I am using InVEST Urban Stormwater Retention Model to simulate the hydrologic results of different scenarios based on the area of urban linear forest. My question is simple:
Should I change the features in soil hydrologic group file according to the changes of land use land cover in different scenarios (i.e., if I change one pixel from impervious road to forest, do I need to change the soil group of that pixel)?
Your time and advice is appreciated!
Stormwater retention model: change soil hydrologic group features according to land use land cover changes
Hi @Yizhi , I’m not an expert on this topic, but I think you should not change the soil group unless the soil type is changing. In your biophysical table, I would expect that the “impervious road” LULC class to have high runoff co-efficient values for all soil groups. In other words, the properties of the soil should have relatively little impact on retention and runoff for areas with impervious landcover types (landcover types with high runoff coefficients). I looked at the sample data for this model to come to these conclusions.
Hi @Yizhi. I agree with @dave that we don’t usually change the soil hydrologic group raster for evaluating scenarios. Instead, we change the land use/land cover raster to reflect our scenarios, and make sure that the runoff coefficients and percolation coefficients in the biophysical table make sense for the different LULC types. These two coefficients are used along with the soil hydrologic group raster to determine runoff. This is why there are, for example columns rc_a, rc_b, rc_c and rc_d, which correspond with the values 1-4 in the hydrologic group raster.
Thank you @dave for your reply! That helps a lot.
Thank you @swolny for your clarification!