Under the circumstances which the standpipe is in full-flow, the free-fall flow of water column generates a suction to t雨水立管在满流情况下，水柱的自由落体对雨水系统的悬吊管、雨水斗产生抽吸力，使常规靠重力流的雨水变成动力流雨水，从而加快雨水的排放。