Assessing flow and sediment dynamics of Lower Brazos and San Bernard Basins
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abstract
The proposed project is aimed to address three priority issues outlined in the master plan project namely: 1) evaluation of flow regimes, offshore sediment plumes, and Brazos Delta growth; 2) examining joint impacts of removal of the Brazos River Flood Gate (BRFG) and the opening of the San Bernard River mouth; and 3) evaluation of rainfall-runoff modeling for coastal watersheds draining into San Bernard Estuary. It was formed with inputs from regional stakeholders including the Brazoria County, the City of Freeport, Texas Water Development Board (TWDB), the US Army Corps of Engineer (USACE), the US Fish and Wildlife Services, Brazos River Authority (BRA), and concerned citizens.
The project will be conducted by a multidisciplinary team featuring experts in hydrology, hydrodynamics, sediment transport, and marine geology at UT Arlington and TAMU Galveston. The initiative will feature concerted field campaigns and modeling experiments aimed at: 1) establishing flow connectivity along regional streams and rivers as well as the Gulf Intercoastal Waterway (GIWW) during major storm events; 2) quantifying the growth of Brazos Delta, and sediment plume sizes and directions in years after Harvey; and 3) performing scenario analysis to tackle aforementioned issues concerning the local communities. The project will fill major regional data gaps, and attain a clearer, holistic understanding of flow connectivity and sediment dynamics along the Brazos River, GIWW west of the BRFG, the San Bernard River, Caney Creek and along the Gulf of Mexico. The outcomes can be used to inform ongoing, as well as future management plans and restoration strategies. These include TWDB regional flood plans for reducing flooding risks, dredging and related strategies for managing sediments along the lower Brazos River, Cedar Lake Systems, for maintaining the stability of San Bernard River Gulf inlet, for preventing shoreline retreat along Sargent beach, and for sustaining freshwater inflows to Cedar Lakes.
Major deliverables of the project include: 1) analyses of bay-side sediment core data from along Cedar Lake Systems, Sargent Beach, and Mitchell’s Cut (Fig. 1), beach sediment sample analyses from a transect extending from the Brazos Delta to Mitchell’s Cut (Fig. 2), and single beam bathymetric data from the Brazos River mouth to Cedar Cut (Fig. 2); 2) coupled hydrologic-hydrodynamic and sediment transport models configured for scenario analysis; 3) assessment of freshwater inflow for San Bernard River and Cedar Creek during flooding events; and 4) outcomes of scenario analysis for flooding, sediment, and San Bernard River mouth stability.
The project will be executed in close coordination with the USACE Galveston District (SWG), and TxSed project led by GLO, and TWDB Region 8 and 10 flood plan group meetings. The PI will work with stakeholders to ensure that solid connections be established with existing and emerging regional management strategies and initiatives.
