Classification of the Oxbow lakes of the Hármas-Körös river and determination of ways for further exploiting the various water regions in the light of the water framework directive

Abstract

Hungary, due to its geographical location, is a country poor in natural water resources. The main aquatic ecosystems of Hungary is a system of lowland rivers, whose sources are located outside the country. Morphometry of this system has changed substantially in the predominant extent as a result of regulatory activities, not natural changes in river beds and river courses (Pálfai 2002). Regulation of the three largest Hungarian rivers – Danube, Tisza and Körös generated hundreds of oxbow lakes. Inventory of that aquatic ecosystems was made in Hungary not before 1962 by the Research Institute of Water Management – 287 oxbow lakes and among them 160 with an area of over 5 ha was recorded (Vituki 1962). Currently, the volume of these reservoirs is 119.4 million m3, of which 87.2 million m3 is a capacity of oxbow lakes located outside the flood dikes and the rest is in the overflowarm of rivers (Pálfai 2002). The value of these natural ecosystems has been underestimated for a long time. During their utilization economic profit was a priority, which often resulted in deterioration of the ecological status. Due to improper use and neglect, more than half of Hungarian oxbow lakes ceased to exist in the last hundred years. The disappearance and degradation of these ecosystems alarmed scientists, also outside Hungary. The tendency to disappearance and the degradation of small water reservoirs in the second half of the twentieth century had already a global dimension. Hungary’s accession to the European Union forced to change this situation, because it came into force the Water Framework Directive. The Water Framework Directive requires Member Countries duty to follow recommendations the specified in the methods of water management and evaluation of habitats and water. The aim of these actions is to maintain the specified criteria of water quality and, if possible, improvement of water quality. The Directive also indicates the necessity of registering of protected areas, but does not address the specifically to the problem of oxbow lakes as a specific local problem of Hungary. Therefore, in Hungary there is now an urgent need to develop a “rapid methods” classification of individual oxbow lakes into one of three specified categories, and determine how to further exploitation of the various water regions.