River flooding happens when heavy rain causes river levels to rise and overflow with large amounts of water. In recent years in Japan, a weather phenomenon known as "linear rainbands" has led to frequent torrential rain and the flooding of rivers. River flooding comes in two forms, and when one accompanies the other, the damage also grows more intense. Knowing the risks in the areas we call home and swiftly fleeing to a safe evacuation site in times of emergency are what is most needed to save lives. We will introduce tools with the latest digital technology that are effective for this purpose.