I am running the SDR model for a basin at two different resolutions (30m and 90m). While I’d expect to get somewhat different results, the difference in sediment export is quite large, and I’m wondering if a gremlin could be creeping in somewhere. My alternative thought is that this might have something to do with the DEM resolution and how it’s being processed, or the threshold flow accumulation value and if that should be adjusted based on the DEM’s resolution? All other input layers are the same; the only input being changed is the DEM.
Welcome! Please read and understand the User Guide before using InVEST. Then, search this forum for answers to your questions before posting new ones. Related posted include these:
Varying the DEM between 30m and 90m resolution versions without changing the threshold flow accumulation (TFA) value will drastically impact export estimates. As stated in the User Guide, TFA
directly affects the expression of hydrologic connectivity and the sediment export result: when a flow path reaches the stream, sediment trapping stops and the sediment exported is assumed to reach the catchment outlet. It is important to choose this value carefully, so modeled streams come as close to reality as possible.