<P> The Ordos Loop formed by an enormous twist of the Yellow River, beginning at Zhongning County in Ningxia and ending with a drastic eastward turn at its confluence with the Wei at Tongguan in Shaanxi . However, the official division for the middle reaches of the river run from Hekou in Togtoh County, Inner Mongolia, to Zhengzhou, Henan . The middle reaches are 1,206 km (749 mi) long, with a basin area of 344,000 square kilometers (133,000 sq mi), 45.7% of the total, with a total elevation drop of 890 m (2,920 ft), an average drop of 0.074% . There are 30 large tributaries along the middle reaches, and the water flow is increased by 43.5% on this stage . The middle reaches contribute 92% of the river's silts . </P> <P> The middle stream of the Yellow River passes through the Loess Plateau, where substantial erosion takes place . The large amount of mud and sand discharged into the river makes the Yellow River the most sediment - laden river in the world . The highest recorded annual level of silts discharged into the Yellow River is 3.91 billion tons in 1933 . The highest silt concentration level was recorded in 1977 at 920 kg / m3 (57.4 lb / ft). These sediments later deposit in the slower lower reaches of the river, elevating the river bed and creating the famous "river above ground". From Hekou to Yumenkou, the river passes through the longest series of continuous valleys on its main course, collectively called the Jinshan Valley . The abundant hydrodynamic resources stored in this section make it the second most suitable area to build hydroelectric power plants . The famous Hukou Waterfall is in the lower part of this valley on the border of Shanxi and Shaanxi . </P> <P> In the lower reaches, from Zhengzhou, Henan to its mouth, a distance of 786 km (488 mi), the river is confined to a levee - lined course as it flows to the northeast across the North China Plain before emptying into the Bohai Sea . The basin area in this stage is only 23,000 square kilometers (8,900 sq mi), a mere 3% of the total, because few tributaries add to the flow in this stage; nearly all rivers to the south drain into the Huai River, whereas those to the north drain into the Hai River . The total drop in elevation of the lower reaches is 93.6 m (307 ft), with an average grade of 0.012% . </P> <P> The silts received from the middle reaches form sediments here, elevating the river bed . During 2,000 years of levee construction, excessive sediment deposits have raised the riverbed several meters above the surrounding ground . </P>

Where is the hwang ho river located on a map