Brief introduction of He Lanhe

He Lan is also known as Lanzhou River. Lan County Records says: "Green River" originated at the foot of Matou Mountain in Hekou Township, Lan County, and its upstream source is also known as Lancheng River, with larger tributaries such as Puming River and Hehui River flowing into Fenhe River after entering loufan county. The length of rivers in Lvliang is 56.7 kilometers, with a total drainage area of 1 146 square kilometers and an area of 1055 square kilometers. The annual average runoff is 66.8 million cubic meters, and the annual average sediment discharge is 5.47 million tons. The river water quantity varies greatly in seasons, with the normal flow rate of only 1.8 m3/s, the flood flow rate of 1.70 m3/s and the maximum peak flow rate of 1.879 m3/s( 1.958).