Creating a Bathymetric Contour Map of Small Earth Dams in Duhok Governorate: A Comparative Study

Abstract

The accumulation of sediment in the bottom of the dam is one of the major causes contributed to dam failure. This in turn creates risks of flooding for villages and cities below it. The aim of this research is to investigate the output of the bathymetric contour map of the bed of small Earth dams in Duhok at three different locations (Kashkan, Zawita and Skreen) as well as to determine the volume of accumulated sediment for each one at different periods of establishment. In addition, a comparison between the current statuses and the design life of each one was achieved. Both vertical depth and horizontal position measurements are implemented using two methods. The first one is the manual and direct method using lead line rope, weight, total station and DGPS for data collection in Zawita and Kashkan reservoir. While, the second method used the Acoustic Doppler Current Profiler (ADCP) integrated with the Global Positioning System (GPS) to record both vertical depth and horizontal position measurements automatically in Skreen dam. The ADCP was calibrated for adjusting the axes (heading, roll and pitch) before collecting data. The data of ADCP were processed and analyzed using River Surveyor Line software and the bathymetric contour map of the selected reservoir's bed was created using AutoCAD civil 3D software. Also, the volume of sedimentations of each selected Earth dam was calculated from the difference between the created topographic surface of the reservoir bed and its original one. The results show that the volume of the sedimentation in kashkan reservoir is about 13810 m3 for the period of 2009 to 2018, Zawita reservoir is about 4449 m3 for the period 2010 to 2018, Skreen reservoir is about 4608 m3 for the period 2009 to 2018, and the design life of each one estimated by state was approximately similar to the finding of this research.