What is Li Bing's great contribution to digging salt wells?

Li Bing was a famous water conservancy expert during the Warring States Period. He led the Bashu people to cut down mountains and transport earth, and found underground brine in Chengdu Plain when building Dujiangyan project. "Huayang National Records and Records" also said: "Nan 'an County ... will rule the Yi River. The county irrigates the famous beaches ... Second, salt irrigation, with Li Bingping. "It is clearly pointed out that Li Bing once leveled the salt flats formed by underground brine outflow. At that time, after Qin occupied Shu, a large number of immigrants brought all kinds of advanced technologies from other places, including the technology of drilling wells in the Central Plains. In addition, the rapid increase of population in Sichuan will inevitably lead to the urgent demand for more salt supply. In this situation, Li Bing pioneered the digging of salt wells, which not only enriched the country and benefited the people, but also promoted the development of drilling technology. His great achievements can be said to be no less than his contribution to water conservancy.