Blackwater

Objectives

Improve the understanding of hydrology and tidal flow processes through a coastal marsh, including the effects of sediment geochemistry, freshwater impounding, sea level rise, ground water inputs, anthropogenic effects, and the influence of wind and waves.

Statement of Problem

Deterioration and loss of marsh and forested wetlands at Blackwater National Wildlife Refuge is being caused by rising sea level, invasive species, degraded water quality, and human activities. The relative contribution from the various causes is unknown. Wetland restoration is planned for the Refuge, but without a better understanding of the reasons for wetland loss and the hydrology of the system, it may be ineffective.

Strategy and Approach

The USGS will deploy field instrumentation at a number of sites to monitor tidal stage, stream discharge, ground-water discharge and water-quality parameters in the marsh. A variety of instrumentation configurations will be deployed depending upon available funding and parameters of interest for any particular task of the project. The USGS will retrieve, analyze, and interpret the data on a regular basis, and provide results and assessments to the cooperator organizations. The project is subdivided into three related tasks: 1) monitoring the effectiveness of a barricade at Stewart's Canal for preventing saltwater intrusion into the upper reaches of the marsh, 2) monitoring changes in water quality and hydrologic response on the Little Blackwater River, a major tributary, resulting from the construction of a planned 3200-home development within the watershed, and 3) monitoring tidal flow and water quality within the main part of the Blackwater National Wildlife Refuge wetland before and during marsh restoration, and investigating the underlying causes and processes of marsh deterioration.