Development of a Water Resource Forecasting Tool for the Black River Basin, New Mexico

Alterations in land use, and more recently the impacts of climate change, are understood to be influential factors affecting both water supply and demand in the arid southwest. Due to its ecological importance and hydrological characteristics, the Black River Basin in southeastern New Mexico provides a unique setting to test and quantify such effects. Originating in the Guadalupe Mountains, the Black River is a spring-fed tributary to the Pecos River—their confluence just a few miles upstream of where the Pecos flows into Texas. The Black River contains key aquatic species of concern, such as the Texas hornshell mussel (Popenaias popeii), whose populations have become confined to the Black River. The basin is underlain by productive karst and alluvial aquifers that are the primary sources of water for local farming and industry. Many irrigators have turned to selling groundwater formerly used for agriculture to oil and gas extractors, raising concerns about diminished return flows to the aquifer. This study examines the effects of changes in groundwater use on the flow of the Black River in order to inform effective and innovative management solutions. The Water Evaluation and Planning model (developed by the Stockholm Environment Institute) was used to simulate basin conditions and develop supply estimates under various demand and climate change scenarios. Flow measurements from source springs and river gages determined water supply, while records of groundwater pumping and surface diversions were used to determine water demand. Data availability and reliability constrained calibration of the initial model to a 10-year period. The model parameters were adjusted to reflect scenarios that depict potential policy and market-based management strategies, including land use changes, while also considering a range of climate change scenarios.