Although there is little control over the hydrologic cycle, and the primary water supply is firmly fixed, water can generally be managed and conserved as it becomes available through precipitation.
Water management begins with soil management.
Soil erosion begins with a drop of water blasting, like a small bomb, soil particles. The soil begins to move, and small rills are formed as the water finds its way across the soil surface. Unchecked, it will result in a large gully. Over several million years, that gully could turn, quite literally, into the Grand Canyon found in the southwestern United States. Another form of erosion is sheet erosion, which, like the name indicates, moves the soil surface in a large, usually unseen, thin sheet.