Plitvice Lakes National Park

About

Plitvice Lakes National Park is one of the oldest and largest national parks in Croatia. In 1979, Plitvice Lakes National Park was inscribed on the UNESCO World Heritage list, for its outstanding and picturesque series of tufa lakes, caves, and connected waterfalls. The national park was founded in 1949 and is in the mountainous karst area of central Croatia, at the border with Bosnia and Herzegovina. The important north–south road that passes through the national park area connects the Croatian inland with the Adriatic coastal region. The protected area extends over 296.85 km2 (114.61 sq mi). About 90% of this area is part of Lika-Senj County, while the remaining 10% is part of Karlovac County.

The national park's lakes are arranged in cascades. Sixteen lakes can be seen from the surface. The lakes are renowned for their distinctive colors, ranging from azure to green, grey or blue. The colors change constantly depending on the quantity of minerals or organisms in the water and the angle of sunlight.

The name Plitvice was first mentioned in a written document in 1777 by Dominik Vukasović, the priest of Otočac. This name was designated because of natural phenomena that have created the lakes. Nature formed shallow basins (Croatian pličina or plitvak, plitko means "shallow"), which have been filled with water. For centuries, water has changed the limestone and thus the landscape of this area. The emerging travertine barriers decelerated and retained the flowing water. These dams are continuously growing in height.

The area of Plitvice Lakes National Park extends across two political subdivisions or counties (Croatian županija ). Its 296.85 km 2 (114.61 sq mi) area is divided between Lika-Senj County (90.7 percent) and Karlovac County (9.3 percent), hence the national park authority is under national jurisdiction. The overall water body area is about 2 km 2 (0.77 sq mi). The two largest lakes, Prošćansko jezero and Kozjak, cover about 80 percent of the overall water body area. These lakes are also the deepest, with a depth of 37 and 47 m (121 and 154 ft) respectively. None of the other lakes in the park exceeds 25 m (82 ft) in depth. The elevation drop from the first lake to the last is 133 m (436 ft). [ citation needed ]

The area of Plitvice Lakes National Park extends across two political subdivisions or counties (Croatian županija ). Its 296.85 km 2 (114.61 sq mi) area is divided between Lika-Senj County (90.7 percent) and Karlovac County (9.3 percent), hence the national park authority is under national jurisdiction. The overall water body area is about 2 km 2 (0.77 sq mi). The two largest lakes, Prošćansko jezero and Kozjak, cover about 80 percent of the overall water body area. These lakes are also the deepest, with a depth of 37 and 47 m (121 and 154 ft) respectively. None of the other lakes in the park exceeds 25 m (82 ft) in depth. The elevation drop from the first lake to the last is 133 m (436 ft). [ citation needed ]

The availability of water, influenced by the configuration of the terrain, has a great impact on the biodiversity of this area. The Plitvice Lakes are surrounded by various mountains. The western side of the national park area is enclosed by the Mala Kapela mountain, while the eastern side is enclosed by the Lička Plješivica mountain, which also represents the border with Bosnia and Herzegovina. Plitvice Lakes National Park is situated in the Plitvice plateau which is surrounded by three mountains that are part of the Dinaric Alps : Lička Plješivica mountain ( Gola Plješevica peak 1,640 m), Mala Kapela mountain (Seliški Vrh peak at 1,280 m), and Medveđak (884 m). The afforested mountain slopes serve as reservoirs. They are also a refuge for many animal species. The large difference in altitude in a narrow space between the mountains in the south and the Korana river in the north represents a significant criterion for biodiversity in this region. The overall difference in elevation within the national park area is 912 m (the highest elevation is Seliški vrh at 1279 m, the lowest elevation is reached at 367 m at the bridge across the Korana river).

The Plitvice Lakes originate in the south of the park area at the confluence of Bijela Rijeka ("White River'") and Crna Rijeka ("Black River"). These rivers originate south of the municipality of Plitvički Ljeskovac and unite at one of the bridges in this village. From this place onwards to the lakes, the water masses are referred to as Matica (English for "water current", can also mean "root" or "origin"). At the bay of Liman (also called Limun ), a part of Prošćansko jezero, another small river flows into the lakes. This river is fed by permanent springs; the water quantity, however, varies. Temporarily, water from other, usually dry, creeks reaches Prošćansko jezero from the west.

Tufa sediments have been formed from the Pleistocene onwards in sinkholes or depressed areas between the surrounding mountains. Generally seen, the underground of the Plitvice Lakes could be categorized into two zones. The Upper Lakes in the south predominantly consist of dolomite rock. The Lower lakes in the north predominantly consist of limestone rock. Dolomite rock is slightly harder than limestone. Though fragile upon physical influence, dolomite rock has lower water permeability properties. In contrast, limestone rock is more compact and massive, but has a higher water permeability.

The availability of water, influenced by the configuration of the terrain, has a great impact on the biodiversity of this area. The Plitvice Lakes are surrounded by various mountains. The western side of the national park area is enclosed by the Mala Kapela mountain, while the eastern side is enclosed by the Lička Plješivica mountain, which also represents the border with Bosnia and Herzegovina. Plitvice Lakes National Park is situated in the Plitvice plateau which is surrounded by three mountains that are part of the Dinaric Alps : Lička Plješivica mountain ( Gola Plješevica peak 1,640 m), Mala Kapela mountain (Seliški Vrh peak at 1,280 m), and Medveđak (884 m). The afforested mountain slopes serve as reservoirs. They are also a refuge for many animal species. The large difference in altitude in a narrow space between the mountains in the south and the Korana river in the north represents a significant criterion for biodiversity in this region. The overall difference in elevation within the national park area is 912 m (the highest elevation is Seliški vrh at 1279 m, the lowest elevation is reached at 367 m at the bridge across the Korana river).

The Plitvice Lakes originate in the south of the park area at the confluence of Bijela Rijeka ("White River'") and Crna Rijeka ("Black River"). These rivers originate south of the municipality of Plitvički Ljeskovac and unite at one of the bridges in this village. From this place onwards to the lakes, the water masses are referred to as Matica (English for "water current", can also mean "root" or "origin"). At the bay of Liman (also called Limun ), a part of Prošćansko jezero, another small river flows into the lakes. This river is fed by permanent springs; the water quantity, however, varies. Temporarily, water from other, usually dry, creeks reaches Prošćansko jezero from the west.

Tufa sediments have been formed from the Pleistocene onwards in sinkholes or depressed areas between the surrounding mountains. Generally seen, the underground of the Plitvice Lakes could be categorized into two zones. The Upper Lakes in the south predominantly consist of dolomite rock. The Lower lakes in the north predominantly consist of limestone rock. Dolomite rock is slightly harder than limestone. Though fragile upon physical influence, dolomite rock has lower water permeability properties. In contrast, limestone rock is more compact and massive, but has a higher water permeability.

On average, the annual precipitation rate at the Plitvice Lakes is 1,500 mm (59 in). Usually, in spring and fall (autumn) the largest rain quantities are measured. The average relative air humidity is 81.8 percent. In January, the average temperature is 2.2 °C (36 °F). During the summer months of July and August, the temperature rises to 17.4 °C (63 °F). The general average annual temperature is 7.9 °C (46 °F). Snow falls from November until March. Usually, the lakes are frozen during December and January.

The lakes of Plitvice are a result of century-old processes and the sedimentation of chalk, which is abundantly available in the waters of this karst area. These sedimentations are called tufa or travertine (both are called sedra or tuf in Croatian, apart from many other names like bigar or vapneni mačak ).

In geological terms, the actual phenomena molding the Plitvice Lakes are quite young. The complex processes of dissolution and sedimentation of limestone require specific climatic preconditions. These have only existed since the end of the ice age about 12,000 to 15,000 years ago, according to tufa radiocarbon datings.

Apart from weather and temperature factors, the water quality and other natural factors are significant for the creation of these natural phenomena, prevailing at the Plitvice Lakes. By passing through the limestone underground the karst rivers dissolve chalk (calcite), which concentrates in the water. The saturation level of calcite within the frontal flows is thus very high. The water becomes significantly mineralized, super-saturated with calcium and magnesium-hydrogencarbonate.

The quantity of calcium hydrogencarbonate (calcium bicarbonate) dissolved in water depends on the quantity of dissolved carbon dioxide in the water. Generally, the following could be said: The colder the water, the higher the quantity of dissolved calcium hydrogencarbonate. Depending on the conditions for the alteration processes, scientists identified limestone dissolution rates of 0.01 to 4 millimeters a year (it is possible that by the effect of rainwater about 1 m 3 of limestone is dissolved in about 10,000 years). [ citation needed ]

Measurements of carbon dioxide quantities in the water show that they correspond with continuous sedimentation processes in the Plitvice Lakes area. Carbon dioxide quantities at the springs are about twenty times higher than in the atmosphere. The quantity of carbon dioxide decreases along the water route. The Plitvica river, for example, loses even up to 97% of its original quantity of carbon dioxide along its route.

The area of a river, in which the formation of tufa occurs, is called precipitation area. Along the Korana river, for example, measured from its origins, tufa is being formed only along the first 10 to 15 km (9.3 mi), even if according to pH measurements the conditions would be favorable further down the river. At the ground of Lake Kozjak a constant yearly sedimentation of 0,8 millimeters during the past 3,000 years has been ascertained. Yearly, the barriers are growing up to 13 millimeters in height. Tufa formation processes thus surpass erosion activities, which would destroy the sensitive barriers of the lakes. It is estimated that the tufa sedimentations at the ground of the lakes date back 6,000 or even 7,000 years.

The precipitation of calcium carbonate, however, does not occur right at the springs of the rivers that flow into the Plitvice Lakes. For the precipitation of carbonate chalk (calcium carbonate) the water needs to reach a certain mineral saturation level. At the springs this saturation level is about 1. For the precipitation, the water saturation level needs to be higher than 3. At the same time, the pH value of the water needs to be above 8,0 (slightly alkaline).

In the course of time, older barriers can be flooded by rising water levels since other barriers have outgrown the older ones. 400 years ago, there were two lakes in place of today's Kozjak lake. In the lowest third of the lake, at the level of Matijaševića draga, a crown of an underwater barrier that is 40 m high, is stretching 4 m below the water surface. This barrier certainly formed a magnificent waterfall in the past. The travertine barrier at the Kozjak bridges at the current end of the Kozjak lake, however, grew faster. Thus, 400 years ago two lakes merged in one. That is why the greatest depths of Kozjak lake are in its lower basin (north from the little island).