New Mexico Geological Society Annual Spring Meeting — Abstracts

Bosque del Apache National Wildlife Refuge (refuge), located along the Rio Grande near San Antonio, New Mexico, provides a critical stopover for migrating waterfowl and is managed by U.S. Fish and Wildlife Service. The 57,331 acre refuge is made up of several different habitats principally defined by their water requirements, including active floodplain, seasonal wetlands, and desert. Understanding the magnitude and variability of different components of the refuge water budget is critical to managing the refuge water use and to achieving the essential mission of protecting wildlife for future generations. The refuge relies on surface water deliveries and on groundwater pumping to create wetland habitat. Unlike traditional agriculture, the refuge irrigates in winter months when evapotranspiration losses are at their lowest for the benefit of migratory birds. Groundwater infiltration and flow are not measured by the refuge’s surface water outflow gages, but any unused irrigation returned to the system through the subsurface could augment the refuge’s return-flow credit. Measurement of discharge inflows and outflows as well as estimates of groundwater fluxes, evapotranspiration and precipitation are being used to develop the water budget. This study will address specific research questions such as: what is the groundwater flux from the refuge to the main return-flow drainage system, what surface water data gaps exist that may cause potential errors in the water budget estimates, and how might spatial variations in irrigation and in evapotranspiration between different managed and unmanaged habitats contribute to return flows? Along with addressing these specific research questions, the final product will include documentation of a method to calculate consumptive use in a managed riparian wildlife habitat.