the Korana, whose source, Dobra Voda, is located at an elevation of 870 m above sea level, but is relatively insignificant in terms of discharge () when compared to the main source of the Sana river. The mouth of the Sana is located in Novi Grad, at an elevation of 117 m above sea level. The Sana has a high karstification coefficient of 0.43 at the Ključ measuring station, which has the consequence of the Sana watershed being relatively undeveloped and having few surface streams. The tributaries of the Sana river are the Banjica (53 km2 watershed area), Gomjenica (776 km2 ). Kozica (120 km2), Ribnik (447 km2 ), Sanica (468 km2), Kijevska rijeka (64 km2), Dabar (111 km2), Zdena (65 km2), Blija (133 km2), Majdanuša (60 km2) and Japra (355 km2). The Sana flows through both entities of Bosnia and Herzegovina. Its source is located in Republika Srpska, after which it crosses the entity line and enters the Una - Sana Canton where it flows through Ključ and Sanski Most. After exiting Sanski Most, it crosses the entity line again and takes a sharp left turn at the foot of the Kozara mountain, after which it enters Prijedor and continues to flows towards its confluence with the Una in Novi Grad. The major cities and towns located on the banks of the river are Prijedor, Sanski Most and Ključ. There are multiple measuring stations in Bosnia and Herzegovina on the Sana, and their data is show in the table below: Unac The Unac river is the longest headwater of the Una, and, at their confluence, has a larger discharge and a larger watershed. The longest headwater of the Unac, Šatorski potok, flows out of Šator lake under the Šator mountain at an elevation of 1460 m above sea level. The largest town on the Unac is Drvar, through which the river is regulated. The river is 66 km long and, throughout its course, flows through multiple gorges and canyons, the deepest one lying between Crno vrelo and Bereka in the National Park itself. It is 350 m deep and noted for its hydromorphological, geological, hydrological characteristics and its biodiversity. Throughout its course there is pronounced karst influence, and the river is partially disappears as a losing stream in part of its course, only to reappear at Crno vrelo, a couple of kilometers before its mouth. There are multiple measuring