Regarding the history of the Grand Canal, it is well known as common knowledge.
He picked up the teacup and took a small sip, smiling and saying, "The older generation said, in the past, there were no locks on the Grand Canal; instead, a stone dam was built within to elevate the water level of the canal. The water overflowed from the dam to ensure that boats could sail."
"How could boats sail with a dam built?"
"At that time, there weren't these large boats we have now, only small wooden boats weighing a few tons, at most tens of tons. When boats passed over the dam, if it was a downstream boat, wooden planks would be used to cover the cargo hold tightly secured, and the lock operator would steer, plunging from the dam into the water below, then resurfacing."
