Sustainable management of water resources through Real Time Control with University of Cape Town dam as a case study

Mogano, Malesela Michael

Sustainable management of water resources through Real Time Control with University of Cape Town dam as a case study

Thesis / Dissertation

2023

Abstract

There is a growing interest in South Africa to supplement water demands by harvesting stormwater as concerns over the security of the country's water supply increase. Studies have demonstrated the potential for stormwater harvesting (SWH) to simultaneously provide water to meet non-potable water demand and mitigate flooding by minimising stormwater flows to downstream locations of urban catchments. To determine pathways to enhance these benefits, application of Real-Time Control (RTC) system to operate a dam outlet could potentially be used to store stormwater. To investigate the economic viability of harvesting stormwater through RTC from an existing dam, a case study was performed on a representative urban catchment – the UCT watershed, located in Cape Town, South Africa. RTC procedures were applied to the UCT dam operations to initiate pre-storm releases in real time based on rainfall forecast. Four different stormwater harvesting configurations that modelled non-potable water demands were developed. A catchment stormwater model and a Life Cycle Cost Analysis (LCCA) were used to model the four configurations. The study identified benefit in application of RTC linked to increase in harvested stormwater and reduction of water loss through overflow. Continuous simulation was employed at the UCT dam to determine the prospects of enhancing SWH to deliver non-potable water for irrigation of sports fields. The study compared performance of Static control approaches to SWH with application of RTC. The dynamic management of the UCT dam with RTC approaches increased yield and volumetric reliability whilst maintaining the required level of service of a stormwater harvesting system. Static control approaches result in water savings of approximately 9% in comparison to RTC. In addition, Static configurations harvested stormwater at a relatively low unit cost in comparison to RTC configurations. Hence, RTC approaches increase yield and volumetric reliability with relatively low-cost implications. In addition, RTC approaches has the potential meet about 6.4% to 10.9% of the residences potable water demand respectively whilst satisfying irrigation demands if stormwater could be fully treated. It was found that SWH with RTC required special design as it provides an active operation which, across varying climatic conditions optimizes the performance of the system. It was concluded that the SWH system with RTC technology exhibits great potential; the ability of an RTC system to provide centralised control and failure detection, which can be readily adapted to variation of climate and local conditions over both the short and long term provides a system that is more stable and reliable.

Keywords

Engineering

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