HYDRO-MORPHOLOGICAL RESPONSES OF THE DRÁVA RIVER ON VARIOUS ENGINEERING WORKS
HYDRO-MORPHOLOGICAL RESPONSES OF THE DRÁVA RIVER ON VARIOUS ENGINEERING WORKS

Summary/Abstract: The hydrology and morphology of the Dráva River is mainly influenced by dams and reservoirs built on the upstream section, but groins and cut-offs also affect the channel development. Our aims are to summarize the hydrological and morphological responses of the Dráva River given on different engineering works and to determine its evolutionary way. Based on the morphological analysis four evolutionary phases are distinguishable of the Dráva River. These phases reflect the timing of the disturbance and the response of the river. In its natural state, until the late 19th century, the upper section had and anastomosing-braided pattern, while the lower section was meandering. As the consequence of cut-offs the length of the Dráva, its sinuosity and temporally its channel width decreased, and the channel pattern changed from meandering-anastomosing to braided. Later, the groin constructions resulted in simpler morphology, as islands disappeared and the complex system of the side channels also vanished. Finally, as a response of dam and reservoir constructions the channel started to incise. The fragile fluvial system of the Dráva represents a graded evolution, and nowaydas the Dráva is probably in a »far-from-equilibrium« state.

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