General information on Neretva River and its tributaries

Neretva is the longest and the richest Balkan tributary of the Adriatic Sea. Its source is located on 1.227 meters above sea level, under the Grdelj peak which is the part of Lebrsnik Mountain. Actual length of the river from its source to the Adriatic Sea is 230 kilometers. In her upper flow, Neretva passes through a valley parallel to the mountain range without crossing it. Neretva's upper part is up to 600 meters in depth, and this section of the river is called Borač whereas the latter section of the upper flow (around Rama River's estuary) is called Župa. Before it joins with Rama, Neretva flows towards northwest, and as it takes in the Rama tributary it suddenly shifts towards south. From there its valley cuts through the mountain ranges under a right angle. Such valleys are called cross over valleys. This part of the Neretva River is characteristic for steep canyons with sides ranging in height from 800 to 1200 meters. These canyon sides are almost completely deprived of vegetation; they are composed of limestone deposits which are, according to the geologists estimate, over 175 million years old. In the area of Borač, Neretva's fall is very steep and her valley is very narrow. When it comes to Župa its fall becomes much lower and her valley wider. Within the canyon Neretva is very fast, with numerous cascades and smaller waterfalls. Neretva has all of the characteristics of a mountain river with relatively steep fall and high mechanical energy. As it leaves the canyon, Neretva enters the valley of Mostar from where it goes through canyon and into her final section which begins from city of Čapljina onwards. This final section of the river is wider and has a large flooding area around the river basin. Width of the river in her final sections varies from 100 to 150 meters while her depth ranges from 1m along the majority of the river to 20 meters at certain whirlpools. Neretva's annual water discharge into the Adriatic Sea is over 8.830.000.000 cubic meters. At Metkovići, town located at the border between B&H and Croatia, Neretva's hydroelectric potential is 4.905.600.000 kWh per year. The middle section of the river is considerably different today, as opposed to the river before 1953. In 1953 an arch dam, 80 meters high, was erected 5 km upstream from Jablanica. This way the river was transformed into an artificial lake up to Konjic. Volume of the Jablaničko artificial lake is around 290 hm3 at full capacity. The maximum length of the lake is 30 km and its surface is around 1.440 ha. Maximum depth of the lake is 80 meters while the lakes peaks and lows vary and can even reach differences of 25 to 30 meters.

Rama hydro-accumulation was formed at Rama river, part of the Neretva watershed, in 1986. The length of this hydro-accumulation is 12 km, and it covers a surface of 1.500 ha. Maximum depth is 95 m, whilst the oscillations in water level can rise even to 55 m. From 1981 to 1987 three more dams were erected on Neretva River and thus formed three new water accumulations. Hydro-accumulation Salakovac exists from 1981. Length of this artificial lake is 20 km and it covers a surface of 314 ha, its maximum depth is 34m with oscillations of 5m. The last of the hydro-accumulations to be formed was hydro-accumulation Mostar in 1987. Length of this artificial lake is around 10 km with a surface of 112 ha. Maximum depth of the lake is 20m with oscillations up to 5m.

Geographic position and geomorphologic characteristics of Neretva River and its hydro-accumulations

Neretva river flows through a basin bordered by mountains Bitovnja (1700 m) and Vranica (2112 m) in the north, mountains Prenj (2103 m) and Cvrsnica (2226 m) in the south and Bjelasnica (2062 m) in the west. Hydro-accumulation Jablanica spreads towards northwest and borders with Rama hydro-accumulation. Artificial lake Jablanicko covers Ostrozac and several smaller basins. This river has made its bed in the area of high limestone, and partially in the area of mesosoic limestone. In this section there is a high influence of Mediterranean from the southeast and continent from northeast. Geological bed of the Neretva River and the accumulation lake in these parts is made of rocks dating from Mesozoic era, whilst the very basin of the lake is made of geologically significantly younger stones. Part of the basin from Konjic down to the mouth of Neretvica tributary is filled with lake sediments dating from Tertiary, with highest percentages of clay, marl and conglomerate. Earlier bed of the valley is covered with alluvial sediment, mainly mud and sand. Such or similar bed structure is also characteristic for the lower segments of the basin. At Ostrozac, Neretva leaves the Tertiary zone and enters into the zone of slate down to the Rama tributary mouth. This is where we have the first signs of well known Jablanica volcanic gabbro. From here Neretva goes into a narrow part of her canyon which continues down to Jablanica. Downstream from Jablanica the river made its bed through fluviglacial sediment, mostly hard cemented conglomerate. River banks are mostly steep and inhospitable. It is important to point out the significant percentage of limestone in this whole basin area, which is the main element in forming the actual river bed of Neretva.