Rivers Erosion, Weathering, Sediments and Deposits

The five major rivers that flow into the Chesapeake Bay are: 1. Susquehanna 2. Potomac (Shenandoah) 3. Rappahannock 4. York 5. James

Rivers bring fresh water into the Chesapeake Bay. The Chesapeake Bay is an estuary, so the salt water from the ocean mixes with the fresh water from the rivers.

Runoff from the rivers can affect the abiotic factors of the Chesapeake Bay. These are non-living factors, such as water, temperature, soil, light that influence the ecosystem.

Running water affects the landscape.

Rivers run downhill, and the more steep the ground, the runoff moves faster.

Fast water has more energy and creates more weathering and erosion.

When the river has more energy, the river is straighter When the river has less energy, the river may become a meandering stream or river.

Vocabulary: Erosion vs. Weathering Weathering The chemical or mechanical breaking down of rocks or materials. Erosion Process by which earth material is moved from one area to another by water or wind.

Weathering and Erosion is common along river and stream banks throughout the Chesapeake Bay watershed.

Bluffs and deep walled valleys Canyons

Rivers carry sediment. Sediments are materials such as rock fragments and grains of sand that have been transported by wind, water, or glaciers.

1. Dissolved load fine sediment that is dissolved.

Sediments…continued 2. Suspended load sediment suspended (floating) and transported through the stream. 3. Bed load: larger sediment that does not float.

In the Chesapeake Bay, there exists sediment pollution. These sediments include clay, silt, or sand that eventually settle to the bottom. Sediments are natural, but too much creates harmful conditions for the Bay’s plants and animals.

Examples of Sediments Affecting the Bay Smother bottom dwelling animals such as oysters and clams.

Examples of Sediments Affecting the Bay Sediments cloud the water, preventing light from getting to the leaves of underwater grasses. (submerged aquatic vegetation), also known as SAV.

Turbidity = Water Clarity Suspended sediments block sunlight and increase the turbidity.

Sediments can also carry toxic materials, including nutrients, especially containing phosphorus and nitrogen compounds.

Agriculture and the Bay Agriculture (farming) in the Chesapeake Bay watershed is the largest factor for introducing fertilizers into the bay.

Reducing Sediments can be done by: 1.silt fences – capture the sediment around construction sites.

Silt fences

Reducing Sediments can be done by: 2. Plant trees – help slow erosion

Forests filter and slowly release sediment from the land.

Moving Water Can Erode Banks Trees (Forests) and Vegetation Help Slow Erosion

When Europeans first arrived to the Bay region, 95% of watershed were covered in forests. Today, only 58% of the watershed is covered by forests.

Reducing Sediments can be done by: 3. No till farming – farmers can avoid disturbing the earth

No Till Planting

New and varied methods are being used to reduce sediment reaching the Bay and other waterways.

Other ways of reducing sediments: Reduce roads and parking areas (asphalt) Plant buffers, which allow plants to filter water and trap sediments

Rivers carry sediments when the river has enough energy. When the river slows down, the sediment is dropped as “deposits.”

When the river slows down, deposits are created.

As a stream empties into a body of water such as a lake, gulf, or bay, sediment is deposited forming a delta.

When the river is fast moving, the deposit can form an alluvial fan.

Streams with many bars and islands separated by river channels are called braded streams.

A floodplain is next to a river that is created from river sediment and is periodically flooded.

River Notes 38 SusquehannaPotomacRappahannockYork James fresh Estuary abiotic light landscapedownhill faster weatheringerosion straighter meandering stream or river

39 rock water “load” Fine sediment you cant see. Sediment that is floating * muddy water. Larger sediment that does not float. pollution clay conditions plants animal bottom cloud light turbidity toxic phosphorusnitrogenagriculture

40 Silt fences Planting trees No till farming deposits loses energy delta alluvial fan river

41 When materials are broken down or worn away. Use of force to break apart material Teeth breaking down food / Glaciers Use of chemicals to wear down or break apart Sulfur oxideNitrogen oxide rain chalk Larva / eggs water Erosion Flooding, during hurricane ocean waves

ws#9 – The Watershed Story Read Story either as a class, small group or independently. Answer questions on ws#9! Collecting as a SUMMATIVE!!! 42

ws#8- Abiotic vs Biotic 45 Turn in this paper to Mrs. Knot!! I will look at your paragraphs!!!

Have a wonderful weekend! Enjoy your video….. Bill Nye – Watersheds What is a watershed? More Watersheds Bill Nye – Water TreatmentWater Treatment Bill Nye - WetlandsWetlands 46

Sources