This has caused Watarase-gawa River to have a raised bed near Ashikaga City and brought devastation to the forests in Ashio, and when hit by Typhoon Kathleen, it became the major cause of the flood.
このため、渡良瀬川は足利市付近で天井川となり、足尾の山林の荒廃とともにカスリーン台風襲来時は洪水の主原因となった。