I'm conducting a basic sensitivity analysis and have some questions about the erosion parameters. I'm increasing or decreasing the erosion parameters by 50% and comparing the output with the baseline model output (using the same values for all 3 erosion parameters). The study area is a subset of Mobile Bay, in the southern mainland of Mobile County. Accretion parameters are defined as 5 mm/yr. The model output for 2100 (A1B Max scenario) is affected very little by varying the erosion parameters. I tried tripling the baseline value (1.74 m/year) I'm using for the erosion rate, and there are only a few more pixels of tidal flats converted to open water at the land/water interface, compared to the baseline model. Otherwise the outputs are nearly identical. I expected variations in the erosion parameter to have a stronger affect on the outcome.
The SLAMM technical documentation says that there must be a minimum of 9 km of fetch for the erosion model to kick in. There are some useful posts in this forum that say a minimum of one cell must be designated as open water next to the shoreline so that the model can recognize the land-water interface. If the model encounters a blank cell as it moves across the water surface, it assumes that the fetch is infinite from that point. All my input layers have the same spatial extent and resolution, and extend out over 1 km into open water. In this particular region, the dominant wetland type is irregularly flooded marsh, which transitions directly to open water. Does anyone have ideas as to why the erosion parameter is having very little affect on the model outcomes? Thank you!