Restoration of Freshwater Inflows: the Use of Spatial Analysis for Hydrologic Planning in the Anahuac National Wildlife Refuge, USA

Upstream agriculture and infrastructure development can greatly alter downstream hydrology, cutting off water sources and modifying connectivity that is critical for wetland survival. For tracts within the Anahuac National Wildlife Refuge (ANWR) located on the Texas Gulf Coast, our overall objective was to identify how much freshwater was needed to offset these processes. We sought to examine the historical trajectory of wetlands change, identify how to optimally route water through former agricultural canals, and make initial gross estimates of the volumetric water requirements. To prioritize specific restoration actions given the extremely flat topography of this sheet flow landscape, we used a combination of field survey by Unmanned Aerial Vehicles (UAVs), direct observation via airboats, Global Navigation Satellite System (GNSS) technologies, and remote assessment using aerial photography, LIDAR datasets, and Geographic Information Systems (GIS). We found that the optimal solution would minimize construction work and the quantity of water needed for purchase, while maximizing the inundation across the landscape. The unique combination of spatial technologies applied in this study provides a template for future work in similar sheet flow-fed landscapes affected by hydrologic disconnection and relative sea level rise.