Properties of Tigris River Bed Material at Mosul City

Abstract

In this research the characteristics of bed material of 35km of Tigris river from Badoosh tothe end of Mosul City was studied ,nine locations were selected for sampling surface and subsurfacematerial, at each location samples are collected from left and right bank of the river. Analysis ofthese samples show that the gravel surface bed material of Tigris river had D50 equal to 33mm witha dominant size very coarse and coarse gravel with a percentage 42%, 36% , respectively, sand isalmost mislaid in this layer. The particles of surface layer had a disc shape with a percentage 51%and blade 19%, spherical 17%, and cylindrical 13%. The results show that the right bank particlesare coarser than left bank. The subsurface bed material consist of gravel and sand, the D50 of thislayer was equal to 17mm, the domain size was coarse gravel with a percentage 29% , sandpercentage in this layer was about 17%. The subsurface layer is unaffecting on any changes in flowregime because it is completely protected by gravel surface layer. Comparison of obtained resultswith previous results shows that there is no significant changes occurred in properties of the riverbed material except little changes in composition of surface layer especially in the fine material.The river under the current flow conditions with flow rate in around of 500m3/s will reserve to thesame bed material properties in the future.