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.
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.
When the river slows down, deposits are created. http://www.fgmorph.com/fg_3_23.php
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. 00-68-14 5-6 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