EXAMINING PATTERNS AND DRIVERS OF SPATIAL AND TEMPORAL VARIABILITY IN PLAYA HYDROPERIOD ON THE KANSAS HIGH PLAINS

Playa wetlands are at the lowest point in closed watersheds and receive sediment in runoff from the surrounding watershed. Over the last century, significant portions of the landscape have been converted to row-crop agriculture. During the same period, regional temperatures increased considerably, though rainfall did not exhibit clear trends. Given the dramatic changes in land cover and climate, it is likely that playa hydroperiod has declined and will continue to decline due to increased sediment delivery and evapotranspiration rates. This research seeks to determine how changes in land cover and climate affect timing and duration of water storage in playas. Objectives include: 1) compile local precipitation and temperature data; 2) monitor seasonal variability in playa hydroperiod; and 3) evaluate trends in watershed land cover and morphology, temperature and precipitation, thickness and volume of accumulated sediment, and playa hydroperiod for 70 playas on the High Plains of western Kansas.

Watershed land cover and morphology were assessed using remote sensing and GIS techniques and volume and thickness of sediment accumulation were measured in the field. High spatial and temporal resolution satellite images from the Planet Imagery Archive (www.planet.com) from January 2016 to December 2018 were visually inspected for each month to determine playa water status (i.e., dry, moist, or standing water). Monthly average temperature and precipitation data were compiled from 13 weather stations near the study sites for January 2016 to December 2018. Bivariate correlation analysis and one-way analysis of variance were conducted to assess relationships among watershed land cover and morphology, temperature and precipitation, thickness and volume of accumulated sediment, and playa hydroperiod.

Preliminary results indicate precipitation amount and frequency exert the most influential controls on playa hydroperiod. However, considerable spatial and temporal variability in playa water storage conditions suggest other factors such as watershed land cover and morphology influence playa hydroperiod. Further data analysis is being conducted to evaluate these relationships. These data are essential to assist resource managers in identifying “high-value” playas for protection and/or restoration.