The origin of Kuncheng Lake

Kuncheng Lake is called "Hu Kun" in Yuejueshu, the earliest local chronicle in the Eastern Han Dynasty: "Seventy-six acres of land, reaching the county (referring to Wuxian-the author) for 175 miles, is a hidden lake." Because its southern boundary is close to Kunshan, and the waters of Yangcheng Lake depend on it, Kunshan is called "Hu Kun" (Northern Song Dynasty Zhu's "Continued Wu Jun Tu Jing"). Why is it also called Hidden Lake? I'm afraid this has something to do with Jiang Shang's seclusion in Changshu. The southeast and southwest of Changshu ancient city are located in low-lying areas. Whenever there is a flood, Kuncheng Lake and Monk Lake overflow into lakes. Rebuilding Chang Zhao's Records of Mountains and Rivers says: Kuncheng Lake and Shang Hu are "separated by a pool, but once flooded, it is boundless". "Tong Mingzhi" said that the two lakes were merged into one, also known as "Eight-character Lake". Mencius said that Jiang Shang lived in seclusion on the coast of the East China Sea in order to escape the tyranny of Zhou Wang. Textual research by historians in Tang and Song Dynasties shows that the coast of the East China Sea refers to Changshu. Jiang Shang was hidden in Shang Hu, while Shang Hu and Kuncheng Lake were often merged into one lake in ancient times, so Kuncheng Lake was named "Hidden Lake".