Variable: Surface water supply and use index

Variable ID: sui

Originator:U.S. Geological Survey
Publication Date:2025
Title:USGS National Water Availability Assessment Data Companion website
Geospatial Data Presentation Form:Digital datasets
Online Linkage:https://water.usgs.gov/nwaa-data/data-file-directory?path=data/integrated-water-availability/iwa-assessment-outputs-conus-2025/sui/

Larger Work Citation(s):

Citation Information:

Originator:Miller, O.L., Martinez, A.J., Cashman, M.J., Powlen, K.A., Padilla, J.A., and Stets, E.G.
Publication Date:2024-12-09
Title:Water budget results for a water availability assessment across the conterminous United States for water years 2010-2020
Geospatial Data Presentation Form:Digital datasets
Online Linkage:https://doi.org/10.5066/P1CFYEHO
Publisher:U.S. Geological Survey – ScienceBase

Citation Information:

Originator:Stets, E., Miller, O., Cashman, M., Powlen, K., Martinez, A., Archer, A.A., and Padilla, J.A.
Publication Date:2025-01-11
Title:Local water use and climate drive water stress over the conterminous United States with substantial impacts to fish species of conservation concern
Geospatial Data Presentation Form:Digital datasets
Online Linkage:https://d197for5662m48.cloudfront.net/documents/publicationstatus/240601/preprint_pdf/3e71524f57457d69e1fc51577b205ace.pdf
Publisher:Authorea Preprints

Description:

Name:Surface water supply and use index

Variable ID:sui

Units:Fraction (frac)

Summary:

The surface water supply and use index (SUI) expresses the fraction of the median long-term water supply at a HUC12 that is unavailable either because of climatic variability (e.g. an unusually dry year) or because the water is used consumptively for crop irrigation, thermoelectric power, or public supply. Higher values indicate a higher potential water limitation because a higher proportion of the typical water supply is unavailable. The SUI varies between 0 (no apparent limitation) and 1 (total depletion of the local water supply). The proportion of the long-term median supply that is available for all beneficial uses, including environmental flows, can be calculated as 1-SUI. For example, a SUI of 0.2 means 80% ( (1-0.2) x 100%) of flows remain available for all other uses.

Technical Description:

SUI is calculated as water availability (wa) divided by long-term median water supply (mws). In equation form: SUI = wa/mws. It represents the departure from the natural median flow for each month. Water availability is calculated as the modeled water supply for any given month (ws) minus the consumptive water use for that month (wc), wa = ws-wc. The calculation is carried out for each month for each HUC12 included in the analysis. The mws is calculated for each month of the year at each HUC12 to account for regular seasonality in the water supply. Therefore, departures from typical annual cycles in mws will appear as variations in SUI. Values of SUI were limited to the range 0 to 1. Excess supply or consumption can cause SUI 1, respectively. In arid environments, mws can be a small number and relatively small departures result in large SUI values. HUC12 catchments with no ws and wc (0/0) are assigned a value of 1 (severe water limitation), because of the lack of water available for any potential consumptive use.

Parent Model:

Name:National Water Availability Assessment Outputs (CONUS 2025)
Model ID:iwa-assessment-outputs-conus-2025

Time Period of Content:

Time Period Information:

Range of Dates/Times:

Start Year/Month:200910
End Year/Month:202009

Status:

Scenario:Historical

Spatial Domain:

Description of Geographic Extent:Lower 48 United States

Bounding Coordinates:

West Bounding Coordinate:-126.0
East Bounding Coordinate:-66.2
North Bounding Coordinate:49.7
South Bounding Coordinate:24.4

Geospatial Data Needed to Map Output:

Description of Spatial Resolution:12-digit hydrologic unit codes

Citation Information:

Title:October 2020 version of the Watershed Boundary Dataset
Online Linkage:https://www.sciencebase.gov/catalog/item/67082a0fd34e969edc5a1cca

Access Constraints:Some files are too large to open in spreadsheet programs. For ideal viewing of these files, please use a text editor to ensure all data are retained.

Entity and Attribute Information:

Detailed Description:

Entity Type:

Entity Type Label:sui_historical_CONUS_200910-202009_describe.txt

Entity Type Definition:

Text (txt) file containing summary information for the dataset. For each metric (huc12_id, year_month, and sui_frac) it provides the total number of dataset observations, the number of distinct values, and various summary statistics.