TO: Technical Advisory Group for the Napa County Groundwater Sustainability Agency
FROM: Brian D. Bordona, Director of Planning, Building and Environmental Services
REPORT BY: Jamison Crosby, Natural Resources Conservation Manager
SUBJECT: Update on Napa Valley Integrated Hydrologic Model updates and streamflow depletion model scenarios
RECOMMENDATION
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Provide an update on streamflow depletion model scenarios and model updates to the Napa Valley Integrated Hydrologic Model (NVIHM).
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Procedure
Staff introduces.
Questions and answers with the TAG.
Public comments.
BACKGROUND AND DISCUSSION
The Napa Valley Integrated Hydrologic Model (NVIHM) was developed by LSCE from 2020 through 2021 to support key elements of the Napa Valley Subbasin Groundwater Sustainability Plan (GSP). NVIHM is a numerical model which simulates landscape, surface water and groundwater processes and interactions using an integrated approach and is an important tool used to explore and understand the complex hydrologic interactions throughout the Napa Valley Subbasin (Subbasin). Originally, the NVIHM was calibrated through Water Year (WY) 2019 and has been updated annually based on climate and reported water use. The NVIHM continues to match observed values in wells with similar fit statistics as the calibrated model. Monthly streamflow at the Napa River Pope Street and Oak Knoll USGS gages also align with observed values.
LSCE is developing updates and refinements to NVIHM to better represent key physical processes and elements in the landscape, streams, groundwater dependent ecosystems, and the groundwater system. As previously presented to the TAG, the total water use as measured by total evapotranspiration (ET), is variable across the Subbasin. Multiple data sources, including local sensors as well as remotely sensed data, are being used to update modeled ET. Data specifically compiled by Napa County, including refined stream geometries, well locations, and land use are being in...
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