Presentations 2016

Intercomparison of C2VSim and CVHM Groundwater Budgets for DWR Subregions in the Central Valley

UC Davis

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Accurate estimation of groundwater (GW) budgets and effective management of agricultural GW pumping remains a challenge in much of California’s Central Valley (CV) due to a lack of irrigation well metering. CVHM and C2VSim are two regional-scale integrated hydrologic models that provide estimates of historical and current CV distributed pumping rates and changes in GW storage. However, both models estimate these components of the GW budget using conceptually different agricultural water models with uncertainties that have not been adequately investigated. Here, we evaluate differences in distributed agricultural GW pumping and change in storage estimates for both models at the regional and sub-regional scale. Results show wide-ranging, but mostly poor agreement for model estimates of distributed agricultural GW pumping and changes in GW storage. Discrepancies were generally greater at the sub-regional scale than at the regional scale. These findings suggest that estimates of these important water budget components are sensitive to conceptual differences between models, which ultimately can impact conjunctive-use water management decisions in the CV.