Development of probabilistic operating rules for Hluhluwe Dam, South Africa

Ndiritu, John; Odiyo, John O.; Makungo, Rachel; Mwaka, B.; Mthethwa, N.; Ntuli, C.; Andanje, A.

doi:10.1016/j.pce.2016.10.017

Cited by 14 publications

(15 citation statements)

References 23 publications

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“…For three shopping centres (Gateway, Liberty and Phoenix) where the supply to demand ratio exceeds unity, over-year storage behaviour occurred if large storages were used. Reliability-based analysis for over-year storage is well developed and widely applied in South Africa [48][49][50] and it is decided to confine the current analysis to within-year storage behaviour. This is accomplished by reducing the effective roof areas for the three centres (Table 1) to obtain supply to demand ratios less than unity.…”

Section: Formulating Generalized Storage-yield-reliability Relationshipsmentioning

confidence: 99%

Generalized Storage–Yield–Reliability Relationships for Analysing Shopping Centre Rainwater Harvesting Systems

Ndiritu

Moodley

Guliwe

2017

Water

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Abstract:The objective of this study was to develop guidelines for analysing rainwater harvesting (RWH) systems of shopping centres in South Africa. A model consisting of three dimensionless relationships relating rainwater supply and demand to storage capacity, yield and reliability was formulated. Data from daily simulation of potential RWH systems of 19 shopping were used to obtain the relationships. The simulations revealed within-year storage behaviour with considerable variation of annual yield. By applying the Weibull plotting position formula, yield-reliability relationships were derived. The aim to maximize yield and reliability whilst minimizing storage identified Pareto-optimal combinations of the three variables and these combinations were used to develop two dimensionless relationships. An additional relationship based on the dependence of the slope of the yield-reliability plots on yield was formulated to enable analysis of hydrologically non-optimal systems. Verification tests using four RWH systems obtained results that matched those from simulation and the model could therefore be applied for RWH feasibility analysis and preliminary design. This study highlights the need to incorporate inter-annual variability in RWH analysis and shows how reliability can be used to quantify this. This study further demonstrates how reliability can be fully integrated into regression relationships for generalized RWH analysis.

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Section: Formulating Generalized Storage-yield-reliability Relationshipsmentioning

confidence: 99%

Generalized Storage–Yield–Reliability Relationships for Analysing Shopping Centre Rainwater Harvesting Systems

Ndiritu

Moodley

Guliwe

2017

Water

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“…900000 m 3 for Gateway shopping centre). A reliability-based analysis approach for multi-year storage requires the use of a large number simulations using stochastically generated hydro-climatic data and stochastic over-year storage systems analysis methods are reasonably well developed and widely applied in South Africa [32,33,34]. It was therefore considered appropriate to confine the current analysis to within-year storage behaviour and this was accomplished by reducing the effective roof areas for the 3 centres in Kwa Zulu Natal to obtain supply to demand ratios less than unity.…”

Section: Simulation Analysismentioning

confidence: 99%

Generalized Storage-yield-reliability Relationships for Sizing and Assessing Shopping Centre Rainwater Harvesting Systems in South Africa

Ndiritu¹,

Mondli²,

Yashiren³

2017

Preprint

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The objective of this study was to develop guidelines for rainwater harvesting system sizing of shopping centres in South Africa. Three generalized dimensionless relationships relating rainwater supply and demand to tank size, yield and reliability were developed based on 101 years long daily time step simulations of rainwater harvesting of 19 shopping centres located in four regions. Daily rainfalls were obtained from nearby rainfall stations and daily non-potable demands were based on the size of the retail area. The simulations revealed within-year storage behaviour with considerable variation of the yield specified as the number of days for which demand was met each year. The Weibull plotting position formula was applied on the time series of yields to obtain yield-reliability relationships. Simulation results of the hydrologically optimum systems were used to develop two of the generalized relationships and an additional one based on the dependence of the slope of the reliability – yield plots on the optimum yield was formulated to enable analysis of hydrologically non-optimal systems. Most of the relationships fitted best to the non-linear power law form with high correlation coefficients averaging 0.92 and ranging from 0.82 to 1.00. The application of the models for tank sizing and assessing system performance is demonstrated.

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“…However, more often than not there is the circumstance that a predefined policy could not able to accomplish the objectives of a best policy. Thus, the enhancement of the operational policy of the reservoirs is essential [27,36], and the simulation of reservoirs along with the optimization algorithms can be an efficient and effective methodology for fine-tuning the rule curves [16,35]. The operation of the reservoir is a large scale multi-objective optimization problem, involving agriculture, hydrology, hydropower, reliability, and environment flows [37][38][39].…”

Section: Introductionmentioning

confidence: 99%

“…The development of operation of reservoir is a complicated problem, which includes multiple decision variables, several conflicting and contradictory objectives together with significant uncertainty and risk [16,28,36]. Designing and attaining operating rules for multi-reservoir structures is a challenging job and has been extensively generated during the scientific past of researches that are associated with the management of water resources [30,31,40].…”

Section: Introductionmentioning

confidence: 99%

“…During last decades, evolutionary optimization methods, viz. genetic algorithms, have become popular in the application of global optimization in the field of planning and management of reservoirs [16,18,20,22,23,27,35,36,50]. While, almost all of the prevalent algorithms are accomplished in undertaking complicated and complex planning and management problems, evolutionary algorithms methods have been able to attract a vast amount of consideration vis-à-vis, their capability in optimizing complex systems [31,34,44].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Optimisation of Multipurpose Reservoir Operation by Coupling Soil and Water Assessment Tool (SWAT) and Genetic Algorithm for Optimal Operating Policy (Case Study: Ganga River Basin)

2018

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Reservoirs are recognized as one of the most efficient infrastructure components in integrated water resources management. At present, with the ongoing advancement of social economy and requirement of water, the water resources shortage problem has worsened, and the operation of reservoirs, in terms of consumption of flood water, has become significantly important. To achieve optimal reservoirs operating policies, a considerable amount of optimization and simulation models have been introduced in the course of recent years. Subsequently, the assessment and estimation that is associated with the operation of reservoir stays conventional. In the present study, the Soil and Water Assessment Tool (SWAT) models and a Genetic Algorithm model has been employed to two reservoirs in Ganga River basin, India in order to obtain the optimal reservoir operational policies. The objective function has been added to reduce the yearly sum of squared deviation from preferred storage capacity and required release for the irrigation purpose. The rule curves that were estimated via random search have been discovered to be consistent with that of demand requests. Thus, in the present case study, on the basis of the generated result, it has been concluded that GA-derived optimal reservoir operation rules are competitive and promising, and can be efficiently used for the derivation of operation of the reservoir.

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Development of probabilistic operating rules for Hluhluwe Dam, South Africa

Cited by 14 publications

References 23 publications

Generalized Storage–Yield–Reliability Relationships for Analysing Shopping Centre Rainwater Harvesting Systems

Generalized Storage–Yield–Reliability Relationships for Analysing Shopping Centre Rainwater Harvesting Systems

Generalized Storage-yield-reliability Relationships for Sizing and Assessing Shopping Centre Rainwater Harvesting Systems in South Africa

Optimisation of Multipurpose Reservoir Operation by Coupling Soil and Water Assessment Tool (SWAT) and Genetic Algorithm for Optimal Operating Policy (Case Study: Ganga River Basin)

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