The geographical environment of that ancient town

The main rivers in that ancient town are Xiaojiang, Yili and Haihe.

Xiaojiang originates from Qingshui Sea in Xundian County, flows into Jinsha River from south to north, with a total length of 148km, and the downstream flows through Nagu Town for 28 km, with a drainage area of 60.4 square kilometers and a riverbed elevation difference of 305 meters, with an average gradient of 10.9%.

The Yili River originates from Yemachuan, Daibu Town, Huize County, flows through Qiaojia County from south to north, and flows into Jinsha River, with a total length of 122km, a drainage area of 2,558km2, a riverbed height difference of 1400m and an average flow of 15.9 m3/s for many years. ..

Haihe River originates in the north of Gubazi in Yu Na, flows south through the tunnel, then turns north, and flows into Xiaojiang through Wangjiashan. The total length is 28km, the average annual discharge is 1.24m3/s, the drainage area is 19 1.7km2, the river bed height difference is 1220m, the average slope is 40.3%, and the effective irrigation area is 212/kloc-0.