Keywords

8.1 Introduction

Urban drainage infrastructures (UDIs) have had major impact on human and environmental health, urban life quality, and development of cities [1, 2]. UDIs have a long history in urban areas from the time when the traditional open gutters were in place until now that most UDIs’ components are underground, and those open gutters/channels have mainly been replaced with closed conduits and piped systems. In fact, the history of using stormwater collection systems coincides with the appearance of human civilization, i.e., thousands of years ago. Although the main goal of drainage systems is to collect surface runoff and flood flows, combined sewer systems in some countries are used to collect and convey both surface runoff and sanitary sewage in the same conduits. As cities grew, the need for larger drainage systems increased, which resulted in more investments in UDIs [3]. However, the performance of combined sewer systems has been found unsatisfactory due to unwanted discharge of untreated wastewater into receiving water bodies that can be the main source of water supply in urban water metabolism [4]. Generally, flooding, erosion, water quality reduction, and environmental issues are probable hazards threatening the performance of UDIs [3].

There is no doubt that efficient water infrastructure consisting of many structures and elements [5] can be vital to reach the United Nations’ 2030 goals [6], which are known as sustainable development goals (SDGs) and were adopted based on a universal agreement [7]. However, water infrastructure is already under massive pressure from external drivers especially urbanization, population growth, and more importantly climate change.

Despite great importance of UDIs in achieving SDGs, external drivers such as climate change, population growth, and urbanization can undermine the satisfactory performance of UDIs. Although climate change is known as the continuous changes in some climatic variables such as precipitation and temperature [8], the change indicates a rapid rate over the last century [9] due to anthropogenic activities by greenhouse gas emissions from fossil fuels and land-use changes [10, 11]. Temperature, precipitation, relative humidity, and incident solar radiation are some affected parameters in a changing climate. In addition, an increase in world population has been predicted [12], and another projection showed a greater percentage of the world population will be living in urban areas [13]. These stressors can substantially impact natural and human-made structures. UDIs can both affect climate change (e.g., increasing greenhouse gas emissions, acidification, and eutrophication) and also be influenced by climate change (e.g., as a result of changes in urban flooding) [14]. Aging is another problem of current urban infrastructures [15, 16] including UDIs [17] that threatens their sustainability. As displayed in Fig. 8.1, UDIs must overcome a number of obstacles (i.e., aging of infrastructure, climate change, population growth, and urbanization) before reaching a sustainable future, through adaptation strategies. In Fig. 8.2, some problems that happened as a result of malfunctioning of UDIs in Tehran, Iran, are illustrated, which normally threaten the transportation system and public health.

Fig. 8.1
A flow diagram includes urban drainage infrastructure that affects aging, climate change, population growth, and urbanization. These lead to adaptation strategies and a sustainable future.

UDI: how to reach a sustainable future

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Fig. 8.2
3 photographs of water logging and flooding in streets due to improper drainage in Tehran, Iran.

Examples of UDIs’ failures in Tehran, Iran

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Over the previous decade, various research works studied the impact of climate change [12, 18] and possible adaptation strategies [11, 19]. Reviewing these works demonstrates that the previous studies mainly neglect the role of achieving SDGs and the impact of urbanization; however, most of them emphasize the importance of climate change impacts on UDIs. It should be noted that the performance of current UDIs is affected by climate change and urbanization [3], and applying sustainable drainage can be very challenging for real-world cases [20]. The main aim of the current chapter is to review the impacts of climate change and urbanization on UDIs and potential adaptation strategies to alleviate these negative impacts and help reach a sustainable future.

8.2 Climate Change, Population Growth, and Urbanization

Climate change is one of the most pressing world problems. It refers to the long-term persistent variations in the climate that happen either naturally or as a result of anthropogenic activities [21]. Carbon dioxide, methane, nitrous oxide, water vapor, and fluorinated gases are the most important gasses that are responsible for the greenhouse effect [22]. Human activities are the main reason behind the global increase in greenhouse gases [23] – among all activities, using fossil fuels and land-use changes have had the greatest effect on global carbon dioxide increases [21]. Other impacts of climate change can include changes in migration [24], wildfires [25], extinction of plant and animal species [26], and social and political conflicts [27]. Figure 8.3 depicts some of the featured changes that can happen by climatic changes and affect urban infrastructures.

Fig. 8.3
Three illustrations of the climatic factors include an increase or decrease in frequency and intensity of rainfall, an increase in the global mean temperature and solar radiation, and an increase in sea level.

Projected changes of climate variables due to climate change

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On the other hand, it has been predicted that the world’s population will reach 9.8 billion by 2050 [28]. Another projection, for 2050, indicated that approximately 68% of the entire population of the world will reside in urban areas [13]. Hence, climate change, urbanization, and population growth can be considered the current important world stressors that can jeopardize the conditions of both natural and artificial systems like UDIs.

8.3 SDGs and UDIs

Global goals are an alternative name for SDGs that were set out by the United Nations General Assembly in 2015. Seventeen SDGs with 169 targets are included in the 2030 agenda for sustainable development, which started to be implemented from 1 January 2016. The framework of the goals was prepared in a way that can be acceptable scientifically, politically, and publicly. The final objective of SDGs is to provide sustainable health for all (from planet to local communities), by accounting for poverty, inequality, climate change, environmental degradation, peace, and justice [7, 28]. All 17 SDGs can be categorized into four sections related to people (goals 1–6), prosperity (goals 7–12), the planet (goals 13–15), and peace and partnerships (goals 16 and 17). It can be observed that many of these goals depend on each other, for example, zero hunger in a region affects the poverty of that region. Water is clearly mentioned in goal 6 (clean water and sanitation), which per se underpins many goals such as goals 1 (poverty), 2 (food), 3 (health), 4 (education), 7 (energy), 8 (economics), and 10 (equity) [7].

Since water is harvested, supplied, treated, and delivered through water infrastructure, the dependence of many goals and their associated targets to water infrastructure is undeniable. Flood control is another major task of water infrastructure [29] that is normally handled through drainage (stormwater) systems. UDIs can contribute to reaching goal 1 by reducing climate-related disasters on poor people, goal 3 as death rate and illnesses due to water pollution and contamination can be reduced or eradicated, goal 6 through affordable water production, pollution reduction, etc., goal 9 by making infrastructure and industries efficient, resilient, and eco-friendly, goal 11 by considering the environmental and financial problems associated with water in cities, goal 12 by controlling the release of wastes to water, and goal 13 by increasing public awareness related to climate change impacts and adaptation. Due to the role of UDIs in collecting and supplying water, mitigating flood, conveying water, and contributing in wastewater treatment, they play a significant part in providing safe and affordable water, preserving ecosystems, and other SDGs, which cover seven goals (1, 3, 6, 9, 11, 12, and 13) and their targets.

8.4 Climate Change and Urbanization Impacts on UDIs

In Table 8.1, the main probable impacts of climate change and urbanization on UDIs are reviewed. The capacity of the current UDIs and the quality of water are affected by these drivers. More specifically, floods can be generated because of sea-level rise and increased precipitation that both occur due to climate change. In addition, urbanization as a result of increased desire to live in cities, as mentioned in Table 8.1, increases the risk of flood formation and its associated consequences. Flooding endangers public health, threatens public transportation systems, increases financial losses and number of deaths, and results in untreated water, e.g., wastewater and sewage being released into receiving bodies (sea, lakes, etc.). Based on Table 8.1, the impact of climate change and urbanization can be categorized into four sections in which some problems arise themselves.

Table 8.1 Probable impacts of climate change and urbanization on UDIs
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8.5 Performance Improvement of UDIs

Water infrastructure can be divided into three main sub-systems including water supply systems, stormwater systems, and wastewater systems. Needless to say, any new development or rehabilitation of any water infrastructures can be quite expensive, and their construction may take years. Clearly, their failures can result in loss of lives and property damage [30]. Another issue is that many of them were built many years ago which make them more vulnerable.

The impacts of climate change and urbanization on UDIs and their role in gaining SDGs were discussed in the previous sections. The probable impacts of these drivers may cause problems for the operation of UDIs and reaching SDGs. Hence, adapting UDIs to future changes is an urgent need. It was reported that UDIs cannot deal with the effects of climate change and urbanization [1, 12] that necessitate applying the adaptation measures. Design criteria that consider the impacts of urbanization, population growth, and climate change [12] should be added to the future design. Other flood control methods that are listed in Table 8.2 can mitigate flood impacts and reduce the excessive pressure on UDIs due to climate change and urbanization.

Table 8.2 Adaptation strategies to counteract future problems in UDIs
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8.6 Conclusions

UDIs can contribute to achieving a future sustainable for all; however, it is under pressure from external drivers such as climate change, urbanization, and population growth. The impacts of these stressors not only prevent fulfilling the main functions of UDIs but also undermine reaching SDGs. This chapter investigated the requirements of SDGs in UDIs, the impacts of climate change and urbanization on UDIs, and the adaptation strategies that can be employed to tackle climate change and urbanization and making UDIs ready to achieve the universal goals of the United Nations. The role of UDIs seems to be major for achieving seven SDGs (goals 1, 3, 6, 9, 11, 12, and 13) while climate change and urbanization can cause various problems for UDIs, and the different adaptation strategies were proposed in the literature to mitigate these problems and adapt UDIs to future changes.