Looking at the shore of the lake in the hazard map, residential areas (retaining walls) are at high risk from rapids and hills are at low risk.
This is because, by creating an artificial ground and securing a horizontal surface, rainwater etc. loses a place and rapids occur locally at a place near a slope such as stairs.

The conventional foundation of a house has only the value of supporting a dwelling unit. I attempt a sustainable update by combining the different values that the foundation treat the water with the landscape.
The new value foundation of water treatment also affects the function of living, creating a new cityscape in relation to water.