Replenishment types and water system characteristics of Nujiang River

Rivers in China can be roughly divided into six inflow areas and outflow areas. The dividing line between the two areas is: Daxinganling-Yinshan-Helan Mountain-the eastern end of Qilian Mountain -200 mm annual precipitation line. The northern and western parts of this line are internal flow areas, and the southern and eastern parts of this line are external flow areas.

The main rivers in the inflow area are Tarim River in Xinjiang and weak water in the west of central Inner Mongolia, and there are also some inland rivers in the south of Hetao Plain. The main rivers in the outflow area are: Heilongjiang, Liaohe, Haihe, Huanghe, Huaihe, Changjiang, Minjiang, Zhujiang and Lancang, which flow into the Pacific Ocean. Nujiang River, Yarlung Zangbo River and other water systems flowing into the Indian Ocean; The Irtysh River in the north of Altai Mountain in Xinjiang flows into the Arctic Ocean.

The hydrological characteristics of the internal flow area are: short flow and small flow; It is mainly supplied by melting ice and snow, and the flow varies greatly in seasons, and there is a phenomenon of cut-off in winter. The hydrological characteristics of the outflow area are: 1, with long flow and large discharge; 2. Rainwater is the main supply, and the flow rate changes with rainfall; 3. The river to the north of Huaihe River has a large sediment concentration and an ice age; 4. Generally speaking, the upstream reaches have high velocity and abundant hydraulic resources.