What are the Physical Factors of Flooding Risk?

-If there is Lots of Rainfall, then it can be Too Quickly to be Absorbed which allows an Increase in Discharge -Geology of some of the Rocks, like Granite and Shale, are Impermeable meaning it won't allow Filtrating -Prolonged Rainfall can make the Soil Saturated, Decreasing the Filtrating Rate and Increasing the Surface Run off -Relief [Lands Gradient] can also Affect it, as it affects the Velocity of the Water. Faster Velocity = Reaches the Channel Quicker