This data release provides a monthly irrigation water use reanalysis for the period 2000-20 for all USGS Watershed Boundary Dataset of Subwatersheds (Hydrologic Unit Code 12 [HUC12]) in the conterminous United States (CONUS). Results include reference evapotranspiration (ETo), actual evapotranspiration (ETa), irrigated areas, consumptive use, and effective precipitation for each HUC12. ETo and ETa were estimated using the operational Simplified Surface Energy Balance (SSEBop, Senay and others, 2013; Senay and others, 2020) model executed in the OpenET (Melton and others, 2021) web-based application implemented in Google Earth Engine. Results provided by OpenET/SSEBop were summarized to hydrologic response units (HRUs) in the National Hydrologic Model (NHM; Regan and others, 2019) to estimate consumptive use and effective precipitation on irrigated lands. Irrigated lands for the CONUS were provided by the Landsat-based Irrigation Dataset (LANID; Xie and others, 2019) for each year of the reanalysis period. Consumptive use estimates provided by the NHM were disaggregated to HUC12s using area weighted intersections with HRUs and the relative proportion of irrigated lands in each intersected area. This data release includes data and source code required to develop the irrigation reanalysis workflow along with the scripts and data required to replicate the output results. The workflow has three main steps that were automated using python scripts: 1) convert daily OpenET/SSEBop results into input for the NHM, 2) run a modified version of the NHM that is an application of the GSFLOW software package (GSFLOW version 2.3) to estimate daily results, and 3) post-process NHM results to monthly, then summarize and disaggregate ETo, ETa, irrigated areas, consumptive use, and effective precipitation to all HUC12s in the CONUS for the period 2000-20.

Actual evapotranspiration (ETa) values estimated for specified areas including 1) total county areas; 2) potentially irrigated areas within each county; and 3) mapped extents of irrigated lands within each county provided by some states. These ETa estimates were provided to the USGS National Water Use Science Project by the USGS Earth Resources Observation and Science (EROS) Center (Gabriel Senay and MacKenzie Friedrichs, written communication, 2/20/2017) and are based on 1-square kilometer resolution 2015 Moderate Resolution Imaging Spectroradiometer (MODIS) satellite data analyzed through the operational Simplified Surface Energy Balance (SSEBop) model using methods of Senay and others (2013). Reference: Senay, G.B., Bohms, S., Singh, R.K., Gowda, P.H., Velpuri, N.M., Alemu, H., and Verdin, J.P., 2013, Operational evapotranspiration mapping using remote sensing and weather datasets: A new parameterization for the SSEB approach; Journal of the American Water Resources Association, 49 (2013), pp. 577–591.

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, 2023), 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, 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.

This data release contains the output of the Irrigation Water Use Estimation Disaggregation and Downscaling Model (IWUEDD) along with the scripts and data resources required to replicate the output results. The IWUEDD is used to estimate monthly irrigation withdrawals and consumptive use for each 12-digit hydrologic unit code (HUC 12) subwatershed in the conterminous United States. The HUC 12-level estimates are separated into groundwater (GW), surface water (SW), groundwater and surface water combined (TW), and consumptive use (CU). The IWUEDD developed monthly estimates by disaggregating and downscaling previously published annual county-level irrigation withdrawal and consumptive use data complied as part of the National Water Use Science Project, National Water Census as presented in U.S. Geological Survey data release, “Estimated use of water in the United States county-level data for 2015” (Dieter and others, 2018).

The supplemental data presented here contains raster data in .tif format of the empirically estimated mean annual (1987-2015) net evapotranspiration (ETnet) for the Harney Basin Groundwater Evapotranspiration Area. The final mean annual ETnet estimate for the Harney Basin was determined using both empirical and physics-based methods. The final ETnet estimate was combined with additional data to estimate groundwater discharge through evapotranspiration (ET) in the Harney Basin. See Garcia and others (2022) for a detailed description of how these data were estimated and evaluated.

This dataset includes 1km resolution monthly timescale estimates of evapotranspiration (ET) for the 2000-2015 timespan. These new SSEBop-WB estimates were developed by combining a previously published long-term annual average evapotranspiration map based on water balance constraints with the SSEBop remote sensing ET product (see Associated Items). The combination aims to leverage the advantages of each approach in gaining both the temporal resolution of remote sensing data and the long-term magnitude constraints of ground-based data. This data release also includes other supporting data associated with the publication of these estimation methods in a concurrent journal article. Analyses in the journal article included comparisons between SSEBop ET, the MOD16 remote sensing ET product, and the new SSEBop-WB ET in a variety of settings against ET data from 119 flux towers across the U.S. Residuals between the remote sensing methods and the flux tower data were mapped spatially, and these maps are included in the data release as well. The methods are fully described in the forthcoming article accepted for publication in Remote Sensing as of November 2017; this dataset will be updated with its full citation when available. See also the metadata file for additional information, or contact the authors with questions.

This USGS data release consists of three data sets used as the basis for estimates of groundwater discharge from evapotranspiration in Tule Valley and part of Sevier Valley, UT. The data sets are a mapped groundwater discharge area (GDA), a mean modified soil adjusted vegetation index (MSAVI), and evapotranspiration (ET) units derived from the MSAVI within the GDA. The GDA represents the area within each valley where discharge from evaporation by open water or bare soil and transpiration from phreatophytic plants exceeds the volume of water contributed by precipitation. The GDA was delineated during field reconnaissance of the study area using techniques similar to those used in previous studies throughout Nevada and eastern Utah. The mean MSAVI image is based on two Landsat 5 Thematic Mapper (TM) scenes representing midsummer conditions in 2007 and 2008. MSAVI was calculated for each TM image which were then combined by averaging the pixels within each scene. The resultant mean MSAVI image was used to estimate vegetation assemblages (ET units) within a mapped groundwater discharge area.

This metadata record describes monthly input and output data covering the period 1900-2015 for a water-balance model described in McCabe and Wolock (2011). The input datasets are precipitation and air temperature from the PRISM group at Oregon State University. The model outputs include estimated potential evapotranspiration (PET), actual evapotranspiration (AET), runoff (RUN) (streamflow per unit area), soil moisture storage (STO), and snowfall (SNO). The datasets are arranged in tables of monthly total or average values measured in millimeters or degrees C and then multiplied by 100. The data are indexed by the identifier PRISMID, which refers to an ASCII raster of cells in an associated file named PRISMID.asc. Water-balance model inputs and outputs also can be linked to a file (PRISMID_LL.csv) of latitude and longitude values in a separate comma separated data file based on PRISMID values. Each input and output variable comma separated file contains 10 years of monthly data for all 481639 PRISMID raster cells in the conterminous United States. The files containing input and output data can be georeferenced by joining them to an ASCII raster of PRISMID cells, named prismid.asc. The source for the input data is the PRISM (Parameter-elevation Relationships on Independent Slopes Model) Group at Oregon State University (http://www.prism.oregonstate.edu/historical/ and http://www.prism.oregonstate.edu/recent/). These data were downloaded from the PRISM web site on various dates.

Actual evapotranspiration (ETa) rates from the Operational Simplified Surface Energy Balance (SSEBop) method, before and after bias corrections (Sepúlveda, 2021), are presented for basins located wholly or partially within the Northwest Florida Water Management District (NWFWMD) and parts of Alabama and Georgia. The SSEBop annual rates are provided at about a one square-kilometer scale from 2000 to 2017. Annual ETa rates calculated from the application of the water-balance method (wbETa) to 5 basins in the NWFWMD and annual land-use ETa (luETa) rates calculated from monthly average crop coefficient ratios are also provided in this data set. A GIS shapefile provides land-use type and annual ETa rate for each year of record. Data are tabulated in spreadsheets for each basin and are referred to by the name between parenthesis: Lower Ochlockonee basin (Lower_Ochlockonee), Apalachicola – Chipola River basin (Apalachicola_Chipola), Lower Choctawhatchee River basin (Lower_Choctawhatchee), Yellow River basin (Yellow), and Escambia – Perdido River basin (Escambia_Perdido). Inflows and outflows from various sources in the water-balance equation used to calculate annual average wbETa rates for each basin are presented in this dataset.