Groundwater Data Management System, Davis-Woodland Water Supply Project
Woodland-Davis Clean Water Agency

West Yost developed a groundwater Data Management System (DMS) for Yolo County to support the Woodland-Davis Clean Water Agency’s Davis Woodland Water Supply Project. The DMS was developed as an Arc Hydro for Groundwater Geodatabase and contains detailed geologic, land and water use mapping; well construction details; borehole lithology information; pumping and diversion records; and groundwater quality data. GIS tools were applied to the geologic data to 2- and 3-D representations of the aquifer system. The DMS was developed to support the Yolo County Integrated Water Flow Model (IWFM), which is being used to evaluate ASR in the Cities of Davis and Woodland. Key project challenges included developing 3-D representations of the subsurface geology and assigning pumping rates in agricultural and rural residential areas, where pumping records are very limited or nonexistent. The 3-D representations of the subsurface geology were developed by applying GIS tools and expert geologic knowledge of the study area to published geologic mapping, available well log information, and digital elevation models of the study area. Pumping rates in agricultural areas were estimated with DWR’s IWFM Demand Calculator using DWR land use and NRCS soils mapping as model inputs. Rural residential pumping was estimated based by Census Tract information using estimated per capita rates.

Quantification of Water Budget/Numerical Modeling: The West Yost team used the California DWR Modeling Support Branch’s Integrated Water Flow Model (IWFM) to develop a three-dimensional groundwater flow model for Yolo County. This model was used to assess ASR scenarios for a range of baseline conditions (without ASR), existing conditions with ASR, and future conditions with ASR. The model results supported ASR design efforts and preparation and adoption of the required CEQA Supplemental Environmental Impact Report (SEIR).