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AN ASSESSMENT OF THE INSTREAM FLOW REQUIREMENTS: THE CASE OF MAZOWE RIVER CATCHMENT

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan www.asabe.org

Citation:  Paper number  701P0904,  . (doi: 10.13031/2013.17429)
Authors:   Tichatonga Gonah
Keywords:   instream flow requirements, river rehabilitation, naturalization, sustainable watershed management, flow regulation

In a bid to determine the status of instream flow requirements and if they are being met, the researcher carried out a case study comprising of the Mazowe river basin, falling under Mazowe catchment, one of the hydrological catchments of Zimbabwe. As the concept of instream flow requirements is still new in Zimbabwe, this justifies the need for carrying out such a research. The major objectives were to enlighten the status of instream flow requirements in Zimbabwe and to establish the effect of dams on flow regimes. This study was carried out by considering a sample of 15 sub hydrological zones falling under this river catchment. It is mainly runoff data that was integrated into the Hydrological Database and Analysis Tool (HYDATA) model to come up with the most important input parameters of the Hughes and Munster desktop methodology that was used to estimate the instream flow requirements. The researcher quantified the instream flow requirements and reconciled these with the river catchment water resources potential revealing that most of the river systems are having their environmental water needs being met. Dams have been found to regulate flow regimes through increased or decreased flows and the base flow index was discovered to be linearly related to the instream flow requirements. The researcher concluded that there is a potential of carrying out environmental rehabilitation particularly river restoration and expanding other water uses. The researcher has recommended the need for more research and investment into the issue of environmental flows with the overall goal of achieving sustainable allocation and utilisation of our scarce water resources.

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