Clustering oxbow lakes in the Upper-Tisza Region on the basis of stable isotope measurements

SummarySeveral times a year the River Tisza floods areas between dikes, fills the oxbow lakes on the floodplain and changes their water. However the water addition in the oxbow lakes does not only take place through flooding; it is also likely that water can seep under the surface through the gravelled layers of the old river-beds, and furthermore, precipitation also plays a role. Our goal with this study is to acquire a full, comprehensive picture of the water addition of the oxbow lakes in the Upper-Tisza Region. Surface and groundwater samples were taken from the River Tisza, the oxbow lakes and the boreholes around four oxbow lakes, and stabile isotope ratios were measured. We can get information on the origin, the evaporation and the state of the waters, and the depth of the water table with the help of δ18OVSMOW (‰) and δDVSMOW (‰). During the examination the question we addressed was how oxbow lakes can be classified according to their water addition on the basis of their stable isotope ratios. The results from the Tisza and the oxbow lakes, as well as the results from the oxbow lakes on the reclaimed side and the floodplain are also isolated.

► Stabile isotopes show differences between the floodplain and the reclaimed side.
► Underground water addition from the River Tisza cannot be detected in oxbow lakes.
► Statements are also sustained by a statistical method.