Assessing Ground Water Vulnerability with the Type Transfer Function Model in the San Joaquin Valley, California

Stewart, Iris T.; Loague, Keith

doi:10.2134/jeq2004.1487

Cited by 14 publications

(7 citation statements)

References 28 publications

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“…The simplicity of using mobility–leaching indices for regional‐scale nonpoint‐source vulnerability assessments as demonstrated here is extremely seductive relative to exhaustive numerical simulations driven by the coupled nonlinear partial‐differential equations of variably saturated fluid flow and solute transport (e.g., Stewart and Loague, 2003, 2004). The regional‐scale assessments presented here clearly show that there are differences in the estimated vulnerabilities due to variability in the chemical and soil properties, variability in the recharge estimates, and the uncertainty within the databases.…”

Section: Discussionmentioning

confidence: 99%

“…Inspection of Table 2 reveals that for several chemicals, considerable uncertainty is associated with the chemical information (e.g., coefficient of variation values greater than one for K oc and/or t 1/2 ). The chemicals featured for the vulnerability assessment illustrations (i.e., maps) in the Results section, due to their high profiles within the SJV (e.g., Loague et al (1998a,b); Stewart and Loague, 2004), are dibromochloropropane (1,2‐dibromo‐3‐chloropropane), also known as DBCP, and atrazine (2‐chloro‐4‐ethylamino‐6‐isopropylamino‐S‐triazine).…”

Section: Methodsmentioning

confidence: 99%

“…An early approach to assess groundwater vulnerability across large areas was the standardized DRASTIC system (Aller et al, 1987). Past assessments of groundwater vulnerability for the SJV include the index‐based approaches reported by Meeks and Dean (1990) and Zhang et al (1995), the discriminate and logistic regression analyses reported by Teso et al (1988, 1995, 1996), the transfer function approach reported by Stewart and Loague (2004), and physics‐based simulations of flow and transport reported by Loague et al (1998a,b) and Burow et al (1999).…”

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confidence: 99%

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Data Related Uncertainty in Near‐Surface Vulnerability Assessments for Agrochemicals in the San Joaquin Valley

Loague

Blanke²,

Mills

et al. 2012

J of Env Quality

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Precious groundwater resources across the United States have been contaminated due to decades-long nonpoint-source applications of agricultural chemicals. Assessing the impact of past, ongoing, and future chemical applications for large-scale agriculture operations is timely for designing best-management practices to prevent subsurface pollution. Presented here are the results from a series of regional-scale vulnerability assessments for the San Joaquin Valley (SJV). Two relatively simple indices, the retardation and attenuation factors, are used to estimate near-surface vulnerabilities based on the chemical properties of 32 pesticides and the variability of both soil characteristics and recharge rates across the SJV. The uncertainties inherit to these assessments, derived from the uncertainties within the chemical and soil data bases, are estimated using first-order analyses. The results are used to screen and rank the chemicals based on mobility and leaching potential, without and with consideration of data-related uncertainties. Chemicals of historic high visibility in the SJV (e.g., atrazine, DBCP [dibromochloropropane], ethylene dibromide, and simazine) are ranked in the top half of those considered. Vulnerability maps generated for atrazine and DBCP, featured for their legacy status in the study area, clearly illustrate variations within and across the assessments. For example, the leaching potential is greater for DBCP than for atrazine, the leaching potential for DBCP is greater for the spatially variable recharge values than for the average recharge rate, and the leaching potentials for both DBCP and atrazine are greater for the annual recharge estimates than for the monthly recharge estimates. The data-related uncertainties identified in this study can be significant, targeting opportunities for improving future vulnerability assessments.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

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Data Related Uncertainty in Near‐Surface Vulnerability Assessments for Agrochemicals in the San Joaquin Valley

Loague

Blanke²,

Mills

et al. 2012

J of Env Quality

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“…Their applications are reported in numerous articles to estimate the evolution of groundwater quality at an aquifer outlet (Beltman et al 1996;Eberts et al 2012;Lerner and Papatolios 1993;Osenbrück et al 2006;Stewart and Loague 2004).…”

Section: Analytical Models Of Transfer Functionsmentioning

confidence: 99%

Assessing groundwater quality trends in pumping wells using spatially varying transfer functions

et al. 2015

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When implementing remediation programs to mitigate diffuse-source contamination of aquifers, tools are required to anticipate if the measures are sufficient to meet groundwater quality objectives and, if so, in what time frame. Transfer function methods are an attractive approach, as they are easier to implement than numerical groundwater models. However, transfer function approaches as commonly applied in environmental tracer studies are limited to a homogenous input of solute across the catchment area and a unique transfer compartment. The objective of this study was to develop and test an original approach suitable for the transfer of spatially varying inputs across multiple compartments (e.g. unsaturated and saturated zone). The method makes use of a double convolution equation accounting for transfer across two compartments separately. The modified transfer function approach was applied to the Wohlenschwil aquifer (Switzerland), using a formulation of the exponential model of solute transfer for application to subareas of aquifer catchments. A minimum of information was required: (1) delimitation of the capture zone of the outlet of interest; (2) spatial distribution of historical and future pollution input within the capture zone; (3) contribution of each subarea of the recharge zone to the flow at the outlet; (4) transfer functions of the pollutant in the aquifer. A good fit to historical nitrate concentrations at the pumping well was obtained. This suggests that the modified transfer function approach is suitable to explore the effect of environmental projects on groundwater concentration trends, especially at an early screening stage.

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“…Ground water and leaching models. The type transfer function (TTF) simulation approach was applied by Stewart and Loague (2004) to assess the regionalscale NPS groundwater vulnerability for the San Joaquin Valley of California. Results indicated that areas having high potential vulnerability to atrazine leaching were related to soils with low organic carbon content and sandy loam and loam textures.…”

Section: Bmps For Nps Controlmentioning

confidence: 99%

Nonpoint Sources

Gang¹,

Qiang²,

Zhang³

et al. 2005

Water Environment Research

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As rainfall, snowmelt, and irrigation run over the land or through the ground, pick up pollutants, and carry them into rivers, lakes, and coastal waters or introduce them into ground water, nonpoint sources (NPS) pollution occurs. The most significant NPS pollutants are nutrients (particularly nitrogen and phosphorus) and sediments. The primary agricultural sources of nutrients which can contribute to NPS pollution are animal manure and fertilizer. This article reviews 2004 literature on several aspects of NPS pollution, including general policy, economics, attitudes and general; NPS characterization; best management practices (BMPs) for NPS control; modeling and monitoring; and NPS control and management. POLICY, ECONOMICS, ATTITUDES, AND GENERALThe U.S. Environmental Protection Agency (EPA) and State water quality agencies are placing increasing emphasis on addressing the problems caused by NPS pollution, which is now the leading cause of water pollution in the United States (Davenport, 2004). EPA has implemented several programs under the Clean Water Act that attempt to address this issue, including the development of water quality standards for nutrients, implementation of State nonpoint source programs, and point source regulations for animal feeding operations. Frisvold (2004) examined the effects of U. S. 2528federal farm programs on agricultural water use and water quality. Agriculture has been identified as the largest contributor to NPS water pollution. Nonpoint pollution from agriculture is also an important environmental policy issue in Spain and the European Union (Martinez and Albiac, 2004). The ongoing policy decision process analyzing results indicated that abatement measures based on input taxes and standards on nitrogen appeared to be more suitable than the National Irrigation Plan.A statewide assessment of the impacts of phosphorus-index implementation in Pennsylvania has been done by Kogelmann et al. (2004). Results showed that various regions of Pennsylvania would be affected by the P-index restrictions for different reasons. Soil P was found to increase with increasing animal density and the highest animal density areas had a large number of nutrient impaired streams. Gergel et al.(2004) tested the Environmental Kuznets Curve (EKC) in Dane County, Wisconsin, using NPS pollution time series data for Lake Mendota throughout the 20th century. The EKC did not describe the relationship between all ecological and economic indicators tested. The results showed that the increasing pollution with increasing wealth and economic prosperity could not be expected to improve all aspects of the environment.During the last three decades, coastal zones around the globe have shown increasing evidence of degradation, primarily due to human activities. Eutrophication resulting from increased nutrient input and chemical pollution from point and nonpoint sources were among the most serious threats to the health of coastal marine communities (Marcus, 2004). The coastal areas of the Southern Baltic Sea were highly ...

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Assessing Ground Water Vulnerability with the Type Transfer Function Model in the San Joaquin Valley, California

Cited by 14 publications

References 28 publications

Data Related Uncertainty in Near‐Surface Vulnerability Assessments for Agrochemicals in the San Joaquin Valley

Data Related Uncertainty in Near‐Surface Vulnerability Assessments for Agrochemicals in the San Joaquin Valley

Assessing groundwater quality trends in pumping wells using spatially varying transfer functions

Nonpoint Sources

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