2. The climate in the middle reaches is dry, the evaporation is greater than the precipitation, the flow is small, and the seasonal changes are drastic, which increases the sediment concentration.
3. The downstream area is flat and the water flow is slow, which is not conducive to sediment erosion and discharge into the sea.
To sum up, the sediment concentration is relatively high after the middle reaches of the Mississippi River.
Extended data
The Mississippi River and its flooded plains have nurtured more than 400 different wildlife resources, and 40% of waterfowl in North America migrate along the Mississippi River. Although the natural vegetation in the Mississippi valley itself is the product of climate and soil rather than rivers, the swamps and stagnant water in Mississippi are worthy of ecological attention.
From the swamps in Minnesota to the coastal swamps in the delta, small areas rich in plants and animals are common along the river. In these areas, dense natural vegetation, relatively independent natural environment and plants provided by sedge, pond grass and millet provide good habitats for waterfowl.