A research on the prevention of torrent and flood damages: A case study on Düzce-Kaynaşlı

Western Black Sea Region is one of the most sensitive region of Turkey in terms of torrents, floods and landslides. Torrents and floods in this region occur frequently and it causes huge destruction.The aim of the study is to determine the improvement works and precautions at the upstream of the watershed, in stream beds, agricultural and residential areas in order to protect Kaynaşlı district against torrents and floods. The study determined the land misuse and changes of land use status on Kaynaşlı watershed. Flood potential of watershed is analyzed with regard to morphometric characteristics. Maximum current levels regarding the various recurrence intervals are estimated based on the rainfall-runof correlations. Flood analysis was conducted for Kaynaşlı and Kurur creek watersheds, using GIS integrated HEC-RAS software. Lastly discharge of the Kaynaşlı creek was calculated based on its cross-section.High levels of some parameters in the watershed as a result of morphometric analysis show that the risk of torrent and flood is high. Analysis of stand maps depict that total area of forest land is diminishing in watershed. Forest structure is also degraded.Agricultural use is main use on the lands with high slope. 68 % of the current agricultural lands are on the land class VII which should be allocated to the forests.Kaynaşlı creek has inadequate cross-section to allow maximum current with 1000 year recurrence which is presumed for the watersheds with high level of casualty risk. Neither does it have the capacity for maximum current with 100 year recurrence. As a result of flood analysis in Kaynaşlı and Kurur creek watersheds areas that maybe deteriorated by flood were specified and mapped. The study includes some suggestions about the precautions to be taken in the watersheds and creeks.