About Watersheds

How Watersheds Work

• Although water flows into a watershed, not all of it flows back out again. When rain falls on land that is dry, it soaks into the soil. Some of this water will stay in the upper layers of soil where it moves downward, through the soil and into a body of water. Some of the water goes deeper, where it may remain for long periods before moving back up to the surface. This movement depends largely on the soil and the conditions in that particular watershed. Clay or rocky soils, for example, absorb less water more slowly than sandy soils and results in more runoff to streams. Already wet soil can't absorb as much water either, which results in rapid runoff. The material covering the land area in some watersheds will also affect the rate of water flow. Surfaces like concrete result in fast runoff into storm drains that typically lead directly to a body of water. Flooding is more common in areas where surfaces like this are abundant.

Types

• Watersheds may either be open or closed systems. In an open-system watershed, the rainfall flows into a particular body of water. In a closed system, the rainfall evaporates back into the atmosphere or is absorbed into the soil. Both types of watersheds may be a variety of sizes. Some cover just a small area of land, such as a marshy area near a stream, while others include entire states.

Significance

• Watersheds provide an area for water to drain and soak into the ground where its used by plants and soil, and they provide a home for wildlife. They provide fresh drinking water for humans as well. Watersheds are affected by several types of pollutants including pesticides, agricultural waste and untreated sewage. Vegetation is important to watersheds because it slows down the runoff and prevents soil erosion. This helps lower water temperatures and provides clean water. Protecting watersheds is crucial. Pollutants that affect watersheds will also harm the environment and wildlife, and can negatively impact our health as well.

Protection

• It is crucial that watersheds are protected because of their significance to humans and wildlife. To protect watersheds around you, never pour chemicals such as household cleaners or solvents down the drain. Keep land areas clean and free of garbage. Clean up pet droppings and use natural pest control methods whenever possible. Recycle and reduce waste to prevent pollution. Planting native plant species also limits the use of chemical fertilizers and pesticides because these plants thrive, where non-native species require more care and chemical treatment.