Lessons From Navajo Nation Water Resources, Utilizing Earth Observations to Monitor Drought
Authors: Castillo Rene 
Published: February 2023

Emergency planning is the act of preparing for emergencies to reduce losses, human and environmental. The planning process is never complete, threats change and the tools we utilize to address them advance. Drought occurrences within North America and the magnitude of drought impacts reveal the persistent vulnerability of the United States to drought, specifically in the indigenous community. Until recently, drought management was largely response oriented, with little to or no attention to mitigation and preparedness. In 2002, the Navajo Nation developed a drought contingency plan but within the past 20 years no adaptation has occurred. With the increase in adverse impacts of climate change in recent years, an emergent need to revise the drought plan to place more emphasis on mitigation has been expressed by the Water Management Branch of the Navajo Nation. Quantification of the main components of drought mitigation and planning include the assessment of who and what is vulnerable and why. Historically, drought mitigation efforts were restricted by data availability, financial capabilities, and data acquisition. The current contingency plan utilizes the Standardized Precipitation Index (SPI) on a 6-month time scale alone. Yet current research shows that drought is a complex natural hazard where no singular index can adequately capture the impacts across the main categories of drought. As the definition of drought is variable across place, time, and discipline, the addition of diverse indices could provide more insight for the development of a further detailed and tailored drought contingency plan. As such, it has been found that assessing all categories of drought could improve the Navajo Nation&#8217;s drought contingency plan by exposing new concepts not yet considered in mitigation efforts. Adding to the currently utilized index that is based off the sole parameter of precipitation, evaluated here is how temperature, humidity, snow cover, vegetation health, and stream flow. These additional factors are able to compare the meteorological drought vulnerability and severity assessment with the Standardized Precipitation Index (SPI) through the development of a web app to display multivariate indices. Hydrological drought should best match meteorological drought both spatially and temporally with agricultural and socioeconomical drought varying the most from the Standardized Precipitation Index (SPI) used for the Navajo Nation Drought Contingency Plan (2002). By applying diverse indices and social data to the Navajo Nation and developing maps across Google Earth Engine and GIS platforms, gaps in risk and vulnerability assessments can be addressed for preparation and mitigation efforts. Predictors for differing categories (hydrological, agricultural, and socioeconomic) may not predict the same important indicator(s) as the meteorological SPI, further establishing a need for multi-index integration and future drought research. This study identifies a methodology for remote and spatial, GIS-based assessment of drought indexing and vulnerability assessment across the Navajo Nation to address broader water management. The identification of insightful drought indices and drought vulnerability is an essential step in addressing the risks and vulnerabilities across the Navajo Nation and may lead to better informed mitigation-oriented drought management for tribal governments, both Navajo and within North America.