|
|||||
|
|
Erosional scours and meander development in response to river engineering: middle Tisza region, Hungary |
|
| Authors: | Ágnes Cserkész-Nagy Tamás Tóth |
| Institution: | a Dept. of Physical and Applied Geology, Eötvös Loránd University, Pázmány P. s. 1/c, Budapest H-1117, Hungary b Geomega Ltd., Mester u. 4. I/2, Budapest H-1095, Hungary c Middle-Tisza District Environment and Water Directorate, Ságvári Krt. 4, Szolnok H-5000, Hungary |
| Abstract: | We present a case study on how riverbed morphology of the engineered and meandering Tisza River of the Pannonian Basin (Hungary) has changed during post-engineering times. The objectives were (1) mapping the location and morphology of scours and point bars, (2) reconstructing their changes in a 150 year time-scale in response to engineering work, (3) describing the differences of quasi-natural and engineered channels and (4) distinguishing of local and general causes, both natural and anthropogenic.Recent erosion and deposition have been traced on continuous ultrahigh resolution (UHR) seismic profiles. These results were matched up to channel cross-sections and to time-series planimetric and bathymetric maps. The topography of the riverbed is determined primarily by two factors: the plan view geometry of the channel and the lithology of the substratum. As well as naturally developing scours in the river bends, shallower and elongated, slightly refilled ones appear on straight reaches or in engineered channels. Elongated bed scours and extraordinary forms are related to local human effects. However, erosion is observed everywhere in the investigated 102 km long Middle-Tisza region. As a result of cut-offs the gradient increased and, as a consequence, the riverbed became incised.Sedimentation is reflected in accelerated point bar development, which resulted in intensive lateral migration and increasing sinuosity, which is enhanced in the vicinity of human interventions. Changes do not propagate far away. Channel adjustments happened in two phases: rapid incision was followed by a slower sinuosity increase in order to obtain a new dynamic equilibrium. |
| Keywords: | Scour Point bar development River engineering Tisza River Morphological changes Centennial scale |
| 本文献已被 ScienceDirect 等数据库收录！ | |