Urban resilience is “the capacity of individuals, communities, institutions, businesses, and systems within a city to survive, adapt, and grow no matter what chronic stresses and acute shocks they experience” (100 Resilient Cities, 2016, p. 16).
Cities worldwide occupy approximately 2 percent of the earth’s land surface but are home to over half of the world’s population. In the 20th century, there was significant urban growth, with the world’s urban population increasing more than ten times from 220 million to 2.8 billion. Urbanization is continuing to accelerate rapidly in the 21st century, and it is projected that by 2050, two out of every three people will be living in urban centres. This means an additional 2.5 billion people could be added to urban areas by the middle of the century.
Cities have experienced a massive surge in urbanization due to the economic prosperity and civic amenities they offer. They are the main drivers of economic growth, accounting for 80% of it. Cities and towns also play significant roles in social transformation and are hubs for artistic, scientific, and technological innovations in culture and education. The history of cities and towns is closely intertwined with modern civilization.
Urban Growth and Hydrological Engineering.
Hydrological engineering advancements contributed to urbanization’s unprecedented growth. Cities expanded to access water sources for residents’ basic needs. Researchers estimate that large cities transfer over 500 billion litres of water daily over 27,000 kilometres. If these canals and pipelines were connected, they would stretch halfway around the world. The volume of water transferred annually to cities equals the flow of 50 Ganga Rivers. Dams, levees, reservoirs, pipe networks, and pumping stations provide cities with this water. Dams and reservoirs now intercept 35% of river flow, up from 5% in 1950.
An analysis of urban growth and challenges in developing countries.
Developing nations will drive urbanization in the 21st century. India, China, and Nigeria are expected to contribute 35% of the world’s urban population growth from 2018 to 2050. Africa and Asia will experience significant urban expansion, doubling their urban populations between 2000 and 2030. By 2030, 81% of the world’s urban population will be in developing countries. India, China, and Nigeria will add 416 million, 255 million, and 189 million urban dwellers, respectively. By 2050, an additional 2.5 billion people will live in urban areas, with Asia and Africa accounting for up to 90% of this increase.
The next few decades will see a significant increase in urbanization and a movement of global poverty from rural areas to cities. As urban populations grow, so do the world’s slums. This rapid urban expansion will result in a coexistence of prosperity and poverty, especially in Africa and Asia, where the urban population is expected to double between 2000 and 2030. By 2028, New Delhi is projected to become the most populous city in the world.
Global warming is causing the situation to worsen for people with low incomes, who bear the brunt of the changing climate. The risk of environmental change-related hazards has increased in cities and urban areas, where adaptability is limited, especially in informal settlements and low- and middle-income nations. People experiencing poverty often live in low-lying areas or near water bodies without access to WASH services. Climate change-induced events like heavy rain, urban floods, storms, droughts, and heat waves have already resulted in the loss of thousands of lives and significant property damage each year.
Global warming causes rising sea levels, increasing flooding in coastal cities. By 2050, over a billion people in low-lying areas will be at risk from coastal climate hazards. The rising sea levels also mean more intense storms and heavier rainfall, further increasing the risk of flooding and damage. Interestingly, the IPCC report predicts that global warming will also result in more severe droughts, affecting an additional 350 million people at 1.5°C warming and 410.7 million at two °C warming. The United States, China, India, the Philippines, and Indonesia have experienced the highest number of disasters in the past twenty years.
Grey infrastructure is vital in human life but can also have adverse effects like heat islands, reduced recharge potential, flooding, and depletion of ecosystems. According to the WHO, cities consume a lot of energy and produce significant greenhouse gas emissions. It is becoming clear that traditional engineering solutions may not be enough for 21st-century cities. The construction and use of grey infrastructure need to change to meet climate mitigation targets discussed in COP27, 2022 (UNFCCC).
They are developing solutions in engineering to work harmoniously with nature.
Water is essential for life, but too little or too much can be problematic. Using impermeable concrete in urban areas has contributed to the urban heat island effect and led to rainwater runoff and flooding. The grey structures we've built to control water movement are expensive and have limitations. There is a growing recognition that our solutions must shift towards working with nature rather than preventing it. This involves integrating blue-green solutions and adopting a circular approach within cities to optimize resource use and mitigate climate change effects.
The challenges of urban circularity in cities are increasing due to the linear management of resources such as water, food, materials, and energy. The current ” take-make-dispose ” system leads to resource depletion, ecosystem degradation, and a biodiversity crisis, resulting in a growing demand for resources in urban areas. There is a need to comprehensively redesign existing urban water management practices and approaches, considering the interconnectedness of various components of urban water usage.
The current water management should be transformed into a circular approach to efficiently manage resources and reduce the need for new resources through recovery and reuse. This will support economic growth in cities without increasing resource consumption and help mitigate environmental impact. We believe incorporating Blue Green Infrastructure into urban planning provides numerous benefits to the community.