Journal of the Faculty of Engineering and Architecture of Gazi University 35:2 (2020) 1015-1025 Investigation of sedimentation effects on Seyhan Dam Reservoir Şerife Pınar Güvel 1* , Recep Yurtal 2 1 General Directorate of State Hydraulic Works, 6 th Regional Directorate, Adana, 01120, Turkey 2 Çukurova University, Faculty of Engineering, Department of Civil Engineering, Adana, 01330, Turkey Highlights: Graphical/Tabular Abstract  Sedimentation effects on reservoir management  Sediment accumulation in Seyhan Reservoir  Investigation of reservoir water storage capacity loss In this study, GIS technology is used to evaluate spatial and temporal changes of sediment accumulation in the period of hydrographic measurements in Seyhan Dam Reservoir. Sediment observation data of Çakıt and Körkün streams, which are the sediment source of Seyhan Reservoir in present, are used to determine the current state of sedimentation in the reservoir. Calculations made by researches with various techniques in previous years and GIS results to examine the change in storage volume in Seyhan Dam Reservoir between measurement years are presented. Since Çatalan Dam was taken into operation, the transport of sediment from main line of Seyhan River has been prevented, and technical measures developed in Çakıt branch are considered to be important in terms of sustainable management. Figure A. Seyhan Reservoir elevation-volume graph based on hydrographic measurements Purpose: In this study, it is aimed to investigate the changes in water storage capacity and the changes in bottom topography by additional data and developments in addition to GIS supported analyzes based on hydrographic measurements of Seyhan Dam Reservoir, and to provide the current results with respect to reservoir management in Seyhan Dam Reservoir by evaluating the current state of sediment accumulation. Theory and Methods: GIS technique as a decision support tool is used in evaluation of distribution of sediment accumulation in Seyhan Dam reservoir. Water storage capacity loss is estimated by using hydrographic measurements and sediment observation data. Results: It is determined that the maximum reservoir volume in Seyhan Dam Reservoir is reduced by 0.30% from 2005 to 2017 by evaluating the sediment observation data of E18A028 Çakıt Stream-Salbaş sediment observation station and E18A020 Körkün Stream-Hacılı Bridge sediment observation station. Conclusion: As a result, sediment accumulation in Seyhan Dam reservoir is investigated by evaluating hydrographic measurements and sediment observation data of Çakıt and Körkün streams and current results on the effects of sediment accumulation on the reservoir operation in Seyhan Dam Reservoir are obtained. Keywords:  Seyhan Dam  Reservoir management  Water resources management  Geographic information system  Sediment accumulation Article Info: Research Article Received: 26.04.2018 Accepted: 27.11.2019 DOI: 10.17341/gazimmfd.418702 Correspondence: Author: Şerife Pınar Güvel e-mail: spinar.guvel@dsi.gov.tr phone: +90 322 459 05 90