| Autor: |
Hachemi, Kamel, Grecu, Florina, Ioana-Toroimac, Gabriela, Constantin (Oprea), Dana Maria, Ozer, André |
| Zdroj: |
Mediterranean Geoscience Reviews; June 2021, Vol. 3 Issue: 2 p159-173, 15p |
| Abstrakt: |
The geomorphological, geological, hydrological and climatic context of the Vedea-Oltenița Danube sector in Romania is characterized by Pre-Quaternary sedimentary deposits (Mesozoic, Cenozoic). The surface of the fluvial islands is exclusively formed of Quaternary alluvial materials and covered by vegetation which stabilizes them (islands). The study of the riverbed dynamics and its islands is essential due to the limited understanding of the interdependence relationships between water, relief and sediments, as well as of their effects on the fluvial system. The objective of this work is to study the recent dynamics of the island system of the Vedea-Oltenița sector in a short interval. The use of SAR imagery (Synthetic Aperture Radar) provides spatial and temporal monitoring, regular and fine surfaces, taking into account the sensitivity of the radar signal towards the types and properties of the terrain, which makes possible to determine, monitor and analyze the changes occurring between the different acquisitions. In this diachronic study, we have used SAR images from the ERS-1/2 and ENVISAT ASAR satellites from 1995 to 2010, where we have recorded and mapped 11 islands and 25 sub-islands during this period. This analysis has showed and confirmed the increase in accumulations in this short period of 15 years. It has also allowed to estimate the annual speed of this accumulation at around 22.68 m2/year and a radius of around 2.69 m/year. This study has also demonstrated the role of major flooding phenomena in the acceleration of sediment accumulations in islands and under islands in this sector. The Danube island system continually undergoes several natural and anthropogenic forces. The continuous deterioration of these phenomena can activate the appearance of other sub-islands which can lead to new islands. |
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