Water and Conservation
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. Because the water supply comes to us as precipitation falling on the land, the destiny of each drop of rain, snowflake, and hailstone depends largely on where it falls--and on the kind of soil its covering.
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.
Erosion takes place anywhere there is bare soil, on farms, ranches, school yards, new construction sites, homes, parks, and forests. A rainstorm or heavy shower drops millions of tons of water on the land. The force of that water can severely affect the landscape if proper precautions haven't been taken. Drop by drop, the water beats away at the soil, loosening soil particles and moving them short distances or even far away. This action, soil erosion by water, is a natural event.
Erosion is the source of sediment that fills reservoirs, lakes, and streams with potential pollutants that could kill aquatic life. The sediment can shorten the life span of dams and reservoirs, clog navigation channels, and affect the quantity and quality of water delivered to towns and cities.
Water and bare, unprotected soil equals an erosion problem that can be controlled through vegetative conservation practices. The idea is to intercept and reduce the impact of the falling or running water, allowing the water to either soak into the soil for later use by plants, or to safely and carefully run off in a controlled manner.
The branches and leaves of grass, trees, bushes, shrubs, and even weeds, help break the force of raindrops and hold the soil in place. Mulching protects the soil when it has no growing cover. Small dams on upper tributaries in watersheds help control the flow of water and protect the streams from accelerated erosion.
Where cultivated crops are grown, plowing and planting on the contour, terracing, and using grassed waterways to carry surplus water from the fields are some of the conservation practices that slow running water and protect soil from erosion.
In cities and suburbs, where much of the land is covered by streets, buildings, shopping centers, airports, and industrial developments, precipitation runs off as much as ten times faster than on unpaved land. And, since this water cannot soak into the soil, its volume is increased as it flows into storm drains or through sewer systems. As it moves with such velocity and volume, it will prick up and carry debris and other pollutants to streams and rivers.
In urban areas, the same basic water conservation and management principles apply: intercept the force of the running water, slow it down, control it, and reduce the amount of water leaving the land surface.
As populations grow, the demand for water for human uses increases. Yet there is only so much water available. The use of water in industrialized nations continues to grow. Sound management of the water available affects the quantity and quality of water to meet the needs of expanding populations, often in locations with little water supply.
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