可持续城市排水系统外文文献翻译2020

可持续城市排水系统外文翻译2020

英文

Policies for sustainable drainage systems in urban contexts within

performance-based planning approaches

Viviana Pappalardo，DanieleLa Rosa

Abstract

In the context of increased urban pluvial flooding risk associated with climate changes and urbanization processes there is a rising demand for a shift from storm-water management approaches that rely on conventional systems, to those aimed at mitigating the eco-hydrological impacts of urban development by the use of Sustainable Urban Drainage Systems (SUDS).

Current planning approaches and policies should effectively deal with environmental challenges, especially when looking at the sustainable storm-water management.

Policies for SUDS can find a fertile ground in performance-based planning which aims at achieving a set of planning objectives without imposing specific binding indications, but allowing for flexible solutions. Starting from the identification of a set of “performance-based criteria”, this paper discusses different approaches concerning the adoption of SUDS in cities by examining various policy tools. Exemplifying cases of these policies application across international cities are reviewed to

evaluate their prevalent performance-based character. The introduced criteria are also used to analyse criticalities, challenges and general implications about the implementation of the different kind of policies in new and existing urban developments. Results suggest that policies cannot be considered purely performance-based but rather have a hybrid character and can be implemented also under mainly conformative planning systems.

Keywords: Urban pluvial flooding risk, Sustainable urban drainage systems, Performance-based planning, Urban policies

Storm-water management through sustainable urban drainage systems and the theory on planning systems

(Urban) Pluvial flooding risk is an intrinsically anthropogenic concept as it is identified in impacts and damages caused on urban areas (communities, environment and economics) and because its unders tanding is strictly related to the individuals’ perception (O’Neill, Brereton, Shahumyan, & Clinch, 2016). The awareness of the unlikelihood of any flood risk being prevented is the base of the recent shift in flood risk management (Schelfaut et al., 2011).

Strategies underpinning a more sustainable storm-water management may include various structural and non-structural measures (Dawson et al., 2011), such as the control of runoff volumes and peaks, the increase of drainage systems capacity, new building regulations (Gourbesville,

2012), and spatial design approaches based on nature-based solutions. In order to minimize the hydrological impacts of urban development on the surrounding environment through water flow regulation, the adoption of Sustainable urban Drainage Systems (SUDS) as components of green infrastructure in urban contexts (Pappalardo, La Rosa, Campisano, & La Greca, 2017) is increasingly being recommended both at the strategic planning level and at the practice stage (Fletcher et al., 2015; Lloyd, Wong, & Chesterfield, 2002). SUDS are indeed considered as nature-based drainage features of the urban green infrastructure, specifically devoted to storm-water management (Fletcher et al., 2015; Jayasooriya & Ng, 2014; Massoudieh et al., 2017).

Unlike conventional and mono-functional engineered measures, SUDS measures could become an additional planning tool for designing more resilient urban systems and reassessing the relationship between the built and not-built components of the urban environment (Lennon, Scott, & O’Neill, 2014). The provision of runoff mitigation against pluvial flooding, as well as the better protection of hydrological dimension of landscape is achieved through infiltration, retention and evapotranspiration (Pappalardo, 2017), which are provided by solutions such as green roofs, permeable pavements, rain gardens, infiltration trenches and constructed wetlands. Accordingly, the capacity of the urban system to manage water flows is enhanced along with the integration of

these nature-based drainage systems, thus strengthening the overall performance of the urban settlement.

Whenever the desirable level of environmental quality does not correspond to the current level, the need for new public policy arises (Field & Field, 2009). The public concern of (urban) pluvial flooding risk is based on the perception of the actual hazard, vulnerability and exposure of an urban area and on the consensus on the future acceptable level of risk and damage, which is sensitive to the uncertainty due to climate change and urbanization processes. Urban design and policy responses are centred on the need to pursue adaptive and/or mitigation options (White, 2010) and should better integrate water and flood management in urban planning. Accordingly, current available planning approaches and policies are required to effectively manage the rapid changes imposed by environmental, climate and socio-economic dynamics, and to drive transformation processes by shaping equitable, healthful, and attractive environments (La Rosa, Takatori, Shimizu, & Privitera, 2018).

Worldwide, planning approaches are based on planning systems and cultures which differ in typologies due to institutional contexts, historical and cultural reasons, legal and administrative systems (Nadin & Stead, 2008; Rivolin, 2008). A broad conceptualization of the planning systems’ nature distinguishes two basic models, “conformative” and “performative” (Baker, Sipe, & Wypych, 2005; Frew, Baker, & Donehue,

2016; Rivolin, 2008).

Planning systems are normally based on the ideal assumption that the implementation of any plan represents the spatial translation of a collective strategy and long term-decisions. If the implementation of the Plan is the result of a set of mandatory decisions, the traditional zoning would display spatial rules according to a “top-down” approach. Under a conformative approach, a project is legitimated to be developed because it conforms with the plan. Under a performative approach a project would pass through the approval stage only after having proved to be capable to perform the agreed collective strategy (Rivolin, 2008). The basic assumption of the performative approach is that the plan is the reference framework for the regulation of land uses, whose implementation depends on the approval of projects conditioned by result-based measurement. Such an approach could be used both at the operational and strategic level in order to attain the desired outcomes and so to perform the agreed collective strategy (Baker et al., 2005; Rivolin, 2008).

The analysis of the two planning approaches is not much investigated in literature and contrasting arguments are given on how to avoid inconsistencies between plans and implemented projects. Some authors consider the static conformative planning as a powerful tool for direct land use control (Frew et al., 2016). Others stress that improved environmental management and protection could be more properly

achieved with the use of standards that set acceptable environmental performance and allow to respond flexibly to the changing conditions of the urban environment (Frew et al., 2016; Ottensmann, 2005; Roughan, 2016). Legitimizing planned spatial developments on the compliance with the plan might avoid inconsistencies between projects and plan’s strategies only in theory. At the same time, allowing the spatial developments that prove to perform plan’s strategies might effectively align project’s outcomes with site-specific goals included in the plan.

Instead, arguments converge on the basic need for planning schemes to adopt indications and benchmarks for post implementation performance evaluation. This point is not solely a feature of performance-based planning systems but of planning more generally (Frew et al., 2016), considering the existing lack of performance evaluation in practice and the acknowledged importance of plans’ outcomes assessment (Kramer, 2014; Laurian et al., 2010).

Performance-Based Planning (PBP) does not denote an approach truly novel whilst the “conformative” one is however more pred ominant worldwide. More widespread in North America, UK and Commonwealth regions of Australia and New Zealand (Frew et al., 2016), PBP is yet increasingly tested across Europe and considered as a possible way to solve the tension between the intent of maximizing flexibility and the desire of local governments for land use control (Frew, 2011; Laurian et

al., 2010).

The key to the consistent and successful consideration of SUDS for all sites undergoing any urban transformation is the inclusion of a sustainable drainage policy within national, regional and local planning (Woods-Ballard et al., 2015). Particularly at the local level and when dealing with specific SUDS projects, the design aspect of SUDS is the crucial point to indirectly encouraging or directly prescribing the use of green infrastructure at the neighbourhood or parcel level.

This study moves from the performance-based planning theory on land use and proposes some possible interpretations into urban policies on sustainable storm-water management.

The aims of this article are threefold: first, to look at the ongoing state of local policy supporting storm-water management and green infrastructure (focusing on SUDS) implementation in urban areas; second, to propose some key criteria to recognize the performance-based character of existing policy tools, referring to some examples implemented according to different contexts and planning systems; third, to identify weaknesses and strengths of policies based on performance-based approaches and to discuss barriers to SUDS’ implementation in urban planning processes.

Policy approaches for SUDS implementation

Any effort to include sustainable storm-water management in urban

planning must be the result of a shared vision that brings people together in determining a common view for the future of the city. This is valid at different levels, from strategic planning to the definition of local development plans and any other regulatory instruments. This principle should guide the plan and its implementation and represents the pillar to which the community will look once the plan is fully implemented (Kramer, 2014).

The quest to the correct approach to manage storm-water and to stimulate the adoption of sustainable urban drainage systems is crucial for the eventual success of any urban plans in the short and long run. Policy efforts should provide site-specific frameworks of strategies for funding, acquiring public land, using existing vacant areas, providing incentives for storm-water discharge reduction, and requiring the achievement of certain level of environmental performance in private realms.

Specifically, this paper focuses on the topic of water quantity issues (e.g. control of storm-water runoff peaks and volumes) only, but considers policy tools that have been widely adopted to generally discourage the contribution to storm-water runoff discharges and to encourage the consideration of green compensation measures into site design.

There are three general philosophies and associated policy-tool-design/planning approaches in response to the problem of

storm-water control in urban areas. The first approach is to ban, the second is to incentivize and the third is to educate. In general, each of these philosophies inherits the so-called “Polluter-Pays Principle”. This principle, with its many translations, has been interpreted differently according to the socio-geographical contexts. It has a pedagogical effect of encouraging individual responsibility for generating pollution, due to the acknowledgement that who acts with the consequence of producing pollution should pay for the damages generated. It may play a valuable normative role in society (Nash, 2000), with two resulting effects on waste reduction and development of more effective technologies.

Traditionally, regulatory instruments have been used to achieve the most common planning objectives (Clinch & O’Neill, 2010). In particular, flood risk management has been dominated by planned adaptation (in contrast to autonomous/individual/spontaneous one) (Filatova, 2014), which is primarily command-and-control in nature.

Traditional “command and control” (CAC) regulations set uniform standards (technology-and performance-based standards) for the sources of runoff (Parikh, Taylor, Hoagland, Thurston, & Shuster, 2005). Basically, this implies the direct regulation of an activity/behaviour by legislation that states what is permitted and what is illegal. The “command” is related to the standards/targets requirement established by an authority that must be complied with. The “control” consists in the

negative sanctions that may results from non-observance.

Although this approach is still common among various environmental policy areas, emerging incentive-based approaches, referred as market-based policy instruments (MBi), are increasingly being implemented in various jurisdictions (Clinch & O’Neill, 2010; Field & Field, 2009) and work as means for individual adaptation (Filatova, 2014). MBIs rely on market mechanisms and economic variables to provide incentives for communities to avoid negative environmental externalities, to expend equal marginal cost of abatement by incorporating externalities of their activities or by accounting for the positive externalities of mitigation-adaptation measures (Filatova, 2014; Parikh et al., 2005). Not only have these tools been investigated increasingly in the last decades from economists and environmental policy researchers, but they also are becoming of great interest and impact for scientists, due to their potential significance for flood control and integrated water management (Shuster and Rhea, 2013).

Economists conclude that market-based regimes are more economically efficient (Nash, 2000), traditionally identifying two macro-categories, which are price-based instruments and quantity-based instruments (Clinch & O’Neill, 2010; Field & Field, 2009; Parikh et al., 2005; Stavins, 2003; Whitten, Coggan, Reeson, & Gorddard, 2007). They are regulations aimed at delivering socially-desired outcomes by

encouraging behaviour change through market signals, rather than through explicit control directives (Filatova, 2014; Stavins, 2003).

While the available policy approaches for controlling an excess storm-water runoff are based on the CAC and MBi, education and outreach programs are increasingly becoming an important –yet not totally alternative- means to affect effectively individual behaviours. Whether education is practised through demonstration projects or by publishing technical design materials, creating outreach materials and offering technical assistance programs can be potentially adjusted and calibrated according to people backgrounds, cultural level and flexibility in understanding (Frey, Kosco, Williams, LaDuca, & Tech, 2015).

Conclusions

Urban development modifies the natural drainage process by replacing natural soil with impervious surfaces, dramatically affecting the regulating services provided by urban ecosystems and increasing risk of pluvial flooding (Goulden, Portman, Carmon, & Alon-Mozes, 2018). Among existing planning systems and approaches, performance-based planning claims a role that is alternative to the traditional conformative planning and that could be more suitable to regulate and drive urban developments and other land use transformations to more sustainable urban environments. Policy instruments work as a hinge between planning systems and practices and to induce change by leveraging on

people behaviour.

This study presents polices to support the implementation of SUDS in urban settlements under the framework of performance-based planning. Although the difficulties in proposing an exhaustive classification of existing cases, the macro-categories presented in this paper can help to build a general policies’ framework of policies for water management.

In particular, a set of interpretation criteria is proposed to recognize the performance-based character of existing policy tools investigated and discuss the planning implications of these criteria with reference to policies’ implementation issues.

Planned transformation of urban settlements –which in principle should be steered, controlled but also participated – may be driven by a combination of command-and-control and market-based instruments, which should work complementary (Filatova, 2014). This requires a proper combination between coercive prescriptions and processes of voluntary adaptation.

Our analysis indicates that policies for SUDS cannot be considered purely performance-based but have a hybrid character and can be designed also under mainly conformative planning systems.

However, performance standards may act as a reference to determine the policy’s success and adapt ongoing policies based on the performances achieved along their life cycles. To ease participation and

acceptability, key stakeholders need to agree on clear, specific, measurable environmental objectives on the performanceobjectives to be achieved.

Policies for storm-water management and urban pluvial flood risk mitigation through green infrastructures and SUDS should consist in the internalization of the costs of externalities abatement, by adjusting the application of a liability principle. The interrelation between the two corollary goals - the externalities reduction and the implementation of effective measures and technologies (Nash, 2000)- explicitly represents the existing connection between performance-based planning and the promotion and implementation of SUDS.

中文

城市可持续排水系统：基于绩效的规划方法

摘要

在与气候变化和城市化进程相关的城市洪水泛滥风险增加的背景下，对从依赖常规系统的雨水管理方法向旨在通过以下方法减轻城市发展的生态水文影响的方法的需求不断增长：可持续城市排水系统（SUDS）的使用。

当前的规划方法和政策应有效应对环境挑战，尤其是在考虑可持续雨水管理时。

SUDS的策略可以在基于绩效的计划中找到沃土，该计划旨在实

现一组计划目标，而无需强加特定的约束说明，但可以提供灵活的解决方案。从确定一组“基于绩效的标准”开始，本文通过研究各种政策工具，讨论了有关在城市采用SUDS的不同方法。审查了这些政策在国际城市中的示例应用，以评估其基于绩效的普遍特征。引入的标准还用于分析在新的和现有的城市发展中实施不同类型的政策的关键性，挑战和一般含义。结果表明，政策不能仅仅考虑基于绩效，而是具有混合特征，并且也可以在主要是符合性的计划体系下实施。

关键词：城市小水灾风险，可持续的城市排水系统，基于绩效的规划，城市政策

通过可持续的城市排水系统进行雨水管理和规划系统理论

（城市）洪水泛滥风险是一个固有的人为概念，因为它被识别为对城市地区（社区，环境和经济）造成的影响和破坏，并且因为其理解与个人的看法密切相关（奥尼尔，布雷顿，沙胡米扬），＆Clinch，2016）。预防洪水风险的可能性的认识是近期洪水风险管理转变的基础（Schelfaut等，2011）。

支持更可持续的雨水管理的策略可能包括各种结构性和非结构性措施（Dawson等，2011），例如控制径流量和高峰，增加排水系统容量，制定新的建筑法规（Gourbesville，2012），以及基于自然解决方案的空间设计方法。为了通过水流量调节将城市发展对周围环境的水文影响最小化，在城市环境中采用可持续城市排水系统（SUDS）作为绿色基础设施的组成部分（Pappalardo，La Rosa，Campisano和La Greca，2017年）越来越多地在战略规划水平和实践阶段被推荐