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香港亟待改变洪水风险管理方式

菲丝•陈、艾德里安•麦克唐纳和戈登•米切尔指出,如果香港政府无法应对日益加剧的洪灾威胁,香港的经济成功可能会迅速终结。

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7月,一场由台风“灿都”引起的区域性大暴雨横扫了香港,一小时内降雨量高达150毫米,由此引起的洪水造成3死亡,3000余座房屋受损。这样的事情似乎会变得越来越频繁。气候变化让世界许多沿海城市越来越容易受到洪水的袭击,这是海平面上升、更加强烈的台风、风暴潮和迅速城市化的结果。位于南海之滨的香港正是这些城市中的一个。今年夏天的洪水是一个警告,政府必须改变以工程为主导的风险应对方式。

20世纪60年代以来,香港经历了136次严重风暴,每年都有六到七场台风光顾,经常会引发洪水。在过去三十年里,洪水造成380多人死亡,并引起了巨大的财政损失。单单是1992年5月的一场风暴就造成了超过1亿港元(1290万美元)的损失,受害范围包括房屋、鱼塘、农田和电信设施。

在这次受灾之后,香港政府成立了渠务署(DSD),主要目的是监管洪水的应对工作。迄今,渠务署已经投入200多亿港元(26亿美元),改善洪水基础设施,实施技术解决。但是,就如台风灿都所显示的,这种工程主导的方式是不够的。包括英国在内的各国采用“与洪水共存”或者“为水留出空间”等概念的可持续洪水风险处理方式,为缓解洪水、社会经济发展和环境关系的共赢战略提供了新的选择。这些战略可作为香港以及更广大的珠江三角洲地区的有效参考。

香港经常被称为亚洲的世界大都市,是最重要的全球性金融中心之一。2009年,它的人均GDP为43800美元,全世界排名第十五。它还是2008年世界第五大最贵的城市,但这个繁华富裕的城市却面临着日益严重的威胁。根据世界卫生组织灾难流行病学研究中心(CRED)的数据,目前香港有42.4万人口和价值1000亿港元(129亿美元)的财产易受风暴的损害,经济风险水平高居全世界第七位。香港主要是丘陵地貌,这在许多地方限制了城市的发展,规划者们只能通过在洪水易发地区的土地整治来开辟更多的城市空间。700多万人口挤在低洼的沿海地带,就造成了一种紧张状况:尽管香港政府已经意识到这个地区在洪水面前的脆弱性,但它仍然热衷于开发那个最危险的区域,而且减轻洪水威胁的意识依旧非常淡薄。

今年七月人身死亡的悲剧是一个当头棒喝,让香港意识到眼前是一个更具挑战性的未来。按照气候变化的趋势,风暴、海平面上升和强降雨将更加频繁香港气象台 (HKO)报告说,香港的年降雨量从20世纪50年代的2265毫米,增加到90年代的2518毫米。此外,从1900年到2008年,区域性雨暴的周期变短。在这种背景下,尽管香港楼市如火如荼,规划者必须停止在洪水易发地区建房。我们必须接受这个事实:洪水是很难控制的,必须准备好“与洪水共存”,准备好更大的蓄洪空间。

在这一点上英国可以提供非常有用的经验。该国在过去的一个世纪中曾经遭受过若干次严重的洪灾,其洪水管理政策值得借鉴。重要的是,英国的(洪水)战略承认未来的气候变是不可预测的,洪水是自然的一部分,我们再也不能只用硬性的工程方法来控制洪水,必须采取适应方式,赋予社区应对危机的能力。英国在洪水问题上的总体性政策宣言(即25号规划政策宣言,简称为PPS25),提供了更多减轻洪水危害的办法。其中包括了“为水留出空间”的概念,旨在提供更大的蓄洪空间,并限制在高危地区的开发规划。最好的办法就是在建设之前进行规划,因此PPS25保证了评估过程和可持续性评估能把所有开发项目的社会、经济和环境方面都考虑在内。它还通过公众参与,广泛接触所有利益相关者,进一步实施了成本收益评估。

公众参与是进展的关键。英格兰亨伯河口湾的海岸洪水管理计划(CFMP)是一个很好的范例。这个计划欢迎当地社区和NGO加入到项目进展的评估委员会中来。毫无疑问,在决策过程中这个程度的公众参与会增加项目实施的时间,另一方面,它提供了灵活、开放和互动的方式,保证计划在洪水管理上切实吸纳了当地的关切,有助于将对洪水管理过程认识中的偏见最小化。有关部门还能够从这一过程中掌握新的情况和经验,比如可以把居民对当地洪水历史的知识作为其计算模型的补充。

再回到香港。渠务署的核心战略——1996年的《雨水整体排放计划 》(DMP)下进行的大多数工作都是工程主导型的。该计划的项目包括拓宽和取直主要河道,如新界深圳河和锦田河,修建下水道,恢复蓄洪池,以及对城市主要排水渠的水力情况进行监控。

由于只注重用技术解决问题,如今香港已经很难找到一条‘自然溪流’了,因为几乎所有河流都变成了人工渠。这些工程项目常常没有充分考虑可持续性问题,研究已经表明河流治理工作造成了负面的生态影响。比如,随着1997年深水湾区建起洪水工程设施(这里是一片具有高度生态价值的湿地和重要的鸟类栖息地),34.6万平方米的鱼塘面临消失的危险。此外,1990年代的河流治理造成香港32种淡水鱼类中的11种如今已经濒临灭绝。

渠务署在某种程度上已经认识到失误,开始在元朗分洪河道的混凝土水渠上进行生态恢复试验。试验的主要构想就是补偿环境损失,重建湿地栖息地,比如为鸟类、淡水鱼类、青蛙和蜻蜓铺设芦苇垫、修建水塘。这可能会指向一个更加可持续的治洪方式,但进展较缓慢,而且目前也没有其它混凝土水渠的生态恢复项目在开展。

渠务署的信息共享方式也受到关注。从本世纪初开始,渠务署一直在对人口密集地区的强降雨进行洪水风险建模和绘图,并向公众发布有关水浸黑点的信息。但是,总体来说,这些黑点只能涵盖很小一片地区,人们无法获取至关重要的信息。渠务署必须提供更加透明的洪水风险数据,让公众为洪水做好准备。世界其它地方都是这么做的,比如在澳大利亚,洪水绘图通过定点提供了详细的风险数据。

此外,渠务署的注意力主要局限在城市和乡村问题上,但是香港还面临着海岸洪水的危险,比如大澳渔村的洪水海洋和海浪监测由香港气象台负责,而海堤维护和海滩改善则由土木工程拓展署(CEDD)负责。尽管危险在加大,但香港的海岸洪水管理的战略依然模糊和不足,政策依然缺失。这里和香港洪水风险管理的每个层面都需要一种更加协调一致的方式。现在,尤为急需的就是为香港和更广大的珠江三角洲地区制定一个长期、可持续的洪水管理战略。
 

作者简介:菲丝·陈为副研究员,艾德里安•麦克唐纳为教授,戈登•米切尔为高级讲师,三人均供职于利兹大学地理学院。

首页图片来自 Marc Oh!

 

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qimei.q

亡羊补牢

十年前就看香港电视台不断播山泥倾泻危险的广告,播了好多年,可是也只是叫人们遇到洪水时候不要出去,虽说亡羊补牢为时不晚,但总是亡了羊才去补牢,十几年了都不吸取教训在防御措施方面下功夫,等到羊全都丢了就补了也没用了。

Better late than never

Ten years ago I saw a commercial about the dangers of landslides continuously broadcasted on a Hong Kong TV station, and it was shown for many years. But it only told people not to go out when there was flooding. Although we say it's not too late to "fix the pen after a sheep has been lost", but we are always fixing the pen when sheep are lost and it's been ten years and no lessons for defensive measures have been learned. There is no use fixing the pen when all the sheep have been lost.

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faithchan

Reply to the comment

Hi, many thanks for your comment. I am not having any bias to defend with the Drainage Service Department, but somehow we need to give some credits to them. They have done a lot of engineering works on flood protection over two decades from 1989. We are yet to know the flood risk in Hong Kong due to lack of the open flood risk information, such as flood map for the public access. However, I do believe the inland and urban flood risk are largely reduced after many flood mitigation projects have been completed.

However, I would like to emphasis the flood management strategies based on the hard engineering approach has been expired, evidences have been well-proved globally, i.e. 1993 Mississippi flood in the USA.

As you mentioned, we really need a comprehensive, long term and sustainable flood risk management strategy to be prepared for the future, i.e. climate change. It is because we may no longer afford to be flooded in light of the huge economic growth and rapid urbanisation process in the Pearl River Delta. We may need to PLAN for the flood risk before the disaster comes. Otherwise, it will be too little too late.

回复评论

你好,感谢发表评论。我不是偏袒渠务署而为他们辩护,但是我们也应该肯定他们的工作。1989年以来的20多年间,渠务署完成了很多防治洪水的工程。香港人之所以对洪水的危害知之甚少,是因为缺少相关的公共信息,比如洪水分布地图等。但是,我认为防洪工程确实大大减少了内陆和城镇地区的洪水风险。

然而,我也想强调,仅以工程防治洪水的策略已经过时。世界上已有很多先例证明了这一点,比如1993年美国的密西西比河洪水。

如你所说,未来我们确实需要全面、长久、可持续发展的防洪战略,例如(从)气候变化(角度来防治洪水)。珠江三角洲快速的经济发展和城市化进程导致我们已经无法负担洪水带来的危害。我们需要在灾害到来之前做好应对计划,否则就太晚了。

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hotdogluke

文章不错,但太西化

文章不错,但最好换一个角度思考。从别人的角度,政府的角度,中国传统文化的思考。文章把Civil Society的概念,在洪水防范这个题材上表现出来,力图追求一个经济,社会,生态三赢的解决洪水模式。想法不错。但是洪水防范是牵一发动全身的事情。应该多从政府和现实的角度出发,才有实用性。香港地太少人太多,跟英国很难相比。给水留空间就是给人少留空间。有我没你。更关键的是留多少空间才够。当然空间越多越好,但是人住哪里?现在排水渠有的也非常大,花费大量人力物力。这说明政府想解决问题,也可以花钱。排水渠再大,它也有限。而且简单易行,十米不够,二十米,二十米不够,五十米。排水渠占用面积而造成的直接和间接成本,可以简单计算,方便规划。如果采用“给水留空间”的模式,需要非常多的技术支持,如细致的洪水基础数据,可靠的数据模型等。再加上公众参与和讨论,众说纷纭。决策过程长不说,也不一定有一致的最终结论。在一个精英文化流行的香港社会,掌权的精英,政府的精英当然不会容忍上面的情况发生。因为这代表低效率和侮辱精英专家智慧。如何解决上述问题和情况,作者应该多想想。公众参与是否应有一个相对固定的流程,如果最后众说纷纭,如何裁判和得出最终结果。更关键是多考虑本地实际情况和政府考虑。不然作者的文章就象洪水一样,来的时候雷霆万钧,走的时候踪影全无。

Nice article, but too westernized

Such a good article, but it would be better if we adopt the perspective of others, of the government, or of the traditional Chinese culture to ponder over the issue. The article applies the concept of “Civil Society” to flood prevention for the purpose of formulating a flood solution model which brings about a win-win situation for economy, society and ecology. It’s a great idea. Nevertheless, flood prevention is a matter where one move will introduce a chain reaction. Practicality cannot be achieved until a realistic governmental perspective is employed. Hong Kong is hardly comparable to Great Britain due to its huge population over limited land. Leaving more space for the water means less space for people. It’s a neither-you-nor-me situation. And a more important issue is how much space is enough. Definitely more space, the better. Then another problem pops up----where should the people live? At present, some drainage channels are pretty big in size, consuming tremendous manpower and materials. It demonstrates the government’s decisiveness to solve the problem and willingness to spend. Drainage channels are still limited no matter how big they are. But it’s easy and feasible to make adjustments. If ten meters are not enough, twenty meters will do; if twenty meters do not work, then fifty meters. The direct and indirect cost caused by land appropriation for the channels can be easily calculated and is easy to be planned. If the model “More Space for Water” is adopted, a lot of technological support is needed, such as detailed basic statistics of floods, reliable data model etc. Meanwhile, opinions are widely divided because of the participation of the public in the discussion. As a result, the decision process will be time consuming. Besides, a final agreed conclusion might also be up in the air. In Hong Kong, a society where elite culture prevails, elite in power and the government certainly won’t allow the situation mentioned above, happen. Otherwise it will be an indicator for low efficiency and an insult to the wisdom of those elites. The author should ponder more over how to solve these problems and situations mentioned above. Is there any necessity for a comparably stable procedure to regulate the participation of the public? Given that opinions are varied, how to make a judgment so as to achieve the final conclusion? It is more important to give more attention to the local reality and government. Otherwise this article will be like a flood: Come and roar like a thunderbolt while leave and go with nothing left.

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faithchan

Reply to the comment

Firstly, Your comments is so good, but don’t forget this is a very short article mainly aim to voice out the flooding problems in Hong Kong and the Pearl River Delta Region. I have no intention to provide any further options, strategies and ideas. However, that is nice to re-think of your idea. To response of your feedback, it has a few points to reply as follow:

1. The concept of civil society and the importance of planning in flood management practice

Yes, civil society is a big concept to follow, you have to consider the principle of environmental justice as well if we are talking about the long term flood risk management strategy coping with sustainable development.

" As pressure from civil society to address perceived environmental inequalities is growing, it is important to understand the nature and extent of any such inequalities" (Walker et al., 2003).

In fact, your view is correct the land use distribution in Hong Kong is stressed, it thus need a comprehensive planning system including flood management. Limitation on land area is surely a matter, but we are suggesting the government and policy maker not to build on the flood plain which is a feasible option, as it is harder to predict the emerging flood risk. Most of the natural or human induced wetland buffer areas in the new territories have been functioned like this for most of the time, the Planning Department of Hong Kong has followed the Outline Zoning Plan (OZP) and clearly identified the restriction of development on the rural area. We are basically asking the government to keep such this kind of land for the concern of the pressure of drainage system and consideration of the natural services (i.e. birds and biodiversity). To achieve a better life wellbeing, a substantial of green space is essential in the city. Then, to conserve the natural wetland or wetland buffer area in Hong Kong can lead to carry out the win-win strategy for the socio-environmental aspects. That is the reason why the article suggested we may have to think about a comprehensive planning and flood risk appraisal (FRA) system may help us to achieve the sustainable and long term flood management practice with social, ecological and economical considerations by referring the UK case (e.g. Planning Policy Statement 25 in England).

回复上述评论

首先,你的评论很出彩,但别忘了这只是一篇重点突出香港和珠江三角洲防洪问题的短文。我没有意图提供更深一层的选择、策略或见解。然而,依你的意见重新做一轮思考也不错。对你的评论,我有几点想反馈的:

1.市民社会的概念,以及决策对于防洪管理实践的重要性
没错,市民社会是一个大的概念,如果要谈论应对可持续发展的长期洪水风险管理策略,则还要把环境正义原则考虑进来。

“当市民社会强调现存环境不公的压力不断增加时,理解自然和这些不公的程度就显得非常重要”(沃克等,2003)

事实上,你的观点是对的,香港的土地使用问题很紧张,因此需要全面的规划包括洪水管理。有限的土地面积确实是个问题,但我们对政府和政策制定者不要在洪泛区承建的提议是可行的,毕竟要预测洪水危险更加困难。新建自然或人造湿地缓冲区大多都是以此为目的。香港规划部是按照分区计划大纲图规划的,而且清楚鉴明了农村地区的规划限制。我们只是要求政府保持这种地,为缓解下水道系统的压力以及保护自然(即鸟类和生物多样性)。要提高生活指数,扩大城市绿化面积是关键。到其时,保护香港自然湿地或湿地缓冲区可实现社会-环境的双赢。这就是为什么这篇文章建议我们该全面规划,通过学习英国,这不但可以实现可持续发展,还可以建立一个综合考虑社会、生态和经济因素的长线洪水风险评估(FRA)系统。

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hotdogluke

切入点

文章谈到的东西很多,框架很大。如果按照作者的意思开展,这是一个需要联合经济,社会,环境,规划,气象,地质等多学科专家的综合大项目。难度可想而知。涉及这么多东西,一起干,同时干,不现实。切入点的选择很重要。我认为公民参与环节是一个不错的发力点。香港官员从过去英殖民时代到今天都不是民主选举出来的,但每个重要官员的履历表都是光彩非凡,高学历,精英典范(其中也不排除中央政府政治意图对某些人职位的影响)。他们提出的解决洪水方案是经过事前仔细思考的,有理由,有根据的。但为什么民众不一定支持,甚至强烈反对呢?先不去讨论谁对谁错,首先要沟通。通过沟通,双方了解对方想法,才能讨论。公众参与的平台和机制是非常需要的。这平台不光是给政府和民众有一个沟通的渠道,还给各方面的专家学者提供表达他们专家意见的机会。这不是给政府拆台,制造困难,而是使政府的政策想法让民众多一些了解,同时政府也可以知道民众的感受,在专家学者的意见辅导下,一个科学理性的一致结论就比较容易得出来了。

Point of penetration

This is a very long article which talks of many things. If we begin according to the author's meaning, then this is a large-scale, comprehensive project which necessitates joint efforts by many experts in the fields of economics, the environment, planning, meteorology, geology, and so on. You can imagine the degree of difficulty. Because the issue relates to so many different things, it would be unrealistic to attempt to undertake everything together, at the same. Selecting a point of penetration is very important and I believe that mass participation is a good motivational force. Not all Hong Kong ministers, from the period of British colonialism to the present day, have been democratically elected, however every important minister has had an outstanding CV, has been highly educated and has been an elite model (not excluding the impact of the political intention of the central government on some people's positions). They have good grounds for proposing this approach to overcoming floods - it is reasonable and is based upon careful consideration of prior events. But why are people not necessarily supportive, or even in fierce opposition to this method? Let's not talk about who is right and who is wrong, what we need to do first of all is communicate. We can only begin discussions once both parties understand each other's opinion. There is a huge need for a mechanism and platform for mass participation. This platform not only gives governments and the people a means of communication, but also gives academic experts on either side an opportunity to voice their expert opinion. This won't undermining the government or create difficulties, it will make sure that the people better understand the ideas behind government policies whilst also giving the government a better insight into their citizens' experiences. Under the guidance of academic experts, a scientifically rational, unanimous conclusion will be reached with relative ease.

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faithchan

回复上述评论(继续)

2、工程洪水管理和洪水评估系统的限制

另外,世界上大多数都市化城市都遭受着城市洪水的袭击,由于城市排水系统被垃圾或污染物堵塞入孔而影响其功效。这就意味着核心问题不是防洪技术或排水工程,不如加宽排水沟或者增加洪水存储系统,或者提高防汛设施水平,比如安置防洪墙等,诸如类似问题已经在巴西的圣保罗市实践过了。应该看到香港已经在防洪设施上花费了200亿港币,如渠道河、城市排水系统和各种洪水工程方法。我明白香港的一些洪水泛滥地区已经形成了惯性,因此必须依靠艰难的工程学洪水评估方法进行灾情缓解。然而正如我在文章中提到的那样,渠务署已经开始采用可持续的方式,例如在最近的洪水管理实践中应用可持续城市排水系统(SUDs)。

鉴于气候变化,未来的气候趋势难以预测,如海平面上升、地面下陷、高频高强度风暴、冰雹频发等。对于长期洪水管理战略,我们需要寻求一系列改进的方法用于洪水管理实践。通过战略环境评估、生物多样性行动计划、生态系统服务评估等评估系统。

实际上我同意你对于突破点的评述,我们可能需要在洪水风险评价中加强与利益相关者的合作与磋商。这其中当然包括你提到的公众。磋商之后,将评估产生的所有结果转化成临时决议或政策将有助于改善目前的洪水管理措施。

洪水风险评估方法提供了备选、立法指导和政策,因此在评估过程之后,我们可以大范围征集来自社会、经济和生态方面的标准和意见,并积极制定政策,在综合技术开发领域达到可持续洪水风险管理。

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2. Limitation from hard engineering flood protection approach and FRA system

Moreover, most of the urbanised cities in the world are suffering from the urban flooding by the effectiveness and efficiency by their land drainage system, for example, urban drainage system will be affected by the waste or pollution matters for the dust and litters block the inlet of manholes. It then implies the core problems are not due to the techniques of stormwater or drainage engineering, i.e. enlargement of drainage culvert and flood storage system; or the level of flood protection infrastructure e.g. flood wall installation, etc. Such the similar problems has experienced from Sao Paolo in Brazil. It has been noticed that Hong Kong has spent over 20 billion Hong Kong Dollars on flood infrastructure projects, i.e. river channelization, urban drainage and various flood engineering approaches. I understand some flood-plain areas in Hong Kong that have been well developed with properties, then it has to rely on hard engineering FRA approaches for flood mitigation. But as I mention in the article, the Drainage Service Department has started to adapt the sustainable options such as applying Sustainable Urban Drainage System (SUDs) in their latest flood management practice.

In light of climate change, the future climatic regime is difficult to be predicted, i.e. sea-level rise, land subsidence, frequencies and intensities of storm, precipitation rate, etc. For the long term flood management strategy, we need to seek for a variety of adaptation options on flood management practice. Through the appraisal system such as Strategic Environmental Assessment, Biodiversity Action Plan, Ecosystem Services assessment, etc.

Actually, I agree with your comments on penetration point, we may need to enhance the engagement and consultation process for a good communication between stakeholders in the Flood risk Appraisal. That is certainly including the public as you have mentioned. After the consultation process, it will then helpful to transform all outcomes in the flood risk appraisal into the provisional plans and policies on improving the current flood management practice.

The flood risk appraisal approach provides options, legislative guidance and policy outcomes Therefore, We can deliver a wide range of criteria and concerns from social, economical and ecological aspects after the appraisal process coping with the planning policy to achieve sustainable flood risk management in the PRD region.