4.6 Watersheds

Characteristics of a given watershed

Area, length, slope, soil, vegetation types, and divides with adjoining watersheds

Watersheds

All of the land that drains into a specific body of water (river, lake, bay, etc.)

What determines watersheds

By sheds: ridges of land divide watersheds (diff. Runoff directions)

What plays a large role in how watersheds drain

Vegetation, soil composition, and slope

More vegetation in watersheds

More infiltration and groundwater recharge

Greater slope in watersheds

Faster velocity of runoff and more soil erosion

Soil permeability determines

Runoff vs infiltration rates

What affects the H2O quality of a watershed

Human activities

Clearcutting/ logging

Removing vegetation increases runoff and soil erosion (which can dam tributaries)

Development

Can alter the flow of water through the system by increasing erosion, runoff, or by physically altering the course of a waterway

Impermeable surfaces

Blacktop and concrete limit water infiltration. Oils and other contaminants build up and then are washed into the watershed

Farming

Waste from cattle contaminates ground and surface water. Fertilizers also contribute to contamination

Industry

Hazardous waste and heavy metals could leach out and contaminate water supply

Damming

Disrupts the flow of water through the system. Drastically impacts life above and below the dam

What makes estuary habitats like the salt marshes in the bay highly productive

Mix of fresh and salt water + nutrients in sediment

What ecosystem services do Estuaries and wetlands provide?

Tourism revenue, water filtration, habitats for food sources, and storm protection

What leads to eutrophication in the Chesapeake Bay

Nutrient Pollution (N & P)

Major N/P sources

Sewage treatments plants, animal waste from CAFOS, synthetic fertilizer from ag. Fields and lawns

What are the effects of clear cutting on watersheds

Soil erosion and increased soil & stream temperature

Soil Erosion

-Caused by loss of stabilizing root structure

-Removes soil organic matter and nutrients from orest

-Deposits sediments in local streams

Increased soil and stream temperature

-Loss of tree shade increases soil temperature

-Loss of tree shade along rivers and streams warms them