Agricultural Irrigation in This Drought: Where is the Water and Where Is It Going?

University of California Giannini Foundation of Agricultural Economics | May 14th, 2015

In the midst of its fourth year of drought, California now faces an estimated reduction in surface-water availability of 8.8 million acre-feet (maf) out of 29 maf in agri

In the midst of its fourth year of drought, California now faces an estimated reduction in surface-water availability of 8.8 million acre-feet (maf) out of 29 maf in agricultural applied water statewide. However, groundwater, the buffer water supply during drought, is replacing about 6.2 maf of surface water via additional pumping. This increased groundwater pumping is in addition to the 1.5 maf of annual average groundwater overdraft in the Central Valley. The net reduction of 2.6 maf in the total supply in 2015 may result in about 564,000 acres fallowed statewide, or about 120,000 more acres than last year's fallowing estimates.

Agricultural Land Stewardship (Resource Management Strategy)

California Department of Water Resources (DWR) | July 29th, 2016

This resource management strategy focuses primarily on private land in agriculture including cultivated land and rangeland. Agricultural land in California comprises abou

This resource management strategy focuses primarily on private land in agriculture including cultivated land and rangeland. Agricultural land in California comprises about 31.6 million acres (California Department of Conservation, Division of Land Resource Protection, Farmland Mapping and Monitoring Program 2008). About 12.4 million of these acres are cultivated, while the remaining 19.2 million acres are rangeland (California Department of Forestry and Fire Protection 2010). Agricultural systems in California are varied in the way resources are used, ranging from intensive conventional agriculture (irrigated crop cultivation) to more extensive systems such as livestock grazing, each with a different relationship to natural resources. They also affect and are affected by surface hydrology and groundwater recharge in different ways. Stewardship of this land requires constant balancing among natural constraints, market forces, and ever-changing social expectations. Institutions and policies have been developed in response to these challenges. Public investment in water infrastructure (reservoirs, canals, drains, levees, dykes) has been in the forefront of these. This resource management strategy report focuses on agricultural land stewardship (ALS) strategies that can be incorporated into relevant adaptive management of agricultural land at different levels, including landscape, regional and project.

Agricultural Losses from Salinity in California’s Sacramento-San Joaquin Delta

University of California, Davis (UC Davis) | April 5th, 2014

Sea level rise, large-scale flooding, and new conveyance arrangements for water exports may increase future water salinity for local agricultural production in California

Sea level rise, large-scale flooding, and new conveyance arrangements for water exports may increase future water salinity for local agricultural production in California’s Sacramento–San Joaquin Delta. Increasing salinity in crop root zones often decreases crop yields and crop revenues. Salinity effects are nonlinear and vary with crop choice and other factors including drainage and residence time of irrigation water. Here, we explore changes in agricultural production in the Delta under various combinations of water management, large-scale flooding, and future sea level rise. Water management alternatives include through-Delta water exports (current conditions), dual conveyance (through-Delta and a 6,700 Mm3 yr?1 [or 7500 cfs] capacity peripheral canal or tunnel) and the flooding of five western islands with and without peripheral exports. We employ results from previous hydrodynamic simulations of likely changes in salinity for irrigation water at points in the Delta. We connect these irrigation water salinity values into a detailed agro-economic model of Delta agriculture to estimate local crop yield and farm revenue losses. Previous hydrodynamic modeling work shows that sea level rise is likely to increase salinity from 4% to 130% in this century, depending on the increase in sea level and location. Changes in water management under dual conveyance increase salinity mostly in the western Delta, and to a lesser extent in the north, where current salinity levels are now quite low. Because locations likely to experience the largest salinity increases already have a lower-value crop mix, the worst-case losses are less than 1% of total Delta crop revenues. This result also holds for salinity increases from permanent flooding of western islands that serve as a salinity barrier. Our results suggest that salinity increases could have much smaller economic effects on Delta farming than other likely changes in the Delta such as the retirement of agricultural lands after large-scale flooding and habitat development. Integrating hydrodynamic, water salinity, and economic models can provide insights into controversial management issues.

Agricultural managed aquifer recharge (Ag-MAR)—a method for sustainable groundwater management: A review

Critical Reviews in Environmental Science and Technology (Taylor & Francis) | March 28th, 2022

More than two billion people and 40% of global agricultural production depend upon unsustainable groundwater extraction. Managed aquifer recharge (MAR), the practice of s

More than two billion people and 40% of global agricultural production depend upon unsustainable groundwater extraction. Managed aquifer recharge (MAR), the practice of strategically recharging water to replenish subsurface storage, is an important subbasin scale practice for managing groundwater more sustainably. However, it is not yet reaching its full potential to counterbalance growing global groundwater demand. Agricultural managed aquifer recharge (Ag-MAR) is an emerging method for spreading large volume flows on agricultural lands and has capacity for widespread global implementation. Yet, knowledge gaps, synergies, and tradeoffs in Ag-MAR research still exist. We identify six key system considerations when implementing Ag-MAR: water source, soil and unsaturated zone processes, impact on groundwater, crop system suitability, climate change and impact on greenhouse gas emissions, and social and economic feasibility. We describe the present distribution, need for common terminology, and benefits of Ag-MAR including groundwater storage, increased environmental flows, and domestic wells support. We then outline major gaps, namely, water quality impacts, and crop health and yield. We showcase the multidisciplinary approach needed for communication and coordination of Ag-MAR programs with stakeholders and the public and provide a framework for implementation. Finally, we outline a vision for the path to Ag-MAR implementation. Ag-MAR is an important approach for achieving groundwater sustainability. However, it is one of many necessary solutions and does not offset the need for groundwater conservation.

Agricultural risks from changing snowmelt

Nature Portfolio (Springer Nature) | April 20th, 2020

Snowpack stores cold-season precipitation to meet warm-season water demand. Climate change threatens to disturb this balance by altering the fraction of precipita

Snowpack stores cold-season precipitation to meet warm-season water demand. Climate change threatens to disturb this balance by altering the fraction of precipitation falling as snow and the timing of snowmelt, which may have profound effects on food production in basins where irrigated agriculture relies heavily on snowmelt runoff. Here, we analyse global patterns of snowmelt and agricultural water uses to identify regions and crops that are most dependent on snowmelt water resources. We find hotspots primarily in high-mountain Asia (the Tibetan Plateau), Central Asia, western Russia, western US and the southern Andes. Using projections of sub-annual runoff under warming scenarios, we identify the basins most at risk from changing snowmelt patterns, where up to 40% of irrigation demand must be met by new alternative water supplies under a 4 °C warming scenario. Our results highlight basins and crops where adaptation of water management and agricultural systems may be especially critical in a changing climate.

Agricultural Water Conservation and Efficiency Potential in California

Pacific Institute | June 10th, 2014

Agriculture uses about 80 percent of California’s developed water supply. As such a large user, it is heavily impacted by the availability and reliability of California

Agriculture uses about 80 percent of California’s developed water supply. As such a large user, it is heavily impacted by the availability and reliability of California’s water resources.  Agriculture can also play an important role in helping the state achieve a more sustainable water future. The challenge is to transition to an agricultural sector that supplies food and fiber to California and the world and supports rural livelihoods and long-term sustainable water use.

Agricultural Water Use Efficiency (Resource Management Strategy)

California Department of Water Resources (DWR) | July 29th, 2016

The agricultural water use efficiency strategy describes the use and application of scientific processes to control agricultural water delivery and use to achieve a benef

The agricultural water use efficiency strategy describes the use and application of scientific processes to control agricultural water delivery and use to achieve a beneficial outcome. It includes an estimation of net water savings or increased production resulting from implementing efficiency measures as expressed by the ratio of output to input, resulting benefits, and strategies to achieve efficiency and benefits.

Aliso Water District Groundwater Sustainability Plan

Aliso Water District Groundwater Sustainability Agency | January 17th, 2020

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