A Dynamic Spatial Simulation Model of Land Loss and Marsh Succession in Coastal Louisiana

A spatial simulation model was constructed to help understand the historical changes in the Atchafalaya/Terrebonne marsh/estuarine complex in south Louisiana and to project impacts of proposed human modifications. The model consists of 2,479 interconnected “lcells,” each representing 1 square km. Each cell in the model contains a dynamic, nonlinear, simulation model that has evolved out of the modelling work mentioned in the previous chapter. Variables include water volume and flow, relative elevation, sediment, nutrient, and salt concentrations, organic standing crop, and productivity. The model produces weekly maps of all the state variables and habitat types. Habitat succession occurs in a cell in the model when physical conditions change sufficiently, so that the new conditions better match the “signature” of another habitat. In this chapter we: 1) summarize the history of the Louisiana coastal land loss problem and suggested solutions; 2) briefly discuss the model's structure, data base, and degree of fit with historical data; 3) discuss the uses and implications of the model, particularly as regards the estimation of the impacts of canals and levees on coastal marsh systems; and 4) outline the potential interface between the model and management agencies to provide solutions to pressing coastal management problems.