What could be learned from monsoon seasons?

Every year in many parts of the world we see monsoons and rainy seasons that last longer than 40 days and 40 nights. From those can we determine things like erosion rates, topography changes, effects on major structures such as mountains?

But could those factors be calculated and are they relevant?We know that the various monsoons have been going on since long before the folk that believe there was a Biblical flood date the flood and that the Biblical flood myths have rain for only 40 days and 40 nights. So if we look at things like erosion during monsoon seasons over thousands of year, many orders of magnitude longer than 40 days and 40 nights, would that not exceed the volume described in the Biblical stories?