Groundwater Dependent Ecosystem Connections to Hydrometeorology and Management in Arid Environments

Groundwater dependent ecosystems (GDEs) rely on the presence of subsurface or surficial expressions of groundwater. These systems are receiving more attention in the Great Basin, USA, and in other arid environments where groundwater development is increasing, and where the limit of groundwater development is based on the natural groundwater discharge. Phreatophyte shrublands, meadows, springs, and riparian areas are GDEs that provide critical habitat for many sensitive species in arid and semi-arid environments. 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 vegetation vigor changes within GDEs, historical vegetation vigor is paired with hydrometeorology archives and land and water use change information. 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 changes are evaluated through analyses of historical vegetation indices, evaporative demand, annual and seasonal precipitation, groundwater levels, land and water use histories, and the complementary relationship of evapotranspiration and evaporative demand. Results clearly illustrate strong connections between vegetation vigor, evaporative demand, precipitation, and groundwater levels. Groundwater development in many areas of the Great Basin has caused noticeable changes in vegetation vigor beyond the historical natural variability. Having three decades of high resolution Landsat satellite imagery, paired with retrospective hydrometeorology information, provides new perspective on how GDEs respond to hydrometeorology and groundwater development, and offers a new and unique long-term monitoring opportunity.