Bekithemba Gumbo

Water losses and the political constraints to demand management: the case of the City of Mutare, Zimbabwe

The question posed in this paper is: why is the concept of water demand management rarely implemented on the ground? To answer this question the paper presents data on the water supply situation in the City of Mutare, Zimbabwe. It describes Mutare’s water infrastructure, the patterns of water use during the period 1980–2000; and our attempts to identify and quantify water losses in the system. Suggestions are made how these losses can be reduced, which would involve relatively modest resources. The question is then asked why these measures have not yet been taken. The paper contrasts this to the Pungwe scheme, a new water supply project of huge proportions which was conceived and implemented fairly quickly. The fact that water is a vital yet finite and fugitive resource explains why powerful water coalitions may emerge between engineers, financiers and politicians. It is the experience from Mutare and elsewhere that such coalitions tend to favour supply-side solutions to water scarcity. For effective adoption of water demand management it is essential to acknowledge this political dimension. As a strategy it is suggested that: (a) stakeholders should be better informed about alternative solutions to water problems; (b) a new generation of engineers trained in integrated water resources management is needed with the skills to carefully study the problem definition before rushing to solutions; and (c) financiers should be made aware of the relevance and economic rationale of demand management solutions.

Aspects of the water resources management practice with emphasis on nutrients control in the Chivero Basin, Zimbabwe

Abstract This paper summarises the results of a study on qualitative, quantitative and environmental aspects of water resources management in the Lake Chivero basin, which is the main source of water supply of the City of Harare, Zimbabwe and is in advanced stage of eutrophication. In terms of water quality, an integrated database has been developed, combining existing monitoring data about natural water quality, effluent discharges and urban storm drainage, and data from research investigations during the period 1995–2000. Background pollution in the basin varied from 0.1 to 0.3 mg/l and from 0.1 to 0.4 mg/l for nitrates and phosphates (as total P), respectively. Spatial variations along the major rivers showed a steady trend of increase in nutrient levels with a peak in 1998. At Marimba River confluence the annual median values recorded were 3.5 and 4.4 mg/l for ammonia and phosphates, respectively, thus exceeding the effluent discharge regulations 7–9 times. The major nutrient sources contributing to this status are associated with operational problems of the treatment facilities and diffuse sources of pollution from pastures irrigated with effluent, as well as from urban storm water. In environmental terms a first step was undertaken towards the development of a biological water quality monitoring system, by evaluating the habitat and a-biotic characteristics of the pristine regions of the basin. As to water quantity, it was found that the existing infrastructure is capable to satisfy present water demand, but the abstraction amounts to 77% of the water generated in the basin, which could be considered as an upper limit. It is not yet clear how some provisions of the new Water Act, such as the recognition of the environment as a legitimate water user, will be implemented. With regard to urban water management, the research focused on the development of a rainfall runoff model for the composite catchment area of the Marimba river basin, a sub-urban micro catchment of the Lake Chivero basin. The paper discusses the above findings, and suggests integrated solutions, considering the provisions of the new Water Act. The extensive amount of data accumulated and analysed during this study could form a sound basis for the development of a Management Information System of the basin, based on a GIS. Such a system could be useful for the catchment councils involved.