Precipitation Minus Actual Evapotranspiration During Avg Conditions

Runoff is a measure of the water available for storage. It is determined by both the water supply and the demand of the existing vegetation. Annual mean runoff measures the "average" vegetative demand and thus provides a comparative index on the potential available runoff. Specifically, Annual Mean Runoff is the expected surplus water that would discharge to surface or groundwater flows during a series of years with average precipitation. Larger values indicate more runoff under mean conditions.

Data and Resources

Additional Info

Field Value
Last Updated January 17, 2025, 06:42 (UTC)
Created January 17, 2025, 06:42 (UTC)
category /Water Security/Quantity
collection_name California Landscape Metrics
creation_method The Center for Ecosystem Climate Solutions at UC Irvine (CECS) is working with the State and Federal governments in developing scientifically rigorous, stakeholder-informed methods that have produced tailored, integrated data for land management decision makers. The CECS DataEngine model tracks monthly water balance from 1986 to 2021. The Annual Mean Runoff layer is calculated using this CECS DataEngine model logic forced with a series of 4 years that each received precipitation according to the timing and magnitude of the 30-year climate Normal Precipitation (SPI = 0 by definition). The model water inputs are determined from downscaled PRISM gridded datasets (<https://prism.oregonstate.edu/>). In the case of the Annual Mean Runoff, this reflects the monthly 30 year Normal for each pixel calculated for 1991-2020. Actual evapotranspiration (AET) is calculated from Landsat observations and eddy covariance during 2021, along with information on local monthly irradiance that accounts for Top of Atmosphere (TOA) and topographic effects, as well as monthly temperature and drought stress. Precipitation Minus Actual Evapotranspiration is calculated as the difference; it provides an excellent measure of the long-term runoff from upland pixels. Areas with a higher P-ET produce greater runoff, and areas with a low P-ET tend to produce little or no runoff during average or dry years. See https://doi.org/10.1029/2012JG002027 and https://doi.org/10.1073/pnas.1319316111 for further information.
data_units mm/y
data_vintage 09/2021
encoding utf8
file_name WaterFlux_Runoff_202109_202312_T1_v5
format GeoTiff
harvest_object_id 24156fb3-ae13-4315-a78c-1615948bc0ec
harvest_source_id a2637971-af12-457f-ae4a-831d2202a539
harvest_source_title WIFIRE Commons
maximum_value 4028.0
metric_definition_and_relevance Runoff is a measure of the water available for storage. It is determined by both the water supply and the demand of the existing vegetation. Annual mean runoff measures the "average" vegetative demand and thus provides a comparative index on the potential available runoff. Specifically, Annual Mean Runoff is the expected surplus water that would discharge to surface or groundwater flows during a series of years with average precipitation. Larger values indicate more runoff under mean conditions.
minimum_value -2000.0
spatial {"type": "Polygon", "coordinates": [[[-124.5090833859125, 32.4242698701859], [-113.49380570277376, 32.4242698701859], [-113.49380570277376, 42.1119747450123], [-124.5090833859125, 42.1119747450123], [-124.5090833859125, 32.4242698701859]]]}
tier 1