Factors Influencing the Occurrence of Inundated Playa Wetlands During Winter on the Texas High Plains

Frequency and duration of playa inundation (i.e., hydroperiod) are major influences on the spatial and temporal distribution of flora and fauna in the western Great Plains. We used a 10-year data set of 221 playa wetlands to develop models of factors influencing the probability of a playa being flooded during January. We evaluated the relative influence of landscape and precipitation variables on the probability of a playa being inundated during January. Of the surveyed playas, 67% were inundated in >= 1 year and 33% never contained water in January. Our selected model indicated that the proportion of grassland in the watershed, mean annual rainfall, the previous year's total rainfall, and playa size as variables in the top ranked models for the probability of a playa being inundated during January. Proportion of grassland in the watershed had the largest positive effect. The probability of a playa being inundated during January increased from west to east across the THP and on average, we would expect individual playas to be inundated approximately once every 11 years, with similar to 30% of the playas inundated at a frequency greater than 1 year out of 10. Playas with cropland watersheds had diminished hydrologic function.