Hidrológiai Közlöny, 2016 (96. évfolyam)

2016 / 3. szám - HISTORICAL SNAPSHOT - Borics Gábor - Ács Éva - Boda Pál - Boros Emil - Erős Tibor - Grigorszky István - Kiss Keve Tihamér - Lengyel Szabolcs - Reskóné Nagy Mária - Somogyi Boglárka - Vörös Lajos: Water bodies in Hungary - an overview of their management and present state

Water bodies in Hungary - an overview of their management and present state

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G. Borics , E. Acs , P. Boda , E. Boros , T. Erős , I. Grigorszky , K.T. Kiss , Sz. Lengyel , N.M. Re- skóné , B. Somogyi and L. Vörös

MTA ÖK, Danube Research Institute, 1113 Budapest, Karolina str. 29. Hungary

** MTA KVI-PLUSZ Office for Environmental Testing Limited Liability Company, I2ll Budapest, Szállító str. 6.

*MTA ÖK Balaton Limnological Institute, 8237 Tihany, Klebeisberg Kuno str. 3. Hungary

Abstract

Due to its geographical position and climatic characteristics Hungary has many types of surface waters ranging from large rivers to small streams, or from large steppe lakes to small soda pans. These waters have diverse flora and fauna, and provide various ecosystem services for human well-being. Differences among the water types in size, depth, chemistry or biology determine their differential responses to anthropogenic disturbances, and thus their restoration or protection requires different management strategies. With this study the authors aim to review the water-related problems had to be faced and resolved by the experts during the last centuries, and show the achievements reached in the field of water quality management in Hungary.

Keywords

Water types, pollution, restoration.

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INTRODUCTION

Waters of the Carpathian Basin played a significant role in the evolution of the landscape, and thus, in the socioeconomic life of the population. The ancestors of the Danube, Tisza and Drava rivers created the Great Hungarian Plain which is one of the largest alluvial plains in Europe, covering an area of approximately 100,000 km2. Due to the low runoff and partly to human activities extended wetlands developed on the river flats, which occupied more than 20% of the plain up to the middle of thel9th century. At this time, the increasing demand for arable lands and improvement of transport infrastructure (roads and railways) in the Tisza valley required to initiate one of the largest river regulations in Europe. As a result of this comprehensive engineering work many meanders were cut off, the straightened rivers were embanked and the wetlands were drained. Now the length of the embankments and the extension of the area protected from the floods are larger than those in the Netherlands. Although extension of the water-related ecosystems decreased in Hungary during the last two centuries, many unique types of water bodies still can be found here (Borics et al. 2014). Lake Balaton, which is the largest shallow lake in Central Europe or Lake Velencei and Lake Fertő, which are the westernmost representatives of the large saline steppe lakes of the Eurasian steppe zone have high conservation value and play important role in the economy of the country. The remaining wetlands, hundreds of oxbows, artificial reservoirs and pit lakes are characteristic parts of the landscape and have also significant local interest. The astatic soda pans constitute a special type of the inland saline waters. Effective managing of the conservation and rational use of the various types of waters is a really challenging task for the experts, because these tasks require type or site specific approaches. The aim of this study is to give an overview of the relevant types of waters in Hungary, and to show the results of those measures that were implemented to restore and improve their quality.

RESULTS

River Danube

The Danube is the second-longest river of Europe (after the Volga River), originating at Donaueschingen, Black-Forest (Germany) where the two small creeks, the Breg and Brigach confluence (Liepolt 1967). Then the Danube flows southeast for 2,850 km, passing through 10 countries including Hungary before entering the Black Sea. The Danube flows through many cities, including four national capitals (Vienna, Bratislava, Budapest and Belgrade) more than any other river in the world. Its banks, lined with castles and fortresses, formed the boundary between great empires, and its water served as a vital commercial highway between nations. Since the completion of the German Rhine-Main-Danube Canal in 1992, the river has been part of a trans-European waterway from Rotterdam on the North Sea to Sulina on the Black Sea, ranging a distance of 3,500 km.

The Danube enters Hungary at the Little Alföld plain. There the river stream slows down abruptly and loses its transporting capacity, so that enormous quantities of gravel and sand settle on the bottom. Later Danube enters the Visegrád Gorge, the wooded hills of Pilis, Visegrád and Börzsöny. The meandering Danube created a wonderful landscape that became nature lovers' paradise. The Danube then flows through Budapest, and across the vast Great Alföld plain. The whole area of Hungary is the part of its drainage basin. The length of the main channel of the river in Hungary is 417 km, therefore the Danube is the dominant element of the country's hydrography. The natural regime of river runoff changes constantly as a result of the introduction of stream-regulating equipments, including dams and dikes such as the Gabcikovo Dam. Because of the dam we have to face the following environmental consequences: intensive degradation of the Danube River bed downstream (especially at the Old Danube river bed); decreased water level; increased sediment supply; increased amounts of bedload and higher intensity of bedload movements; reduced flood capacity; decreased channel stability.