As a civil and environmental engineer I think that levees should be built to a 2 or maybe five year storm height and no more. That's analogous to the natural berm that rivers deposit along their banks. Floodplains should be used for crops and not much else. Frequent flooding nourishes the soil with sediments, and prevents them from moving further downstream, like what is happening now at the end of the Mississippi, the largest "dead zone" in the Gulf of Mexico ever observed by man. Upstream flooding minimizes downstream flooding.

Whenever we mimic nature we are usually correct. When public health officials settled on a concentration of fluoride to put in the public water supply, they used the percentage that occurred naturally in sea water. That turned out to be beneficial, inexpensive and caused no harm.

The medical profession has the Hippocratic Oath, which states: “first, do no harm”. The engineering and public policy professions should abide by the same oath.