A GIS-Based Framework to Identify Opportunities to Use Surface Water to Offset Groundwater Withdrawals

The over-use of groundwater is an increasing issue even in regions of the U.S. traditionally characterized by abundant rainfall and surface water. Part of the groundwater withdrawals in these regions can potentially be replaced by surface water, and quantitative spatial analysis to demonstrate this potential may help to spur policy changes. However, one challenge for this type of spatial analysis is the lack of groundwater withdrawal data at the watershed scale. For example, estimates of groundwater withdraw are only available at the county-level for most of the U.S., which is not granular enough to be useful for local management decisions. The present study developed a GIS-based framework for spatially disaggregating available groundwater withdrawal information based on ancillary information such as the well’s minimum casing diameter. This information was used to identify potential opportunities where surface water could be used to offset groundwater withdrawals. The application of this framework to irrigation water demand in the state of Louisiana shows that a significant fraction of groundwater withdrawals can potentially be offset by available surface water. This basic framework can be complemented with additional considerations such as the availability of surface water to more fully evaluate water management scenarios.