Pathways to water resilient South African cities (PaWS)
This project aims to identify opportunities for integrating water supply alternatives within the urban water system through the implementation of nature-based solutions as part of a water-sensitive urban design approach in Cape Town and Johannesburg. The research will include physical experimentation through a pilot-scale implementation and assessment of stormwater harvesting and managed aquifer recharge; as well as an exploration of the governance processes for enabling the transition to water sensitive cities.
The problem of water scarcity is a top concern for South African cities. Cape Town is currently experiencing a drought that has led to a water supply crisis with the city declared a Disaster Area. This declaration has enabled the city to access funds for accelerated construction of several small desalination plants and the drilling of the Cape Flats and Table Mountain aquifers to augment water supply. Johannesburg is a historically water-scarce city, relying on Inter-Basin Transfers (IBT’s) from Lesotho for water and like Cape Town, recurring droughts are resulting in uncertainty in water supply. Desalination and IBT’s are indicative of both cities’ continued path-dependence on centralised, hard water infrastructure whose negative environmental impacts also in light of projected climate change is increasingly recognised.
Water management is an essential part of urban sustainability. However existing centralised water provision models are increasingly viewed as ill-suited to address prevailing problems including climate change and resource pressures. There are increased calls for adaptive urban water governance to address the environmental and socio-economic uncertainties confronting urban water systems.
Sustainable urban water management (SUWM) is an umbrella term for various nature-based approaches to water management that take a total urban water cycle view through the integration of built water infrastructure with green infrastructure in a decentralised manner. Approaches that link storm-runoff and wastewater to water supply are also known as Water Sensitive Urban Design (WSUD), Sustainable Drainage Systems (SuDS); they help to return urban rainfall-runoff processes to natural hydrological cycle flows, by reducing runoff volumes and peak flows, improving infiltration, and reducing pollutant loads.
There is a need to explore under-exploited water resources such as stormwater harvesting and managed aquifer recharge with treated sewage effluent that can simultaneously augment water supply and enhance urban resilience. However, the quality of stormwater in South African cities is generally poor due to infrastructure deficits, with point and non-point source pollution in runoff flows. Harnessing SWH and MAR with treated effluent would be more feasible if the quality of runoff being infiltrated or stored is improved through pre-treatment with green infrastructure options such as swales, biofiltration cells and constructed wetlands. These elements also offer cities the benefits of flood risk management and improved biodiversity, opportunities for food production through edible green infrastructure and increased liveability.
Whilst there is consensus within the urban water fraternity on the need for a shift to more adaptive approaches, how such transformations in the design, implementation and governance can be realised remains unclear, particularly in the highly compartmentalised infrastructure sectors typically found in South African cities.
Recognising the economic, environmental, technological and governance challenges in the South African urban water sector, the South African government developed the Water Research Development and Innovation Roadmap. One focus area is the unlocking of water supply alternatives such as SWH and groundwater through the use of WSUD approaches. There is a need for assessing the technical feasibility of these alternatives and the governance implications of hybridising built water infrastructure with nature-based solutions. The project will also contribute to the achievement of SDG’s 6, 9, 11, 13 and 17 of ensuring access to drinking water and integrated water resources management; promoting urban resilience to climate change and cooperative governance for sustainable development. It will also support the national priority of increased urban green infrastructure and facilitating engagement and coordination between stakeholders in the management of human settlements.
The project will explore the opportunities for transitioning towards water-sensitive futures in Cape Town and Johannesburg, with the following research questions and objectives:
- What are the possibilities for institutionalising the hybridisation of built infrastructure with nature-based solutions in both cities?
– The objective is to explore pathways for policy embedment and upscaling of such infrastructural integration with a view to engendering an enabling governance environment.
- What is the potential for integrating nature-based solutions into the urban water cycles of the two cities to augment water supply?
– The objective is to physically experiment with, map and evaluate, the design and integration of stormwater harvesting / treated effluent options and managed aquifer recharge with built infrastructure within the urban fabric.
The research is organized as a case study using Cape Town and Johannesburg as cases. In each city a transition management process methodology will be deployed. The first work package will consist of initiating pilot transition arenas based on system and actor analyses, as well as on peer-to-peer nomination of members representing diverse stakeholders. Here, action research will be undertaken to steer and enable co-creative processes of developing city-specific WSUD visions based on the benchmarking exercises, progress of the 1:1 physical experiments with SWH and MAR. The arena will also explore avenues for embedding results from experiments and mainstreaming WSUD visions with responsible city stakeholders and regular policy frameworks.
A second work package will consist of physical solutions in Cape Town, where the focus will be on 1:1 experiments and assessment of the feasibility of SWH and MAR as nature-based solutions to augment water supply. For Johannesburg, a outlining/mapping of the city water cycle will be undertaken and possible case sites where stormwater can be linked to water supply explored and assessed to develop a decision-support tool to aid in the assessment of landscape-level and subterranean WSUD options.
We have just held two stakeholder workshops in respectively Johannesburg (7th of June) and Cape Town (5th of June). Key stakeholders working with urban planning, water and green space management and urban planning attended to hear about the project and discuss the possibilities for connecting stormwater to water supply in the two cities.
We have also had internal project discussions and visited possible case sites in Cape Town and Johannesburg.
Meet us at the IWA conference in Copenhagen 18th - 22nd October 2020.
The project is funded by Danida’s Window 2 programme and is a collaboration between the University of Copenhagen, Department of Geosciences and Natural Resource Management (IGN) and University of Cape Town, Future Water Research Institute.
Project: Pathways to water resilient South African cities (PaWS)
Coordinator: Lise Herslund
Start/end: May 1, 2019 - April 30, 2022