He is known as the author of the Commentary on the Water Classic (Shuijingzhu), a monumental work on China's geography in ancient times.
[1] Li used his position as an official with business in different places to carry field investigations.
He is known to have visited the area belonging to the present-day Henan, Shandong, Shanxi, and Jiangsu provinces.
[2][3] Another source for his knowledge was the study of ancient geographical books he had access to, like the Classic of Mountains and Seas (Shanhaijing) completed by the time of the early Western Han dynasty) and the Water Classic (Shuijing), written by Sang Qin during the Three Kingdoms period and later commentated on by Jin dynasty writer Guo Pu.
[3] The book maps and describes the rivers and streams along with the history, geography and culture of the surrounding region.