LAUSR

We used Landsat imagery to examine surface-water dynamics over the past 27 years in 39 salt lakes (salinas) of the Southern High Plains of the U.S. These groundwater- and precipitation-fed wetlands are regionally unique habitats with high salt concentrations and halophytic biota that may be vulnerable to hydrological changes from groundwater extraction for agriculture coupled with drought. We documented amounts and occurrences of water within the 39 salinas, comparing summer and winter (representing periods of high and low groundwater demand, respectively) in 1986–2013. During this span in our study area, total and irrigated cropland acreage increased, and the saturated thickness of the Ogallala Aquifer decreased by ~18.3%. There was variation in inundation frequency by salina, with two never holding water during our study. A third of the salinas went dry at least once, slightly more in summer than winter. Occurrence of water was not simply a function of basin size or to depth to the aquifer. These wetlands are being impacted by human changes to the landscape that are diminishing groundwater inputs, effectively creating novel wetlands that are now primarily supplied by precipitation rather than groundwater, with altered hydrological and ecological traits that may exacerbate regional vulnerability to climate change.