wed, 11 Mar 2009 00:00:00 +0000

The study of water migration and contaminant transport in soils is of fundamental importance in hydrologic science. Movement of agrochemicals (nitrates, atrazine) and industrial solvents (TeE, carbontetrachloride) to the groundwater is of great public concern. In order for these chemicals to reach the groundwater, they must pass through the vadose zone. Thus, in order to predict travel times of contaminants toward the groundwater or to understand the underlying transport process, we need to characterize and sample the unsaturated zone. The need for an economical, readily available monitoring system with a broad range of applications is required by the practicing groundwater scientist and vadose zone hydrologist, given the growing recognition of the interdependence of the unsaturated zone and saturated zone processes. At present, there are few, if any, cost effective and practical field monitoring devices which incorporate the sophisticated sampling and data acquisition array...

Contaminant Transport in Groundwater for Environmental Performance Assessment

Wed, 11 Mar 2009 00:00:00 +0000

A methodology for simulating 3-D flow and reactive solute transport through statistically anisotropic heterogeneous porous media was developed and demonstrated. First, a method for generating 3-D flow fields in statistically anisotropic heterogeneous porous media was presented. Sample flow fields were generated and analyzed to demonstrate the method and examine the characteristics of 3-D subsurface flow. This stochastic technique was then coupled with a mobile-immobile domain model for simulating the sorption processes. Model results for the spatial moments of the solute plume were shown to capture the major trends observed in the field-scale experiment performed at Borden. These simulations were based on basic site information and independent laboratory data was used to determine the sorption parameters. In a second application of the model, a series of simulations was completed to investigate the coupled effects of heterogeneities of subsurface hydraulic properties and nonequilibrium...

Selenium Removal by Constructed Wetlands: Role of Biological Volatilization

Wed, 11 Mar 2009 00:00:00 +0000

Selenium-laden effiuents from oil refineries are polluting San Francisco Bay, California. One environmentally-friendly way of cleaning up selenium (Se) from effiuents is by plant and microbial Se volatilization using constructed wetlands. Using mesocosms, we investigated the role of biological Se volatilization in a 36-hectare constructed wetland located adjacent to San Francisco Bay. The constructed wetland was highly effective in removing Se from selenite-contaminated oil refinery wastewater: 89% of the Se was removed. Inflow Se concentrations of 20-30 ug L-1 decreased to < 5 ug L-l in the outflow. Most of the Se was removed by immobilization into sediments and plant tissues where Se concentrations reached ~5 and ~15 mg kg-1, respectively. Biological volatilization may have accounted for as much as 10 to 30% of the Se removed. The highest mean rates of Se volatilization for vegetated sites were 190, 180 and 150 p.1gSe m-2 day-1 (rabbitfoot grass, cattail and saltmarsh...

Modelling runoff and erosion effects of wildland fires

Thu, 16 Oct 2008 00:00:00 +0000

Millions of dollars are spent annually in California on erosion control measures after wildland fires despite the lack of quantitative evidence that such measures are needed or beneficial. Application of grass seeding and other measures after a fire are often justified on the basis of a perceived concern about the risk of debris and mud flows endangering property and lives. While the effectiveness of such measures can be seriously questioned, the risk may nonetheless be significant. We have conducted a two year study to test and expand a recently developed physically-based model for predicting the spatial pattern of landslide potential. This model can be applied at any time and serve as part of planning document to prepare for the effects of fire. The model uses digital elevation data and is based on simple assumptions about runoff and slope stability mechanisms; in it's simplest form the model is parameter free and easily calibrated.

We first tested the model in the...

Optimization of groundwater remediation strategies in aquifers affected by slow desorption processes

Thu, 16 Oct 2008 00:00:00 +0000

Most of the major groundwater contamination in California, including that inundating the San Fernando, San Gabriel and San Bernadino Valleys, will be addressed using some variation of the pump-and-treat technology. The pump-and-treat strategy is often judged to be unsuccessful because of difficulties encountered in recovering the contaminants from relatively stagnant zones within stratified aquifer systems. These zones can exist at the particle scale, as intraparticle or intra-aggregate porosity, and at the larger scales, as low permeability layers or lenses interspersed in substantially more permeable layers. This work focuses first on achieving an efficient numerical solution to a system of groundwater flow and contaminant transport equations that sufficiently captures the dynamics of slow desorption in a two-dimensional porous medium. The upstreamweighted, multiple cell balance (UMCB) method is developed and verified here to provide such a solution. Next, this work focuses...

Climate variability and snow pack in the Sierra Nevada

Wed, 15 Oct 2008 00:00:00 +0000

An important part of the water supply in California and the western United States is derived from runoff fed by mountain snow melt. Snow accumulation responds to both precipitation and temperature variations, and forms an interesting climatic index, since it integrates these influences over the entire late fall-spring period. The study area includes the Sierra Nevada, which accumulates most of the snow pack and comprises a major portion of the water-bearing region of California. The purpose of this study is to shed light upon the link between climate and year-to-year variability in the snow pack. Specifically, we wanted to determine (a) the dependence of snow pack and streamflow upon natural climate variability, and (b) if the relationships linking snow and streamflow to climate variations are stable over the history of instrumental records by using pre-1948 historical records to test the results from 1948-present. The basis of the study will be several long series of historical...

Expression of in situ biomarkers in striped bass

Wed, 15 Oct 2008 00:00:00 +0000

The proposed project has the following objectives : 1) Identify and sequence the striped bass (BB) glutathione Stransferase(s) (GSTs) gene(s); 2) Use the identified sequences as a probe to compare GST mRNA levels in control versus laboratory and/or selected field exposed SB.

The goal of this research is to develop a biomonitoring model for specific California surface waters utilizing SB, the popular game fish which is present in this environment. An approach based on the increased/decreased expression of GSTs will be used to screen the effect of experimental exposures of SB to toxic chemicals including polycyclic aromatic hydrocarbons, rice field herbicides and pesticides for their hepatoxicity. GSTs are a multigene family of enzymes catalyzing the conjugation of numerous electrophiles with reduced glutathione (GSH) by formation of the thioether bond. These reactive electrophiles include metaboli tes and endogenous compounds, drugs and pollutants. For the majority of...

Institutional aspects affecting management of groundwater in California

Tue, 14 Oct 2008 00:00:00 +0000

This project investigated the effectiveness of existing groundwater management institutions utilizing economic models and institutional analysis to suggest alternative institutional arrangements and the feasibility of obtaining them. Several existing groundwater basins were chosen for study. A sensitivity analysis showed the change in economic incentive with a change in various parameters suoh as discount rate, availability of surface water, etc.

The present groundwater institutions and laws in California were developed under very different conditions than now exist creating inefficient groundwater management; moreover, these institutions and las are entrenched in an institutional framework into which billions of dollars has been invested yielding a resistance to change. Most institutional change has resulted from threatened legal or court action and the lack of supplemental surface water supplies. When supplemental surface water is lacking, a groundwater management scheme...

Political structure and management decisions in California's agricultural water districts

Mon, 13 Oct 2008 00:00:00 +0000

In California, special districts which provide agricultural customers with water supplies and service control the vast majority of water rights and contracts. The structure of these districts has been identified as an impediment to changing water management and distribution practices. This study explores how differences in the governance rules and political structures among these water-supply district "cooperatives" affect their management decisions.

Most districts use either the common "universal suffrage / one-man, one vote" CPV) electoral system, such as irrigation districts, or a "land-owner enfranchised / assessed-value-weighted vote" (AVV) method, such as California water districts, to elect board members and to approve various tax and bond measures. AVV districts most closely mirror what would be used in an aggregate wealth-maximizing cooperative; PV districts distribute a greater amount of benefits to non-land-owners. As a result, PV district managers tend to...

Feasibility of using bioaugmentation with bacterial strain PM1 for bioremediation of MTBE-contaminated vadose and groundwater environments

Mon, 13 Oct 2008 00:00:00 +0000

Widespread contamination of groundwater by MTBE has triggered the exploration of different technologies for in situ removal of the pollutant. After laboratory studies revealed that bacterial strain PMl is capable of rapid and complete MTBE biodegradation, the organism was tested in an in-situ bioaugmentation field study at Port Hueneme Naval Base, Oxnard, CA. Two small pilot test plots (A and B) located down gradient from an MTBE source were injected with pure oxygen at two depths. One plot (B) was also inoculated with Strain PMl. MTBE concentrations upstream from plots A and B initially varied temporally from 1.5 to 6 mg per L. By six months after treatment began, MTBE concentrations wells downstream from the injection bed substantially decreased in the shallow zone of the groundwater in both plots, even in the absence of Strain PM 1. In the deeper zone, downstream MTBE concentrations also decreased substantially in Plot A and to lesser extent in Plot B. Difficulties in delivery...

Dissolved Organic Carbon (DOC) Production from Cultivated Organic Soils on Twitchell Island, Sacramento - San Joaquin Delta, California

Mon, 13 Oct 2008 00:00:00 +0000

Agricultural drainage from Delta islands is known to be a significant contributor of DOC (Dissolved Organic Carbon) that forms TI-IMs (Trihalomethanes) when drinking water is chlorinated. The current agricultural practices create seasonal wet-dry cycles in the fields so that salinity, sodicity, temperature and moisture content of soils are varied. This study was carried out to understand the influences of the current agricultural practices on the production of DOC and THM from surface (oxidized) and subsurface (reduced) peat soil of the Sacramento-San Joaquin Delta. Both abiotic and biotic factors are examined independently in order to identify the major DOC and THM precursors production processes. Abiotic factors examined with successive batch soil solution extraction were salinity (EC from °to 4 dS/m) and sodicity (SAR from °to co) that affect the coagulation and dispersion of soil organic matter (SOM). Biotic factors examined with S-week batch incubation were temperature...

Quantifying sediment resuspension linkages to nutrient enrichment in the existing and future Salton Sea

Thu, 4 Sep 2008 00:00:00 +0000

The UC Davis research involved a 24-month study (including a 4-month measurement program) in the Salton Sea to directly measure sediment resuspension using an array of OBS instruments and an acoustic wave height and current profiling instrument (AWAC). The data provided by these instruments, in conjunction with existing UC Davis temperature recording instruments in the Sea and the existing CIMIS meteorological network, point to the existence of a quasi-equilibrium condition for the suspension of sediments in the lake.

Non-linear relations were developed between the wind intensity and turbidity near which were in relative agreement with relationships from reviewed literature. In particular, the extended García and Parker formulation with DLM-WQ shows the best prediction to describe the seasonal trends as well as short-term variations. The relationship was incorporated into the existing DLM-WQ model.

DLM-WQ, combined with this new sediment model, was used to more...

California-2100: Assessing Future Water Resources over California

Thu, 4 Sep 2008 00:00:00 +0000

This project implemented the initial phase of California-2100 (Cal21), which is aimed at making and evaluating high resolution estimates of climate change over California out to the year 2100. The initial WRC component of this project has been focused on evaluating how well regional climate models reproduce the variations of important components of the water budget for California, and estimating the effects of the increases over the past century in irrigation in California on regional climate, especially snow accumulation. The results show that global warming has a large effect on precipitation, snow water, surface temperature, low level winds and soil moisture They also show in summer that irrigation has a strong effect on the differences between recent and past conditions in maximum temperature, surface latent and sensible heat fluxes, surface moisture, and surface humidity.

Do constructed flow through wetlands improve water quality in the San Joaquin River?

Thu, 4 Sep 2008 00:00:00 +0000

The efficacy of using constructed wetlands (CW) to improve water quality of irrigation tailwaters was studied in the San Joaquin Valley, California. Two CWs were monitored during the 2004 and 2005 irrigation season, a new CW (W-1) and 12-year-old CW (W-2). Input/output waters from CW were collected weekly and analyzed for a variety of water quality contaminants. Organic carbon, nutrient and sediment retention efficiencies were evaluated from input/output concentrations. Results indicate that CW-2 was more a more efficient contaminant removal system for most water quality constituents. CWs were most effective at removing total suspended solids (TSS). Average TSS removal at CW-2 was 98% in 2004 and 83% in 2005. At CW-1, mean TSS removal was 90% in 2004 and 87% in 2005. Average total N removal efficiency was 41% in 2004 and 29% in 2005 for W-2, compared to 31% in 2004 and 21% in 2005 at W-1. Total P removal efficiency was 63% in 2004 and 24% in 2005 at W-2, compared to 27.5% in...

Development of Biosensors for Real Time Analysis of Perchlorate in Water

Thu, 4 Sep 2008 00:00:00 +0000

Perchlorate (ClO4 -) contamination of ground water is a widespread problem in the U.S., which can adversely affect human health and wildlife. Current methods for detecting and quantifying ClO4 - in water are time consuming, expensive, and subject to error due to complex procedures and various interferences. Thus, there is an urgent need to develop a method that can accurately detect and measure low concentrations of ClO4 - in the field. This study reports the construction of a ClO4 -- reductase based biosensor for rapid determination of ClO4 - in water. Using a 3 mm GCE (glass carbon electrode), we successfully constructed a ClO4 - sensing bio-electrode by coating an aliquot of the enzyme on nafion (ion-exchange matrix) layer pre-coated on the polished surface of the GCE. Amperometric [i/t] measurements revealed linear increases in current in relation to time and ClO4 - concentration. The biosensor responded strongly to ClO4 - at concentrations as low as 1 μg/L and the sensor...

Non-native fish in mountain lakes: effects on a declining amphibian and ecosystem subsidy

Thu, 4 Sep 2008 00:00:00 +0000

Wilderness water resources often provide wildlife habitat and associated recreational opportunities, such as angling or birdwatching. Introduced trout in mountain lakes could affect terrestrial wildlife by changing ecosystem subsidy, which is the flow of nutrients and organisms from aquatic to terrestrial habitats. Trout prey upon larval amphibians and aquatic insects, and the adult stages of aquatic insects and amphibians are prey for bats, birds, snakes, and other terrestrial insectivores. The indirect effects of introduced fish on terrestrial wildlife have rarely been considered, and there have been no prior experiments testing effects of fish stocking on the Cascades frog (federal and California species of special concern). We conducted a four-year replicated whole-lake experiment to assess whether changes in fish abundance could aid frog recovery and whether trout predation of larval amphibians and aquatic invertebrates indirectly affects the density of terrestrial predators....

Structure and seasonal changes of nematode communities from vernal pools (Santa Rosa Plateau)

Thu, 4 Sep 2008 00:00:00 +0000

Vernal pools are ephemeral wetlands, typically with a diverse and highly adapted flora and fauna. We conducted the first nematode survey on record for this ecologically important habitat. Soil samples were collected on six dates from four locations in and around each of two vernal pool basins in the Santa Rosa Plateau Ecological Reserve. Nematodes from plant roots and debris were extracted in a mist chamber separately from the rest of the soil, which was sieved. An estimated fifty-two nematode genera were isolated, including at least sixty-three species. Soils from the two pools were substantially different in the composition and dynamics of their nematode communities. Nematode abundances were analyzed using the nonparametric Friedman test. Significant differences are observed between/among exact locations, sample dates and extracted sample fractions. Differences in abundance patterns are also significant across nematode genera. Simple feeding experiments were conducted to...

Mechanisms for Addressing Third-Party Impacts Resulting from Voluntary Water Transfers

Wed, 20 Aug 2008 00:00:00 +0000

This research uses laboratory experiments to test alternative water market institutions designed to protect third-party interests. The institutions tested include taxing mechanisms that raise revenue to compensate affected third-parties, and a free market in which third-parties acti vely participate. We also discuss the likely implications of a command-and-control approach in which there are fixed limits on the volume of water that may be exported from a region. The results indicate that there are some important trade-offs in selecting a policy option. Although theoretically optimal, active third-party participation in the market is likely to result in free-riding that may erode some or all of the efficiency gains, and may introduce volatility into the market. Fixed limits on water exports are likely to result in a more stable market, but the constraints on exports will result in lower levels of social welfare. Taxing transfers and compensating third-parties offers a promising...

Steelhead and Chinook Salmon Bioenergetics: Temperature, Ration, and Genetic Effects

Tue, 15 Jul 2008 00:00:00 +0000

The bioenergetics of two anadromous native salmonid fishes in California were investigated, concentrating on effects of water temperature and ration size on juvenile Nimbus Hatchery strain steelhead (Oncorhynchus mykiss irideusy and juvenile Nimbus strain chinook salmon (Oncorhynchus tshawytscha). Nimbus strain steelhead reared at water temperatures of 11, 15, and 19°C and ration levels of 100 and ca. 87% satiation showed increases in growth rates, food consumption rates, and upper acute thermal tolerance at increased temperatures. Temperature generally did not affect steelhead oxygen consumption rates, swimming performance, or thermal preference. Ration level affected oxygen consumption rates. Juvenile Nimbus strain steelhead differ from some other anadromous and resident rainbow trout strains. Nimbus strain chinook salmon reared at water temperatures of II, 15, and 19°C and ration levels of 100 and 25% satiation showed increases in growth rates and food consumption rates...

Effects of Herbaceous Riparian Vegetation on Streambank Stability

Tue, 15 Jul 2008 00:00:00 +0000

Riparian vegetation is widely thought to stabilize stream banks, but this effect has rarely been quantified. We evaluated how riparian vegetation affects bank erodibility along the South Fork of the Kern River at Monache Meadow. Our methodology combines remote sensing estimates of bank migration rates with field measurements of bank strength. Our results demonstrate that vegetation communities significantly affect bank erodibility of a meandering montane meadow stream.

The South Fork Kern River at Monache Meadow is an ideal location for studying vegetation effects on bank erosion. The stream bank soils are relatively homogenous, but are colonized by two distinct vegetation communities: a dry meadow community dominated by sagebrush and non-native grasses, and a wet meadow community dominated by rushes and sedges. We measured rates of channel migration in the wet meadow versus dry meadow by analyzing four decades of aerial photographs. Over 40 years, the stream channel...

Qsar analysis of the chemical hydrolysis of organophosphorus pesticides in natural waters

Tue, 15 Jul 2008 00:00:00 +0000

Statistical techniques for screening experimental or literature chemical databases for compounds exhibiting potential environmental activity are becoming increasingly utilized in environmental analysis as pragmatic and economical complementary tools to enhance or augment costly traditional analytical procedures. Utilizing the predictive modeling approach, it is often argued, implicitly permits an unlimited number of chemicals to be screened for specific behavioral or physicochemical characteristics in a variety of environmental and biological matrices, consequentially conserving the financial resources for exhaustive testing, yet providing a methodology that helps to insure that questionable compounds are more thoroughly tested. Moreover, such techniques provide a database of exhaustive test results from which investigators and regulators can extract relevant information for further research or decision-making.

To assess the efficiency of statistical modeling methods...

Potential of Long-lead Streamflow and Drought Forecasting in California

Tue, 15 Jul 2008 00:00:00 +0000

The research problem studied here is whether regional streamflows can be identified and potentially predicted based on the impact ofEl Nino, La Nina and the Southern Oscillation. The research focused on the following question: Can streamflow and drought in California be predicted by scientifically understanding ENSO and large scale circulation patterns? ENSO is defined as the EI Nino/Southern Oscillation climatic phenomenon. For decades, the prediction of streamflow and drought has intrigued hydrologists; our current research suggests that ENSO strongly affects streamflow and thus could be an important factor in making long range forecasts of streamflow.

Researchers have determined that ENSO events have significant worldwide impacts on such events as precipitation, temperature, floods, droughts and wildfires. ENSO is a warm event in the tropical Pacific Ocean and is considered a significant perturbation of the general atmospheric circulation. EI Nifio events have been...

Microbial Denitrification of Groundwater using Microporous Membranes

Tue, 8 Jul 2008 00:00:00 +0000

Microbial denitrification, a frequently used and relatively inexpensive method of removing nitrate from wastewater, has been applied to the treatment of potable water supplies, on a limited scale, using packed bed reactors. However, two significant drawbacks exist in transferring wastewater denitrification technology to the treatment of domestic water supplies: (1) the water is intimately mixed with microbial cultures and (2) organic compounds must be supplied as an energy source to drive the denitrification reactions and residual organics can be a water quality problem. Process configurations used experimentally have included both packed beds and fluidized beds. Denitrifying microbial cultures have been supported on sand, ceramics, polymers, clay, alginate gel, and agar gel. Work with conventional support materials (sand, ceramics, polymers, clay) has been relatively straightforward in that the microbial cultures are grown on support surfaces and water containing nitrate is...

Geophysical Imaging For Contaminated Site Characterization

Tue, 8 Jul 2008 00:00:00 +0000

The analysis and management of groundwater flow problems often involve the prediction of fluid flow and/or contaminant migration patterns. These phenomena, however, are strongly influenced by the heterogeneity of the hydrogeological properties of the soil. The purpose of this project is to derive joint geophysical-hydrogeological procedures for the characterization of subsurface flow parameters. The first part of this study presents a formal stochastic approach for the integration of surface seismic data and well data into the identification of the spatial arrangement- location, geometry, and interconnectedness of lithofacies. Towards this goal, the lithology of the subsurface is represented through a random indicator function whose spatial structure is identified from seismic reflection data and well logs. Seismic interval velocities and measures of their uncertainties are computed from normal moveout corrections to the seismic reflection data. Calibration curves constructed...

The effect of recreation on water quality

Tue, 8 Jul 2008 00:00:00 +0000

The purpose of this research was to assess the effect of motorboat usage on the long-term lead concentration of a multipurpose reservoir, Turlock Lake in Stanislaus County, California. As the study was made during two drought years. it was possible to examine the effects of large volume changes in the lake. Samples were taken at weekly intervals at the inlet canal where water enters the lake, at the outlet and at the boat dock, then lead analyses were made.

An apparent correlation was found to exist between the lead level at the boat dock and the boats per-unit-volume. Also, at the boat dock, the largest lead concentration correlated with the highest boat concentration. The inlet and outlet lead data obtained were treated in terms of a simple plug-flow model. In order to correlate between the change in lead concentration obtained from the plug-flow model and boat concentration, a calculation was made to estimate the number of boats that would have to be launched on the...

Mass transfer and kinetics study of the ozonation of refractory organics in waste waters

Tue, 8 Jul 2008 00:00:00 +0000

Treatment of industrial and municipal wastewater containing refractory organic compounds is of primary concern. In this research, the feasibility of ozonation as a treatment process for the removal of 2,4,6-trichlorophenol was studied. The chemical kinetics of the reaction between 2,4,6-trichlorophenol (TCP) and ozone were determined.

A wetted-sphere absorber was used to measure rates of absorption of ozone into aqueous buffered solutions of TCP. Gas consisting of approximately 2.5% ozone in oxygen was contacted with aqueous buffered TCP solution flowing over a sphere in a laminar liquid film. Absorption data were obtained by measuring the change in the liquid phase concentration of TCP from the inlet to the outlet of the absorber. A rigorous numerical model for this diffusion/reaction process was used to analyze the absorption data in order to determine the second-order rate constant of the reaction between ozone and TCP. Results were obtained over the temperature range...

Chromium in the San Francisco Bay Estuary: a Study of Cycling, Speciation, and Anthropogenic Inputs

Wed, 2 Jul 2008 00:00:00 +0000

Trace metal inputs to estuarine ecosystems can have substantial impacts on their environmental quality. However, it is imperative to understand background processes which affect trace metal cycling in order to quantify the impacts of human activities. Chromium is an important industrial metal, with known sources surrounding San Francisco Bay. It also has substantial natural sources, being the tenth most abundant element on the planet. Therefore, this research is directed at quantifying the relative magnitude of natural and anthropogenic fluxes of Cr to the San Francisco Bay estuary.

Episodic flushing of a wetlands area, the Yolo Bypass, appears to be the predominant source (up to 980 kg d-l) of dissolved chromium to the San Francisco Bay estuary. Depletion of [Cr]/[Al] in suspended particulate matter within the entrapment zone of the estuary suggests that that chromium is solubilized by weathering of aluminosilicates. Conversely, other processes (e.g., internal inputs,...

Long Term Variability of Fresh Water Flow into the San Francisco Estuary using Paleoclimatic Methods

Wed, 2 Jul 2008 00:00:00 +0000

Sediment cores were raised from fringing marshes along the northern reach of the San Francisco Bay. A variety of stratigraphic analyses were utilized to reconstruct sea level and river flow (salinity) over the past 7000 yr. Over thirty A.M.S. dates provide chronostratigraphic control. An overall trend in RSL rise of 0.12-0.14 cm/yr is established for the northern reach of the estuary. River discharge was broadly comparable to modem flows. However, an extended period of higher flow commenced approximately 3800 yr and continued for almost 2 millennia. Superimposed upon these general trends are numerous short-term events. Acute droughts and salinity intrusion occurred during the period of high river flow. No extreme flood events are noted during this period, although evidence for abnormally high discharge occurs at other times.

Arsenic Geochemistry in Source Waters of the Los Angeles Aqueduct

Wed, 2 Jul 2008 00:00:00 +0000

Arsenic is a widely distributed constituent of geologic materials, with an average crustal abundance of 1.8 ppm. The natural processes of weathering of arsenic-containing minerals and volcanism contribute arsenic to groundwaters, surface freshwaters, and seawater. Recently, increased attention has focused on arsenic geochemistry in natural waters. This attention has been motivated by concern over the human health effects of arsenic exposure; consumption of drinking water can be a significant, if not the primary, route for ingestion of inorganic arsenic. Since the concentrations of inorganic arsenic in various foods and source waters can vary widely, the exposure of any individual or group depends strongly on both diet and the quality of locally supplied drinking water.

Two field studies were conducted to examine arsenic occurrence and redox speciation in natural waters in California with elevated arsenic concentrations. In Hot Creek, located in the Owens Valley, elevated...

Extending Traditional Technology of Aquifer Characterization Through Numerical Models

Wed, 2 Jul 2008 00:00:00 +0000

This is the final Technical Completion Report of Projects No. W-830 funded by the Water and Wildlands Resources Center of the University of California. This report consists of two parts. Part 1 entitled, "Hydraulic Characterization of Aquifers, Reservoir Rocks and Soils: A History of Ideas" is an integrated review of the development of hydraulic characterization methods in the fields of Civil Engineering, Soil Physics, Groundwater Hydrology and Petroleum Engineering. The narrative portion of this part is followed by a set of over 500 references pertaining to hydraulic characterization which represent our current knowledge of hydraulic characterization methodologies in the earth sciences and engineering. The second part entitled, "A Numerical-Model/Spreadsheet Integration for Hydraulic Characterization of Aquifers, Reservoir Rocks and Soils" presents a new interpretive tool that is under development for hydraulic characterization of groundwater systems, petroleum reservoirs...

Modeling and Stochastic Analysis of Contaminant Transport in Soils and Aquifers

Wed, 2 Jul 2008 00:00:00 +0000

The effort that led to this report is twofold. First, it deals with the development of fundamental transport equations and their solutions; they describe the effect of low-permeability zones on the motion and spread of contaminant plumes in high-permeability porous layers. Second, it concerns the development of an analytical multi phase-transport model that describes leaching of pesticides in soils and their fate and transport in groundwater. Using Monte Carlo simulations, the effect of stochastic precipitation, random adsorption, and random (bio )chemical reaction, on the probability distributions of the herbicide Simazine, is investigated under conditions typical to the City of Fresno in California.

The transport equations that are developed in Chapter 2 describe the capacitance of low permeability layers to store and release reactive constituents by diffusion and mechanical mixing. It is shown that under quasi-steady conditions and a mean flow parallel to the bedding,...

Partitioning and Bioavailability of Polynuclear Aromatic Hydrocarbons in an Intertidal Marsh

Tue, 1 Jul 2008 00:00:00 +0000

Polycyclic aromatic hydrocarbons (PAHs) are trace organic pollutants now so ubiquitous in aquatic ecosystems that the major organic signature in urban storm runoff is that of weathered PAHs. PAHs are formed by combustion of organic matter including petroleum and wood but anthopogenically produced PAHs have increased greatly over the last century. PAHs are a problem in the environment since some are potent carcinogens to humans and wildlife alike. PAHs include the most toxic fraction of tobacco smoke, benzo(a)pyrene, naphalene, and phenanthrene and are often found in association with other organic pollutants such as chlorinated biphenyls (PCBs), and organochlorine compounds such as DDT. The persistence of PAHs in the environment and their concentration in the fat of living organisms increases the toxicity of PAHs and current regulatory standards are based on the bulk concentration of PAHs in the sediments and the amount of organic carbon in the sediments. Our research was intended...

Gold Mining Impacts on Food Chain Mercury in Northwestern Sierra Nevada Streams

Tue, 1 Jul 2008 00:00:00 +0000

More than three million kilograms of mercury are estimated to have been lost into northwestern Sierra Nevada rivers during the course of gold mining in the Gold Rush period of the last century (1840s - 1880s). Mercury was used extensively in the gold recovery process to amalgamate fine gold particles. Gold mining has continued at a less intensive scale through the present, with a relative resurgence of dredging operations during the past decade. In this study, we investigated mercury levels in aquatic invertebrates and trout in the rivers of this region of the Sierra Nevada to determine the localized impacts of mining-derived mercury. These organisms were used as indicators of the bioavailable fraction of mercury, specifically that portion which can enter, transfer through, and be concentrated by the food web. The biota samples were used to determine relative "hot spots" of mercury contamination and to rank the various streams and rivers as to relative bioavailable mercury...

Optimal Management of Groundwater Basins of Degraded Water Quality for Conjuctive Use

Tue, 1 Jul 2008 00:00:00 +0000

In Southern California and elsewhere in heavily populated arid areas, existing potable water delivery and supply systems are increasingly being overtaxed in meeting current and projected water demands, both on an annual and peak demand basis. In a number of cases, such as portions of Riverside County, Southern Orange County, and San Diego County, numerous small groundwater basins, often with degraded water quality, could be integrated into the local water delivery systems providing new water supply and storage elements to the systems. Several water agencies in Southern California are already trying to accomplish this, however, the complex dynamic nature of the problem make it difficult to assess costs and benefits and to select the optimal alternative.

The purpose of this research is to analyze management alternatives and to develop methods for evaluating costs and benefits in order to optimize the use of these groundwater basins for conjunctive use. The San Juan Basin,...

Evaluation of Rangeland Stream Condition and Recovery using Physical and Biological Assessments of Nonpoint Source Pollution

Tue, 1 Jul 2008 00:00:00 +0000

Livestock grazing is the most common land use in the western United States, and has caused widespread degradation of water quality as a result of impacts to stream and riparian ecosystems. The problem is especially severe in the arid Great Basin, where stream channels and associated vegetation occupy small areas and carry low runoff, but are exposed to intense grazing pressure due to congregation of livestock in areas of shade and water supply. The federal Clean Water Act requires states to assess nonpoint source water pollution, including that resulting from livestock grazing.

Water quality has traditionally been evaluated using water chemistry criteria (e.g. for point source pollution), but these measures may not be effective in detecting nonpoint source water quality problems typically caused by livestock grazing. More responsive monitoring parameters for rangeland streams may include physical characteristics of stream channels, and biological measures of the characteristics...

Geometric Modeling of Rainfall Fields

Tue, 1 Jul 2008 00:00:00 +0000

Accurate rainfall modeling is of vital importance for the proper management of our environment. Rainfall descriptions are required, among others, to model pollution migration, to address issues related to climate change (i.e. global circulation), to estimate extreme weather events, and to manage our watersheds. Adequate environmental planning can only be accomplished with reliable rainfall quantification. Even though several sophisticated (stochastic) rainfall models exist, they do not capture all the variability observed at a fixed location when a storm passes by. Typical models approximate the irregular and intermittent rain patterns (of a fractal and/or multifractal nature) by superimposing randomly arriving smooth Euclidean objects (i.e. rectangular pulses), and consequently preserve only some statistical features of the rainfall series (fields) (e.g. mean, variance, spatial correlations, etc.). Since these representations are typically limited by their analytical tractability...

Integrated Planning and Management for Urban Water Supplies Considering Multiple Uncertainties

Tue, 1 Jul 2008 00:00:00 +0000

Urban water supply planning has changed greatly in recent decades, and has generally become a much more technically serious endeavor. (Urban water supply has always been a politically serious endeavor, with abundant sources of uncertainty (Lund, 1988a, b).) Yet for all the serious and fine technical work and research on urban water supply engineering and economics, it often seems that such work has not provided a clear unified approach for combining the many technical measures available for water supply system planning and management. This report seeks to provide such a unified analytical approach, addressing the integrated economical use of yield enhancement, water transfer, and demand management measures in a context of risk and uncertainty from many hydrologic and institutional sources.

Colloidal fouling of reverse osmosis membranes

Mon, 30 Jun 2008 00:00:00 +0000

The general objective of this project was to better understand the role of chemical factors in colloidal fouling of reverse osmosis membranes. The results of this research are of paramount importance for efficient operation of RO installations used in water reclamation and reuse and in potable water treatment.

Fouling experiments of thin film composite and cellulose acetate reverse osmosis membranes by aluminum oxide colloids are described. Membrane fouling was investigated at various solution chemistries under fixed hydrodynamic conditions. Results show that the fouling rate increases with an increase in the ionic strength of the solution. Fouling was significant at high ionic strengths, including in the presence of background dissolved organic matter, resulting in a gradual decrease in product water flux and salt rejection. Under the chemical conditions tested, colloidal fouling was found to be reversible, thus indicating that pore blockage is not an important mechanism...

Developing a New Micrometeorological Method to Estimate the Surface Energy Budget and

Mon, 30 Jun 2008 00:00:00 +0000

This project considers the micrometeorologicel processes that govern the use of water by plants and the availability of soil moisture. Evapotranspiration (ET) was obtained from the residual of the energy budget terms, including a new method, that of surface renewal, to estimate one of the energy budget terms. This method appears to offer some alternative to somewhat more cumbersome methods presently used for ET estimates and crop coefficients. Evapotranspiration estimates are considered very important to the state because evapotranspiration represents the major component of agricultural water usage.

Data from experiments carried out in 1988 through 1994 were analyzed to validate the new method. The plant canopies considered in these experiments were an English walnut orchard, a maize canopy, a grass canopy, and other short. Sensible heat was estimated using the eddycovariance and other methods, and then compared to the new method. Project results show that regression...

Microorganism Detection by Multiple Non-Specific Oligonucleotide Probes or "Gene Probe Spectroscop"