Groundwater Dependent Ecosystem Connections to Hydrometeorology and Management in the Great Basin

Groundwater dependent ecosystems (GDEs) rely on the presence of subsurface or surficial expressions of groundwater. These systems are receiving more attention where groundwater development is increasing, or where the limit of the appropriation of groundwater is based on capturing natural discharge for beneficial use. Phreatophyte shrublands, meadows, springs, and riparian areas are GDEs that provide critical habitat for many sensitive species in the Great Basin. While GDEs are vital for ecosystem services and function, their spatial and temporal variability is poorly understood with respect to local and regional scale hydrometeorology, and rangeland and groundwater management. Long term monitoring of GDEs is often a key requirement for evaluating the effectiveness of restoration and preservation, and identifying potential impacts from groundwater development. To better understand natural and anthropogenic changes of GDEs in the Great Basin, historical vegetation vigor is paired with historical hydrometeorology and known rangeland management and groundwater development activities. The Google Earth Engine cloud computing and environmental monitoring platform is utilized to access and analyze the entire Landsat archive along with downscaled National Land Data Assimilation System (NLDAS) gridded weather forcings of solar radiation, air temperature, humidity, windspeed, and precipitation. GDE connections to hydrometeorology and management are evaluated through analyses of historical vegetation indices and land surface energy balance estimates, evaporative demand anomalies and land surface-atmospheric feedbacks, annual and seasonal precipitation, groundwater levels, and rangeland management history. Results of this analysis clearly illustrate that there are strong negative correlations between changes in vegetation vigor, land surface energy balance, and evaporative demand anomalies, and positive correlations between changes in vegetation vigor, land surface energy balance, and depth to groundwater. Rangeland management and groundwater development in many areas of the Great Basin has caused noticeable changes in vegetation vigor beyond the historical natural variability.