Environmental Impacts and mitigation Measures on water quality during Merowe Dam construction

Abstract

The major objective of this research is to study the environmental impacts and mitigation measures on water quality during construction of Merowe dam located 400 Km down stream of Khartoum northern Sudan near fourth cataract. The construction across the Nile river. The major pollutants include discharges from the construction leading to changes in water quality which will eventually affect the people living north of the dam (downstream). The specific objective of the research is to provide timely water quality data to check the water quality impacts of the dam, and the general objective to determine the pollution due to Merowe dam construction and to propose solution for the mitigation measures of the resulting discharges during construction. The research was based on the analysis of river's water quality (from April 2007 to March 2008) in the upstream and downstream areas where samples were collected at fixed frequencies, seasonal data collection was conducted and compared with local and international standards in order to discover any adverse changes in water quality. The parameters measured were of bacteriological, physical and chemical nature. The results obtained revealed that slight chemical pollution (Iron content more than 0.5 mg/l downstream, upstream is not more than 0.3 mg/l all over the year and nitrate content more than 7 mg/l downstream, 4 mg/l upstream) and physical (turbidity content exceeded 1000 NTU downstream), the results indicated no bacteriological pollution, the chemical and physical changes seems to be due to the discharges which would be controlled making effective pretreatment. IV The over all results revealed there is no significant effect on water quality, there are many units installed in the river downstream such as oil booms to control and avoid the spread of oil spills and the pretreatment plants to avoid the accumulations of heavy metals and reduce bed sediment and water turbidity.