We have learned about loess soil which is formed by transporting silt to new form resulting new deposit with the help of wind. Silt can be transported long distance as dust due to its particle size (fine enough to blow). Not only with wind, it also transported with water.
Clay and silt are responsible to produce turbidity property in water; when silt is found to pollute water, the phenomenon is called siltation. Silt is carried to ocean with water current or stream.
The excess amount of silt is harmful to water quality which can impact aquatic environment. In case of construction project where excess amount of silt disposal, discharge or any form of silt release can impair water quality, we use silt fence. Dear reader we will discuss about silt fence in details in our upcoming posts.
Silt deposition often enriches and makes fertile soil. The deposition we meant is due to flood which we observed in ancient civilization (Egyptian).
Sometimes silt deposition forms new land between water bodies due to formation of obstruction against water current (the prominent example is Bangladesh). In last 50 years, Noakhali district in Bangladesh gained over 73 square kilometer land.
The causes of presence of silt in rural river are
a. Erosion due to plowing of agricultural field
b. Clearfelling of forest
c. Due to converting forest to agricultural land.
The main source in case of urban river is construction activity disturbing soil.