Nanchong is rich in precipitation. The average annual precipitation is 1000 mm, excluding evaporation, the annual total water is about 4.191 billion cubic meters, and the average annual runoff depth is about 313 mm. The distribution of runoff depth is generally consistent with that of precipitation. The depth of runoff is larger in areas with more precipitation than in places with less precipitation. The groundwater in Nanchong is mainly distributed in the Quaternary alluvial and diluvial layers on both sides of the main and tributaries of Jialing River in Nanchong. There are mainly two kinds of pore water in loose accumulation and pore fissure water in clastic rock. Jialing River is the largest river flowing through the city. Its main stream is 301 km long. The Jialing River and its larger tributaries on the left bank, Donghe River and Gouxi River, the larger tributaries on the right bank, Xihe River and Baixi River (Hao) constitute a rich water system in Nanchong. Shengzhong reservoir, formed by intercepting the upper reaches of Xihe River, is located at the junction of southern, Langzhong and Jiange counties (cities). It has a rainfall collecting area of 1756 square kilometers and a total storage capacity of 1.339 billion cubic meters. It is the largest artificial reservoir in Southwest China.