An Assessment of the Multiple Uses of Small Dams, Water Usage and Productivity in the Limpopo Basin
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An assessment of the multiple uses of small dams, water usage and productivity in the Limpopo Basin. BY SIMBARASHE RUSERE (R015141Q) Supervisor Dr A. Senzanje An Undergraduate Research Project Submitted in Partial Fulfilment of the Requirements of the Degree of Bachelor of Science Honours in Agricultural Engineering May 2005 Department of Soil Science and Agricultural Engineering University of Zimbabwe P.O. Box MP 167 Mt Pleasant Harare Acknowledgements First and foremost, I would like to express my sincere gratitude to my supervisor Dr Senzanje for the generous support and guidance he gave me throughout the year whist working on this research. I’m also grateful to Mr. S. Ncube, for the tolerance, encouragement and support during data collection in Filabusi. Appreciation is also expressed to my family, friends, colleagues and the university staff for informed constructive criticism and moral support whist working on this project. 2 Abstract Zimbabwe has a long history of dam construction dating back to the 1920s. The dams range from small reservoirs to large dams used to supply water for urban mining and industrial areas and large-scale irrigation. Small reservoirs have been built in the former large-scale commercial farming areas and communal areas with the aim of improving the people’s livelihood through their multiple uses. Despite the long history of small dam usage, there has not been a comprehensive study on the multiple uses focusing on the volume of water withdrawn and water use efficiency in a bid to establish their usefulness. This research therefore focuses at volume quantification on consumptive uses of the small dams and water productivity. However utilisation of the small dam is a function of how it is managed and the influence of various institutions and organisations related to the community. Methods used to gather information included questionnaire survey on small dam users, interviews with various organisation and institutions, observation and secondary data. Small dams were found to be very important in the communities’ well being as they are put to a number of uses, which are livestock watering, domestic use, irrigation, fishing, brickmaking, and collection of Cypress spp. reeds used for roofing. Livestock consumes the bulk of the water, the least being brickmaking. Water productivity as well as the economic value is generally the same per use when comparing with the dams, due to close location of the dams. On all dams, traditional leaders and the community are pivotal in management of the small dams. However, more interaction between various organisations and the community is called for as well as awareness on dam utilisation and catchment conservation. 3 Table Of Contents CHAPTER 1 .................................................................................... 1 Introduction ........................................................................................ 7 1.1 Justification........................................................................................................................................... 8 1.2 Objectives........................................................................................................................................... 10 1.2.1 Main objective............................................................................................................................. 10 1.2.2 Specific objectives....................................................................................................................... 10 1.3 Hypothesis .......................................................................................................................................... 10 CHAPTER 2 .................................................................................. 11 Literature Review .............................................................................. 11 2.1 Background and Development ........................................................................................................... 11 2.2 Technical Aspects of small dams ....................................................................................................... 12 2.3 Environmental Aspects of small dams................................................................................................ 14 2.4 Socio-economic aspects...................................................................................................................... 16 2.4.1 Water Use Efficiency................................................................................................................... 18 2.5 Management and Institutional Analysis ............................................................................................. 19 CHAPTER 3 .................................................................................. 21 Methodology..................................................................................... 21 3.1 Introduction ........................................................................................................................................ 21 3.2 Study Area.......................................................................................................................................... 21 3.3 Questionnaire Design ......................................................................................................................... 23 3.4 Pre-test................................................................................................................................................ 24 3.5 Sampling............................................................................................................................................. 24 3.6 Data collection.................................................................................................................................... 25 3.6.1 Questionnaire Administration...................................................................................................... 25 3.6.2 Interviews .................................................................................................................................... 25 3.6.3 Secondary Data and Observation................................................................................................. 26 3.7 Data Analysis...................................................................................................................................... 26 3.7.1 Multiple uses ............................................................................................................................... 26 3.7.2 Quantifying volume of water used .............................................................................................. 26 3.7.3 Water Productivity....................................................................................................................... 27 3.7.4 Economic value ........................................................................................................................... 27 3.7.5 Management and Institutional Analysis ...................................................................................... 28 CHAPTER 4 .................................................................................. 29 Results ............................................................................................. 29 4.1 Dam Profiles....................................................................................................................................... 29 4.1.1 Dewa Small Dam......................................................................................................................... 29 4.1.2 Denje Small Dam ........................................................................................................................ 31 4 4.1.3 Avoca Small Dam........................................................................................................................ 32 4.1.4 Makoshe Small Dam ................................................................................................................... 34 4.2 Small Dams’ Uses .............................................................................................................................. 36 4.3 Volume of water used......................................................................................................................... 37 4.3 Water Productivity.............................................................................................................................. 39 4.4 Economic Value of Water .................................................................................................................. 39 4.5 Management and Institutional Issues.................................................................................................. 40 4.5.1 Venn diagram .............................................................................................................................. 40 4.5.2 Organisations and Institutions ..................................................................................................... 41 CHAPTER 5 .................................................................................. 45 Discussion ........................................................................................ 45 5.1 Uses .................................................................................................................................................... 45 5.2 Volume of water used........................................................................................................................