《水经注·卷十八》
武水发源于杜阳县的大岭旁。大岭东西长三百步，南北宽二百步，人们称为赤泥现；清波流经山涧，俗名大横水，可能就是杜水。
水发杜阳县大岭侧，东西三百步，南北二百步，世谓之赤泥岘，沿波历涧，俗名大横水也。疑即杜水矣。
Wu River originates besides Daling of Duyang County. Daling is three hundred paces long from east to west and two hundred paces wide from north to south, and people call it Red Clay Mound. The clear water flows through the mountain stream, and people commonly call it Dahuang River, which might be Du River.