Morphological Variations of A Certain Tigris River Reach For Different Periods in Iraq

Abstract

A morphological variations occurs in the paths of rivers due to many reasons such as the hydraulic changes in the natural flow regime of rivers in-addition to the human activities on rivers such as dams constructions on rivers. Many morphological variations created on Tigris river reach within Mosul city, north Iraq for different periods between 1956 to 2002 had been studied such as the changes on the river width specially near the bridges sites and also the development of the dimensions of the islands and bars within the river reach. The available topographic maps and also an aerial photographs were depended during the data analysis with some field reconnaissance . The research work concluded that one of the main reasons for the development of the islands is the flow regime variation of Tigris river as a result of the Mosul dam operation which in-turn leaded to a reduction in the transported sediment load in the reach due to the released high stream power clear water discharges of sediment from Mosul dam. The second reason was the reduction in the water level which in-turn change the middle and side islands in the river with the growing vegetation cover such as trees and weeds specially in the sites downstream the meander of Al-Rashidia Village and downstream Al-Shuhadaa bridge and upstream Ninevah bridge and finally upstream the fourth bridge in Mosul city.