4)RUNOFF: Runoff is the occurrence of excess water from watershed or drainage basin that flows on the surface. The flow is as a result of precipitation above waterways, groundwater runoff from deep percolations, subsurface runoff that infiltrates the surface soils, and surface runoff that flows on the land surface. As the water flows, it can be used for agricultural and domestic purposes, it may seep into the ground, stored in reservoirs or water bodies, or evaporate into the atmosphere.