Kristina N. Katich
时间：2016-09-18 来源：微水会 作者：城市雨水管理的明天
Kristina N. Katich:城市雨水管理的明天
今年夏天雨水特别多，全国各地普遍降雨量比较大。不论对老城区还是新城市来说，这些雨水都是个挑战。许多城市因降雨出现内涝，开启了“看海模式”。这背后，有许多悲惨而无奈的故事。城市雨水管理逐步成为了一个关系到人民群众生命财产安全的重大问题，也逐步成为大家关注的热点。鉴于此，水世界-中国城镇水网采访了亚洲开发银行东亚区域开发部城市发展专家Kristina N. Katich，希望能找到大家关注的问题的答案。
Kristina N. Katich的专业研究领域是气候适应性城市。去年在珠海举办的 “第十届中国城镇水务发展国际研讨会与新技术设备博览会”上，她曾做了题为《推进中国城市雨水管理》的发言。今天，她将以国际视角，通过成功的案例，从政策、技术、前景等方面分析探讨雨水管理的未来。
(左一：Kristina N. Katich）
Kristina N. Katich: 有趣的是，我工作在城市雨水管理领域是因为我对整体规划与社会公平感兴趣。起初，我学习建筑，因为我感觉建筑有其内在的社会和实用价值——创造美丽、有用、安全的空间。随着职业的发展，我转向了城镇环境规划与管理，也就开始了灾难管理与城市雨水管理。对我个人来讲，我不太喜欢防洪的硬派工程；渠化、涵洞、堤坝会破坏维护城镇环境的自然进程。这些技术把洪水的风险转移到了抵御洪水能力更差的下游社区，却把大量快速流动的洪水涌向那里。相反，我更喜欢尽可能多的采用软工程的办法，因为基于环境和景观的洪水管理可以在很多方面极大的有益于城市。尽管我总是喜欢基于自然的方案，我对 “日光”的办法，即打开20世纪七八十年代铺设、下挖的水道，以形成自然的城镇水道很感兴趣。我的研究生论文研究的是气候适应性城市，我研究了首尔的昌溪川项目。除了辅助城市雨水管理，这个项目通过建立公园，使城市更具活力。尽管开始当地居民反对，这个项目不仅大大的改善了生活环境，也提高了当地的土地价值。该项目已获得国际认可，并被认定为最佳范例广泛在美国等国家采用。
Kristina N. Katich:城市雨水管理的最终目标是确保所有的居民——富人、穷人、年轻人、老年人——每个人都有一个安全的环境。城市开发尊重环境并与自然环境共生很重要。亚洲的很多快速开发的城市忽略了低劣规划的基础设施对自然环境的影响，随着时间的推移，这些影响将挑战城市的可持续发展。铺装路面、管道化城市河流意味着城区吸收的雨水越来越少。正如我之前谈到的，这增加了下游洪水泛滥的风险，同时也危及城市水供给，通过地面沉降破坏建筑物的基础；世界上的城市，例如墨西哥城、雅加达、北京，因为铺装路面阻止了含水层的回水，正在慢慢的下沉。
Kristina N. Katich:城镇建设的形式和速度对雨水自然循环有巨大的影响。在中国，城镇规划通常没有包含足够多的雨水管理规范。许多城市开发较快，有向外扩张而不是增加密度的趋势。城市开发增加了不透水路面，减少了储存区，从而增加了城市地区的径流。
Kristina N. Katich:我最近刚从荷兰回来，荷兰的水管理经验给我留下了深刻的印象。众所周知，荷兰通过堤坝、堤岸的使用，开垦大片土地，以及传统荷兰风车的使用，在管理他们的国家与海洋的关系方面有着悠久的历史。不那么广为人知的是，这个国家本质上是默兹河、莱茵河、斯海尔德河冲积的大三角洲。另外，超过80%的人口住在城市里，有很高的年均降水，城市雨水管理、控制河面高度以防止洪水泛滥极其重要。
Kristina N. Katich:中国最明显的一大问题是大多数城市只有小型或者管道排水系统。在许多国家，雨水系统通常包括小型系统和大型系统。小型系统用于应对不密集的雨水，设计应对2到10年一遇的暴雨。小型系统通常包括地下管道和沟渠。另一方面，大型系统用于应对严重的暴雨，设计应对50到100年一遇的暴雨。大型系统通常包括旁路通道，绿化带和道路，用来处理超过小型排水系统处理能力的径流。2012年，亚洲开发银行和住建部支持的一项中国城市雨水管理研究表明，这是中国城市最薄弱的问题之一(http://www.adb.org/projects/45512-001/main)。这项研究找出了一些优秀城市示例，例如亚洲的吉隆坡，以及一些西方城市。
Kristina N. Katich:雨水管理最明显的技术更新可以从透水路面的演变看出来。过去的几年，这一领域有了突飞猛进的进展。过去，透水路面意味着铺石头或路砖的时候，留有空隙，让水可以渗入。这种办法在小范围内有效。现在，许多透水路面更复杂，有多层，不仅吸收水，而且过滤，导向附近的沼泽或者水道，因此减少了排水和污水处理的负担。透水路面种类和复杂程度不同，给开发人员和管理者在预算范围内，满足设计要求的更多的选择。透水路面可以减少径流，防止水体淤积，控制污染物，同时可以和铺装地区的树木共存。
Kristina N. Katich:对任何有志于从事雨水管理，以及中国的读者，我鼓励他们在低影响开发以及基于自然的城市排水解决方案方面学习。气候变化将会导致更频繁更密集的降雨，将会超过亚洲城市现有的已疲于应对的降雨量。哪怕城市没有采取有效的措施，个人依然有能力通过参与雨水收集、绿色屋顶、低仰角绿化带贡献自己的力量。最终，多个个体的贡献将会在城市防洪中发挥重大作用。
我们感谢Kristina N. Katich和我们分享雨水管理领域的经验和看法，首尔的昌溪川项目、鹿特丹的Benthemplein水上广场、吉隆坡的“智能通道”，都给我们留下了深刻的印象。先进的透水路面设计，正印证着“科学技术是第一生产力”，改变着城市雨水管理与规划的未来。先进的理念，先进的技术，加上我们无数雨水管理领域内孜孜以求的工作者，相信我们的雨水管理会做得更好，相信我们的城市会更好。
附：Kristina N. Katich《推进中国城市雨水管理》发言PPT:
Kristina N. Katich
Urban Development Specialist,
East Asia Regional Department (EARD)
Asian Development Bank
Field of Study: Climate adaptation and cities
(1st left：Kristina N. Katich）
1. When did you start your study in urban storm water management? There might be something or some technology that impressed you very much in your career, could you share your story with us?
Interestingly, I came to work on urban storm water management out of an interest in holistic planning and social equity. Initially, I trained as an architect, as I felt that architecture had inherent social and utilitarian values – the function to create beautiful, functional, and safe spaces. As my career developed, I moved on to urban and environmental planning and management, which ultimately led the issues of disaster risk and urban storm water management. Personally, I am less of a fan of hard engineering approaches to prevent flooding; channelization, culverts, and dams tend to disrupt the natural processes which are required to maintain the urban environment. These techniques pass the flooding risks to downstream communities which may have even less capacity to absorb and cope with large amounts of fast-moving water. Rather, I prefer to use soft-engineering approaches as often as possible, as environmental and landscape-based flood management can greatly benefit cities in a variety of ways. While I have always preferred nature-based solutions, I was particularly impressed with the practice of, “daylighting,” or the opening up of natural urban waterways which were previously paved over or culverted during the 1970s and 1980s. My graduate school thesis focused on climate adaptation in cities, and through this, I learned of the Cheong Gye Cheon Project in Seoul. In addition to helping manage urban storm water, the project also revitalized the heart of the city through the creation of a public park. Despite initial resistance from area residents, the project has greatly improved not only their living environment but also increased local land-values. The project has gained international recognition and is considered a best-practice which is now being adopted in other countries, such as the United States.
(many additional photos available on this website)
2. In your point of view, what’s the finalpurpose of urban storm water management? In order to accomplish this, what parties should be involved and what effort should be devoted?
The final purpose of urban storm water management is to ensure a safe and secure urban environment for all residents – rich, poor, young, old – everyone. It is important that urban development respects and considers its symbiosis with the natural environment. Rapid urban development in many Asian cities has neglected the impact that poorly planned infrastructure has had on the natural environment, and overtime, this neglect is challenging the sustainability of cities. The paving of roads and culverting of urban rivers means that less and less rain water can be reabsorbed in urban areas. As I mentioned before, this increases flood risks downstream, but also threatens the urban water supply and undermines the foundations of buildings through land subsidence;cities around the world, such as Mexico City, Jakarta, and Beijing, are slowly sinking because paved roads prevent water from recharging urban aquifers.
In many cases, poorly planned urbanization and stormwater management practices create an unnecessary burden of poorer communities which cannot absorb the possible physical and economic impacts of floods. For example, land and construction prices may be cheaper in flood- or land slide-prone areas, leading them to live in these areas. In the case of flooding, not only could they lose their home and belongings, but their safety and livelihood could be at risk.
There are three huge obstacles to urban storm water management. One is that flooding does not recognize municipal boundaries, and upstream activities hugely affect downstream communities. This can make it difficult for cities to coordinate with each other and other levels of government on urban development and storm water management infrastructure and practices. Additionally, this can make financing storm water management investments very difficult at the municipal level. Secondly, even within cities, there is often poor coordination between government agencies. The individual activities of many agencies – including environmental protection, emergency management, solid waste management, transport, urban development, and others – can affect a city’s ability cope with flood risk. There are often unclear and overlapping responsibilities as well as a lack of understanding and information sharing between agencies. Finally, there is a lack of political will to improve a problem which isn’t visible every day. Unless a city has recently experienced significant urban floods, urban storm water management is usually low on a government’s agenda – particularly in countries or cities with short political cycles. Many governments prefer to build infrastructure that is visible to its citizens 365 days a year; urban storm water infrastructure is largely underground and its construction can be problematic for traffic and other daily activities of city residents. Unless there is a large rainfall or river flooding event, the investment in hard urban storm water infrastructure will go unnoticed and unappreciated. Urban storm water management requires coordination, financing, comprehensive planning, and a vision at creating a safe and environmentally-friendly urban environment.
3. How can urban construction affect natural cycling of storm water? How to accomplish harmonious management between people and nature?
The type and speed of urban construction can have a huge effect on the natural cycling of storm water. In the People’s Republic of China (PRC), urban planning has frequently not included sufficient storm water provisions. Many cities have developed quickly, with a tendency to expand outward rather than by increasing density. City development increases impervious pavement and decreases storage areas, resulting in increased runoff in urban areas.
Drainage systems that were designed to meet the needs of the original service areas are unable to carry extra storm water runoff from newly paved areas in the catchment area. The increase of storm water from the newly developed areas in upstream areas overloads the existing pipelines downstream, leaving storm water with no place to go.
As cities expand outward, rivers that used to be in rural or peri-urban areas become urban rivers. With this, the water-carrying and storage capacity of these rivers decreases due to siltation and possibly garbage if the city has poor solid waste management, as well as the encroachment of development, namely buildings, highways, and bridges. High intensity land development changes the surrounding natural terrain and topography, and alters the natural flows of river systems, floodplains, and lakes.
This is one reason that the Sponge City concept that is being pursued in the PRC is so important. The Sponge City pilots will hopefully demonstrate that investment in ecologically-designed storm water management practices should be used in all Chinese cities. Known as “Green Infrastructure” or “Low Impact Development” (LID) in Western countries, the basic principle is to minimize the impacts on natural and ecological systems caused the development and construction of artificial systems, such as drainage channels and pumping stations. LID aims to simulate natural ecological conditions through the storage, infiltration, evaporation, retention, and reduction of surface runoff, thereby increasing groundwater replenishment. LID minimizes runoff and nonpoint source pollution (NPS) caused by rainstorms by using decentralized and small-scale source control mechanisms and appropriate technologies. The objective is to maintain, as much as possible, the pre-development conditions of the natural environment and hydrological cycle.
4. In the field of urban storm water management, are there any cities that have made great progress?Are there any useful experiences that we could learn from?
I recently returned from a trip to the Netherlands and I was very impressed by the Dutch experiences in water management. It is well known that the Netherlands has a long history in managing the relationship that their country has with the sea, reclaiming large areas of land through the use of dikes, levees, and the traditional Dutch windmills. What is less widely known is that the country is essentially a large delta for the rivers Meuse, Rhine, and Scheldt. Additionally, over 80% of the population is urban and the country has a high average yearly rainfall rate, making it very important for Dutch cities to manage storm water and river levels to prevent flooding.
Of the cities with the most aspirational approach to their storm water management is Rotterdam. Located in the delta of the Rhine and Meuse Rivers, Rotterdam has taken a very active and holistic approach to managing their vulnerabilities to not only flooding by also the potential climate change impacts. Under most models, climate change will affect not only the frequency, but also the intensity of rainfall events. The impacts of climate change on local weather patterns are already being felt, but few cities have had the political will and resources to plan for the potential impacts. Since 2013, Rotterdam has had its own climate adaptation strategy which required the identification of local vulnerabilities and created a framework for future resilience planning and investments.
Recognizing that the city’s traditional flood defenses as being inadequate for future risks, the city began to access other ways to collect and channel storm water to prevent localized flooding. The interventions in Rotterdam range from small scale – such as supporting the development and planting of green roofs and rainwater harvesting– to large scale, such as the redesigning of their existing dikes to allow for multipurpose uses.
Innovative projects related to reducing flood risks in Rotterdam, such as the Benthemplein water plaza, have gained global recognition among urban planners. Integrating public recreational space, greenery, and water storage, Benthemplein water plaza was the world’s first large-scale water square. A multi-level space with different seating and activity areas, the plaza becomes a water reservoir during heavy rains. Wide gutters collect rain water and funnel it towards the deeper basins of the park for collection. The basins allow for the rainwater to be reabsorbed into the ground over a 24-hour period; in cases of extreme rain events, the water is drained to a nearby water way, thereby reducing the load on Rotterdam’s sewage system.The park with its substantial greenspaces and public spaces for sports and socializing has revitalized the area around it and become popular with local students and residents.
Overall, I think that Rotterdam serves at an excellent example of storm water management for cities in the PRC, not only for their holistic climate-aware approach to risk, but also for the integration of small scale efforts such as green roofs. Every drop of water that is reabsorbed in the city can have an impact on local and downstream flood prevention.
5. When summer comes, the rain increases. Recently, it rained heavily in several cities in China, even hail in some district. The torrent rain is a challenge to the drainage system.Are there any effective strategies in drainage and flood prevention?
One of the significant problems in the PRC is that most cities have only minor, or pipeline drainage systems. In many countries, stormwater systems are typically comprised of both minor and major systems. The minor systems are designed to discharge less intensive rainstorms with a design return period of two to ten years. The minor systems commonly consist of underground pipes and ditches. On the other hand, major systems are designed for severe rainstorms with a design return period of 50 to 100 years. Major systems commonly include bypass tunnels, greenbelts, and roads which are used to handle the runoff which exceeds the capacity of the minor drainage system. In 2012, the Asian Development Bank supported a study with the Ministry of Housing and Urban Rural Development on urban storm water management in the PRC which identified this as being one of the biggest weaknesses of Chinese cities (http://www.adb.org/projects/45512-001/main) . The study identified a number of good examples in Asia such as Kuala Lumpur, and as well as many Western cities.
In Kuala Lumpur, a “Smart Tunnel” was constructed with multiple uses. The tunnel is a three-level structure of 12m diameter. The lower compartment is used for discharging runoff during normal rainstorms. The middle compartment is used for traffic in ordinary times and will be closed and utilized as a drainage tunnel in rainstorm events with a five-year return period and above. The upper deck and the whole tunnel will be fully closed from traffic in case of extreme rainstorms for discharge of stormwater.
The PRC has since enforced a number of new regulations which will improve and encourage the construction of urban drainage and urban flood-protection facilities, as well as introducing the sponge-city concept.
6. Recently, are there any new materials, devices, or latest technologies which could improve storm water management dramatically?
Some of the most significant technological advances related to storm water management can be seen in the evolution of permeable pavements. Over the past few years, this field has grown significantly. In the past, permeable pavement signified the placement of stones or pavers with gaps between them to allow water to filter through, which works well on a small scale. Now many permeable pavements are more complex, featuring multiple layers which serve to not only absorb water, but also filter and convey it to swales or other nearby waterways, thereby avoiding the overloading of storm drains and sewers. The variety and complexity of permeable pavements vary, giving developers and governments more options to find options within their budget to fit their design requirements. Permeable paving has been shown to reduce run-off, prevent siltation in water bodies, control pollutants, and allow the root systems of urban trees to coexist thrive within paved areas.
7. Finally, do you have any advice to those who are willing to start their career in storm water management? Or anything you would like to say to the Chinese audience?
For anyone interested in starting a career in storm water management, as well as for the Chinese audience, I would encourage them to educate themselves on the concepts of low impact development and nature-based solutions to urban drainage. Climate change will bring more frequent and potential more intense rainfall, which will surpass the rainfall levels that already cripple Asian cities. Even if cities fail to take action, individuals still have the capacity to do their part by engaging is activities such as rainwater harvesting, green roofs, and low-elevation greenbelts. At the end of the day, many individual actions can make a big difference to prevent urban flooding.