In Huixian County, Gansu Province, the main tributaries are: Yongning River, one of the larger tributaries in the upper reaches of Jialing River, which is the second largest river in the county. It originates from the southern foot of Qinling Mountain and flows into Gao Qiao, Liulin and Yongning Township of Tianshui County through the northern slope of Dashanliang (August, 2064), with a total length of 65,438. Rivers in the territory are 68km long, with an area of 813km2, accounting for 30% of the county's total area. The average annual flow is 15.3 m3 /s, and the total annual runoff is 482.38 million m3. The annual average self-produced water volume 1.9 1 100 million cubic meters, and the inflow volume is 285.57 million cubic meters. The average erosion modulus for many years is 467 (ton/km2). The average annual sediment transport for many years is 968,000 tons. The national reserve of hydraulic resources is 35,000 kilowatts, which is an important energy and natural resource for farmland irrigation in this county. Luohe: Originating at the southern foot of Laoye Mountain in the north of the county, it flows through 8 towns and villages in the county, including Luojiang, Yang Ni, Yushu, Fuzhen, Lichuan, Yinxing, Shuiyang and Dahe, with a total length of 8 1km and a drainage area of 923km2. The average annual flow is 8.8 cubic meters per second, and the total annual runoff is 277.64 million cubic meters. For many years, the average self-produced water is 223.44 million cubic meters, and the imported water is 54.2 million cubic meters. The reserve of hydraulic resources is 1.77 million kilowatts. The drainage area accounts for 34% of the county's total area, with an average width of 12.9 km. There are two tributaries of Fuzhen River and Yangni River in the upper reaches, accounting for 52.3% of the total area of hilly valleys in the middle of the county, and it is an important agricultural production base in the county. On the other hand, due to the large concentration of geological structure and agricultural land in the middle and upper reaches of Luohe River and some inappropriate human activities, the natural ecological balance has been affected to varying degrees, and some soil erosion has occurred, which is one of the areas with large soil erosion in the county. Xihe River: Also known as Tianjiahe, it originates from the southern foot of Xiao 'an in Yushu Township, with a total length of 42km and an average gradient of 49‰, with a drainage area of 256km2 and an average width of 6. 1 km. It flows through five towns, such as Yushu, Ginkgo, Chengguan, Shuiyang and Jialing, and flows into Jialing River at the lower dam of Tianjiahe in Jialing Township. The annual average flow rate is 1.44 m3/s, the annual average self-produced water quantity is 45.39 million m3, the annual runoff is 45.39 million m3, and the annual average erosion modulus is 692 (ton/km2). The average sediment transport for many years is 73,700 tons, and the water resource is 4,900 kilowatts, which is one of the areas with large soil erosion in this county. Mayan River: Originated between Bagua Mountain and Laoye Mountain in Beiling Mountain System in the northwest of the county, with a total length of 33. 1km and a drainage area of 359.4km2 ... with a domestic area of 304km2 and an overseas area of 55.4km2.. The annual average flow is 4. 12m3 /s, the annual total runoff is 65438+2997m3, the annual average self-produced water is 8497m3, and the inflow is 45m3. With a reserve of 4,400 kilowatts, hydropower resources are the main rivers for developing small hydropower in remote areas in the northwest of the county. Donggou River: The largest river on the left bank of Jialing River in this county, which originates from the west foot of Dongjie Mountain, has a total length of 23. 1 km, a drainage area of 9 1 km2, an annual average flow of 0.687 m3 /s, an annual runoff of 265,438+0.65m3, and a hydropower reserve of 350,000 kW, making it the most abundant in the southeast of this county. Sucheng River: Located in Mayan Township in the north of the county seat, it is a tributary of Mayan River, with an altitude of105 38' and a latitude of 34 02'. Originated from Dashanba. The upper reaches are in Yan Guan, Li County, Ma Yuan Township, Xihe County, and Suzhou City in Qincheng District. It flows through Hexi Village, Wangji Village and Dangzheng Village in Mayan Township. In Huguang Village, the shops merged into Maya River. The drainage area is 262 square kilometers, the length of the main channel is 28 kilometers, the river gradient is 20‰, the annual average flow is 1.84 cubic meters per second, and the total annual runoff is 58.05 million cubic meters. Cut in the middle of the valley, the valley is narrow, the river is steep, the mountain vegetation is poor, the slope is large, and the landslide is obviously developed. [12] Hongya River, in the north of liangdang county, is a tributary of the Yangtze River and Jialing River. The Flaming Mountain and Qinling Mountain, which originated in the northern foot of Qinling Mountain in the south of Beidao District of Tianshui City, flows through Tianshui and Liangdang from north to south and flows into Jialing River in Shimaping, Shaanxi Province. The length of the river is 6 1 km, and the average gradient is 1.2%. The basin covers an area of 829 square kilometers. The average annual runoff is 6.5438+69 million cubic meters. [27] Liangdang River, also known as Guangmiao River. The Yangtze River system is a tributary of Jialing River. Originated in the northern mountainous area of Dayang Township in the northwest of liangdang county, it flows southward through Sun, liangdang county, Yuchi and Zhaner Lane, and flows into Jialing River at the mouth of the county seat. The river is 62. 1 km long, with an average annual gradient of 1/50, a drainage area of 347 square kilometers and an average annual runoff of 75 million cubic meters. There are 53 main tributaries, such as Shanghe and Hongdonggou.