1-An Analysis of Minimum Flow Requirement in a River from Ecological Considerations.

Abstract

Disposal of effluents originating from municipal, industrial and agricultural sources into rivers is a traditional concept. River flow has limiting self purification capacity. Disposal of effluents in excess to the self purification capacity affect the bio-diversity and the ecosystem maintaining by the river. Restriction of the normal flow by artificial barriers, such as dam, across the river without considering likely changes in the cycle of bio-diversity and ecosystem may alter socioeconomic and socio-cultural aspects of people depending on the river's water. In the present paper, an analysis of minimum flow requirement to achieve the water quality standards of category `13',as prescribed in the IS:10500, for organic pollutants, has been carried out by simulating the BOD and the DO of the river for a 310 km stretch of Brahmni river down below the Rengali dam. The enhanced stream water quality model, QUAL2E developed by the US-EPA, has been used as a modeling tool. Out of the three analyses of minimum flow requirement alternatives; (i) augmentation of flow, (ii) control of pollution by treatment of effluents, and (iii) partial flow augmentation and partial treatment of effluents, option (iii) showed the preferred one from ecological considerations.