A high-resolution integrated hydrology-hydrodynamic model of the Barataria basin system

摘要

The Barataria Basin, a bar-built estuarine system located directly west of the Mississippi Delta, has been experiencing a significant land loss, especially since the leveeing of the Mississippi River for flood control purposes in early 20th century. Recent efforts to alleviate the land loss problem include the construction of man-made freshwater diversion structure in order to divert river water as well as its associated suspended sediments from the Mississippi River into the Barataria Basin. In order to implement an ecologically friendly management plan of those diversions, a careful examination of the anticipated salinity alterations resulting from the operation of the diversions is required. A high-resolution (O (100m)), integrated hydrology-hydrodynamic model of the Barataria Basin has been developed to simulate the local hydrological cycle over the surrounding drainage basin and hydrodynamics within the basin. A hydrological model of local freshwater runoff from the surrounding drainage basin is coupled to a two-dimensional depth-integrated hydrodynamic model of the basin. The integrated model is forced by observed tides coming from the Gulf of Mexico, local wind, rainfall and evaporation over the model domain, salinity and temperature estimated at the open boundary located offshore of the mouth of the bay. Estimated local precipitation and evaporation over the model domain provide hydrological forcing to the hydrological model, that in turn simulates local runoff into the hydrodynamic model. A novel feature of the hydrodynamic model is its use of a very accurate advection scheme, thus, enabling accurate simulation of salinity variations in response to changes in various hydrological forcing functions. A flood event that took place during the tropical storm Allison in June 2001 resulted in significant sea-level changes especially in the upstream region of the basin. The integrated model appears to be able to capture a significant portion of the observed sea-level variations during the flood. Significant effects on water level and salinity are observed in the multiply connected channels through the marsh in the vicinity of operating diversion structure and in the open waters downstream.