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A Bayesian approach to infer nitrogen loading rates from crop and land-use types surrounding private wells in the Central Valley, California

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A Bayesian approach to infer nitrogen loading rates from crop and land-use types surrounding private wells in the Central Valley, California
European Geosciences Union | May 7, 2018...
Summary
This study is focused on nitrogen loading from a wide variety of crop and land-use types in the Central Valley, California, USA, an intensively farmed...
This study is focused on nitrogen loading from a wide variety of crop and land-use types in the Central Valley, California, USA, an intensively farmed region with high agricultural crop diversity. Nitrogen loading rates for several crop types have been measured based on field-scale experiments, and recent research has calculated nitrogen loading rates for crops throughout the Central Valley based on a mass balance approach. However, research is lacking to infer nitrogen loading rates for the broad diversity of crop and land use types directly from groundwater nitrate measurements.

Relating groundwater nitrate measurements to specific crops must account for the uncertainty about and multiplicity in contributing crops (and other land uses) to individual well measurements, and for the variability of nitrogen loading within farms and from farm to farm for the same crop type. In this study, we developed a Bayesian regression model that allowed us to estimate land-use-specific groundwater nitrogen loading rate probability distributions for 15 crop and land-use groups based on a database of recent nitrate measurements from 2149 private wells in the Central Valley.

The water and natural, rice, and alfalfa and pasture groups had the lowest median estimated nitrogen loading rates, each with a median estimate below 5 kg N ha -1 yr -1. Confined animal feeding operations (dairies) and citrus and subtropical crops had the greatest median estimated nitrogen loading rates at approximately 269 and 65 kg N ha -1 yr-1, respectively. In general, our probability-based estimates compare favorably with previous direct measurements and with mass-balance-based estimates of nitrogen loading. Nitrogen mass-balance-based estimates are larger than our groundwater nitrate derived estimates for manured and non-manured forage, nuts, cotton, tree fruit, and rice crops. These discrepancies are thought to be due to groundwater age mixing, dilution from infiltrating river water, or denitrification between the time when nitrogen leaves the root zone (point of reference for mass-balance derived loading) and the time and location of groundwater measurement.

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A Comparative Study for Estimating Crop Evapotranspiration in the Sacramento-San Joaquin Delta

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A Comparative Study for Estimating Crop Evapotranspiration in the Sacramento-San Joaquin Delta
University of California, Davis (UC Davis) | April 23, 2018...
Summary
Consumptive water use by crops, often referred to as evapotranspiration (ET), is frequently the largest component of an agricultural region’s water balance. This study...
Consumptive water use by crops, often referred to as evapotranspiration (ET), is frequently the largest component of an agricultural region’s water balance. This study investigates crop consumptive use in the Sacramento-San Joaquin Delta (“Delta”) of California using a comparative approach with several prominent methods for estimating crop ET, including estimates based on crop coefficients, water balances, energy balance using remote sensing, and field measurements.

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A global spatial analysis reveals where marine aquaculture can benefit nature and people

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A global spatial analysis reveals where marine aquaculture can benefit nature and people
PloS ONE | October 9, 2019...
Summary
Aquaculture of bivalve shellfish and seaweed represents a global opportunity to simultaneously advance coastal ecosystem recovery and provide substantive benefits to humanity. To identify marine...
Aquaculture of bivalve shellfish and seaweed represents a global opportunity to simultaneously advance coastal ecosystem recovery and provide substantive benefits to humanity. To identify marine ecoregions with the greatest potential for development of shellfish and seaweed aquaculture to meet this opportunity, we conducted a global spatial analysis using key environmental (e.g., nutrient pollution status), socioeconomic (e.g., governance quality), and human health factors (e.g., wastewater treatment prevalence). We identify a substantial opportunity for strategic sector development, with the highest opportunity marine ecoregions for shellfish aquaculture centered on Oceania, North America, and portions of Asia, and the highest opportunity for seaweed aquaculture distributed throughout Europe, Asia, Oceania, and North and South America. This study provides insights into specific areas where governments, international development organizations, and investors should prioritize new efforts to drive changes in public policy, capacity-building, and business planning to realize the ecosystem and societal benefits of shellfish and seaweed aquaculture.

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A Measure of Snow: Case Studies of the Snow Survey and Water Supply Forecasting Program

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A Measure of Snow: Case Studies of the Snow Survey and Water Supply Forecasting Program
U.S. Department of Agriculture (USDA), Natural Resources Conservation Service | September 1, 2010...
Summary
Snow depth and snow water content data have been collected and disseminated throughout the W estern United States for over 100 years. Early...

Snow depth and snow water content data have been collected and disseminated throughout the W estern United States for over 100 years. Early Snow Survey and Water Supply Forecasting data were gathered through the efforts of university scientists. In 1935, the Soil Conservation Service (SCS) was given $36,000 to establish a formal cooperative Snow Survey and Water Supply Forecasting (SSWSF) Program. The agency was charged with the responsibility for “conducting Snow Survey and Water Supply Forecast s and forecasting of irrigation water supplies.” The new program would also develop consistent methods for measuring snow and reliable models for water supply forecasting.

Using a case study approach, this report assesses the various uses of data gathered and published by the SSWSF Program and estimates the value of those data in terms of both the market and non-market values of the information. Additionally, it evaluate s the relative merits of maintaining the program as a publicly funded program as opposed to privatizing the program.

This study finds that the SSWSF Program is generating both market and non-market benefits to the U.S. economy and to U.S. society as a whole that are worth significantly more than the cost of the program. Should climate variability increase — as is expected by many of those interviewed in the course of completing this study, and as current climate research strongly suggests — the value of the information provided by the SSWSF Program will increase accordingly.

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A Technical Advisor’s Manual Managing Agricultural Irrigation Drainage Water: A guide for developing Integrated On-Farm Drainage Management Systems
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A Technical Advisor’s Manual Managing Agricultural Irrigation Drainage Water: A guide for developing Integrated On-Farm Drainage Management Systems
California State Water Resources Control Board | September 29, 2005...
Summary
This manual is part of a two-part educational and outreach program to educate landowners and technical advisors about the advantages, disadvantages, costs, environmental...
This manual is part of a two-part educational and outreach program to educate landowners and technical advisors about the advantages, disadvantages, costs, environmental regulations and other considerations in developing and implementing an Integrated On-Farm Drainage Management program for salinity control.

The first part of the educational program focused on the production and distribution of a guidance manual designed for landowners. It was released in 2004.

This manual is the second component of the program, and is designed to provide technical consultants and support personnel with the tools they need to assist farmers with developing and implementing an effective IFDM program.

An IFDM system can serve as a viable alternative for landowners who may not choose to participate in a voluntary land retirement program for drainage-impacted lands. Once irrigation systems have been optimized to maximize water use efficiency and to minimize the production of subsurface drainage water, an IFDM system can be designed to enable the landowner to process the resulting drainage water on-farm. Interest in IFDM is increasing.

The merits of IFDM have been recognized by the U.S. Environmental Protection Agency and the State Water Resources Control Board through the award of a Clean Water Act Section 319(h) Grant to educate farmers and to train professionals about IFDM implementation. Both manuals were funded by the grant, targeting the needs of the landowners, water/drainage district managers, engineers and technical professionals.

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Addressing Nitrate in California’s Drinking Water Technical Report 1: Project and Technical Report Outline

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Addressing Nitrate in California’s Drinking Water Technical Report 1: Project and Technical Report Outline
University of California, Davis (UC Davis) | July 2, 2012...
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Addressing Nitrate in California’s Drinking Water Technical Report 2: Nitrogen Sources and Loading to Groundwater

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Addressing Nitrate in California’s Drinking Water Technical Report 2: Nitrogen Sources and Loading to Groundwater
University of California, Davis (UC Davis) | July 2, 2012...
Summary
Nitrate loading to groundwater in the Tulare Lake Basin and Salinas Valley is widespread and chronic, and is overwhelmingly the result of crop and...
Nitrate loading to groundwater in the Tulare Lake Basin and Salinas Valley is widespread and chronic, and is overwhelmingly the result of crop and animal agricultural activities. Urban wastewater, septic systems, and other sources may have significant localized impact. Due to long transit times, the impact on groundwater resources is a legacy for years and decades to come.

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Addressing Nitrate in California’s Drinking Water Technical Report 3: Nitrogen Source Reduction to Protect Groundwater Quality

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Addressing Nitrate in California’s Drinking Water Technical Report 3: Nitrogen Source Reduction to Protect Groundwater Quality
University of California, Davis (UC Davis) | July 2, 2012...
Summary
Although reduction of anthropogenic loading of nitrate to groundwater aquifers will not reduce contamination in the short term (due to long travel times), reduction...
Although reduction of anthropogenic loading of nitrate to groundwater aquifers will not reduce contamination in the short term (due to long travel times), reduction efforts are a critical component of any long term solution to the problem of high nitrate in drinking water. Technologies are available for reducing the transfer of nitrate to groundwater from surface sources. Such technologies involve (1) reducing the amount of nitrogen (N) discharged or applied to the land and (2) controlling the amount of water applied to land which serves as the carrier of nitrate. Many of these source control methods require changes in land management and upgrading of infrastructure.

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Addressing Nitrate in California’s Drinking Water Technical Report 4: Groundwater Nitrate Occurrence

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Addressing Nitrate in California’s Drinking Water Technical Report 4: Groundwater Nitrate Occurrence
University of California, Davis (UC Davis) | July 2, 2012...
Summary
This report reviews the hydrogeology and groundwater quality in the Tulare Lake Basin (TLB) and Salinas Valley (SV). We also assembled groundwater quality data...
This report reviews the hydrogeology and groundwater quality in the Tulare Lake Basin (TLB) and Salinas Valley (SV). We also assembled groundwater quality data from nearly two dozen local, state, and federal agencies and other sources into a dataset, here referred to as the (Central) California Ambient Spatio-Temporal Information on Nitrate in Groundwater (CASTING) dataset. The dataset combines nitrate concentrations from 16,709 individual samples taken at 1,890 wells in the Salinas Valley (SV) and from 83,375 individual samples taken at 17,205 wells in the Tulare Lake Basin (TLB) collected from the 1940s to 2011, accounting for a total of 100,084 samples from 19,095 wells. Almost 70% of these samples were collected from 2000 to 2010; only 15% of the samples were collected prior to 1990. Half of all wells sampled had no recorded samples prior to 2000.

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Addressing Nitrate in California’s Drinking Water Technical Report 5

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Addressing Nitrate in California’s Drinking Water Technical Report 5
University of California, Davis (UC Davis) | July 31, 2012...
Summary
This report explores methods and costs of remediation of groundwater nitrate contamination in the Tulare Lake Basin and Salinas Valley. Groundwater cleanup, or remediation,...
This report explores methods and costs of remediation of groundwater nitrate contamination in the Tulare Lake Basin and Salinas Valley. Groundwater cleanup, or remediation, is one of the most difficult actions in the environmental sciences, even when done on the scale of a small contaminant plume (1000s of cubic meters). Remediation of entire groundwater basins has never been attempted at the scale and depths of the Salinas Valley and Tulare Lake Basin, on the order of billions of cubic meters.

This analysis shows that direct remediation to remove nitrate from large groundwater basins is extremely costly and not technically feasible. In situ remediation, though technologically infeasible as a regional remedy, is appropriate in certain areas of shallow groundwater with high contaminant levels. Traditional pump and treat (ex situ) methods are too slow to produce results on the regional scale in an acceptable time frame, prohibitively expensive, and impractical to implement.

A novel form of pump-and-treat remediation is possible in the study area, but not yet widely practiced. By monitoring the nitrogen content of pumped irrigation water, and taking that ambient nutrient source into account when calculating additive fertilizer amounts, farmers can reduce the amount of nitrogen input to the aquifer. Such an approach is not unlike phytoremediation and is herein called “pump-and fertilize.”

Pump-and-fertilize is part of an effective nutrient management program. Due to the nature of irrigation with groundwater, it is as much a source reduction method as it is a form of groundwater remediation. Hot spot and pump-and-fertilize remediation alone will not solve the problem of groundwater nitrate contamination. A new approach is needed that combines regional groundwater and nitrogen management strategies. This approach would include monitoring, source reduction, maximization of clean groundwater recharge across agricultural landscapes, pump-and-fertilize, and in situ treatment targeted at shallow, high-concentration plumes to place regional water quality on a trajectory toward improvement. Modeling and monitoring of regional groundwater quality are integral to an effective long-term management strategy.

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A Bayesian approach to infer nitrogen loading rates from crop and land-use types surrounding private wells in the Central Valley, California

A Bayesian approach to infer nitrogen loading rates from crop and land-use types surrounding private wells in the Central Valley, California

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A Comparative Study for Estimating Crop Evapotranspiration in the Sacramento-San Joaquin Delta

A Comparative Study for Estimating Crop Evapotranspiration in the Sacramento-San Joaquin Delta

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A global spatial analysis reveals where marine aquaculture can benefit nature and people

A global spatial analysis reveals where marine aquaculture can benefit nature and people

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A Measure of Snow: Case Studies of the Snow Survey and Water Supply Forecasting Program

A Measure of Snow: Case Studies of the Snow Survey and Water Supply Forecasting Program

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A Technical Advisor’s Manual Managing Agricultural Irrigation Drainage Water: A guide for developing Integrated On-Farm Drainage Management Systems

A Technical Advisor’s Manual Managing Agricultural Irrigation Drainage Water: A guide for developing Integrated On-Farm Drainage Management Systems

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Addressing Nitrate in California’s Drinking Water Technical Report 1: Project and Technical Report Outline

Addressing Nitrate in California’s Drinking Water Technical Report 1: Project and Technical Report Outline

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Addressing Nitrate in California’s Drinking Water Technical Report 2: Nitrogen Sources and Loading to Groundwater

Addressing Nitrate in California’s Drinking Water Technical Report 2: Nitrogen Sources and Loading to Groundwater

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Addressing Nitrate in California’s Drinking Water Technical Report 3: Nitrogen Source Reduction to Protect Groundwater Quality

Addressing Nitrate in California’s Drinking Water Technical Report 3: Nitrogen Source Reduction to Protect Groundwater Quality

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Addressing Nitrate in California’s Drinking Water Technical Report 4: Groundwater Nitrate Occurrence

Addressing Nitrate in California’s Drinking Water Technical Report 4: Groundwater Nitrate Occurrence

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Addressing Nitrate in California’s Drinking Water Technical Report 5

Addressing Nitrate in California’s Drinking Water Technical Report 5

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