A formula was developed to calculate how much sediment is trapped by reservoirs in the Yellow River. From 1950 to 2003, 19.6 billion tons of sediment were held back, with most in Sanmenxia and Xiaolangdi reservoirs. To solve environmental issues downstream, it's suggested to create better water regulation plans for existing reservoirs, design new ones with regulated discharge, and plan for managing water and sediment in the whole river system.