Hydrologic Science Opportunities to Better Understand Water Supply: A Community Perspective

<jats:p>Water Supply refers to the freshwater resources generated through precipitation and snowmelt; stored in snowpack, soil moisture, groundwater, rivers, lakes, and reservoirs; lost through evaporation, transpiration, and sublimation; and redirected via human withdrawals. Characterizing the available water supply is critical for water management, agriculture and food security and long-term water resource planning. Many components of water supply are observable from space, however several critical processes are missing. Water stored in seasonal snowpacks is not currently measured from space at spatial and temporal resolutions necessary to understand its effective contribution to usable water supply. Precipitation measurements struggle in complex terrain, especially in capturing extreme events, quantifying snowfall, and partitioning between rain and snow. Total water storage is measured at very coarse resolutions rather than at watershed scales that would inform hydrological processes. And losses, such as through evapotranspiration, sublimation and consumption are not well captured. Future efforts to improve our ability to characterize water supply should focus on building missions to fill specific gaps, maintaining continuity of existing missions and building frameworks to leverage all data in a multi-sensor modeling approach. This white paper is an outcome of a community-led, community-engaged effort to elevate hydrologic science opportunities which would have significant benefit to support decision-making for drought, floods, water quality, water supply and water demand.</jats:p>