Effects of urban development on the geomorphological units in rize and natural disasters affecting the city

The City of Rize is located around a bay between the Black Sea in the north, Fener Cape in the west and Taşlıdere in the east. As a province, it is located in East Black Sea Region, between Black Sea coast and northern slopes of Rize Mountains that exceeds the height of 2500 meters. The provincial borders are formed by Derepazarı and Kalkandere in the west and Çayeli Country in the east. The City of Rize is located between Fener Cape and Taşlıdere, and around a bay which is surrounded by hills reaching up to 300-350 meters. While granodiorites and flysches surfaced with the orogenesis, started in the Cretaceous Period, on a Palaeozoic basement cover large areas, Neogene basins can also be observed throughout Rize. Lithologically, volcanic rocks are composed of andesite, basalt, dacite, and rhyodacite. Apart from these units, volcano sedimentary rocks from the Upper Cretaceous Period curop out on the southern part of Rize. Alluvial deposits are observed in coastal plains and widened valley basins. Marine terraces, hills, and valleys, where Rize City is established, are the prominent morphological units. The lithological and geomorphological features of the provincial zone affect urban settlements negatively. The first settlements in Rize go back to 5th Century A.D. and the city was home to different civilizations. As a result of the topographical structure of the area where the city is located, there is a limited area for the expansion and growth of the city. Therefore the coastal plains are used for urban settlements. The efforts of obtaining land from the sea have taken place in a short time after the existing plains were filled by settlements. The first landfilling works began in 1960's, and today these works continue increasingly. Official figures indicate that approximately 70% of the city settlements are on the filled areas. Serious changes occurred in the morphological structure of the coastal areas due to filling operations that have been made for the last 50-60 years. The most significant example of this change is the removal of the natural coastline away with varying distances between 250-500 meters. In the last 10 years, besides filling of the sea, the tea gardens on the hillsides have also been opened to settlement. Significant changes occurred in the geomorphological units due to the expansion of Rize City. These changes mainly occurred as removal of the natural coastline, landfilling of valleys and excavation of hillsides and ridges. Lithology and geomorphology are disregarded in excavation operations in roads and settlement areas. For this reason, increased frequency of natural disasters such as floods, overflows and mass movement of soil is observed. Particularly due to removal or canalizing of stream beds within the urban area, floods and overflows that cause loss of life and property occur with heavy soakers in spring and fall seasons. Apart from floods and overflows, the large scale landslides also create serious risks for settlements. This study was prepared to determine the changes in geomorphologic units with the rapid development of Rize City after 1980, and effects of these changes on natural disasters. Although similar problems are observed in almost every city that is located on the coastline of East Black Sea, Rize City has the biggest concerns in terms of the urban settlement. Rize City has the highest frequency of natural disasters in the mentioned region. The city is an appropriate area for detailed geomorphology studies because of these special conditions.