Effects of morphometric characteristics on flood in Degirmendere sub-watersheds, Northeastern Turkey

ABSTRACT Watershed morphometry refers to the connections between systems of a watershed, such as hydrology, geology, vegetation, and topographic structure. The topographic and hydrological characteristics of the watershed have a great impact on vegetation, retention of rainwater in the soil, and its transformation into runoff, flood, and landslide occurring in the watershed. In this study, watershed morphometric analysis of the Altindere, Zigana and Catak subwatersheds located upstream of the Degirmendere watershed in Turkey was conducted, and the potential of producing floods related to these features was investigated. As the study area, Trabzon Degirmendere subwatersheds were chosen due to flood and landslide events that have occurred in the past and caused loss of life and property damage. By considering the linear, areal, and relief morphometric properties of each subwatershed, their flood effect levels and potentials are revealed. ArcGIS software was used in the analysis. Digital Elevation Model (DEM) with a resolution of 10 m produced from 1:25,000 scale topographic maps was used as a base for the evaluation of these parameters. As a result of this study, when evaluated in terms of the morphometric properties of the watersheds, it was determined that the Zigana subwatershed has the greatest impact on flood production. This study is intended to guide decision-makers to anticipate floods and flood events that will occur in the watersheds in the future.