Risk as a Tool in Water Resource Management
The National Water Act (Act 36 of 1998) (NW A) of South Africa makes provision for a quantity and quality of water to be set aside as a Reserve for the provision of basic human needs and for the protection of the aquatic ecosystem for sustainable development of the water resource. An ecological risk...
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| Format: | Dissertation |
| Language: | English |
| Published: |
ProQuest Dissertations & Theses
01-01-2005
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| Online Access: | Get full text |
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| Summary: | The National Water Act (Act 36 of 1998) (NW A) of South Africa makes provision for a quantity and quality of water to be set aside as a Reserve for the provision of basic human needs and for the protection of the aquatic ecosystem for sustainable development of the water resource. An ecological risk approach to water management with a view to the Reserve based inter aliaon the following:a Ecological risk is explicitly effect oriented.a A risk approach will not only address the stochastic characteristic of the ecosystem, but it will also provide a useful tool to address the potential conflict between user and legislator. A risk approach is explicitly effect oriented.o The probability component of risk supplies a way to bring diverse stressors to a common basis and address the diverse-stressor-multiple source problem. This study aims to provide a tool to apportion the ecological effect impact attenuation rationally among users.In order to accomplish this, attention was given to the following:1. The end-point required by the NW A must be related to end-points at lower organisational levels of the ecosystem. A model is proposed to do this based on the logical relationship between ecological phenomena. Although there is a dearth of information to use in the model, it may contribute to the characterisation of uncertainty with this type of projection.2. The mathematical formulation of the ERA process has apparently not received much attention in the technical literature. A mathematical formulation of the risk of a single stressor is proposed in both probability and fuzzy logic terms. The risk is expressed as the conjunction of the likelihood of effect conditioned on the stressor occurrence and a likelihood of stressor occurrence.3. When diverse stressors occur together and no other information is available on their interactions, the aggregate stressor risk may be expressed as the disjunction of individual stressor risks. The value of this approach is investigated in some hypothetical but realistic case studies.4. The problem of apportionment of impact attenuation burden among mUltiple dischargers of diverse stressors is similar to waste-load allocation (WLA). Obtaining an equitable distribution of the effect attenuation burden that recognises the technological and economic limitations in a catchment. is an optimisation problem. The diverse-stressor-multiple-source problem is first formulated as a fuzzy optimisation problem, which is solved using a genetic algorithm. This approach is investigated in a hypothetical (but possibly realistic) case study. The objective of the optimisation is the maximisation of the acceptability of the regulated situation. For the regulator this is assumed to mean the minimisation of ecological risk, while for the stressor source manager this might be influenced by technological and economic considerations. The degree of attenuation of the stressor is chosen as the control variable. |
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| ISBN: | 9798380807906 |