Influences of Weeds Control on the Effects of Cold Air Spread at Night in Satoyama

Abstract

Satoyama is expected to work as a cooling spot in recent years. On the other hand, in most satoyama, weeds are growing thick by abandonment of satoyama conservation. Compared with the satoyama which has been kept well by weeds control, in satoyama where weeds has not been controlled, it is expected that cold air spread from satoyama is obstructed by lush weeds. Therefore, the purpose of this study was to clarify the influences of weeds control on the effects of air flow at night in satoyama. In this study, air flow was visualized by smoke generator and laser in satoyama, and shot at both areas where weeds have been cut or not. Then the video of air flow was analyzed with 2D fluid analysis, and the speed of air flow in both areas was calculated and compared. As a result, compared with the area where weeds have not been cut, the speed of air flow was faster in the area where weeds have been cut. It showed the possibility that cold air spread was obstructed by lush weeds in satoyama, and it would become faster by weeds control. Currently, the necessity of satoyama conservation has been mainly pointed out from biodiversity conservation. However, the higher motivation of satoyama conservation can be expected by the result of this study which showed the possibility of thermal environment mitigation by satoyama conservation.