Lake Balaton - The Pannonian Basin
The „Lake Balaton“, situated in Western Hungary, is the largest lake of Western and Central Europe and as well the largest steppe lake of Europe. It´s area size is about 600 square kilometers by 79 kilometers length and an average width of nearly 8 kilometers. The Tihany Peninsula is located nearly in the middle of the lakes northern side, where it´s width is only 1.3 kilometers. The average depth is 3.25 meters, the maximum is about 12.5 meters. In cause of this low depth the temperature of the water rises up to 28°C.
As of the lake itself , the famous wine from the vulcanic mountains at the northern lake side, the fish, as well of the beaches, the spas and the thermal sources, the area is one of Hungarys foremost tourist destinations.
As Hungary is landlocked, the lake is often called the „Hungarian Sea“. The romans named it „Lacus Pelso“, as the former Illyrian inhabitants called it „Pelso“, which meant „shallow“. As well, for example, the Germans name it „Plattensee“ through the centuries, which means „shallow lake“. The official name in Hungary is „Balaton“, it derives from the slavic word „blato“. It´s meaning is „mud“, as the area had been a muddy march and the ground of the lake is still very muddy to walk on.
The landscape of the lake is mainly from Mesozoic layers, similar to the rocks of the Alps This crustal segment had been moved to the east before the Alps had been pushed up.fgestaucht. Therefore, the layers kept their original composite up to nowadays. Back 15.000 to 20.000 years ago, the Balaton arosed in the Holocene by erosion Presumably, the basin had been blown free by constantly winds. Near the present town of Keszthely some small lakes had been formed by rain water. They connected to each other during 5.000 years and so enlarged into northeast direction until it got the nowadays size.Geological formations proof of a former active volcanoes, which is visible in the basalt columns of the Badacsony mountains, the spring cone of Tihany and the thermal sources of Heviz (visit this earthcaches as well!).
The river „Zala“ is with 138 km length and a quite low flow volume, one of the smaller rivers in Hungary, however, the largest tributary of Lake Balaton. It leads in the north in the so called smaller „Kis-Balaton“ and marshes there. The marsh areas and reed regions of the Kis-Balaton, work as natural water filter for the Lake Balaton and is a habitat for many rare plants, reptiles and birds. South of Keszthely Zala occurs, enriched with oxygen and purified, out of the swampy area and flows down a few hundred meters to lead into the Lake Balaton. Apart from the Zala the lake is fed of about 30 permanent and 20 periodical watercourses. To regulate the water level of the lake, a lock had been build near the village of Siófok. Surplus water is on the „Sió Channel“ directly led into the Danube. This channel had been built and used in Roman times already. The only source tributary of Lake Balaton is located near Tihany Peninsula.
The water level of the lake is determined by rain, inflow of rivers and watercourses, evaporation and the regulation of the lock at Siofok. Nearly one billion cubimeter of rainwater reach the lake itself or at least the ground water of the area around added by a water flow of the Zala and several smaller streams, which sums nearly 900.000.000 cubicmeters.There is a loss of several centimeters to watch in the summertime in cause of evaporation, which may add up to a loss of six million cubicmeters by just one centimeter of loss a day.
During the construction of the railway lines around the lake, the water level control had become necessary, as the before highly fluctuating level would had damaged the embankmentes and so as well the railway traffic. The flow direction of the channel had been reversed, so that a drainage of the lake to the Danube got possible, regulated by the lock at Siofok. If the level reaches the 110 centimeter mark, the lock will be opened to let the water flow out of the lake. The usual water level is between 70 and 110 centimeter. 1977 it had been increased from just 100 centimeter, which kept more water in the lake and improved the water quality at all. The level is compared to the zero point of the bar at Siofok, which is like 103,41 meters above the Baltic Sea
The rotation of Earth, as well as the winds affect the currents in Lake Balaton. The flow at the surface is due to the main wind direction from northwest to northeast, at the bottom of the lake there is a reverse flow from east to west in cause of the earth´rotation. The strong movements of the water surface generate high flow values between the different basins and within basins and bays. The highest flow values at speeds up to 2 meters per second can be found between the Tihany Peninsula and the shores of Szantòd, where the exchange in the narrow transition between the northern and southwestern basin occurs.
The Kis-Balaton had once been the largest south-west bay of Lake Balaton and with it´s wide swamp area since 2000 years it is a natural biological filter of the lake. In cause of deposits of the lake inflow of the river Zala and as well even more because of massive human interventions since the beginning of the 19. century, the situation led to the separation of the Balaton. Large parts of the former old Kis-Balaton just disappeared. From originally 60 square meter of water area just half of it remaines. The rest of the area got under protection in 1952. The marsh area, however, lost its natural cleansing and protective functions of the Balaton and the famous heron colonies had been heavily threatened. Starting in the middle of the 20. century the Balaton slowly got more and more muddy and swampy and as so of lost it´s natural biological balance. As to improve the water quality in 1976 the renaturation of Kis-Balaton had been started. So nowadays the, so as well called „Little Balaton“, stretches again in 22 kilometers of length, containing a storage of water capacity of 28 million cubicmeters. It´s water level is more or less one to two meters above the one of Lake Balaton. The two interior located lakes are, as part of the Kis-Balaton protectionsystem, back again a natural, biological swamp filter for the water of Lake Balaton. An extension of the protected area is planned up to 2012.
The area is unique in Europe, with its air and light, its flora and fauna. In the European network of natural habitats it is an important ecological, species-rich area. In the swampy humid biotope live numerous, also (strictly) protected fish, plants, reptiles and birds.
In 1979 the Kis-Balaton had been included in the „Ramsar Convention“ for the protection of internationally important wetlands. Since 1997 it is part of the Balaton Uplands National Park („Balaton-Felvidéki Nemzeti Park“), which belongs to the protectionsystem of „Natura 2000“ of the European Union. 1.400 hectars of the 18.000 hectars of the protected Kis-Balaton area are specially protected. This area may only be entered only by professional tour guides of the natural park. Just the park forest „Vörsi Parkerdö“, the Kis-Balaton island „Mariaasszony“, near Vörs, as well as the island „Kanyavar“ and the buffalo reserve „Bivaly reservatum“ are free to enter by visitors.
The mentioned national park had been established in 1997 on the Balaton area of 56.000 hectars. It includes an area on the northern shore of the peninsula of Tihany up to the south-west bank to the marsh of the Kis-Balaton. Geographically, the park is very manifold, including the cones of the period of active volcanism. A special feature is the so called „Stonesea“ in the „Kali Basin“. You will find petrified remnants of the Pannonian Sea. In the Keszthely mountains grow a lot of very rare plants and the marsh area of Kis-Balaton is primarily a bird sanctuary and a buffalo reserve.
To log this earthcache I would like you to do the following:
As I did not find any information board at the Lake Balaton itself and as the area of the Kis-Balaton is even much more worth to visit as of it´s flora and fauna, I would ask you to find the info board there at N46 36.936 / E017 10.097. You will find the answers to the following questions:
1. The biological cleaning system of the Kis-Balaton reduces the incrimination of Lake Balaton of how many percentage?
2. How long does it take for the water of the river Zala to flow once through Kis-Balaton to get the natural cleaning?
3. Next to the info board you will find a wooden bridge. Get a foto taken of yourself on the bridge with the GPS in hands.
You may directly log virtually, added by the mentioned foto. Send the answers to the questions via my profile at geocaching.com, mentioning the cache name.
If you don´t get an answer of me I am not in reach of the internet or everything is correct anyway.
I hope you will have fun with the cache at this beautyful area and send
best regards from Germany