fv6 - watersheds

AP Environmental Science - Unit 4: Earth Systems & Resources

Definition of a Watershed
- A watershed is a channel (stream, river) that concentrates runoff to a main body of water (lake or ocean).
- The discharge point is typically at the lowest elevation of the watershed.
- Headwaters mark the beginning of a watershed.
- Watersheds are separated by ridges or mountains, which form the highest points.
Runoff Movement
- Runoff flows from higher elevations to lower elevations, forming streams and rivers.
- Streams and rivers can diverge into sub-watersheds, but all runoff eventually discharges into a single point.

Characteristics of a Watershed
- Size: Reflects the amount of runoff and the type of water bodies created (river, stream, creek).
- Length: Distance from headwaters to discharge point; affects the time it takes for runoff to reach the discharge point.
- Slope: Steeper slopes increase runoff due to gravity, while flatter slopes promote water infiltration into the soil.
Soil and Vegetation Impact
- Soil type affects runoff absorption and vegetation growth.
  - Sandy or large particle soils absorb more runoff.
  - Fertile soils support more vegetation.
- Vegetation reduces soil erosion and enhances soil fertility.
Key Terms to Review
- Discharge Point: Location where water flows from a river or stream into another body of water.
- Water Filtration: Process of removing impurities from water, making it safe for consumption.

Importance of Watersheds
- A watershed is an area where all water drains into a common outlet, connecting hydrology with land use, pollution, and ecological health.
- Understanding watersheds is crucial for:
  - Managing water resources.
  - Protecting ecosystems.
  - Mitigating human impacts on water quality