Assessing Drought Conditions of the Navajo Nation Reservation using Remote Sensing Data

Concerns over drought conditions in the Southwest United States have increased in recent years. Among the most heavily impacted areas is the Navajo Nation Reservation that extends across parts of Arizona, Utah and New Mexico. This area has experienced a multi-year drought since 1994 with few relief periods in between. The drought has severely affected vegetation health resulting in rangeland degradation, increase in vegetation mortality, and enhancement of desertification. Drought indicators that can be detected by satellite remote sensing include vegetation indices such as the Normalized Difference Vegetation Index (NDVI). In this study, NDVI images were evaluated to further understand drought severity throughout the Navajo Nation Reservation. This project focused on creating a temporally and spatially continuous, long term data set that evaluated NDVI anomalies, which were used to indicate drought in specific locations on the reservation. MODIS/Terra Vegetation NDVI Indices, 16-day L3 Global 500m (MOD13A1), were used to a create climatic mean from 2001 through 2011. NDVI anomalies were then calculated for each July for the years 2012 to 2016. Annual average precipitation values obtained from NASA’s TRMM satellite were evaluated to compare NDVI anomalies with precipitation values.The project’s final output will be shared with the Navajo Nation’s natural resource agencies to provide a greater insight for areas that require greater drought relief.