As a result of a high-level of urban development and the serious impacts of climate change, metropolitan areas all over the world face different risks and challenges of varying degrees associated with their aquatic environments and characterized by water scarcity or overabundance including flooding, heatwaves, torrential rains, and droughts. These extreme weather patterns not only pose a major threat to the lives and property of ordinary citizens but also have a negative influence on sustainable urban development. The creation of the sponge city helps effectively regulate the micro-climate of cities and minimize the impact of urban heat island effect. The promotion of the garden city policy, on the other hand, reinforces food and agriculture education concepts, stimulates public participation, and helps create cities characterized by green health, education, and lifestyles. An effective management of GHG emissions is achieved through the adoption of green transportation, green power, and energy conservation strategies.
Due to climate change, this city is also facing pressing challenges that come with it. In terms of addressing climate change and regional extreme weather, this city has put flood control and river regulation at the core of the city’s long-term climate action plan to make this city a safe and habitable waterfront city for the citizens. However, considering the challenges from extreme climate and competition for water resources in the future, currently Taipei City has formulated its water environmental policy based on the concept of the sponge city. With “Resilience and Adaptation”, “Sustainable Water Usage” and “Vibrant Water Environment” as the visions, the city government will build a safe, sustainable, accessible and eco-friendly water environment.
The 3 visions of a sponge city include the following 6 goals: “Restoring Urban Water Cycle”, Increasing Flood-Resisting Capacity”, “Diverse Water Reuse Sources”, “Stable and Efficient Water Supply”, “Livable Natural Habitat” and “Promoting Waterfront Activities”. Thirteen strategies and 170 plans have been formulated accordingly with a 4-year budget of NT$22.7 billion.
Construction and management will ensure permeable pavement on roads and squares, promote green roofs, increase the city’s flood retention capacity, upgrade wastewater processing, ensure diverse reuse of recycled water, conserve and protect water environment and build a leisure environment with great water accessibility. These measures will help the city retain water, adjust the microclimate via transpiration and build disaster tolerance and resilience facing extreme rainfall, transforming the city into a sustainable sponge city that is resilient, capable of dissipating heat via water and adaptive to all future challenges.
Under the three visions, six goals, thirteen strategies and 170 plans, the city has implemented the following key projects from 2015 to 2018.
Facing the challenges of climate change, Taipei City will continue to work toward becoming a water-friendly and green city by increasing the percentage of green infrastructure at the city’s public facilities. The city plans to, by 2030, reach 80% in green infrastructure at the public facilities and increase water retention capacity by 1.15 million m3 （same level as parks and green spaces）. Another goal is to reach 16% in water recycling in wastewater processing. Through an open government, citizen participation and public-private collaboration, this city can retain more water to reduce floor risk when facing extreme rainfall, dissipate heat to mitigate urban heat island effect at high temperature and provide a stable and diverse water supply to the public and businesses when water resources are in short supply. These will transform Taipei City into a sponge city that provides citizens with great water accessibility and a diverse aquatic ecosystem.
Limited land and high population density of the city make it hard to find space for detention basins. Therefore the city government has actively promoted the installation of rainwater outflow suppression facilities at private buildings to increase flood resilience and reduce flood risks during heavy rains. The government also promotes other water retention measures during the development of public facilities（schools, parks, parking lots, etc.）. Green space and other measures with better water permeability can be used to mitigate the urban heat island effect, improve water environment resilience and distribute rainwater runoffs in the catchment area. For private buildings, install rainwater outflow suppression facilities, increase rainwater detention capacity and reduce peak runoff volume and thus the sewage load is lower during heavy rains. These will prevent an increase in runoff volume during the development of a building’s foundation.
Taipei City also aims to gradually restore the natural water cycle in the city and allow rainwater to replenish groundwater with the “pedestrian environment improvement plan”, which updated and expands parks, squares, parking lots and school campuses. A total of 173,819 m2 of permeable pavement was installed during 2015 to 2018, equivalent to 417 standard size basketball courts. An on-site test at these permeable pavement showed that the peak surface temperature dropped by 2.05 to 3.53 ℃ and runoff dropped by 7.3% to 17.85%, proving that these pavements can adjust the city’s microclimate and mitigate the urban heat island effect.
Public-private partnership is promoted to gradually increase the city’s flood-resisting capacity by installing rainwater outflow suppression facilities at building foundations, which retain a total amount of 113,456 m3 of water. The city government also implements the concept of comprehensive drainage basin planning. In 2015, Jinrui Flood Management Park was built with a total of 27,000 m3 in flood regulating capacity. A flood detention pond with a capacity of 6,000 m3 was built in the Wenshan Sports Center in 2017. Another flood detention pond with a capacity of 46,000 m3 was built in a military police camp in January 2019. The three combined give the city a total of 79,000 m3 in detention capacity, which has boosted its regional flood resilience dramatically.
Garden city is not another green project in the traditional sense. Instead, it encourages people to find any idle space, rooftops, campuses and any interesting corners in a community to grow edible plants and create a friendly urban view based on the diverse value of food/agricultural education, community exchanges, spatial creativity, social welfare, sustainable ecosystem and urban landscaping. More green spaces can help mitigate the urban heat island effect and reduce heavy rain runoffs. Therefore the city government encourages people to build gardens on government-owned idle land, private/ public buildings and private business buildings.Regarding education, students will learn about farming and develop a habit of labor via hands-on experience. They will also learn about plants growing. These activities will encourage students to eat locally grown food and give both students and teachers an opportunity to be close to the nature. As they learn to co-exist with the nature, they will be more willing to protect the environment and follow the concept of a green campus and garden city.
The city has set its GHG reduction targets based on the emissions of 2005（13.0736 million metric tons）, which are 25% reduction by 2030（to 9.8052 million metric tons）and 50% reduction（to 6.5368 million tons）by 2050 respectively. Emissions reduction strategies include the introduction of “Greenhouse Gas Emissions Reduction Supervisory Briefing”, periodic updates of the greenhouse gas emissions information and the promotion of greenhouse gas reduction strategy. Taipei City Government works with other counties and cities in the home/business energy conservation project to encourage the general public to replace non-energy efficient and old appliances with smart energy, increase renewable energy generation, develop electric vehicles and increase green transport. A review on the reduction goal is convened every five years to allow the city to achieve the goal at a steady pace.
As the impacts of climate change are getting worse day by day, various types of disaster risks have escalated accordingly. On top of this, past disaster response experience shows that further disaster prevention and preparedness enhancement are needed to ensure proper response and recovery at all levels after actions toward expected disaster events.
Therefore, Taipei City Government, through disaster potential simulations and risk analysis, formulates annual stage goals and key disaster prevention projects, such as enhancing the speed and accuracy of disaster monitoring and early warning systems as well as compiling, updating and publishing location-based disaster risk information to serve as reference for decision-makers, the general public and communities with high disaster risks. Taipei City Government implements the most effective way by providing age and demographic-specific disaster prevention education through a diverse array of channels to help all understand the disaster risks at their environment.
A comprehensive city disaster prevention plan, evacuation shelters and route planning, periodic maintenance and reinforcement of disaster prevention facilities（retaining wall, embankment, storm water sewer, water pumping station, etc.） have all been implemented. The city government also, based on previous disaster experiences. periodically adjusts disaster prevention strategies, formulates SOPs and checklists, reviews and improves disaster prevention and response policies to ensure the execution of emergency response tasks.
In order to ensure effective post-disaster recovery planning, protect citizens’ lives and property and pursue sustainability of the city, Taipei City Government has included the following in Chapter Four of Taipei City’s Regional Plan of Disaster Prevention and Response: post disaster recovery plan and SOP, necessary financial measures for post-disaster recovery, victim reliefs and compensation, victim placement, reconstruction of infrastructure and public facilities, environmental rebuild, industrial revitalization and stabilization of prices and psychological and life rehabilitation for the victims. Taipei City’s primary institutions and public utility have compiled their responsibilities in “Disaster Prevention and Response Execution Plan” and allocated relevant budgets. To accelerate the post disaster recovery plan and boost the efficiency（since there are so many divisions of labor for post-disaster recovery）, Taipei City Government drafted the “ Taipei City Post-Disaster Recovery Guidelines”, which divides the post-disaster recovery into the following items in its nine chapters and 51 sections: disaster investigation and management, necessary financial measures for recovery, victim assistances, victim placement, environmental recovery, reconstruction of infrastructure and public facilities, industrial recovery and revitalization and psychological and life rehabilitation for the victims.
For post-disaster recovery planning, Taipei City Government will evaluate the disaster scale and needs and establish a recovery tasking commission based on Article 37 of Disaster Prevention and Protection Act and Article 7 of Taipei City Disaster Prevention and Protection Rules, with commission members from various city government agencies. In response to Typhoon Nari, Taipei City Government established the “Taipei City Government Typhoon Nari Post-Disaster Recovery Tasking Commission” in 2001 to conduct a full review of the cause of the typhoon and any deficiency in prevention, response, relief, assistance and recovery system. The commission compiled specific advice for improvement, provided counseling and coordinated the recovery efforts. For any major disasters in the future, Taipei City Government will follow the aforementioned protocols and establish a recovery tasking commission to conduct post-disaster recovery planning.