Groundwater

The water that infiltrates down into the ground will still flow back towards the oceans, albeit it will be slower then runoff. Groundwater movement rates are determined by the type of material (soil, rock) that the water is flowing through. Soil also dictates how much water can be held, and how much can be readily used by plants or even animals. Groundwater maintains base stream flow levels when runoff is not available to supply the river with water.