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TEXAS KEITH LAKE MODELING MANAGEMENT MX964017
Impact/Purpose:
Background: The Keith Lake / Salt Bayou system of wetlands is an important site for over-wintering waterfowl and for the protection of other fauna and flora in the region. Hydraulically-connected shallow lakes such as Keith Lake, along with small bayous, form a large wetland complex. Historical and recent modifications to the landscape, most notably navigation channels, have connected what was once a predominantly freshwater system to tidal waters with marine salinities. At the current time, the wetlands are degrading significantly. Freshwater plants are dying and the organic soil is eroding since it is no longer held together by growing roots and the accumulation of decomposing plants. The delicate balance between estuarine functions and the historical wetland function is controlled by the balance of fresh and salt water in the system. This balance is currently too far toward the estuarine side. The capabilities for technical analyses within the Texas Water Development Board will be used to help regional water and environmental resource managers find cost-effective strategies to address wetland-related concerns that have implications in the context of regional watershed planning.
Objectives: The J.D. Murphree Wildlife Management Area and the adjoining MacFaddin National Wildlife Refuge represent the largest contiguous coastal marsh area in Texas, encompassing about 79,000 acres. Refuge managers have identified a need for freshwater inflow structures at the upper end of the Keith Lake / Salt Bayou system to assist them in managing the salinity gradient within this large area. A model of the system, the TxBLEND model, will allow managers to assess feasibility and benefits of potential remedies. Model development will also produce a model applicable to other microtidal marsh systems of the Gulf Coast.
Tasks will include flow and salinity data collection to support model application and calibration, model configuration work involving parameterization for shallow systems, and model application for wet and dry conditions along with various scenarios of structure placement and operation. Several kinds of data, such as physical, hydraulic, and ambient water quality data, will be collected to support the project objectives. At some sites, recording instruments will be installed to measure salinity and flows over extended periods of times. These long-term data sets capture tidal and meterorologically forced water movements which are difficult to capture by field teams. The types of probes used by field teams and on the recording instruments are very similar, contributing to data comparability.
Description:
The Keith Lake / Salt Bayou system of wetlands is an important site for over-wintering waterfowl and for the protection of other fauna and flora once abundant in the region. This project will help water resource managers find cost-effective strategies to address wetland problems and assist with habitat restoration.