During a heavy thunderstorm, most likely, surface runoff would be in areas that has sloping landscape. Since at these times, these surfaces would be saturated with water causing for not absorbing water into the soil so it would slope down running off to streams. This is one of the reasons of having landslides.
"Forests transport large quantities of water into the atmosphere via plant transpiration. When deforestation occurs, precious rain is lost from the area, flowing away as river water and causing permanent drying."
