Scenarios analysis using water-sensitive urban design principles: a case study of the Cape Flats Aquifer in South Africa

Gxokwe, Siyamthanda; Xu, Yongxin; Kanyerere, Thokozani

Scenarios analysis using water-sensitive urban design principles: a case study of the Cape Flats Aquifer in South Africa | Analyse de scénarios à l’aide de principes de conception urbaine sensible à l’eau: étude de cas de l’aquifère de Cape Flats en Afrique du Sud Análisis de escenarios utilizando los principios de planificación urbana en función del agua: un estudio de caso del acuífero de Cape Flats en Sudáfrica 使用水敏感城市设计原则的情景分析:以南非Cape Flats含水层为例 Análise de cenários usando princípios de design urbano sensíveis à água: um estudo de caso do quífero Cape Flats na África do Sul

2020

Gxokwe, Siyamthanda | Xu, Yongxin | Kanyerere, Thokozani

A feasibility assessment was undertaken on the application of water-sensitive urban design (WSUD) for the Cape Flats Aquifer in Cape Town, South Africa, at the local scale. The study contributes towards the planning of water-sensitive cities in the future. A three-dimensional steady-state groundwater flow model was applied to the Cape Flats Aquifer to predict WSUD scenarios by incorporating managed aquifer recharge (MAR). Analysis of the scenarios of varying recharge estimates and groundwater abstraction rates, predicted using the model, indicated that the water-table distribution and outflows from identified groundwater balance components show direct proportionality to the varying recharge scenarios. A notable increase in these outflows was observed when the recharge rate was increased by 50%. Varying groundwater abstraction scenarios indicated that with increasing abstraction rates, water levels and outflows from groundwater balance components also decreased accordingly. A notable decline in water levels and outflows was established at an abstraction rate of 2.5 and 5 L/s, respectively. Similar to the previous regional studies in the area, the results from the predicted scenarios show that there is a potential for applying WSUD, particularly MAR, at site-specific scale within the Cape Flats Aquifer. However, shallow groundwater levels during wet seasons limit the opportunities for application of WSUD in the area. This finding would provide an important reference to the ongoing debate on the Cape Town water crisis and similar environmental conditions where WSUD is considered.

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