Evidence of Surface Connectivity for Texas Gulf Coast Depressional Wetlands

Depressional wetlands are distributed throughout the United States and provide many essential ecosystem services. It is important, from both an ecological and a regulatory perspective, to understand the surface water pathways that connect such wetlands to each other and to surrounding water bodies. For many of these wetlands systems, the amount of surface water discharged is poorly quantified. In this paper we report on a 45-month study quantifying the surface discharge characteristics of a wetland on the Texas Gulf of Mexico Coastal Plain. The results of this study indicate that surface runoff, although intermittent, occurred regularly and accounted for more than 17% of watershed precipitation over the 45 months, with annual runoff ranging from 0% to 27%. Runoff typically occurred in precipitation-driven pulses and coincided with increased runoff in adjacent waterways. The detailed results of this study and similar observations from other locations run contrary to the widespread perception that depressional wetlands on the Texas Gulf Coast are hydrologically isolated—which calls into question the regulatory policies governing large tracts of coastal plain wetlands (at least 400,000 ha in Texas alone).