I've gotten stumped with my model of ponding on an impermeable surface. I have a DEM of the surface and the corresponding daily rainfall field for a year of data. What I need to do is pour the water onto the surface each day and see where ponds occur (with the assumption that all sinks are natural, which I'm pretty confident in) but I just can't figure out how to do it, if it can be done, in ArcMap.
I've used FlowAcc weighted with the rainfall field but that just gives me sinks. I can't figure out how to weight 'Fill' so that the water is in line with my rainfall field. I thought about trying ArcHydro but it's not readily available. Does anyone know how I can tackle my problem and if ArcHydro would help?
I did something similar a few years ago trying to find on-site rain storage for a retail development. The best I came up with was to take the DEM and raise the lowest elevation by 0.25m increments from the lowest sink. I then subtracted the original DEM from the raised DEMs and got a volume of the difference for each iteration. This gave me a fairly good idea of how much storage there was by elevation.
Using my known rainfall I calculated the volume of precipitation for my study area and then displayed then different intervals based on 100 year and 350 year storms. It was a bit of an iterative process to find the right elevations.
If you want max ponding capacity just subract your base DEM from the Fill DEM and do a volume calculation.