Makungo, R.Mwaka, B.Ndiritu, J.Nyadawa, Chris Nduba2025-03-032025-03-032024-09-06Nyadawa, C. N. 2023. Economic optimization of assurance in stochastic yield analysis of water resource systems. Thohoyandou, South Africa.<https://univendspace.univen.ac.za/handle/11602/2817>.https://univendspace.univen.ac.za/handle/11602/2817MESHWRDepartment of Earth SciencesAllocation of water from South Africa’s already straining water resources systems is a complex task given the ever-increasing water demand. The situation is made worse because of diminishing suitable sites for water resources infrastructure development, limited financial resources, and effects of climate change. To mitigate failure of water supply and ensure progressive water allocation, South Africa adopted a risk-based water allocation system in which it allocates water at different assurances of supply. Since assurance of supply is inversely proportional to yield, some water authorities tend to allocate water at relatively excessive high assurances of supply to mitigate total failure of water resources. This practice of allocating water at excessively high assurances of supply in turn reduces the amount of allocable water from the water resource. Consequently, the practice in turn results in either emerging users being denied access to water and/or lowly prioritised users being curtailed more early/frequently to satisfy the highly prioritised users. This study, therefore, examined prospects of optimizing existing water resources by specifically investigating the prospects of increasing the economic benefits from a water resource through reduction of its assurance of supply. The study therefore conducted a comparative analysis on the Western Cape Water Supply System (WCWSS) to assess if the yield of the system could be increased for more economic benefits by either reducing the assurance of supply only or by adopting an infrastructural development. To achieve this objective, the study compared the net benefits derived from the Berg River Voelvlei Augmentation Scheme (BRVAS) infrastructural development project that would increase the yield of the WCWSS by 23 x106 m3/a, and the net benefits that could be derived from an increase in yield due to reduction of assurance of supply by a margin that would result in a yield similar to that of the intended BRVAS infrastructural project. The second section determined incremental yields from Tzaneen Dam and their corresponding net economic benefits due to reduction of assurance of supply. The third section tested if the optimum assurance of supply of Tzaneen Dam was sensitive to other water resources systems characterized by different hydrological regimes. To conduct this sensitivity analysis, incremental yields and corresponding net benefits due reduction of assurance of supply from, Midmar, Goedertrouw, Mokolo and Boegeberg dams were determined. The comparative analysis demonstrated that the yield of the WCWSS could also be increased by reducing the assurance of supply from the existing 1 in 50 years (1:50) to 1 in 30 years (1:30). It also demonstrated that adoption of reduction of assurance of supply as a method of increasing assurance of supply more economic benefits when compared to yield augmentation through infrastructural interventions as reduction of assurance of supply had a net benefit of R 96.2 x106 while the BRVAS infrastructural intervention had a net benefit of R 15.5 x106. Results established that Tzaneen Dam could be optimised at 1:18 assurance of supply. It was therefore concluded that not all reductions of the assurance of supply result in an incremental increase of the net benefits. Results from the sensitivity analysis revealed that each water resources system is unique as different water resources used in the sensitivity analysis, Midmar, Goedertrouw, Mokolo and Boegeberg Dams had their optimum assurances of supply at 1:12, 1:12, 1:8 and 1:10 levels, respectively. Both the comparative analysis and the sensitivity analyses acknowledge the role played by water availability in socio-economic development, however, for ease of analysis due to challenges of quantifying contribution due to sufficient or insufficient water, the socio-economic aspect was not included in the analysis. Overall, the study highlighted that the economic benefits of a water resource may be optimized by reducing the assurance of supply up to a certain level. The study therefore recommended that this practice should also be considered as an alternative method of increasing water availability from a system.1 online resource (x, 97 leaves) : color illustrations, color mapsenUniversity of VendaAssurance of supplyUCTDRisk-based water allocationRisk of failureWater allocationWater resourcesYieldEconomic optimizationDissertationNyadawa CN. Economic optimization of assurance in stochastic yield analysis of water resource systems. []. , 2024 [cited yyyy month dd]. Available from:Nyadawa, C. N. (2024). <i>Economic optimization of assurance in stochastic yield analysis of water resource systems</i>. (). . Retrieved fromNyadawa, Chris Nduba. <i>"Economic optimization of assurance in stochastic yield analysis of water resource systems."</i> ., , 2024.TY - Dissertation AU - Nyadawa, Chris Nduba AB - Allocation of water from South Africa’s already straining water resources systems is a complex task given the ever-increasing water demand. The situation is made worse because of diminishing suitable sites for water resources infrastructure development, limited financial resources, and effects of climate change. To mitigate failure of water supply and ensure progressive water allocation, South Africa adopted a risk-based water allocation system in which it allocates water at different assurances of supply. Since assurance of supply is inversely proportional to yield, some water authorities tend to allocate water at relatively excessive high assurances of supply to mitigate total failure of water resources. This practice of allocating water at excessively high assurances of supply in turn reduces the amount of allocable water from the water resource. Consequently, the practice in turn results in either emerging users being denied access to water and/or lowly prioritised users being curtailed more early/frequently to satisfy the highly prioritised users. This study, therefore, examined prospects of optimizing existing water resources by specifically investigating the prospects of increasing the economic benefits from a water resource through reduction of its assurance of supply. The study therefore conducted a comparative analysis on the Western Cape Water Supply System (WCWSS) to assess if the yield of the system could be increased for more economic benefits by either reducing the assurance of supply only or by adopting an infrastructural development. To achieve this objective, the study compared the net benefits derived from the Berg River Voelvlei Augmentation Scheme (BRVAS) infrastructural development project that would increase the yield of the WCWSS by 23 x106 m3/a, and the net benefits that could be derived from an increase in yield due to reduction of assurance of supply by a margin that would result in a yield similar to that of the intended BRVAS infrastructural project. The second section determined incremental yields from Tzaneen Dam and their corresponding net economic benefits due to reduction of assurance of supply. The third section tested if the optimum assurance of supply of Tzaneen Dam was sensitive to other water resources systems characterized by different hydrological regimes. To conduct this sensitivity analysis, incremental yields and corresponding net benefits due reduction of assurance of supply from, Midmar, Goedertrouw, Mokolo and Boegeberg dams were determined. The comparative analysis demonstrated that the yield of the WCWSS could also be increased by reducing the assurance of supply from the existing 1 in 50 years (1:50) to 1 in 30 years (1:30). It also demonstrated that adoption of reduction of assurance of supply as a method of increasing assurance of supply more economic benefits when compared to yield augmentation through infrastructural interventions as reduction of assurance of supply had a net benefit of R 96.2 x106 while the BRVAS infrastructural intervention had a net benefit of R 15.5 x106. Results established that Tzaneen Dam could be optimised at 1:18 assurance of supply. It was therefore concluded that not all reductions of the assurance of supply result in an incremental increase of the net benefits. Results from the sensitivity analysis revealed that each water resources system is unique as different water resources used in the sensitivity analysis, Midmar, Goedertrouw, Mokolo and Boegeberg Dams had their optimum assurances of supply at 1:12, 1:12, 1:8 and 1:10 levels, respectively. Both the comparative analysis and the sensitivity analyses acknowledge the role played by water availability in socio-economic development, however, for ease of analysis due to challenges of quantifying contribution due to sufficient or insufficient water, the socio-economic aspect was not included in the analysis. Overall, the study highlighted that the economic benefits of a water resource may be optimized by reducing the assurance of supply up to a certain level. The study therefore recommended that this practice should also be considered as an alternative method of increasing water availability from a system. DA - 2024-09-06 DB - ResearchSpace DP - Univen KW - Assurance of supply KW - Risk-based water allocation KW - Risk of failure KW - Water allocation KW - Water resources KW - Yield KW - Economic optimization LK - https://univendspace.univen.ac.za PY - 2024 T1 - Economic optimization of assurance in stochastic yield analysis of water resource systems TI - Economic optimization of assurance in stochastic yield analysis of water resource systems UR - ER -