 The crossing will consist of two 9.3 m diameter horizontal tunnels, positioned 70 m under the riverbed of the Yellow River.Due to the topography of the Yangtze Plain and the North China Plain, pumping stations will be needed to raise water from the Yangtze to the Yellow River crossing; farther north, the water will be flowing downhill in an aqueduct.The central, or middle, route runs from Danjiangkou Reservoir on the Han river, a tributary of the Yangtze River, to Beijing.