U.S. Geological Survey
Knowledge of groundwater recharge is critical for assessment of water resources and determination of aquifer vulnerability to contamination. California Groundwater Sustainability Plans will require maps of groundwater recharge areas and an understanding of recharge processes. In addition, recharge information will be important for calculating water budgets and applying hydrologic simulation models. This talk will review methods for estimating groundwater recharge that might by appropriate for application in California watersheds in light of established guidelines for implementing the Sustainable Groundwater Management Act.
Estimating recharge is a difficult proposition. A variety of estimation methods are available, including water-budget methods, modeling methods, tracer methods, streamflow hydrograph analysis, and the water-table fluctuation method. A degree of uncertainty is associated with any recharge estimate because of limiting assumptions on which methods are derived, lack of quality data, and spatial and temporal variability of hydrologic processes. A full understanding of the conceptual hydrologic model is a prerequisite for selection of appropriate estimation methods. Time and budget constraints and availability of data should also be considered in the selection process. Most important, though, is a consistency among assumptions made in the conceptual hydrologic model with those inherent to development of the recharge estimation method. A fundamental understanding of the assumptions, data requirements, space and time scales of application, and estimation uncertainty of any estimation technique serves as a basis for proper selection and successful application of recharge estimation methods.
*Early Registration (August 31) is $75 for Members* and $100 for Non-Members*
*Registration after August 31 is $100 for Members* and $125 for Non-Members*
Rick Healy is an emeritus research hydrologist with the U.S. Geological Survey in Boulder, Colorado. He has been conducting research on water and contaminant transport through the unsaturated zone for more than 40 years. His principal areas of interest are estimation of groundwater recharge, numerical simulation of subsurface water flow and solute transport, and the effects of energy development on water resources. He has published several journal articles on groundwater recharge and is the author of the book, Estimating Groundwater Recharge, published by Cambridge University Press in 2010. He also developed the VS2DI suite of programs for simulating water, solute, and heat transport in the unsaturated zone. Rick received a BS and MS in mathematics from the University of Illinois.
Tom McCarthy serves as the General Manager for the Mojave Water Agency (MWA). MWA is one of 29 State Water Contractors with access to California’s State Water Project, MWA also serves as the Watermaster for Mojave Basin Area. Mr. McCarthy is a State of California registered professional civil engineer, as well as a California registered professional geologist. He has a Bachelor of Science in Geological Sciences from the University of Oregon and a Master of Science in Civil and Environmental Engineering from the University of California, Los Angeles.