701+Sediments

Sediments can be harmful to the environment and can be helpful to the environment. Sediments consist of (smallest to largest) silt, sand, gravel, and dead decaying animals and plants (organic matter). When the water stops flowing the sediments all fall on the river bottom and kill anything that they land on. When the water starts up again it picks up the sediments. If the water is moving faster it will be able to pick up bigger types of sediments and move them. The water slowly erodes our land but keeps up our sandy beaches, mud flats, and salt marshes. Forestry and agriculture destroy the protective plant cover and when heavy rains come it washes the soil into the river. When building roads and structures the land becomes bare and the soil gets carried away in to the rivers and storm drains. If you wash off your drive way and all the debris gets washed into storm drains, the water flows into the rivers and it adds a little amount of sediment. When water is flowing it can take away the soil from the river beds and carry them along with its current. Untreated Sewage when dumped into the river or ocean adds the sediment of organic matter (made by organisms) into the water. Salmon farms produce a lot of fish feces and they will either stay in the cage or they will flow downstream with the current. Dams or bridges can cause sediment build up. The flow of water will slow or stop at a dam or bridge and all the sediments will sink to the bottom of the river. In murky water clouded with sediments it makes it hard for underwater plants such as phytoplankton to obtain sunlight to carry out photosynthesis. When there is too much sediment in the ocean it can make certain parts of the ocean hard for boats to pass through. The way the fix that is a costly process called dredging. The beaches are always losing sand because of the current, but the sediment from the rivers always come to replace them. If there are dams and bridges the sediments aren’t able to get to the beaches to replace the lost sand. The beaches end up slowly decreasing in size. Sediments can be good and sediments can be harmful.