Paleoclimatic Indicators of Surface Water Resources in the Chuska Mountains, Navajo Nation

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Long-term records of hydroclimate for the Navajo Nation are acutely limited. Short records can fail to capture the full range of hydroclimatic variability while longer records illuminate more climate information. Without long-term records to document the natural variability of water resources in the Chuska Mountains, anticipating water availability for the Navajo Nation’s most populated and economically productive areas is difficult. Depressions at the crest of the Chuskas collect snowmelt, providing water for Navajo stock animals, wildlife, agriculture and fish. Recent decades are characterized by declining snow water equivalent (SWE) in snowpack of northeastern Arizona. At the same time, tribal members report that surface waters supporting agricultural practices and community resources on the Navajo Nation have begun to go dry from extended drought. This use-based study is a collaborative effort with Navajo Nation Department of Water Resources (NNDWR) to enhance understanding of surface water resources in the Chuska Mountains. First, we will develop a multi-century long tree-ring reconstruction of snowpack in the Chuska Mountains. Second, we will use satellite imagery from the Landsat program and a Modified Normalized Difference Water Index (MNDWI) to generate the first long-term (30-year) record of lake levels in the Chuska Mountains. Periods of cool-season drought during the instrumental period will be compared with satellite-based lake area estimations and historical accounts of Chuska lake levels to examine the relationship between reduced surface waters and snowpack levels. This information reduces uncertainty around variability in the Chuska climate system and is intended to inform NNDWR evaluation of water scarcity implications, assisting with drought planning and decision-making.

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