The "Yoshino-river” is the major river in Shikoku. When viewed from the sky, it is winding like a "dragon". It used to be called "Bekku-river", but now it is called "Yoshino-river". The old Yoshino River was renamed to "former Yoshino River".
Fertile soil was transported from the upstream every flood, that indigo production was thriving. The lower reaches of the river has a long history for indigo industry.
Since there is an embankment that protects the basin from floods, it's not immediately conceivable that "rain" is equal to "flood." But I grew up hearing the fear of the flood from my elders, I feel the scaryness of the rampage river. It will be raining season soon.