Optimum Use of Fresh Water to Restore Baldcypress – Water Tupelo Swamps and Freshwater Marshes and Protect Against Salt Water Intrusion: A Case Study of the Lake Pontchartrain Basin

Abstract

Freshwater wetlands are important in the Mississippi Delta for habitat, water quality improvement, fisheries, carbon sequestration, and as a buffer against hurricane storm surge and waves. Forested wetlands are particularly important as hurricane buffers because of their 3-dimensional structure and their resistance to blow down during hurricanes. Fresh wetlands will be severely threatened by accelerated sea-level rise, more frequent stronger hurricanes, and intense drought that will lead to progressive inundation and saltwater intrusion. The Lake Pontchartrain Basin contains the largest area of tidal freshwater wetlands in the Delta. To ensure sustainability of fresh wetlands, a consistent source of fresh water is needed to counter increasing salinity levels. Sustainable restoration of baldcypress-water tupelo swamps in the Pontchartrain Basin can only be achieved through wise use of point and non-point sources of fresh water. In this paper, we identify potential sources of fresh water in the Pontchartrain Basin and determine the feasibility of engineering these to maximize sheet flow to enhance freshwater wetland health. Sources of fresh water include coastal plain rivers, Mississippi River diversions, non-point source runoff, direct rainfall on wetlands, storm water pumps, and treated municipal effluent. The latter is important because it is available even during drought periods.