LINKING MOUNTAINS TO VALLEYS: EXPLORING THE INFLUENCE OF MOUNTAIN HYDROLOGY on TRADITIONAL ACEQUIA IRRIGATION SYSTEMS

For both socio-economic and environmental reasons, the Rio Hondo, which drains the Sangre de Cristo Mountains north of Taos, NM, is of vital importance when studying the effects of climate change on New Mexico. As a tributary to the Rio Grande, it is an integral part of NM water supply and is therefore particularly interesting as a snow-fed mountain watershed vulnerable to future climate change. Rio Hondo is also unique however, because in its downstream valley it feeds a traditional New Mexican acequia irrigation system that has been in place for centuries. Using GSFLOW, which combines the precipitation/runoff modeling capabilities of PRMS with the groundwater modeling facilities of MODFLOW, we work to marry the deeper mechanisms of recharge within the mountain block with the shallower ground and surface water hydrology of the acequia irrigation valley. This modeling is informed by an end member mixing analysis based on isotopic and chemical characteristics of upstream and downstream surface water, springs, and groundwater well samples. A better understanding of the hydrologic mechanisms both in the mountain block and in the valley will help downstream acequia users better understand the sources of water for the traditional irrigation system and help them plan for the future influences of land use or climate change. A close association with the local acequia governing body and effective communication of scientific findings is therefore an integral part of this project.