River pattern blocking the river

There are two sources of blocking the river: the west and the south. Xiyuan is the positive source, which originated from the three treasures of Daba Mountain at the junction of Sichuan and Shaanxi, with an altitude of 2603 meters. The source is Dashu River, which flows into Nanjiang. Nanjiang, 95 kilometers long in Shaanxi, entered Zhuxi County, Hubei Province at Pengjiatai and was renamed Wanhui River. After the Chunjiang River from the southeast of Xinzhou Town, it is called Sihe River, and after the confluence of the two estuaries in Zhushan County and Nanyuan Guandu River, it is called river blocking. Xiyuan River has a total length of more than 230 kilometers and a drainage area of more than 4,860 square kilometers, with an average gradient of about 4‰.

The Guandu River in Nanyuan originated from Shennongjia, Hubei, with an altitude of 3052 meters. It is called Luoyang River in Shennongjia area, and flows into Yuyin River in Fangxian County from south to north, which is called Jiudaoliang River. In Yiduping, Luohan East River is called Liangtai River, and yangsi He Miao and Machang River are called Baihe after meeting at the old pier. If you continue to flow northward to guandu town, you will be an official crossing the river. Guandu River is an important passage for wood exile in Shennongjia, with a total length of1.27km and a drainage area of 2,885km2, with an average gradient of about 4.6‰. The blocked river flows northward from the two estuaries through Zhushan County, Yao Ping, Ye Tan, Yeda and Huanglong, and flows into the Han River. Estuary elevation154m.

There are Dajiu Lake and Xiao Jiu Lake in the upper reaches of Nanyuan. Dajiu Lake is 7.5km wide and 15km long. Xiao Jiu Lake is1.5km wide and 7.5km long. When there is more water, the water surface of the lake can account for 710 of the whole lake area, and when there is less water, it accounts for 310. Because the dry season is actually an alpine basin, according to the legend of local residents, it was the camp of Xue Gang army in the Tang Dynasty, and Taiping Mountain in the southwest was its outpost.

The river system is dendritic, and the main tributaries on the left bank are Tankou River, Kutao River and Beixing River. On the right bank are Guandu River, Shenhe River and Qinkou River.

The river basin is mountainous throughout the country. Daba Mountain in the west winds eastward, Shennongjia stands tall in the south, surrounded by Putuo and Wudang in the northeast, and the terrain is relatively high. The upper reaches are all high mountains with an altitude of 1200 ~ 2500m, and the lower reaches are medium and low mountains with an altitude of 500 ~ 1200m. The bending coefficient of the main stream is 1.87, which belongs to the curved river type in mountainous areas.