Watershed and Its Importance

Definition of Watershed

• A watershed is a body of land that drains into a central body of water (river, lake, stream).
• Determined by slope; acts like a funnel directing runoff to a central water body.

Factors Influencing Watersheds

• Slope: Determines velocity and direction of runoff. Steeper slopes increase runoff speed and sediment transport.
• Vegetation: Increases infiltration, reduces surface runoff, makes soil more permeable.
• Soil Permeability: Affects runoff vs. infiltration, impacts groundwater recharge and sediment transport.
• Human Activities: Mining, agriculture, and clear-cutting can introduce pollutants and loosen soil, affecting water quality.

Chesapeake Bay Watershed

Overview

• Largest watershed in America, covering six states.
• All tributaries eventually lead to the Chesapeake Bay, a key estuary.

Importance of Estuaries

• Mixture of salt and fresh water, rich in nutrients and sediments.
• Support productive habitats like salt marshes, providing ecosystem services.

Ecosystem Services Provided

• Tourism: Attracts visitors for recreation, supporting local economies.
• Water Filtration: Wetlands trap pollutants, aiding natural water purification.
• Habitat: Breeding grounds for seafood, supporting fishing industries.
• Stormwater Protection: Acts as overflow/surge protection during storms.

Human Impacts on the Chesapeake Bay

Nutrient Pollution

• Excess nitrogen and phosphorus lead to eutrophication.
• Causes algae blooms, blocking sunlight, leading to hypoxia (low oxygen levels).

Sources of Nutrient Inputs

• Sewage Treatment Plants: Overflow leads to nutrient discharge.
• Agriculture: Runoff from CAFOs and nitrate fertilizers.

Other Pollutants

• Endocrine Disruptors: Medications not fully removed in sewage treatment.
• Sediment Pollution: Urbanization and farming increase sediment runoff, affecting aquatic habitats.

Solutions to Pollution

Agricultural Practices

• Cover Crops: Reduce runoff, anchor soil, absorb excess nutrients.
• Manure Management: Improved lagoons, drainage systems for animal waste.

Riparian Buffers

• Vegetation along water bodies acts as filters, reducing pollutants entering water.

Sewage Solutions

• Septic Tank Upgrades: Improved drain fields for natural filtration.
• Biological Waste Removal: Microbes consuming waste, reducing nutrient release.

Conclusion

• Multiple strategies available to reduce nutrient and sediment pollution in watersheds, improving water quality and ecosystem health.