THE ENVIRONMENTAL FLOW METHOD FOR SUPPLEMENTING THE WATER NEEDED FOR THE MANAGEMENT OF SELANGOR RIVER, MALAYSIA

The shortage of water resources is one of the main problems in the world today, and water pollution and under-utilization of water resources are two factors contributing to this shortage. Appropriate supplement environmental flow can have a positive impact on dilution of pollutants, and consequently on fish habitats and the characteristics of the river channels. The purpose of this study is to determine the environmental water demand of the lower Selangor River, known as Sungai Selangor, through the Tennant Method, and then compare the data with the findings in available documents in order to ascertain the most economical and favorable supplement environmental flow method. The results of this study show that the months of November and December between the years 2009 and 2018 were the peak periods of discharge, with it being important for the discharge of these two months to meet 200% of the average annual flow needed to maintain fish habitats and channels in downstream Sungai Selangor. To meet the requirements of supplement environmental flow and improvement of water quality, it is recommended that the spillway working gate of the Sungai Kerling hydropower plant be modified so that the flow can be discharged downstream to supplement the environmental flow. Providing environmental flows for downstream would generate economic benefits and allow upstream and downstream regions to share resources.