DOI: 10.5066/p9lgisum
title: Monthly crop irrigation withdrawals and efficiencies by HUC12 watershed for years 2000-2020 within the conterminous United States (ver. 2.0, September 2024)

description: The USGS has published United States water-use data every five years since 1950. To increase the temporal and spatial availability of water use estimates using nationally consistent methods, the USGS is developing national water-use models for each major water-use category. This data release publishes crop irrigation withdrawals for the conterminous United States (CONUS) that are calculated using modeled irrigation consumptive use (Martin and others, 2024), irrigation efficiencies, and source-water proportions (Dieter and others, 2018). Crop irrigation withdrawals and irrigation consumptive use refer to water removed and consumed, respectively, from a groundwater or surface-water source to produce agricultural crops. Monthly withdrawals provided include groundwater, surface water, and the combined total withdrawal for areas contained in the twelve-digit watershed boundary (HUC12) dataset during the reanalysis period, 2000-2020. HUC12 annual 2000-2020 irrigation efficiencies included in this data release combine efficiencies from irrigation system types (accounting for water lost during application to crops) and conveyances (accounting for water lost during transmission through canals and pipes). Irrigated crops were mapped using the Landsat-based Irrigation Dataset (LANID; Xie and Lark, 2021; Martin and others, 2024) and the Cropland Data Layer (USDA NASS, 2022) that were linked to irrigation system types (USDA NASS, 2014) to estimate irrigation system efficiencies for each HUC12 in the CONUS (Howell, 2003 and FAO, 1989). Conveyance loss volumes (USDA NASS, 2020) were used to estimate and map surface-water conveyance efficiencies. Total efficiencies were calculated for HUC12 units by combining irrigation system and conveyance efficiencies. Irrigation withdrawals and efficiencies were produced using published data sources to provide these estimates in a timely manner. On-going work to develop dynamic maps of irrigation system type and other datasets for the CONUS will be used in the future to refine the estimates provided here. Estimation of irrigation withdrawals using irrigation consumptive use and efficiencies neglects some components of water use for crops, including water used for frost protection, salt leaching, harvesting, and other non-consumptive-use based treatments. For this reason, irrigation withdrawals provided here may under-estimate total withdrawals where non-consumptive treatments are significant.
HUC12 annual 2000-2020 irrigation efficiencies included in this data release combine efficiencies from irrigation system types (accounting for water lost during application to crops) and conveyances (accounting for water lost during transmission through canals and pipes). Irrigated crops were mapped using the Landsat-based Irrigation Dataset (LANID; Xie and Lark, 2021; Martin and others, 2023) and the Cropland Data Layer (USDA NASS, 2022) that were linked to irrigation system types (USDA NASS, 2014) to estimate irrigation system efficiencies for each HUC12 in the CONUS (Howell, 2003 and FAO, 1989). Conveyance loss volumes (USDA NASS, 2020) were used to estimate and map surface-water conveyance efficiencies. Total efficiencies were calculated for HUC12 units by combining irrigation system and conveyance efficiencies.

Irrigation withdrawals and efficiencies were produced using published data sources to provide these estimates in a timely manner. On-going work to develop dynamic maps of irrigation system type and other datasets for the CONUS will be used in the future to refine the estimates provided here. Estimation of irrigation withdrawals using irrigation consumptive use and efficiencies neglects some components of water use for crops, including water used for frost protection, salt leaching, harvesting, and other non-consumptive-use based treatments. For this reason, irrigation withdrawals provided here may under-estimate total withdrawals where non-consumptive treatments are significant.