Examining Playa Wetland Inundation Conditions for National Wetland Inventory, Soil Survey Geographic Database, and LiDAR Data

Abstract

Inundation is a critical parameter of wetland hydrologic performance. This study uses Annual Habitat Survey data from 2004 to 2012 in the Rainwater Basin in south-central Nebraska to examine differences between the actual inundation conditions and three datasets: the National Wetland Inventory (NWI), the Soil Survey Geographic database (SSURGO), and LiDAR-derived depressions. The results show that current wetland inundated areas were well overlaid with these datasets (99.9 % in SSURGO data, 67.9 % in NWI data, and 87.3 % in LiDAR-derived depressions). However, the hydrologic degradation of playa wetlands was not reflected in these datasets. In SSURGO data, only 13.3 % of hydric soil footprint areas were inundated and 26.6 % of footprint areas were covered with hydric vegetation during this period. For playa wetlands identified in NWI data, only 30.7 % were inundated during this period and 60.5 % were covered by hydric vegetation. A significant portion of the playa wetlands were not functioning with either ponding water or supporting hydric vegetation during the peak of the waterfowl spring migration season in the Rainwater Basin. The findings confirm that watershed-level hydrologic restoration and within wetland restoration is crucial to recover the inundation conditions of playa wetlands.