Competition of Nearby River Deltas: How the Brazos River Delta closed the San Bernard River Mouth with the help of Coastal Infrastructure
Abstract
Coastal engineering projects are often aimed at improving channel navigability, but sometimes these efforts create unintended consequences. This study examines the dynamics of two river mouths- the Brazos and the San Bernard- on a heavily engineered coast near Freeport, Texas. The history of both river mouths has been influenced by the diversion of the Brazos River and the construction of the Gulf Intracoastal Waterway (GIWW); together, these changes have led to differing patterns of sedimentation in the two rivers, and the closing of the San Bernard River mouth due to rapid growth of the Brazos delta. To document the closing of the San Bernard and the resultant complications, the morphology of the study area was documented chronologically using publicly available bathymetric surveys, historical nautical maps, LiDAR scans, and aerial imagery. Sedimentation in the GIWW has caused the San Bernard to abandon its natural channel to the sea, and instead flow down the GIWW. The abandoned channel is now filling rapidly with sediment. After Hurricane Harvey, floodwater breached the abandoned channel, and a shallow opening has displayed highly dynamic morphology to the present day. This reduction in flow down the terminal stretch of the San Bernard has reduced the erosive ability of the river, allowing the adjacent Brazos delta to grow, further constricting the mouth of the San Bernard. In conclusion, the combination of reduced flow through the main channel and influence from the Brazos delta suggests that only an engineered river mouth could permanently restore typical flow conditions of the San Bernard.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMEP23E2255M
- Keywords:
-
- 0442 Estuarine and nearshore processes;
- BIOGEOSCIENCES;
- 1825 Geomorphology: fluvial;
- HYDROLOGY;
- 3020 Littoral processes;
- MARINE GEOLOGY AND GEOPHYSICS;
- 4560 Surface waves and tides;
- OCEANOGRAPHY: PHYSICAL