MONITORING AND MODELING CLIMATE CHANGE ON THE NAVAJO NATION, SOUTHWESTERN UNITED STATES

Native Americans of the southwest live on ecologically sensitive semiarid to arid lands with limited resources. On the 65,000 km2 Navajo Nation, southern Colorado Plateau, traditional people often live a subsistence lifestyle. Increased temperature and changing precipitation are transforming the landscape and thereby negatively impacting the residents. For people to continue to inhabit these lands successfully, we must both understand the processes that are rapidly altering these drylands and develop mitigation strategies. Our research objective is to record, assess, and model the interactions between: 1) climate variability, 2) landscape sensitivity to eolian processes, 3) landscape response to changes in native and invasive vegetation, and 4) fluvial processes in relation to flooding and sediment availability. To this end, our team is: 1) using a network of meteorological stations to calculate, and map, ratios of precipitation to potential evapotranspiration; 2) establishing in-situ automated cameras to record changes in dune morphology and capture dust transport; 3) performing repeat high-precision GPS and terrestrial Lidar surveys to assess dune migration rates; 4) using high-resolution remote sensing to record changes in vegetative cover, speciation, and phenology, as well as landscape vulnerability to eolian processes; and 5) documenting planform changes in the Little Colorado River. With this data we are creating a record of climate variables and coincident landscape change on the Navajo Nation that will provide for modeling the effects of climate change on the landscape. Initial assessments indicate that the areal extent of sand susceptible to mobilization has increased significantly; recorded sand dune migration rates are in excess of 35 m/yr and regionally significant dust storms emanating from the study area are becoming common. Additionally, remobilized surfaces are rapidly changing in vegetative cover and composition. Furthermore, channel change, although influenced by changing riparian vegetation, appears to be driven by flow variation that is in turn related to precipitation variability