There is an old saying: "A thousand-mile dike collapses because of an ant hole." To eliminate insect eggs and ants in the soil, earth used to build dams had to undergo special treatment—such as being roasted over fire or mixed with lime—then laid down hot and repeatedly compacted. The people of Qin State used this technique to pave the Qin Straight Road. Seeds could not take root in it, which was why the road had remained utterly barren for thousands of years, yet still level even after long periods without maintenance.
However, such soil was not necessarily effective for waterproof dikes. Nick had always assumed Hongze Lake's dike was built in winding curves because it followed the shoreline. Only after asking did he learn that its shape followed the principle of breaking waves, aligning with the natural direction of the currents. Dams elsewhere were built very straight, and for that very reason, many commoners used them as roads.
West Lake in Hangzhou had once also suffered constant flooding. When Su Dongpo served as an official in Hangzhou, he saw that West Lake had long been neglected, heavily silted up, and overgrown with grass. He raised funds from many sources to restore it, personally planned and designed the project, led soldiers and civilians in dredging the lake, and turned the removed silt from waste into treasure by building Su Causeway, one of the Ten Scenes of West Lake. Bai Causeway was originally called White Sand Causeway. It was renamed in commemoration of Bai Juyi, though he himself had not participated in building it. It was only because Bai Juyi had achieved outstanding results as Hangzhou's governor and won the people's recognition that the causeway was named after him.
Nick had also strolled along both causeways during his time in Hangzhou. It