The Four Corners Region of the southwestern United States is an arid and topographically complex region, with a majority of the annual precipitation occurring during the summer monsoon season and the winter months. The region is home to the Navajo Nation that spans roughly 27,500 square miles and nearly 174,000 people. Lack of infrastructure as a result of minimal economic resources confounded by environmental and climatic factors have limited access to a clean water supply for many Navajo. Access to water resources are critical for the Navajo’s energy-water-food nexus (EWFN) and economic sectors, including agriculture. Currently, precipitation observations at the surface within Navajo reservation boundaries are sparse and radar coverage is insufficient. Limitations of surface precipitation observations distributed throughout the Navajo Nation make hydrologic assessments for water resources difficult. The use of space-borne precipitation observations is believed to provide the best spatial coverage for precipitation observations in the region. This research demonstrates using NASA’s Integrated Multi-satellitE Retrievals for GPM (IMERG) that satellite-based rainfall estimates can be utilized for hydroclimate analysis for stakeholders in the Four Corners Region and for the Navajo Nation. With knowledge of the behavior of the satellite precipitation products, especially on a monthly and seasonal basis, water resource managers in the region and on the Navajo reservation can have access to high-resolution precipitation observations to assess water resources and drought conditions. IMERG V06 is used with data from the North American Land Data Assimilation System (NLDAS-2) to conduct a geospatial water budget analysis for the Navajo reservation. The water budget analysis provides the Navajo Nation with a unique spatial analysis of surface hydrology and provides critical assessments of available water for the establishment of a novel precipitation metric. The precipitation per livestock (PPL) metric is developed using IMERG V06 and the Gridded Livestock of the World dataset to quantify spatial trends in available water through Precipitation-Evapotranspiration-Consumption maps. This research is a proof of concept and aims to provide ranchers and farmers as well as families that keep livestock for cultural traditional purposes to better understand the climatological water demands to maintain their herds.
