How can I simulate rain (2 inches for example) over a surface. Need to show where it pools and the direction to which it travels. Animated.
Small scale - Agriculture - field by field
I think you need at least one soil map, map of the digital terrain model with slopes. Thus it is possible to calculate the infiltration rate and quantity of water runoff.
Without soil infiltration rates, check out the Spatial Analyst Hydrology toolbox.