Civilizations have typically obtained water from surface-water resources throughout most of human history. Only during the last 50-70 years has a significant quantity of water been obtained by pumping groundwater. During this short time, alarming levels of groundwater depletion have been observed worldwide, especially in semi-arid and arid regions that rely heavily on groundwater pumping from clastic sedimentary basins. In order to reverse the negative effects of over-exploitation of groundwater resources, we must transition from treating groundwater mainly as an extractive resource to one in which sustainable management is pursued more aggressively. Numerical groundwater models are valuable tools for characterizing groundwatersystems, but are often hamstrung by limited data and/or poor process representation. Two case studies are presented to highlight both the value and the uncertainty of models for understanding water budgets and representing water-flow processes. (1) A comparison of two regional-scale agricultural groundwater models of the Central Valley shows how conceptual differences and lack of comprehensive groundwater pumping measurements contribute to differences in water budget estimates. (2) Simulations of managed aquifer recharge (MAR) dynamics reveal the influence of alluvial geologic architecture on MAR potential and highlight the value of capturing detailed geologic heterogeneity and physical processes that are not typically included in groundwater models when evaluating MAR potential.
About the Speaker: Stephen Maples
Stephen Maples is a PhD candidate and NSF Graduate Research Fellow in the Hydrologic Sciences Graduate Group at University of California, Davis under the guidance of Dr. Graham Fogg. Broadly, his research interests include assessing groundwater availability and sustainability in agriculturally-dominated regions like California’s Central Valley. His research uses numerical groundwater models to evaluate the feasibility of groundwater recharge, assess questions related to model complexity and uncertainty, and explore feedbacks between surface water, groundwater, climate, and human systems. Stephen received a B.S. in Geological Engineering and an M.S. in Hydrogeology from the University of Nevada, Reno. He has worked as a hydrologist with the U.S. Geological Survey (USGS) Nevada Water Science Center in Carson City, NV.
Host: Erica Woodburn