Part 2 Salt River estuary restoration

Restoration methods for urban rivers on the example of the Salt River in Cape Town, South Africa

Master thesis by Kathrin Krause in Water and Environment, Department of Civil engineering, at the Bauhaus University, Weimar, Germany, 2020

3.3 The National Water Act

The National Water Act, provides the legal framework for the effective and sustainable management of the South African water resources. Published in 1998 the aim of the NWA was to reform the past discriminatory laws relating to water resources. Central to the National Water Act is a recognition that water is a scarce and precious resource that belongs to all the people of South Africa. The NWA recognises water resource management to achieve the sustainable use of water. The act aims to protect, use, develop, conserve, manage and control water resources as a whole, promoting the integrated management of water resources with the participation of stakeholders. Not addressed in the act is the vision on how to rejuvenate impaired river systems. Reference is made to the Catchment agencies as the body “that manages water resources within its defined watermanagement area according to its catchment management strategy” (Department of Water affairs and Forestry, no date).

No mention or vision of the restoration of impaired water bodies was found within the act. The Salt River falls under the Berg River catchment, which includes all Cape Town’s catchments. During this study it was not possible to receive information about future visions or strategies for the catchment, therefore a analysis of relevant Cape Town strategies, which address the upgrading of urban rivers was done in the following section.

3.4 Strategies of the City of Cape Town supporting river upgrade

The City of Cape Town developed in recent years a package of strategies for development with the aim of sustainable development in a resilient city. The overarching strategy being the Integrated Development Plan, which sets the scene in its implementation plan for the environmental, the resilience and the water strategies as well as the Coastal management framework.

3.4.1 Cape Town IDP

The Integrated Development Plan (IDP) gives full effect to the Organisational Development and Transformation Plan and sets out the cities development priorities over five years (2017-2022).

The last years with extreme weather events have deepened city challenges, resilience has emerged as an important urban concept. The cities location on the Atlantic ocean with most of the development low lying or close to the sea, sea level rise poses a major threat to the city. The changing rainfall patterns, temperature and wind extremes have alsready affected the city negatively. These changes can be seen as a result of climate change.

“The City is making a pledge to a concerted effort to improve its resource efficiency and security, as well as to address factors that affect climate change. this includes climate change mitigation initiatives to improve air quality, the diversification of its energy mix, as well as adaptation measures such as conserving biodiversity” (CoCT, 2017).

“Resource efficiency and security of Cape town’s environment, including its natural resources, landscapes, ecosystems and green infrastructure, forms the basis of the city’s economy and plays a crucial role in building resilience. Natural resources include the provision of basic resources such as water and renewable energy (sun and wind), but also ecological services such as air and water purification, flood prevention and mitigation, coastal buffers, the recharge of aquifers, soil production, absorption of waste and pollution, pollination, and carbon sequestration” (CoCT, 2017).

Out of the implementation plan, the following prgrammes are relevant to either the site or the concept of river and wetland rehabilitation in Cape Town.

• Climate change programme, “adapting climate change project due to the considerable risks that the effects of climate change pose in an urban environment, particularly to vulnerable people and communities, the City needs to strengthen Cape town’s capacity to adapt and build resilience to the economic, social, physical and environmental impacts of climate change. The City will aim to reduce Cape town’s carbon footprint in order to contribute to the global reduction of greenhouse gas emissions” (CoCT, 2017).

• Invasive species management “project of the city will be rolled out on all City land across the metro. in line with the regulations of the national environmental management: Biodiversity act (NemBa), act10 of 2004, this will see the identification, control and management of existing as well as new and emerging invasive species, preventing them from spreading and building viable populations” (CoCT, 2017).

• Integrated coastal management “is managing the sensitive dune systems along Cape town’s coastline. as they provide natural buffers against storm surges, the retention of functional coastal dune cordons is a priority for the City in reducing the impacts of climate change” (CoCT, 2017). This programme is described in more detail further down.

• Green infrastructure project, the main focus will be the development of a green infrastructure plan covering the entire City of Cape town area. this plan, scheduled for development in 2017/18, will serve as a planning and management tool for natural open spaces and natural systems in Cape town, including nature reserves and the Biodiversity network, parks, public open space, rivers, wetlands and the coast. A specific focus will be the ecosystem services that these natural assets provide, such as flood attenuation, waste absorption, air and water purification, resource provision, and recreational and cultural benefits” (CoCT, 2017). Thgreen infrastructure plan could not be accessed during this study.

• City resilience programme, “in 2016, the City was selected as a member of the 100 Resilient Cities initiative. This initiative assists cities with their strategic planning to proactively and sustainably address their physical, social and economic challenges. Urbanisation, globalisation, rapid technological advancement and climate change mean that Cape Town’s key systems are increasingly interdependent with other parts of the region, the country and the rest of the world, and are also potentially more vulnerable to disruption. A holistic approach to risk is required – not simply preparing for shocks, but understanding how stresses impact on the ability of our city to thrive and respond in moments of shock” (CoCT, 2017). This programme resulted in the Resilience strategy, which is introduced below.

3.4.2 Resilience Strategy

The Resilience Strategy introduces shocks and stress factors that the city has to prepare for in future. Prioritised shocks that are relevant to this study:

• Rainfall flooding “affecting many Capetonians because of its geographic position. Due to climate change, Cape Town is expected to have more frequent and intense flood events in the future, which can impact large tracts of the city” (CoCT, 2019).

• Drought,”from 2015 to 2018, Cape Town experienced the worst drought in its recorded history. Climate change has increased the likelihood of more frequent and intense droughts in the future” (CoCT, 2019).

• Heat wave, “increased incidences of extreme heat events as a result of climate change are a distinct possibility for Cape Town. The impact of heat waves on vulnerable people, particularly the elderly and young children, can be particularly severe” (CoCT, 2019).

The prioritised stress factor relevant to the study is:

• Climate change, “impacts Cape Town in a number of ways and exacerbates the occurrence and severity of extreme weather events such as droughts, heat waves and storms. Cape Town also has large coastal areas and low-lying residential areas that may be impacted by future sea level rise” (CoCT, 2019).

“Shocks, including climatic events, can strike at any time. There are opportunities to ramp up ambition in supporting actions that build resilience” (CoCT, 2017).

The Resilience Strategy recognises the following climatic changes Cape Town will face in the future:

• “a decreased annual average rainfall and changes in the seasonality of rainfall.

• an increase in mean annual temperature: higher maximum temperatures, more frequent and intense heat waves.

• an increase in average wind speed and maximum wind strength.

• an increase in intensity and frequency of storms: short, high-intensity rainfall events and increased size and duration of coastal storms” (CoCT, 2019).

The goals within the resilience strategy which relate to the rehabilitation of rivers and wetlands are:

• “Rejuvenate our rivers and the spaces around them to create liveable urban waterways” (CoCT, 2019).

The aim is to tansform the urban rivers into “healthy, safe and productive urban waterways which produce multiple resilience dividends, including flood attenuation, new work and recreation opportunities, improved water quality and crime reduction” (CoCT, 2019).

The study found that major parts of Cape Town’s rivers are restricted by urban development. They are piped, channelized, canalized. They receive pollutants from WWTW’s , roads and informal settlements. “The total length of rivers and streams in Cape Town is 1 900 km and the total length of canals and channels is 480 km” (CoCT, 2019).

• Build climate resilience

“Adaptive responses to the impacts of climate change are spread across a multitude of government, organisational, and community plans” (CoCT, 2019).

• Create multiple coastal management forums

“Empowering partnerships between coastal stakeholders to co-own risks related to impacts on the coast and surrounding infrastructure, and networks of resources able to both prepare for and respond to coastal shocks. The integrity and value of Cape Town’s 307 km coastline is dependent upon the interaction of numerous biophysical processes. Storms are drivers of rapid coastal change, often leading to abrupt erosion events and inundation of coastal areas. Historic planning decisions made without the guidance of a City- wide integrated coastal management framework have resulted in the interference with dynamic coastal processes and degraded coastal environments which now form a source of risk to human settlements located in these spaces. Risk may be physical, social or financial and can be transferred to coastal stakeholders over periods of time and over space” (CoCT, 2019).

• Develop and implement a comprehensive citywide heat plan

“Decreased impact of heat waves when they occur through a city-wide plan, understood and owned by individuals, households, communities and businesses, allowing for the city and its economy to thrive under the circumstances, and for human life to be protected” (CoCT, 2019).

• Develop a portfolio of flood prevention capital projects

“Inclusion of a comprehensive portfolio of capital projects designed to reduce the acute risk of flooding across Cape Town in the next iteration of the City’s sector plans that can be considered for implementation over the next decade. Flooding, whether it occurs due to an overflow of water from water bodies, such as rivers or the sea, due to an accumulation of rainwater on saturated grounds, is a significant shock risk in Cape Town. Irrespective of the possibility of extreme rainfall events in our future as a consequence of climate change, the changing form of the city, including densification, new greenfield developments and the growth in informal settlements, all add complexities which can exacerbate flooding events” (CoCT, 2019).

3.4.3 Environmental strategy

Cape Town devloped a Environmental strategy with the Vision to enhance, protect and manage Cape Town’s natural and cultural resources.

The visionary long term goals related to the cities rivers and waterbodies are:

• “excellent air quality in all areas of Cape Town;

• Cape Town’s rivers and wetlands are well managed and where possible planned as cohesive corridors that are well-used recreational spaces and community assets that provide ongoing ecological services;

• Cape Town’s coastline and marine environment are of excellent ecological quality, free from pollution, accessible to all, provide a central role for recreation, and continue to contribute to Cape Town’s economy;

• the natural resource base, including biodiversity and the services provided by green municipal infrastructure, is restored, protected and utilised sustainably;

• the City understands and takes active steps to reduce environmental risk;

• Cape Town’s aquifers are well managed and conserved, and Sustainable Urban Drainage System (SUDS) controls and waste water treatment and recycling are optimised in a manner which promotes a Water Sensitive Urban Design philosophy and positions Cape Town as a leading example of a truly “Water Sensitive City”; (CoCT, 2017)

Principles and directives

• Resilience

The City will ensure a focus on resilience, enabling the city to withstand and mitigate the negative impacts of environmental hazards, proactively reduce Cape Town’s vulnerability, and protect the city’s economy.

The City will:

• “take steps to prevent and minimise the effects of natural and man-made environmental hazards;

• recognise that natural functional ecosystems provide the most efficient and cost-effective buffers to natural environmental hazards;

• ensure that the City has a good understanding of environmental risk, particularly those risks associated with climate change, and develops appropriate plans and tools accordingly;

• prioritise environmental management and infrastructure development and maintenance approaches that emphasise soft engineering, and the restoration and rehabilitation of natural systems;

• where natural defences to environmental hazards do not exist, or have been negatively impacted and thus have reduced effectiveness, proactively work towards rehabilitation of these defences, with the aim of restoring the defensive function;

• ensure that invasive plant and animal species are controlled and/or eradicated as required by national legislation and to minimise the impacts of fires on the city;

• ensure that the city’s natural resources and natural/ semi-natural open spaces are managed according to best practice in order to improve resilience and optimal functioning;

• ensure an appropriate urban-natural interface that protects communities from natural hazards; and

• ensure that climate change risk is taken into account in the management of natural resources and in the approval and implementation of developments” (CoCT, 2019).

• Ecosystems Approach

Ecological infrastructure and ecosystem goods and services will be recognised, protected, and, where possible, pro actively restored.

The City will:

• “protect, invest in and proactively work towards rehabilitation of ecosystems and ecological infrastructure, with the aim of restoring the functioning of these systems and the ecosystem goods and services they provide;

• clearly define, map, manage and rehabilitate ecological infrastructure that provides ecosystem goods and services to the communities of Cape Town;

• recognise the interconnectedness and interdependence of ecosystems and their associated goods and services, and ensure that negative cumulative and downstream impacts are prevented, or where they cannot be prevented, minimised or mitigated” (CoCT, 2019).

• Protected Natural Heritage

Cape Town’s natural heritage is a significant economic and social asset, and contributes significantly to the unique sense of place, strong global identity, and distinctive landscapes that are characteristic of the city.

Principle In taking decisions, operating, and planning for the future the City will ensure that the value of the city’s natural heritage is recognised, protected and promoted, and that the benefits and opportunities it provides to communities are realised.

The City will:

• “ensure that the city’s natural and semi-natural open spaces that protect indigenous biodiversity and landscapes and promote sustainable economic and recreational activities - including nature reserves, critical biodiversity areas, river corridors, wetlands, estuaries, beaches, and the coastline - are appropriately protected and managed; and

• work towards implementation of the Biodiversity Network in order to protect a representative sample of biodiversity pattern, process and natural vegetation to meet national biodiversity targets” (CoCT, 2019).

3.4.4 Water Strategy

“The three-year drought in Cape Town was a 1-in-590-year event based on historical rainfall records. The additional uncertainties associated with climate change now need to be included in future planning, including changes in rainfall, temperature and wind, and a likely increase in the intensity and frequency of extreme weather events” (CoCT, 2019). After the shock of the three=year drought the cities priority lies in water supply, although the water strategy also recognises flood risks and water quality in environmental waters.

The future vision for Cape Town is to become a water sensitive city by 2040. “The City will actively facilitate the transition of Cape Town over time into a water-sensitive city with diverse water resources, diversified infrastructure and one that makes optimal use of stormwater and urban waterways for the purposes of flood control, aquifer recharge, water reuse and recreation, and is based on sound ecological principles. This will be done through new incentives and regulatory mechanisms as well as through the way the City invests in new infrastructure.” (CoCT, 2019)

“In its broadest context, water-sensitive urban design encompasses all aspects of integrated urban water cycle management, including water supply, sewerage and stormwater management. It represents a significant shift in the way in which water and related environmental resources and water infrastructure are considered in the planning and design of cities and towns, at all scales and densities. Increasingly, the terms “water-sensitive urban design” and “water-sensitive cities” are used interchangeably. However, there is a subtle yet important distinction between the two: While “water-sensitive urban design” refers to the process, “water-sensitive city” refers to the destination” cited in (CoCT, 2019). Water sensitive urban design in form of Sustainable Urban drainage is already part of planning new developments. The challenge within the city lies in areas developed without SUDS. Can they be retrofitted?

The Challenges

“Stormwater and urban waterways are often considered a costly problem – water is polluted, and the adjoining areas are often unsafe and remain unused. Cape Town is home to an extensive network of rivers and wetlands. These freshwater systems fulfil a dual function, serving as havens for plant and animal life, as well as ecological infrastructure networks for the management, treatment and conveyance of stormwater and treated effluent” (CoCT, 2019).

“The “built” stormwater infrastructure – roadside gutters, kerb inlets and pipes – interfaces directly with Cape Town’s receiving freshwater and coastal environments. An integrated understanding of, and approach to, the management of these connected systems are essential for the protection of the receiving environment. The ongoing organic and inorganic pollution and littering of Cape Town’s stormwater and freshwater systems poses a threat to both biodiversity and human health” (CoCT, 2019).

“Improved stormwater management is vital for protecting the citizens of Cape Town from localised and more widespread flooding. This also presents an opportunity for the capture and storage of stormwater for productive use” (CoCT, 2019).

“The health of our urban water ecosystems tells part of the story of rivers and wetlands. They are generally not suitable for recreation, and unsightly in places, making them undesirable as public gathering spaces. Another part of the story of our rivers and wetlands is that many are regarded as unsafe due to criminality” (CoCT, 2019).

“Recently, the City significantly increased its ten-year investment programme to upgrade wastewater treatment works in order to achieve an even higher effluent quality standard and to provide capacity upgrades to support city development. In addition, the extension of the treated wastewater effluent distribution system is proceeding annually, steadily increasing the diversity of the City’s water resources by replacing potable water use and reducing the volume of discharge into Cape Town’s rivers and urban waterways” (CoCT, 2019).

Supporting the transition to a water-sensitive city

• Water management

All forms of water in the city – rain, stormwater, groundwater, greywater and blackwater, canals and rivers – need to be managed in an integrated way that makes the best, sustainable use of this scarce resource and reduces the risk and impact of flooding.

• Waterquality

For environmental waters, especially those associated with wastewater discharge, toxicity tests will also be conducted to assess the impact of chemicals on aquatic ecosystems. The City will ensure that wastewater treatment processes are adequately managed, and that effective and credible water treatment technologies are applied to ensure that the final effluent is safe for both humans and the environment.

Currently, the City monitors the quality of river water associated with wastewater discharge to ascertain the impact on receiving water bodies, as required by wastewater treatment plant operating licence conditions.

• Rainfall uncertainty

“It is wise to consider the possibility of a step change in rainfall for Cape Town. Although the impact of climate change is uncertain, it is prudent for Cape Town to develop plans that take this uncertainty into account. This requires a scenario-based planning approach, since the climate is beyond the City’s control” (CoCT, 2019).

3.4.5 Coastal Management Framework

Coastal and sea defence decision framework

Much of the City of Cape Town’s extensive coastline has been developed with fixed infrastructure, thereby significantly restricting natural coastal processes from taking place unhindered. This coastal change may be caused by either erosion or accretion processes, as well as through climate change effects. These climate change effects are manifested through an increase in mean sea level and an increase in the intensity and frequency of coastal storms.

The City will therefore need to consider the implementation of coastal and sea defenses in order to protect vulnerable infrastructure. Ill-informed decision making in responding to pressures caused by coastal processes may exacerbate risk and also lead to the permanent loss of existing beaches and coastal environments. The principles which guide this framework include:

• risk averse decision making

• decisions centred on the common good

• application of multi-criteria assessment for decision making. The City recognises three broad categories of coastal and sea defence options, including:

• engineered responses, i.e. sea walls

• ecosystem-based responses, i.e. use of dunes as buffers

• socio-institutional responses, i.e. development of setback lines. (CoCT, 2008)

3.4.6 Floodplain and River Corridor Management Policy

“In order to ensure sustainable development and associated activities within or adjacent to natural and built stormwater systems, and that there is a balanced consideration of potential flood risk, environmental impacts and socio-economic needs, all developments within these areas shall be planned and designed in accordance with best practice and the requirements and conditions laid down in this policy.”It furthermore ensures administrative actions with respect to land use planning applications that are lawful,reasonable and procedurally fair.

Scope and Application of the policy" (CoCT, 2009).

"This policy is applicable to land use, development or building or activity proposals adjacent to watercourses or wetlands. The principles regarding flood management can also be applied to development in the vicinity of formal stormwater management systems" (CoCT, 2009).

3.4.7 Summary of Cape Town Strategies

The city recognises the risks of climate change in all five strategies. A main focus is on the protection and conservation of the natural resources. The need for restoration of urban waterways is a main goal in the Resilience Strategy. The Water strategy envisages Cape Town as a Water Sensitive City within the next 20 years. The Floodplain and River corridor management policy protects rivers and floodplains from negative impacts of new development, It doesn’t pro actively enhance and restore these.