Alleviating water scarcity by optimizing crop mixes

Nature Portfolio (Springer Nature) | November 6th, 2023

An evolutionary parsimonious approach to estimate daily reference evapotranspiration

Nature Portfolio (Springer Nature) | March 20th, 2024

Anticipating drought-related food security changes

Nature Portfolio (Springer Nature) | September 29th, 2022

Food insecurity early warning can provide time to mitigate unfolding crises; however, drought remains a large source of uncertainty. The challenge is to filter unclear or

Food insecurity early warning can provide time to mitigate unfolding crises; however, drought remains a large source of uncertainty. The challenge is to filter unclear or conflicting signals from various climatic and socio-economic variables and link them to food security outcomes. Integrating lag-1 autocorrelation diagnostics into remotely sensed observations from the Soil Moisture Active Passive (SMAP) mission and food prices, we found dramatic improvement in anticipating the timing and intensity of food crises, except in conflict settings. We analysed drought-induced food crises globally in the SMAP record (since 2015; approximately five per year). The change in soil moisture autocorrelation, which we term the Soil Moisture Auto-Regressive Threshold (SMART), signalled an accurate food security transition for all cases studied here (P 

Applying the connectivity approach: Water and food supply projects in California that connect, link, and engage

California Roundtable on Water and Food Supply (CRWFS) | April 11th, 2014

In delving into the connectivity concept and approach, members of the California Roundtable on Water and Food Supply (CRWFS) felt that it was very important to look to ex

In delving into the connectivity concept and approach, members of the California Roundtable on Water and Food Supply (CRWFS) felt that it was very important to look to existing and emerging projects that were already embracing the concepts being discussed. Projects were selected to highlight the three high priority areas for effecting change: connected thinking, institutional linkages, and public engagement. The five examples included in this booklet as case assessments illustrate several ways the connectivity approach is currently being applied throughout California. The assessments are intended to generate ideas for applying the guiding principles of the connectivity approach and the positive impacts that emerge from them. The assessments are not meant to serve as an evaluation of the merit of the projects. This booklet is intended to accompany From Crisis to Connectivity: Renewed Thinking About Managing California’s Water and Food Supply, which more fully describes the connectivity approach illustrated here.

Aquifer depletion exacerbates agricultural drought losses in the US High Plains

Nature Portfolio (Springer Nature) | January 15th, 2024

Aquifer depletion poses a major threat to the ability of farmers, food supply chains and rural economies globally to use groundwater as a means of adapting to climate var

Aquifer depletion poses a major threat to the ability of farmers, food supply chains and rural economies globally to use groundwater as a means of adapting to climate variability and change. Empirical research has demonstrated the large differences in drought risk exposure that exist between rainfed and irrigated croplands, but previous work commonly assumes water supply for the latter is unconstrained. Here we evaluate how aquifer depletion affects the resilience of irrigated crop production to drought risk using over 30 years of data on historical corn and soybean yields, production areas and aquifer conditions for the High Plains region in the United States. We show that aquifer depletion reduces the ability of farmers to sustain irrigated crop yields and production areas in years and locations with large growing-season water deficits. Our findings demonstrate that drought-related production losses on irrigated croplands increase non-linearly with aquifer depletion, highlighting the need for proactive aquifer conservation interventions to support adaptation and resilience to future increases in rainfall variability under climate change.

Artesian Wells at Pomoma, Cal

Scientific American | January 10th, 1885

N0 portion of the State has made such a rapid progress in the development of its natural resources as have Los Angeles and San Bernardino counties during the past few

N0 portion of the State has made such a rapid progress in the development of its natural resources as have Los Angeles and San Bernardino counties during the past few years. In the fall of 1882, just two years ago, the Pomona Land and Water Company was incorporated for the purpose of developing and placing upon the market in small tracts the virgin lands of this fertile valley.

Assessing the accuracy of OpenET satellite-based evapotranspiration data to support water resource and land management applications

Nature Portfolio (Springer Nature) | January 15th, 2024

Remotely sensed evapotranspiration (ET) data offer strong potential to support data-driven approaches for sustainable water management. However, practitioners require rob

Remotely sensed evapotranspiration (ET) data offer strong potential to support data-driven approaches for sustainable water management. However, practitioners require robust and rigorous accuracy assessments of such data. The OpenET system, which includes an ensemble of six remote sensing models, was developed to increase access to field-scale (30 m) ET data for the contiguous United States. Here we compare OpenET outputs against data from 152 in situ stations, primarily eddy covariance flux towers, deployed across the contiguous United States. Mean absolute error at cropland sites for the OpenET ensemble value is 15.8 mm per month (17% of mean observed ET), mean bias error is −5.3 mm per month (6%) and r2 is 0.9. Results for shrublands and forested sites show higher inter-model variability and lower accuracy relative to croplands. High accuracy and multi-model convergence across croplands demonstrate the utility of a model ensemble approach, and enhance confidence among ET data practitioners, including the agricultural water resource management community.

Assessing the presence of current-use pesticides in mid-elevation Sierra Nevada streams using passive samplers, California, 2018–19

U.S. Geological Survey (USGS) | February 9th, 2023

Passive sampler devices were deployed in six northern California streams five times between November 2018 and December 2019 to measure the presence or absence of current-

Passive sampler devices were deployed in six northern California streams five times between November 2018 and December 2019 to measure the presence or absence of current-use pesticides in surface water. In the targeted areas, there are reported pesticide uses for agriculture, commercial forestry, and rights of way maintenance along with unreported pesticide use at private residences and cannabis grow sites. The sites sampled in this study were not previously monitored for current-use pesticides. Streams in the Sierra Nevada foothills of northern California are important habitats for many sensitive species including salmonids, but the logistics of sampling these areas can be difficult using traditional water-quality sampling techniques, especially when sampling watersheds where contaminant transport is episodic. Chemcatcher passive sampling devices and silicone bands were deployed in these areas to concentrate pesticides for days to weeks at a time. The U.S. Geological Survey, in cooperation with the Central Valley Regional Water Quality Control Board, was responsible for developing passive sampler field deployment and laboratory analytical methods for current-use pesticides, providing pesticide measurements from streams in the study region, and determining how well passive samplers detect pesticides in these environments. Six sites were monitored during the study, and passive sampler extracts were analyzed for a total 155 current-use pesticides in this study. A total of 19 out of the 155 pesticides including 9 insecticides, 5 fungicides, and 5 herbicides were detected in extracts from passive samplers. The most frequently detected pesticides were the herbicides hexazinone and dithiopyr, the insecticides bifenthrin and methoxyfenozide, and the fungicide azoxystrobin.

Bayesian nitrate source apportionment to individual groundwater wells in the Central Valley by use of elemental and isotopic tracers

American Geophysical Union (AGU) | July 31st, 2016

Groundwater quality is a concern in alluvial aquifers that underlie agricultural areas, such as in the San Joaquin Valley of California. Shallow domestic wells (less tha

Groundwater quality is a concern in alluvial aquifers that underlie agricultural areas, such as in the San Joaquin Valley of California. Shallow domestic wells (less than 150 m deep) in agricultural areas are often contaminated by nitrate. Agricultural and rural nitrate sources include dairy manure, synthetic fertilizers, and septic waste. Knowledge of the relative proportion that each of these sources contributes to nitrate concentration in individual wells can aid future regulatory and land management decisions. We show that nitrogen and oxygen isotopes of nitrate, boron isotopes, and iodine concentrations are a useful, novel combination of groundwater tracers to differentiate between manure, fertilizers, septic waste, and natural sources of nitrate. Furthermore, in this work, we develop a new Bayesian mixing model in which these isotopic and elemental tracers were used to estimate the probability distribution of the fractional contributions of manure, fertilizers, septic waste, and natural sources to the nitrate concentration found in an individual well. The approach was applied to 56 nitrate-impacted private domestic wells located in the San Joaquin Valley. Model analysis found that some domestic wells were clearly dominated by the manure source and suggests evidence for majority contributions from either the septic or fertilizer source for other wells. But, predictions of fractional contributions for septic and fertilizer sources were often of similar magnitude, perhaps because modeled uncertainty about the fraction of each was large. For validation of the Bayesian model, fractional estimates were compared to surrounding land use and estimated source contributions were broadly consistent with nearby land use types.

Better late than never: a synthesis of strategic land retirement and restoration in California

Ecological Society of America (Wiley) | August 10th, 2018

Strategic retirement and restoration of agricultural lands is a critical conservation opportunity globally. The objective of this synthesis was to examine whether ecolog

Strategic retirement and restoration of agricultural lands is a critical conservation opportunity globally. The objective of this synthesis was to examine whether ecological habitat assessments, endangered species historical occurrence data, and restoration research can be used to develop evidence-based strategy for retiring and restoring agricultural lands. The San Joaquin Desert (SJD) of California is a prominent example because it experienced an extensive conversion to agriculture. Now, new groundwater regulations will lead to retirement on large areas of agricultural lands over the next 20 years. This presents an opportunity to not only restore some of these lands but also explore the challenges associated with balancing direct human needs with other ecosystem-level functions. California is thus an ideal case study for globally rethinking context-specific, single-case study solutions. We used a systematic review and synthesis to address the following three main questions for habitat recovery of endangered species in the SJD. (1) What are the habitat requirements for key endangered animal species in the region? (2) Is there historical evidence to support an assessment of suitable habitats for these species? (3) What restoration techniques apply to these species? Using the Web of Science and other resources, we reviewed over 1000 independent studies on this topic, refined the evidence, and selected a total of 266 relevant publications. Habitat requirements for each species were described, but there was a critical need to examine quantitative thresholds for these factors to better evaluate habitat suitability of retired lands. There was sufficient evidence of historical vegetation to model suitable habitats and design the physical restoration of retired lands. Direct interventions associated with restoration strategies have been infrequently tested. Sparse and diverse evidence associated with direct experimental manipulations is not uncommon in applied ecology, and synthesis is an excellent tool for highlighting these gaps for future research to examine. This review suggests that retired agricultural land is a viable asset for threatened and endangered species, but to effectively advance restoration research and management, direct tests of restoration techniques and an assessment of relative costs for interventions are needed for a given region.