Whitney P. Broussard III, Institute for Coastal Ecology and Engineering, University of Louisiana at Lafayette, Lafayette, LA 70504: wbroussard @louisiana.edu; Jian Chen, Informatics Research Institute, University of Louisiana at Lafayette, Lafayette, LA 70504: jchen@louisiana.edu; Fabiane B. Santos, School of Geosciences, University of Louisiana at Lafayette, Lafayette, LA 70504: fbs8852@louisiana.edu; Emad Habib, Department of Civil Engineering, University of Louisiana at Lafayette, Lafayette, LA 70504: habib@louisiana.edu; David M. Borrok, School of Geosciences, University of Louisiana at Lafayette, Lafayette, LA 70504: dborrok@louisiana.edu
This presentation is based on research developed through an NSF-funded Water Sustainability and Climate project titled “A surface water management framework to counterbalance groundwater withdrawals in wetter regions of the U.S.” Here, we address the question, “Is there enough ‘excess’ surface water available in the region to address the groundwater supply gap in the Chicot aquifer without harming wetland ecosystems?” We are building a GIS-based tool that can investigate this question through a historical analysis of water use and water availability relationships, and a predictive model of alternative water management scenarios such as rainwater harvesting, the construction of collection reservoirs, or diversions of freshwater to agricultural areas. This presentation focuses primarily on the geospatial framework that will form the basis of our modeling tool.
To date we have extrapolated water bodies in the study area from the National Hydrography Dataset Plus. Location nodes for water users were created based on Louisiana Department of Natural Resources water well data and US Geological Survey Water Use in Louisiana reports. Most of the current estimates for water use are aggregated to the county level. We utilize a disaggregation method to geographically distribute county-level data using dasymetric mapping with object-oriented classifications. This disaggregation method utilizes the National Land Cover Database and the Cropland Data Layer to appropriately distribute the summary data across the landscape. The crop type, land use, and water use are based on user-level information within the Parishes accessed through social surveys, U.S. Department of Agriculture local extension records, and Parish-scale information based on population and agriculture census data. A near-distance algorithm was used to measure the proximity of user nodes to the nearest suitable surface water body.
Rainfall-runoff estimates are currently being developed into an availability budget. Once incorporated into the GIS framework, the model will maximize the number of satisfied users and minimize the distances from the users to the surface water body that can meet their demands. This management tool will operate on many different geospatial scales, which will be useful for water managers and transferrable to many “wetter” regions in the U.S. It will be made feely and openly available to the public.
Keywords: water use, water availability, geospatial model, dasymetric mapping