When heavy rain falls, where is flash flooding most likely to occur?

Flash flooding is most common in low lying regions like valleys, river beds, and geographic depressions. The main cause of flash flooding is when there is nowhere for water to go. This is caused when the ground has little to no absorption capability. Where I live, flash flooding is most often caused when there is an extended period of rain to saturate the soil, preventing quick absorption into the soil, or after a long period of drought when the ground acts as a fired clay and causes water to runoff. In other areas, rain falling on stone can cause flooding, and in rivers surrounded by highlands such as in the mountains, even a small rain can raise water levels significantly, resulting in a flash flood.