**Table 3.** Adaptation priority rating of Warsaw's districts.

Moderate priority to take adaptation action concerns the outer districts of Bemowo, Targówek, Bielany, Białoł ˛eka, Wawer, and Wilanów, with low or moderate climatic threat characterized by less frequent or no occurrence of urban heat island and only local risk of flooding. This group comprises both older districts with high share of built-up areas and a high amount of well-designed greenery (Bielany, Bemowo, Targówek), and developing districts which lack accessible green infrastructure but have potential areas for creating it (Białoł ˛eka, Wilanów). The former are inhabited predominantly by an older population, the latter by younger people.

Low priority was also diagnosed in the outer districts of Włochy, Ursynów, Wesoła and Rembertów, where the climatic threat is very low to moderate due to lower urban density and a larger share of open green areas or forests, and share of vulnerable groups among inhabitants is not significant.

For further analysis in the case studies formula, two neighborhoods were chosen from the district of Mokotów (Figure 1):


According to existing planning provisions [75,76], the biggest changes will concern the Pod Skoczni ˛a, where, as a result of the development of residential and service buildings, the green area will be significantly reduced and it will take the form of a linear park with a water system consisting of retention ponds and water canals. In Sadyba, the plan allows for more dense housing and the development of service functions within existing housing units.

#### *4.2. Neighborhood Resilience in Question*

Case studies are located on the upper terrace of the Vistula valley. For both analyzed neighborhoods, we diagnosed hydrological threats, such as flooding caused by an overloaded sewage system during heavy rainfall. Moreover, there is a risk of inundation in Sadyba related to levees breaking in the Vistula valley and groundwater ponding in Pod Skoczni ˛a. Thermal threats mainly concern Sadyba due to its location away from the ventilation corridor, land cover albedo, and urban structures that impede air exchange. Whereas in Pod Skoczni ˛a, there are no thermal hazards because of the location in the ventilation corridor and the large share of biologically active areas. According to the Warsaw Environmental Atlas [73] the function of the ventilation corridor is to be maintained.

The analysis of natural performance showed that both neighborhoods have high natural adaptive potential, which can be used to minimize thermal and hydrological hazards. In Pod Skoczni ˛a, the adaptive potential is aided by mostly flat relief, water table less than 2 m below ground level, predominantly good soil permeability, good quality soil with water retention capacity (peat), and high proportion of biologically active area. Moreover, the existence of a hydrographic system and location within the ventilation corridor can be considered beneficial. Similarly, the natural adaptive potential of Sadyba comprises flat relief, high proportion of green areas with tree dominance, water table less than 2 m below ground level, and very good soil permeability.

As the natural performance analysis indicated, climatic and hydrological disorders occur in Sadyba but not in the undeveloped area of Pod Skoczni ˛a (Figure 2). However, in the case of implementation of planning provisions, the deterioration of the natural performance in terms of climatic and hydrological functioning had been predicted for both areas. Furthermore, the usage of natural adaptive potential of the study areas and technical adaptation solutions in the planning provisions [75,76] had been relatively low and not compulsory.

The possibilities of implementing adaptation tools varied between the newly designed housing estate and the modernized one. While in Sadyba, the possibility to engage its natural adaptive potential had been limited; in Pod Skoczni ˛a it had been neglected. In Sadyba, a large proportion of impervious surfaces implied constrained infiltration capacity. In Pod Skoczni ˛a, the existing planning provisions

allow for development in areas with organic soils (peats) that are crucial for water retention in the context of adaptation to climate change.

**Figure 2.** Changes in hydrological and climatic performance in neighborhoods: (**A**) Change of ventilation conditions, (**B**) Change of air regeneration and heat reduction conditions, (**C**) Change of infiltration conditions, (**D**) Change of surface runoff volume.

Some adaptation tools identified in Table 1 were introduced in the neighborhoods. These tools included biologically active area index, maximum building height, urban structure, and selected technical solutions (green roofs, permeable pavements) for which optional recommendations were made. Moreover, sustainable rainwater managemen<sup>t</sup> has been introduced as a rule in Pod Skoczni ˛a, while it remains only a recommendation for new investments in Sadyba.

#### *4.3. Building Resilient Neighborhoods*

The implementation of the procedure on the strategic level requires identifying focal areas for adaptive interventions and their spatial distribution. In order to properly locate adaptation actions, the ranking of priority among districts was developed. The method presented in the paper differs from the one in The Warsaw Adaptation Plan [68] (strategy of adaptation to climate change), which identifies priority areas based on data related only to threats resulting from climate change. Our approach, however, also considers demographic vulnerability; its importance was pointed out by Meerow and Newell [8], Shokry et al. [9], and Bła˙zejczyk et al. [69] and the potential to implement green infrastructure [70,71]. Consequently, there was a need to integrate strategic information from different municipal documents [68,71]. The results obtained from both rankings slightly differ, having taken into account the additional criteria allowed for more holistic assessment of districts in terms of their needs and their potential to adapt. Considering evaluation of green infrastructure makes it possible to assign higher priority to districts which lack areas for creating new greenery to sufficiently compensate the climatic risk. With a lesser effect, the social vulnerability index also influenced the position of some districts in the ranking, exposing those inhabited by an older population.

The Warsaw Adaptation Plan [68] recommends that adaptation to climate change should be considered during urban planning, particularly in local spatial development plans. Although plans are potentially powerful instruments for building adaptive capacity at the local level, available planning tools in the Polish legal context are deficient. Moreover, it is also a matter of the designer's skills [14] as well as investor and local authorities' awareness [11,27].

In the literature, there are some guidelines and recommendations on how to design with respect to climatic and hydrological processes, but they are dispersed [13], as evidenced by extensive literature (Table 1). The key for selecting the literature for this paper was the e ffectiveness of the planning and design tools in shaping climatic and hydrological conditions proved by empirical studies. Defined tools like land cover height, vegetation vertical structure and size, biologically active area index, surface runo ff volume, and building structure (expressed by local climate zones [37]) impacting terrain roughness were used to design the criteria for the multicriteria analysis. Due to the fact that there are many interdependent tools to build resilience of neighborhoods and that it is desirable to use them simultaneously to obtain the expected e ffect, the multicriteria analysis method was the best to take into account these interdependencies [72].

The multicriteria analysis described in this paper aims to fill the gap of implementing solutions for building urban resilience which exists at the planning and design level. Moreover, it helps to visualize the possible consequences of planning decisions. The results of the analysis were aggregated on the planning unit level which allowed the assessment of the potential impact of specific planning provisions on climatic and hydrological processes in the unit. Conducting such an evaluation enhances the planning process by introducing the issue of adaptation to climate change.

Nevertheless, in the analysis, some limitations occur connected with the availability of data. The choice of criteria depended on the possibility of estimating the value of indicators in the selected analysis scale (planning level). Furthermore, the scope and accuracy of spatial development plans which comprise zoning, a set of urban indicators, and building lines for planning units do not allow the extraction of detailed information about future urban composition and planned vertical structure of vegetation. This required making assumptions about those properties of the site that will shape the climatic and hydrological conditions in the future. Consequently, the method has the potential to be further extended. Introducing the floor area ratio to di fferentiate the impact of various development scenarios (for example, a scenario with maximal building coverage ratio or maximal building height) may allow the selection of an optimal combination of built-up and biologically active areas on the site in compliance with the planning provisions.

Our analysis of spatial development plans shows that constructing adaptive capacity of the neighborhoods was not the priority. The implementation of planning provisions negatively a ffects the conditions of hydrological and climatic functioning. In case of the Pod Skoczni ˛a neighborhood, where permeable land cover prevailed, the possibility for infiltration will decrease because of an increase in soil sealing. In addition, both housing estates may experience an increase in surface runo ff as a result of fragmentation of green areas and change in the vertical structure of vegetation, which shape the amount of runo ff, as demonstrated by Kim and Park [46] and Deutscher et al. [42]. Moreover, failure to maintain the existing tall trees in the housing estates will result in worse conditions for air regeneration, because, as shown by Zölch et al. [40] and Hertel and Schlink [41], areas covered by trees have a higher cooling e ffect than grass surfaces. Therefore, an update of existing planning provisions in the focal areas is suggested.

For Sadyba and Pod Skoczni ˛a, we recommend correction of existing spatial development plans oriented towards the utilization of natural adaptation potential (Figure 3B). In reference to environmental approach recommendations [1,21–26,28], it comprises modifying zoning, increasing the index of the biologically active area, and adjusting technical solutions to the natural conditions. The modification of zoning refers to the units where identified natural potential was ignored and to the units located within the climatic corridor. To sustain its function in the city's natural system, the protection of a 200-m wide strip of open land in the Warsaw Escarpment areas has been proposed. Zoning as green areas has been suggested for all these units [27]. The increase of the index of the biologically active area was motivated by the need to maintain good climatic and hydrological performance in Sadyba and Pod Skoczni ˛a [33]. Technical solutions aimed at stormwater managemen<sup>t</sup> have been suggested in order to reduce runoff. Research-supported guidelines include the application of permeable pavements and combinations of infiltration and bioretention devices [57,58,60].

**Figure 3.** (**A**) Existing planning provisions in case studies, (**B**) Resilience enhancement proposal.

#### **5. Summary and Conclusions**

Redefining cities to build resilience to climate threats in urban neighborhoods should be carefully conducted from the strategic to the local level. While the strategic and technical tools are well developed, the planning and design phase needs to be more considered. The relationship between the strategic and planning levels ought to be strongly established.

Polish law related to spatial planning addresses climate adaptation indirectly, providing some deficient tools to implement adaptation actions. The planning provisions aimed to build resilience to climate threats are rather facultative than obligatory. Analyzed case studies have shown that, despite available instruments, local spatial development plans in Sadyba and Pod Skoczni ˛a were not formulated to build neighborhood resilience to climate change.

The adaptation of urban areas to climate change by spatial planning and urban design should prioritize the engagemen<sup>t</sup> of natural adaptive potential and the adjustment of adopted solutions to natural conditions. If this is not possible, or if the potential has been limited because of existing or planned development, compensation measures should be implemented (i.e., nature-based solutions, see Table 1—technical solutions). However, we argue that, among a set of adaptation tools provided in this paper, the most important one for building neighborhood resilience is properly conducted urban design.

The procedure proposed in this paper could be a useful, simple method within the planning process to build neighborhoods' resilience to climate threats. It is applicable both when planning new investments and when evaluating the natural performance of existing neighborhoods to enhance their resilience. The method utilizes the indicators from literature like land cover height, vegetation vertical structure and size, biologically active area index, building structure, and surface runo ff volume. Still, it has the potential to be further developed considering the local context and tools available. The procedure consists of the following steps:

	- (a) Identification of needs in response to climatic threats, social vulnerability, and possibilities of implementing adaptation solutions based on ecosystem services. At this stage, rankings of assessment could be helpful, as shown in the paper.
	- (b) Selection of the most vulnerable areas, which have limited potential to benefit from ecosystem services engagemen<sup>t</sup> and are threatened by rapid urbanization.
	- (c) Planning and design level
	- (a) Evaluation of the impact of planning provisions on natural performance (climatic and hydrological functioning) using planning tools embedded in the multicriteria analysis presented in this paper.
	- (b) Implementing adaptation solutions with reference to diagnosed needs and possibilities. Available planning and design tools comprise zoning, urban development indicators, urban morphology, and technical solutions.

The application of this procedure in the Sadyba and Pod Skoczni ˛a neighborhoods in Warsaw has shown various possibilities of using natural adaptation potential and tools. In Sadyba, the natural adaptation potential has already been limited by development, so the possibilities of its incorporation were smaller compared to Pod Skoczni ˛a. This implies the need for compensation measures, including nature-based solutions. However, implementation of these usually requires undertaking renewal actions while adjusting to environmental and technical conditions of existing buildings. In Pod Skoczni ˛a, the range of possibilities was much broader, as the mostly undeveloped area allowed incorporation of natural ecosystems, processes, and features to build a resilient neighborhood. Unfortunately for both neighborhoods, local spatial development plans ignored or neglected natural adaptation potential and only a few solutions to increase the neighborhoods' resilience to climate threats were used. This poor planning will trigger the deterioration of the neighborhoods' natural performance; therefore, enhancement of existing planning provisions is highly recommended.

**Author Contributions:** Conceptualization, K.R.; methodology, K.R. and M.P.; formal analysis, M.P.; investigation, K.R. and M.P.; writing—original draft preparation, K.R. and M.P.; writing—review and editing, K.R. and M.P.; visualization, M.P. All authors have read and agreed to the published version of the manuscript.

**Funding:** The research was carried out as part of the cooperation of the City of Warsaw and the science sector. "The APC was funded by WARSAW UNIVERSITY OF TECHNOLOGY".

**Acknowledgments:** We would like to thank Warsaw City Hall for providing access to data related to Warsaw Green Infrastructure.

**Conflicts of Interest:** The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.
