Complex sentence: The resultant changes to the Missouri River in the upper Great Plains from channelization and impoundment prevent upstream migration, have reduced water flow rates and sediment loads and has brought an end to the seasonal flooding of the flood plains in the region.
Split into simpler sentences: The resultant changes to the Missouri River in the upper Great Plains from channelization and impoundment prevent upstream migration. The reduced water flow rates and sediment loads and has brought an end to the seasonal flooding of the flood plains in the region.