River bed above the river, also known as "river on the ground." Watershed in the watershed is very serious, the sediment is very large rivers, open in the valley, than the slow down in the downstream, sediment accumulation, the river bed constantly elevated, the corresponding rise in water level. In order to prevent water damage, the two sides of the embankment along with the ever-increasing, long years, the river bed over the two sides of the ground, a "hanging river." For example, the Yellow River from the Peach Blossom Valley to the sea, the process of 768 km, about 400 million tons of sediment per year in the river, the river bed year by year to become the world's famous "hanging river" The ground is generally 3 to 5 meters.