Since ancient times, the world’s civilizations, including the Egyptians and Mesopotamians, have sprung up alongside rivers. Rivers were not only used as transport routes, but also played an indispensable role in the development of agriculture. This is because inundations make the soil fertile. On the other hand, as great floods bring disaster, countermeasures have been sought. In Japan too, flood control has been important since ancient times. TAKEDA Shingen, a warlord from the Warring States period (16th century), is known for building an embankment (now called Shingen Tsuzumi) in his domain (present-day Yamanashi Prefecture). In those days, countermeasures involved changing the course of rivers by harnessing the power of nature. In the Meiji era (19th century), businessman KINPARA Meizen invested his private fortune into building a dyke along the Tenryu River. He then proceeded to plant trees in the mountains upstream to prevent flooding. Along the banks of rivers in Japan like the Sumida River, there are many famous cherry blossom viewing spots. It is said that these cherry blossoms were planted to be a flood control measure, as they would attract many visitors who would step on the banks making them solid. Dam construction has become the main weapon against flooding in modern times. Initially many dams provided hydroelectric power, but the need for this decreased as nuclear power plants became more commonly used. Alongside this, residents’ opposition to the construction of dams grew making them a political hot potato. Yanba Dam in Gunma Prefecture became a symbol of this controversy. In the beginning the construction budget was 211 billion yen, but due to planning changes, it is said that the total expenditure, including related construction would exceed 500 billion yen. By the time the Yanba Dam was completed, it was established that bureaucats had ties to a number of the corporations involved and they were criticized for bid rigging. In July 2020, unprecedented rainfall in southern Kyushu caused the Kuma River in Kumamoto Prefecture to overflow, leading to extensive damage. The construction of the Kawabe River Dam, which was to be built on a tributary of the Kuma River, had been halted in 2009. After this disaster, some people said that the Kawabe Dam had been necessary after all. While other people said that it could not have prevented the disaster even if the dam had been constructed. They pointed out that this continuous heavy rainfall could not have been predicted and that the planned dam was only designed to control floods based on data from 50 years ago. The long-term trend of increasing heavy rainfall is thought to be due to global warming. Flooding is expected to increase not only in Japan but also in other parts of the world.