The river Trebižat is a right tributary of the river Neretva. The course of the river is located in a very karst area, which causes water to sink along the riverbed. At its entrance to the territory of the municipality of Ljubuški, the river has the name Tihaljina. It receives the largest spring of constant character and great generosity, the Klokun spring. Downstream from the Kavazbašina bridge (Klobuk), Tihaljina gets the name Mlade and under that name flows through Ljubuško polje. The Mlade River on the left receives the occasional watercourse Grabovo vrelo and the permanent watercourse Vrioštica. After passing under the bridge on Humac, the river gets the name Trebižat. Trebižat has only one permanent tributary Studenčica on its course.