《水经注·卷三十九》
洭浦关在中宿县，洭水流出洭浦关，在右边与漆水汇合，汇流处叫洭口。
关在中宿县。洭水出关，右合溱水，谓之洭口。
Titianpu Pass is in Zhongxiu County. Titian River flows out of Titianpu Pass and merges with Qishui River on the right. The confluence is called Titiankou.