Estimating Groundwater and Surface Water Interactions Using Groundwater Depth August 29, 2017 Kirk Klausmeyer SENIOR SPATIAL DATA SCIENTIST

SANDARD DEFINITION GROUNDWATER DEPTH Interpolated value: Interpolated value: 10’ 10’ 10’ 10’ 10’ 10’

HIGH DEFINITION GROUNDWATER DEPTH Estimated value: 60’ – 50’ = 10’ Estimated values Variable elevation 60’ elevation 10’ 10’ 10’ 10’ 8’ 9’ 10’ 0’ 0’ 50’ elevation 50’ elevation -5’

HIGH DEFINITION GROUNDWATER DEPTH METHOD Land Surface Elevation minus Groundwater Elevation = High Definition Groundwater Depth

Mapping Groundwater and Surface Water Interconnection 0’ 20’ 50’ River Gaining Inter- connected Surface Water Mapping Interconnection based on High Definition Groundwater Depth Losing Uncertain Depth below land surface or top of surface water Likely Disconnected

Groundwater depth based on Spring 2017 levels

Groundwater depth based on Spring 2017 levels

Groundwater depth based on Spring 2017 levels

Groundwater depth based on Spring 2017 levels

Sacramento Valley Maps

San Joaquin Valley Maps

UC DAVIS STUDY CONCLUSIONS Bear River and Feather River Mostly losing (2005-2017) Yuba River Mostly gaining (2005-2012)

Based on Digital Elevation Model, not river surface elevation (stage) LIMITATIONS Based on Digital Elevation Model, not river surface elevation (stage) Does not account for perched aquifers Requires some interpolation of groundwater elevation data