Isotopic evaluation of the National Water Model reveals missing agricultural irrigation contributions to streamflow across the western United States.

ABSTRACT: The National Water Model (NWM) provides critical analyses and projections of streamflow that support water management decisions. However, the NWM performs poorly in lower-elevation rivers of the western United States (US). The accuracy of the NWM depends on the fidelity of the model inputs and the representation and calibration of model processes and water sources. To evaluate the NWM performance in the western US, we compared observations of river water isotope ratios ( O18∕O16 and H2∕H1 expressed in δ notation) to NWM-flux-estimated (model) river reach isotope ratios. The modeled estimates were calculated from long-term (2000-2019) mean summer (June, July, and August) NWM hydrologic fluxes and gridded isotope ratios using a mass balance approach. The observational dataset comprised 4503

SUBMITTER: Putman AL 

PROVIDER: S-EPMC11457154 | biostudies-literature | 2024 Jul

REPOSITORIES: biostudies-literature