**1. Introduction**

Cities and their inhabitants are particularly vulnerable to threats related to climate change (thermal and hydrological in particular), which have a negative impact on human health, quality of life, and urban infrastructure. Creating resilient cities is a major challenge for city builders [1,2]. It applies not only to new development but also to existing urban structures. Creating resilient neighborhoods should be the result of properly implemented urban planning and design [3]; for this to happen, planning documents should contribute significantly, because they shape the natural performance of planned areas. However, this is problematic in terms of the conceptualization of resilience and its implementation in the urban realm.

Meerow et al. [4] and Masnavi et al. [5] stated that the concept of resilience related to the urban realm is inconsistent and contested, but crucial in order to develop the adaptive capacity of urban socioecological systems. For a resilient city to be understood as a socioecological system, it should consist of physical and social sub-systems. The physical sub-systems encompass the natural and built components of an urban structure. The social sub-system is built by human societies. Since system structure determines overall system behavior, systems should not be managed only for productivity but also for resilience [6].

Masnavi et al. [5] indicated three conceptual approaches of resilience thinking present in literature: (1) resilience as recovery, (2) resilience as compatibility or adaptation capacity, and (3) resilience as

change. There are also two levels of resilience: general and specific. A strategic evaluation of urban resilience focused on general resilience proprieties before considering specific resilience. The authors pointed out the importance of the relationship between urban form and urban resilience. The role of spatial planning in building urban resilience to climate change was demonstrated by Jabareen [7] as one of four drivers in his resilient city planning framework.

Adaptive instruments aimed at building urban resilience to climate change should be implemented systemically and strategically, through planning tools to design and technical solutions. The strategic level focuses on a city's general resilience and corresponds to its ecological and social vulnerability [8,9]. The planning and design level relates to the specific urban physical system resilience. According to Aguiar et al. [10], who compared local adaptation strategies in Europe, spatial planning was considered as one of the priority sectors for adaptation. However, there is a little knowledge of how it is implemented in practice at the planning level [11]. Masnavi et al. [5] highlighted the need for further research on spatial morphology and urban spatial structures as tools to build urban resilience. While opportunities at the strategic and technical levels have already been recognized, there is a gap at the planning and design level [5,11–13]. The reason may be internal constraints related to the legal context, for example, available tools and scope of mandatory regulations, or the level of awareness of local authorities and the awareness and skills of designers [11,14].

Such a problem can be observed in Poland, where, at the strategic level, adaptation plans are developed both at the national level [15] in relation to EU policy [16,17] and at the municipal level. Local adaptation plans to climate change were produced in three separate projects including: the Urban Adaptation Plans (MPA44) [18] and the Adaptcity [19], which resulted in plans for 44 cities with over 100,000 residents and the capital city of Warsaw, and the CLIMCITIES [20], which provide training on climate change issues and developing an urban climate adaptation plan for local authorities in cities with populations from 50,000 to 99,000 residents. This paper discusses only the Adaptcity project in more detail as an exemplification.

However, even though climate change adaptation is well recognized at the strategic level, Polish spatial planning system does not directly address this issue. Instead, it requires the provision of proper living conditions and the maintenance of biological balance. The key instruments (the study of conditions and directions of spatial development at the municipal scale and local spatial development plans) are accompanied by environmental study and strategic environmental impact assessment (EIA). Environmental study and strategic EIA in general refer to the natural performance and very rarely comprehensively consider the issue of climatic threats. Nevertheless, planning documents must compulsorily set the principles of environmental protection to include: (1) a rational use of the earth's surface, (2) ensuring protection of landscape values of the environment and climatic conditions, and (3) comprehensive solutions for urban development problems with particular emphasis on: (a) water managemen<sup>t</sup> and (b) arranging and shaping green areas.

From the climate adaptation perspective, a problem occurs in terms of available tools on the planning level. For instance, even though the biologically active area index is the most important indicator, it lacks su fficient legal clarification and authorization. The index does not reflect the impact of vegetation structure and adopted technical solutions on natural performance. Moreover, stormwater managemen<sup>t</sup> is not mandatory to planning provisions and appears mostly as facultative recommendations.

The implementation of adaptation actions to climate change postulated at the strategic level requires the use of urban planning and design tools, but owing to the flawed spatial planning system in Poland as mentioned above, there is a problem in the integration of activities between strategic and planning levels.

This article is focused on the issue of urban planning and design as tools for building specific urban resilience to climate change with reference to urban form. Due to the problems indicated in the introduction, it aims to fill the gap in the implementation of adaptation measures that exists at the planning and design level. To fill that gap, we propose the procedure of building neighborhood

resilience to climate threats embedded in planning (from the strategic to the local level) and designing while focusing on usage of natural adaptive potential. It will be applicable both when planning new investments and when evaluating the natural condition of existing neighborhoods in order to improve their resilience. The practical implementation of the procedure is described on the example of Warsaw, Poland.

To achieve the objective of the paper, a literature review describing resilience implementation with the use of natural adaptation potential and a set of tools for urban planning and design are presented. Next, at the strategic level, a ranking of districts in terms of priority to take adaptation actions has been enumerated, while at the planning and design level a multicriteria analysis to diagnose the natural functioning of the neighborhoods in their existing and planned states has been elaborated. Then, the results and discussion related to the case studies and literature are provided. The paper concludes with proposal of a procedure to integrate the strategic level with the planning and design level.

#### **2. Literature Review**

#### *2.1. Resilience Implementation*

The first step in dealing with the system is to ge<sup>t</sup> a deep understanding of its structure and behavior [6]. Since cities constitute socioecological systems, the integration of ecology with urban planning and design has been recommended to build urban resilience, particularly to climate change. This way of thinking about urban planning already has a long tradition that fits with existing environmental approaches [1,21–29]. According to McHarg and Steiner [30], the design process should start with a comprehensive ecological inventory focused on natural processes in order to integrate them into planning and design. Ecological factors constitute determinants of the environmental capacity to support human activity and suitability for a particular type of land use. The idea is to use nature as a strategic ally through planning and designing around ecosystems services. To achieve natural and social sub-system compatibility, Pickett et al. [1] indicated understanding and using spatial heterogeneity. Ahern [24] proposed five strategies to build urban resilience capacity: (1) biodiversity, (2) multifunctionality, (3) multiscale networks, (4) modularity, and (5) adaptive design. Nature-based solutions (e.g., green infrastructure) are recommended as best practices in adaptation by the European Commission [31]. Nature could be integrated into built components of urban systems by incorporating its forms and features, natural processes, and entire living systems through planning and design [1,32]. In relation to hydrological and thermal hazards resulting from climate change, two natural processes and their determinants are crucial to build adaptive capacity: hydrological cycle and air circulation. Natural adaptation potential for building adaptive capacity of urban physical sub-systems consists of environmental features of the area such as geology, soils, water, and vegetation. These features enable rainwater managemen<sup>t</sup> based on natural hydrological processes and favorable climatic conditions (in particular, optimal thermal conditions). These properties can be employed to minimize hydrological and climatic hazards. Moreover, entire living systems (ecosystems) like forests or wetlands should be integrated to build natural adaptation potential. A set of the most useful tools for urban planning and design level is presented in the next section.

#### *2.2. Tools for Urban Planning and Design*

There is a wide range of nature-based and technical adaptation solutions to climate change suitable for urban planning and design. First, the proper zoning of the area corresponding to its natural predispositions have to be established [21,25,28]. Next, three types of adaptation tools for urban planning and design should be taken into consideration: (1) urban development indicators, (2) urban structure (morphology), and (3) technical solutions (Table 1). These tools are useful for building resilience to thermal and hydrological threats resulting from climate change; their effectiveness has been supported by numerous published researches (Table 1).


**Table 1.** Tools to build resilience at the planning and design level and its impact on climate threats.

Zoning allows the incorporation of the natural ecosystems into building resilient neighborhoods and cities as well as using the natural properties of the areas to create suitable functions of the development. The effectiveness of this ecological approach to urban planning and design has been supported by the Woodlands Neighborhood, designed by McHarg [27].

The urban development indicators support the zoning tool in terms of fitting the development intensity to natural conditions in order to manage natural processes and to provide well-being. The most significant indicators used to shape climatic conditions of the urbanized areas are the biologically active area index (BAAI), the surface runoff indicator, and the maximum building height. According to Szulczewska et al. [33], there is a threshold of 45% of the biologically active area's share to enable proper natural performance in the neighborhoods, especially to provide sustainable stormwater management. The BAAI and surface runoff indicator could be integrated into one indicator as it is implemented in Berlin (Biotope Area Factor), Malmö (Green Space Factor), and Seattle (Seattle Green Factor). Scott et al. [32] stated that one of the methods of adapting cities to future high temperatures is to increase the presence of green spaces. Gill et al. [34] indicated the effectiveness of the increase of BAAI by 10% in his case study of Manchester. The maximum building height in relation to the separation width between buildings shapes the areas' roughness and air circulation conditions in terms of wind flow, velocity, turbulences, and dispersion. The following intervals of building height as obstacles for air circulation can be established: 3–10, 10–15, 15–25, above 25 m [37,67].

Urban morphology is a matter of urban design, which is a crucial tool to incorporate natural adaptive potential into urban composition, and to design natural processes, and adjust them to local environmental performance. The building and vegetation structure and layout, as well as green areas' layout and size, should be considered, in particular, to provide proper climatic conditions. The relationships between both are also important. Stewart and Oke [37] and Krautheim et al. [38] pointed out the width/height ratio (the distance between buildings in relation to their height) as the most useful indicator for climatic conditions in urbanized areas. The best air circulation conditions are in areas where the width/height ratio is above 2.4, between 1.4 and 2.4 air circulation conditions are limited, while below 1.4 they are strongly limited.

Vegetation structure modifies not only the roughness, but also evapotranspiration, which is a key process resulting in cooling surface temperature. This is the reason why vegetation structure plays a significant role as a resilience building tool for both thermal and hydrological threats. The areas covered by trees have higher evapotranspiration than grass surfaces and, consequently, a higher cooling e ffect [40,41]. However, since the coverage of trees has higher roughness and limits horizontal air circulation, while improving convection as a thermally contrasting patch, it is more appropriate to introduce it among intensely urbanized areas rather than in ventilation corridors.

In contrast, it is di fficult to give precise specifications as to how many, how big, and where the green areas should be established, because there are too many variables determining climatic conditions in cities [29]. Therefore, the configuration should always be considered for each case, using existing natural forces, processes, and features. Nevertheless, some data have been provided. According to Asgarian et al. [43], composition, configuration, and structure of green space patches considerably affect the nearest urban land surface temperature of built areas. They pointed out that the patches should be homogeneously dispersed, stating that the bu ffer zone of lower surface temperature reaches up to 200 m. Stewart and Oke [37] indicated the existence of the thermal transitions zones between thermally contrasting local climate zones like green and built-up areas of 200–500 m, depending on surface roughness, building geometry, and atmospheric stability conditions.

The size of green patches is also important: the greater the size, the higher the reduction of surface temperature [43]. Nonetheless, Kensington Garden (100 ha) has the relatively small bu ffer zone of a width of 400 m. Thus, networks of small (2–3 ha) green spaces were recommended by Doick et al. [44] for e ffective cooling of urban environments. Also, Hough [29] stated that a fine net of small green areas, distributed homogenously, is more e ffective than a few large spaces. Apart from size, the crucial features of each green cover patch are: (1) the perimeter-to-area ratio must be minimal—the optimal patches are compact, circular, and rectangular shapes, as well as (2) the core area index—areas with more irregular shapes, which contain more core area, are better than simple, linear shapes [43].

Green areas are also crucial to provide proper hydrological functioning and can be used in stormwater managemen<sup>t</sup> to reduce the risk of flooding in urban areas dominated by impervious surfaces. Generally, green areas minimize runo ff volume; however, the e ffectiveness of the process greatly depends on vegetation structure as well as the layout and size of a patch. Deutscher et al. [42] has shown that areas covered with trees can intercept up to five times as much water as lawns and produce half as much runo ff. Kim and Park [46] indicated that larger and less-fragmented patterns are more likely to decrease peak runo ff. Additionally, the e ffect is amplified by vegetation abundance, especially trees or shrubs, as they increase the storage capacity of an area during flooding.

Finally, technical solutions are to be considered. For adaptation to thermal threats, the modification of the albedo is the point. It could be achieved by technical (cool roofs, facades, or pavements) or nature-based solutions (green roofs, facades, infiltration and bioretention basins and trenches, swales, detention and retention ponds, constructed wetlands, etc.). Adaptation to hydrological threats concerns mostly the sustainable storm water management. Nature-based solutions have a positive impact for both hydrological and thermal threats due to the evapotranspiration process.

#### **3. Materials and Methods**

This study consisted of two stages to comply with the aim of the paper, which was the integration of adaptation activities between strategic and planning and design levels. The first stage presents the

strategic level of the planning process, and its research area encompasses the city of Warsaw within its administrative borders. The second stage corresponds to the local level of planning and design, and it was conducted on two neighborhoods (existing and planned one) chosen from a district with the most urgen<sup>t</sup> adaptation needs based on the results from the first stage.

#### *3.1. Strategic Level*

The first stage of the study involved exploring adaptation needs of Warsaw's districts in context of their potential to implement nature-based solutions. In order to indicate the priority areas for implementing adaptation actions, a ranking of districts was developed. These areas include districts with climatic and demographic risks as well as limited potential for creating green infrastructure. To assess climatic risk, nine indicators were used according to the Warsaw Adaptation Plan [68]: (1) Flood risk in the Vistula valley (Flood), (2) Risk of local flooding after heavy rainfall (Local Flooding), (3) Urban Heat Island, (4) Number of hot nights with minimal temperature above 18 degrees (Hot Nights), (5) Impervious surface coverage (Impervious Surface), (6) Urban Density, (7) Share of built-up areas (Built-up Areas), (8) Estimated increase in residential units (Projected Development), (9) Green areas and forests share (Green Areas).

Demographic vulnerability was estimated based on age structure of inhabitants in districts (percent of the population considered to be vulnerable including people under 4 and over 65 years old) [69]. The potential of green infrastructure was evaluated by eight indicators determining quantitative and spatial potential [70,71]: (1) Share of green infrastructure area in district area (GI Area), (2) Green infrastructure area per inhabitant in district (GI per Inhabitant), (3) Share of recreational green areas in district area (Recreational GI), (4) Share of recreational green areas per inhabitant in district (Recreational GI per Inhabitant), (5) Share of housing areas with recreational green areas within a 500-m distance in district area (Housing with Recreational GI within 500 m), (6) Share of housing areas with recreational green areas above a 500-m distance in district area (Housing with Recreational GI above 500 m), (7) Length of planned bike lanes per 1000 ha of housing area (Planned Bike Lanes Density), (8) Share of potential areas for creating green infrastructure in district area (Potential areas for GI).

The indicators were assessed on a point scale, where those increasing climatic risk scored negative points, while those decreasing the risk gained positive points. Each criterion was scored separately to create three sub-rankings; here, districts were assigned to five classes to facilitate comparison of the results. Final summarized ratings of all three criteria determined the priority of taking adaptation actions in the districts. For further analysis, within the district with the highest adaptation priority, two neighborhoods (one existing and one planned) were chosen based on development plans, exposure to climatic risk and similar natural conditions.

#### *3.2. Local Planning and Design Level*

The second stage of the study included determination of natural adaptation potential and an analysis of the existing urban layout and planning provisions of the chosen neighborhoods. We proposed to identify current and future conditions for ventilation, air regeneration and cooling, infiltration, and surface runo ff using multicriteria analysis in which criteria were inspired by planning tools (Table 1) derived from literature review presented in Section 2. The method consists of the following steps:


3. Calculation of factor's values for planning units (units from local spatial development plans) using weighted arithmetic mean (WAM) as in Equation (1):

$$\%AMM = \frac{\mathbb{C}\_1 \times A\_1 + \mathbb{C}\_2 \times A\_2 + \dots + \mathbb{C}\_i \times A\_i}{A\_1 + A\_2 + \dots + A\_i} \tag{1}$$

where Ci for *i* = 1, 2, ... *n* is the class value assigned separately for each factor in the expert method and A*i* for *i* = 1, 2, ... *n* is the area of class *i* in the planning unit.


$$\mathcal{WGM} = K\_1^{w\_1} \times K\_2^{w\_2} \times \cdots \times K\_l^{w\_l} \tag{2}$$

where *Ki* f *i* = 1, 2, ... *n* o r is the factor rating (WAM) in the planning unit and *wi* for *i* = 1, 2, ... *n* - the factor weight. This function allows to model synergistic interaction between factors [72]. The step results in average conditions for: ventilation, air regeneration and cooling, infiltration, and average surface runo ff in each planning unit.

Next, obtained values (WGM) were classified into four classes of climatic and hydrological conditions (very good, good, moderate, bad). To assess the impact of planned development on hydrological and climatic conditions, the classes in existing and planned state were compared. As a result, three types of changes were distinguished: improvement, no change, deterioration. Criteria values for the existing state were calculated based on data derived from the Warsaw Environmental Atlas [73], topographic objects database (BDOT10k), aerial imagery (orthophoto), and on-site visits.

Criteria values for the planned state were estimated according to urban indicators from planning provisions and included biologically active area index, maximum building height, and percentage of impermeable built-up area. All calculations referred to the planning units specific to local spatial development plans.

The analysis determined natural performance of case studies as well as their sensitivity to hydrological and thermal hazards. In a further step, the degree of usage of the natural potential in adaptation to climate change was assessed.



#### *Land* **2020**, *9*, 387

#### **4. Results and Discussion–The City of Warsaw Case Study**

#### *4.1. Priority of Adaptation to Climate Change in Warsaw*

Warsaw will be negatively affected by climate change, in particular the increase in number and intensity of hot days [74] and frequency of precipitation that causes local flooding [68]. The ranking of the adaptation priority shows differences among districts.

Very-high priority was identified in Wola, Praga Południe, Mokotów, and Zoliborz, while high ˙ priority in Ursus, Ochota, Sr ´ ódmie´scie, Praga Północ (Figure 1, Table 3). These are densely built-up inner parts of the city populated by a vulnerable group of inhabitants, mostly in old age. Climatic threat in those districts comprises urban heat island, high risk of flooding in the event of levee failure in the Vistula valley, and/or inundation due to an overloaded sewage system during heavy rainfall. Simultaneously, the existing amount of greenery and potential areas for creating new green infrastructure is insufficient to compensate the risks.

**Figure 1.** Adaptation priority of Warsaw's districts.

