Scientific Annals of the Danube Delta Institute Tulcea, Romania vol. 24 2019 251 | Page © 2019, Danube Delta National Institute for Research and Development Tulcea, Romania 27. https://doi.org/10.7427/DDI.24.27 Using of GIS Techniques to Assess the Spatial Changes of the Fluvial Islands in the Corabia Area – Bechet Harbor Sector (Km 626-679) between 1910-2017 IORDACHE Gabriel * , BONDAR Constantin, ANGHEL Sorin, MALAGEANU Marian, DUDU Alexandra National Research and Development Institute for Marine Geology and Geoecology – GeoEcoMar, Bucharest * Address of author responsible for correspondence: Gabriel IORDACHE, National Research and Development Institute for Marine Geology and Geoecology – GeoEcoMar, Bucharest gabriel.iordache@geoecomar.ro bstract: The study area is a part of the Lower Danube sector and belongs to the Gura Vaii- Calarasi sub-sector. This area is characterized by a course without important secondary branches and an asymmetric floodplain, very well developed on the left bank. Climate changes and anthropogenic impact from the last centuries have changed the hydro-morphological characteristics of the Danube River significantly. Using GIS methods and techniques in the field of hydrology/river geomorphology facilitates the morphometric analysis of the fluvial islets present in the Danube riverbed through determining their morphometric parameters. All of the parameters that define a fluvial island will be calculated by the detailed analysis of cartographic documents, aerial photograph, and satellite imagery. Based on the historical and recent cartographic sources, satellite imagery and in-situ measurements, the Danube in this sector undergoing a modeling process under the influence of natural and anthropogenic factors. Thus, during the analyzed period there were changes in the width and shape of the riverbed, especially on the left bank, the right bank being higher and more stable. There have been significant changes to the islets in this sector. These consisted in changes in the geometry of the islands, either by increasing their surface or by diminishing them, migrating, sticking to one of the banks and even disappearing some of them over the period under review. Keywords: riverbed, fluvial island, GIS techniques, morphometric parameters INTRODUCTION The Danube River Basin covers over 800,000 km², about 10% of Europe and extends into 19 countries. Over 80 million people live in its basin with many depending on the Danube River for drinking water, agriculture, transport and others (ICPDR, 2015). It connects people with different economic, social, cultural and environmental heritage, as well as various political backgrounds (Sommerwerk et al 2010). The activities of peoples that live in 19 countries have an impact on the natural environment of the Danube River Basin and are also leading to significant problems with water quality and quantity, and substantial reductions in biodiversity in certain parts of the river basin (ICPDR, 2015). During the last centuries, in particular, in recent decades, many of the World's rivers have strongly been affected by human intervention through dams and reservoirs (Surian, 1999). Related dams and structures, people have been changing the natural course of the rivers in the Danube River Basin, mainly for flood defense, hydropower generation, and navigation. Changes in the depth or width of a river typically reduce flow rates, interrupting natural sediment transportation as well as the migration routes of animals. Also, the formation of the fluvial islands along the Danube course has directly reflected all these hydrological changes over time. Fluvial islands are defined as discrete areas of woodland vegetation either surrounded by water-filled channels or exposed gravel (Ward et al. 1999) which exhibit some stability (Osterkamp, 1998) and are not submerged during bank-full flows. Fluvial vegetated islands are key components of fluvial systems as they influence the platform and the biodiversity of these hydro- systems (Wintenberger, 2015). Fluvial islands formation is a natural process affected by the hydrology and sediment transport capacity of the system (Raslan and Salama 2015). MATERIALS AND METHODS The area studied in this paper is a part of the Lower Danube sector and is extended between km 626 (downstream of Corabia harbor) up to km 679 in Bechet harbor area (Fig. 1). The analyzed sector has a A