Because three sides of the corridor are walls that do not allow water to pass through, part of the groundwater beneath the riverbed flows into the corridor, which is more than 200 meters long, and then follows a ditch 3.4 kilometers long to the water intake area.
由於廊道的其他三面都是不透水牆面，河床下的地下水，一部分就流入長 200 多公尺的集水廊道中，再順著 3.4 公里長的圳道流至取水口。