The majority of urban hydrological models focus primarily on differences in the rainfall-runoff ratio between pervious and impervious area. Impervious area (as I have mentioned in a previous post), is traditionally assumed to be the major causal source of changes in the hydrological cycle associated with urbanization. Infrastructure-centric urban hydrologic models assume that water that is infiltrated or evapotranspirated before reaching drains and pipes has “exited” the system. As more and more infiltration-based stormwater control measures are implemented however, this assumption needs to be more closely examined. Are urban soils and the urban subsurface truly effectively inexhaustible in capacity? This question is particularly important when we think about multiday rain events and changes in intensity of rainfall associated with climate change.
Model spinup refers to the pre-production run period that you run your model for to let things equilibrate before you start testing your hypotheses. In this post, I also include some strategies I used to get my model up and running.
I started using ParFlow.CLM, a 3D variably saturated overland flow-subsurface model for my research in small urban watersheds about six months ago. In this post, I list the skills that were needed to start using ParFlow and the right attitude to have going in to this type of project.