Evaluation of Recharge and Evapotranspiration Estimation Methods in the Mississippi Alluvial Plain

Tuesday, December 5, 2017: 11:40 a.m.
David Ladd , Lower Mississippi - Gulf Water Science Center, U.S. Geological Survey, Nashville, TN
Meredith Reitz , National Research Program - Eastern Branch, U.S. Geological Survey, Reston, VA
Brian Clark , Lower Mississippi-Gulf Water Science Center, U.S. Geological Survey, Fayetteville, AR

The Mississippi River Valley alluvial aquifer which underlies the Mississippi Alluvial Plain (MAP) is heavily used for irrigated agriculture and is one of the top three aquifers in the U.S. in terms of groundwater withdrawals for irrigation. Recharge and evapotranspiration (ET) are critical components of the overall water budget in the MAP area. Variations in the magnitude and spatial distribution of these water-budget components due to differing estimation methods could affect the results of the groundwater flow model developed for the Mississippi Embayment Regional Aquifer System (MERAS) used to simulate flow in the MAP area. A comparison of available methods to estimate recharge and ET points out the variability in estimates of these water budget components in the MERAS area. The results for recharge estimates from the PRISM-based calculations used in the original MERAS model are compared to those from the Soil-Water-Balance (SWB) model and from long-term Empirical Water Budget (EWB) estimates. The recharge estimates are examined in areas of differing irrigation intensity, and compared to field-based estimates where available.
David Ladd, Lower Mississippi - Gulf Water Science Center, U.S. Geological Survey, Nashville, TN
David began working for the U.S. Geological Survey (USGS) in late 1992 and serves as a hydrologist and GIS Specialist for the USGS Lower Mississippi-Gulf Water Science Center in Nashville, TN. David has served as both a project manager of studies that focus on GIS methods and an instructor of GIS software and techniques. His current focus pertains to spatial analysis and water-balance modeling in regional studies of groundwater availability.


Meredith Reitz, National Research Program - Eastern Branch, U.S. Geological Survey, Reston, VA
Dr. Meredith Reitz received a B.S. in Physics from Arizona State, and a Ph.D. in Physics from the University of Pennsylvania, where her thesis research focused primarily on rivers and landscape evolution. She then received a postdoctoral fellowship to work at Columbia University’s Lamont-Doherty Earth Observatory for two years. She has been with the USGS in Reston, Virginia since August 2014, where she works primarily on developing estimates of evapotranspiration, recharge, and surface runoff using a variety of remote sensing and ground-based data sources.


Brian Clark, Lower Mississippi-Gulf Water Science Center, U.S. Geological Survey, Fayetteville, AR
Brian Clark is a hydrologist with the USGS. He received a BS from Arkansas Tech (1998) and MS from Baylor University (2000). His research interests include groundwater-flow modeling and geographic information systems.


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