Runoff and Watershed AFTER A PRECIPITATION EVENT 1. Accumulation: water that reaches the surface and compounds. This is typically seen in snowfall. If accumulation is persistent and climate conditions are optimum, accumulation can lead to massive ice caps, over geological time. 2. Absorption: water penetrating the terrestrial surface to be stored as groundwater or used by the biome 3. Runoff: movement of excessive water movement downhill, with greatest efficiency (Water’s behavior will be determined by various factors including infiltration capacity, slope, volume, biome characteristics, etc.) Hydrogeology Streamflow: groundwater that is discharged into a stream or river system. Movement of water into a stream Base flow: the groundwater that supports a stream during periods of low precipitation. Ephemeral – river or stream that only fills after a precipitation event because the climate is arid Ex: Rio Grande River Watershed zones: a large geographic area where water drains using a complex system of channels that often combine and discharge into the sea. Rills: a shallow channel cut into the soil by the erosive action of flowing water (measured in centimeters). A rill is created when rainfall reaches a volume that cannot be absorbed by soil. Very first sign of a runoff. Gullies: a gully forms when rills combine to form a larger channel of water. They form when excessive water runoff occurs and then driers after a precipitation event. Gullies shed into streams Tributary streams: