Wednesday, April 2, 2008 : 3:00 p.m.

Scenario Based Modeling for Future Groundwater Management Planning

Tim Lant, PhD and Vanessa Marie Escobar, Arizona State University

The availability of future water supplies in central Arizona depends on the interaction of multiple physical and human systems: climate, hydrology, water and land-use policy, urbanization, and regulation.  A central problem in the predictive use of groundwater modeling is that climate and population growth predictions impact subsurface hydrology. Surface water supplies, new urban developments and changes in land-use will not be shared uniformly across the region but must be integrated into groundwater plans.  We present our integrated scenario tool WaterSim and show results from integrating this with MODFLOW.  Further feedback effects from groundwater studies may limit future urbanization.   

 We connect two existing models: the WaterSim model, developed at the Decision Center for a Desert City; and the Salt River Valley-1983 groundwater model, developed by the Arizona Department of Water Resources using the MODFLOW application. We built an interface that connects WaterSim to MODFLOW in order to portray groundwater drawdown (at specific points) as a function of climate change, population growth, and groundwater policy.  

 WaterSim is used to calculate the groundwater required by each water provider based on exogenous parameters (streamflow, runoff, population growth, and drought) and policy levers (groundwater policy, retirement of agricultural land, and residential use).  This output is distributed across the water provider areas in the form of pumping schedules for input to MODFLOW for the same period of time.  Outputs are aggregated to show the sensitivities of groundwater to changes in climate, population growth, and land-use under alternative policies over the full range of scenarios produced by WaterSim. 

Tim Lant, PhD, Arizona State University Dr. Lant holds a joint appointment at Arizona State University as the Assistant Director for the Decision Theater and Assistant Research Professor in the Department of Mathematics and Statistics and the Decision Center for a Desert City. He earned his Ph.D. in applied mathematics with specialization in mathematical biology at Arizona State University and holds a master’s in actuarial science and a B.S. in mathematics, summa cum laude, from Georgia State University. Dr. Lant develops scenario-based mathematical and system dynamics models for policy analysis and planning in areas including water and natural resource management, urban planning and sustainability.

Vanessa Marie Escobar, Arizona State University Vanessa Escobar is Master’s Degree student in geological sciences from the School of Earth and Space Exploration at Arizona State University. She earned her B.S. in geology, with distinction, from Sonoma State University in California. Vanessa’s research is concentrated in groundwater sensitivity scenarios and the incorporation of population, climate and urbanization impacts into MODFLOW using a systems dynamic climate model; WaterSim. Previously, she worked as a hydrogeological consultant for Southwest Ground-water Consultants Inc., URS Inc. and the US Army


2008 Ground Water Summit