Accessibility of green infrastructure at the city scale on the example of Łomża and Siedlce
Online veröffentlicht: 27. Juli 2024
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DOI: https://doi.org/10.2478/oszn-2024-0001
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© 2024 Anna Romańczak et al., published by Sciendo
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.
The approach to climate change adaptation of many Polish cities is based on the concept of adaptation measures related to the introduction of various green infrastructure (GI)
Green infrastructure (GI) is a strategically planned network of natural and semi-natural areas with other environmental features designed and managed to deliver a wide range of ecosystem services such as water purification, air quality, space for recreation, and climate mitigation and adaptation (European Commission)
The chosen method of monitoring the effectiveness of the implementation of adaptation policies related to GI conditions and the assessment of adaptation due to the adopted criteria for evaluating the adaptation process, directly affect the success of building community resilience to the impact of climate change [Kabisch et al. 2016; van Minnen et al. 2018]. Use of social and environmental indicators can be one way to assess climate change adaptation related to GI [Dąbrowska-Milewska 2010; Gelan 2021; Martins 2022; Rzeńca et al. 2021; Talen, Anselin 1998]. In order to test this approach, a case study analysis in two cities in Poland was conducted to assess the accessibility of public GI with recreational and leisure value for the residents [Biernacka et al. 2020; Biernacka 2020]. Research focused on analyses of the accessibility of GI in residential areas as a measure for evaluating local adaptation to climate change.
The selection of Siedlce as the first place for this study resulted from previous experience of cooperation with the city authorities on the city’s climate change adaptation plan and the high level of involvement and awareness of the local government authorities regarding the importance of blue–green infrastructure. The second city - Łomża, was selected using a quantitative evaluation method based on assigning values from 1 to 9 to the features of the cities in the indicated categories, depending on their degree of similarity to the city of Siedlce, awarding the highest value with the greatest correspondence of features (Figure 1).
Figure 1.
The selection of cities for the case study of the climate change adaptation assessment method
Source: own elaboration based on LDB (Local Data Bank)
One of the directions of the development policies of the selected cities is to improve the safety of the residents and increase their protection against the negative effects of climate change through the use of blue-green infrastructure, i.e., increasing and developing urban green spaces, revitalising urban parks, and strengthening ecosystem services. The GI actions included in the urban adaptation plans aim to increase the city’s resilience to heat waves and Urban Heat Island phenomenon, and also to reduce flooding and drought phenomena [Miejski Plan…2022; Strategia adaptacji…2020]. In both cities, prepared plans adopt a relatively consistent approach to assessing the development of GI through indicators for monitoring the results of the implementation of the urban climate change adaptation policy (Table 2).
Characteristics of selected cities: Łomża and Siedlce in 2021
| Surface area [km2] | 32.71 | 32.00 |
| Population | 62 019 | 77 354 |
| Population density [person/km2] | 1 898 | 2428 |
| Contribution of municipal green [%] | 1.18 | 1.20 |
Source: own elaboration based on LDB
Monitoring indicators for the development of GI in the city of Łomża and Siedlce
| Share of parks, greens, and neighbourhood green areas in total area [%] | No | Yes | Increase |
| Area of parks [ha] | Yes | No | Increase |
| Number of green and blue infrastructure facilities [units] | Yes | No | Increase |
| Number of tree plantings in urban areas [units] | Yes | Yes | Increase |
| Surface area of new built water management elements in the blue and green infrastructure system [m2] | No | Yes | Increase |
Source: based on the Strategy for Adaptation to Climate Change of the City of Siedlce until 2025 with an Outlook until 2030 and the Municipal Climate Change Adaptation Plan for the City of Łomża until 2030
The study of the accessibility of public GI with recreational and leisure value used the indicator method applied in the analysis of the accessibility of GI in German cities [Grunewald et al. 2017] but introducing minor changes to the assumptions to adapt this method to local conditions of Polish cities and the available necessary spatial data. The indicators of accessibility of GI in the cities of Łomża and Siedlce were determined in two variants, i.e., according to the original method and a modified approach called the author’s approach. The measures of green area size and distance to residential areas adopted in the analyses refer to an idea of a 15-minute city [Moreno et al. 2021]. This concept is to plan the urban space in such a way that all residents have access to their basic needs within close range, i.e., a 15-minute walk, including those related to close contact with nature, which is essential for people’s health.
There were three indicators used to assess the urban space in terms of accessibility and abundance of GI (Table 3). The main measure is the M-index, which shows the proportion of the population in the city living within the designated walking distance zone from selected GI sites. There are two additional indicators S1 and S2 complementing the assessment. The first parameter S1, refers to the size of the GI area located within the assumed zone of walking distance from the place of residence. It indicates the extent to which the population is provided with GI within close walking distance and the intensity of the potential use of green spaces by local residents. Indicator S2, on the other hand, is defined as the area of total green space per inhabitant on a city-wide scale. A combined analysis of these three indicators makes it possible to determine the scale of accessibility of GI facilities of a recreational and leisure nature to the residents of Łomża and Siedlce.
Indicators for assessing the accessibility of GI
| Indicator M | Share of the population living in the designated walking distance zone from GI facilities in the total population of the city [%] | |
| Indicator S1 | GI areas per inhabitant in designated zone [m2/inhabitant] | 300 m from residential areas |
| Indicator S2 | Total area of GI in comparison to the population of the city [m2/inhabitant] | Not applicable |
Note:
by original method;
adopted by author’s approach
The assessment of the accessibility of GI includes the areas of GI accessible to all (public), located in the vicinity of the place of living, i.e., within walking distance for an average inhabitant (regardless age or sex). Indicators were calculated according to the original method (only for GI sites > 1ha) and the author’s method covering all GI (regardless of area). The inclusion of the smallest GI sites (<1ha) in the analyses was due to their significant number and high spatial dispersion in the surveyed cities. The exclusion of the smallest GIs from the analyses would have significantly affected the overall assessment of GI accessibility. Evaluation of the accessibility of GI in two variants would include the role of small green spaces in the creation of liveable urban space to be determined.
Different ranges of buffers were assumed in the spatial analyses of access to green spaces depending on the size of the GI and the type of indicator (Table 3). The distance assumed in the calculation of the M index is determined in a straight line from the GI to the residential areas. It is 300 metres for a site of less than 10 hectares and 700 metres in relation to larger sites, which are equivalent to a walking distance of 500 and 1000 metres, after taking into account different potential obstacles (e.g. pedestrian crossings, intersections, and winding streets). These measures correspond to walking the designated distance at the average pace of a 10–15 minute and 20-minute walk, respectively. The distance of 100 metres adopted by the author’s version of the analysis, reflects a direct 5-minute walk to the GI sites of less than one hectare.
In order to determine the S1 indicator, a single buffer of 300 metres is assumed from residential to green areas. The difference in the approach to determining S1 index (from original methodology) is in the inclusion, taking into account the population size and its location. According to the original method using generalised residential, large-scale zones, this indicator was calculated relative to the total population. In the study of Łomża and Siedlce, conducted according to the author’s method, the general residential zone was replaced by single buildings with a precisely assigned number of inhabitants. This made it possible to include in the calculation of the S1 index only the residents from particular buildings within the 300-metres buffer zone in contact with any GI.
There were two main spatial datasets used in the analyses related to the accessibility of GI, i.e., data on urban GI and urban population. The dataset on urban GI resources was gathered using a basis of information from urban planning documents, i.e., the Studies on the Spatial Development Conditions and Directions, detailed maps of spatial development conditions concerning the different types of natural environment, and information on the state of the greenery. This was the basic source for the identification of the areas that were considered as green and blue infrastructure elements, as maintained by the local government administration [Bożętka 2008]. This dataset, after a thorough review based on the Google Maps - Street View service
Spatial data on population required the creation of a population density model in order to obtain the most accurate description of population distribution in Łomża and Siedlce. In the original methodology for German cities, the area of aggregated and generalised residential zones covered by the buffer was the start for weighing the number of inhabitants assigned to a 100x100 metre grid map from the adopted population density model
Federal Statistical Office (Statistische Bundesamt – Destatis)
Figure 2.
Example distribution of the population of Łomża (city centre area)
Figure 3.
Example of population distribution in Siedlce (central part of the city)
All elements of GI with environmental and landscape values suitable for rest or recreation of the community cover 91.6% of the total GI in Łomża (689.05 ha) and 84.9% in Siedlce (453.58 ha). This represents 21.1% and 14.24% of the city’s area, respectively. The system of GI in the urban public space is mostly made up of urban greenery, forests, natural areas, sports and recreation areas, cemeteries, and allotment gardens (Figure 4). Among all types of GI, forests (56% in Łomża and 43% in Siedlce) and urban greenery dominate in terms of numbers (separate places), while natural areas (nearly 76% in Łomża) and forests (37% in Siedlce) dominate in terms of area. Almost all categories of GI were included in the accessibility survey with the exception of allotment gardens, which was omitted due the general population of the city’s limited access to them (Figures 5 and 6).
Figure 4.
Share of different types of public GI in Łomża and Siedlce by surface and number of sites
Figure 5.
GI in the public space of Łomża
Figure 6.
GI in the public space of Siedlce
Small sites (less than 1 ha) predominate numerically in the GI system, reaching over 50% of all GIs in the surveyed cities, and even up to 60% in Łomża (Figure 7). The largest green area (over 10 ha in size) accounts for slightly more than 5% of sites in Łomża and almost 18% in Siedlce among urban GI facilities.
Figure 7.
Number of GI facilities in Łomża and Siedlce in designated area size ranges
Expressing the share of people living in the designated zone of close access to GIs, depending on the adopted assumptions, the M index reached a value of 90.57% in Łomża and 72.29% in Siedlce in the variant including all publicly available GI, and 89.95% and 69.54%, respectively, in the variant excluding small GI (Table 4). The study considers some variation in the group of facilities in each GI category depending on the assessment option. This approach provided an opportunity to assess the importance of the smallest GI sites in making the city resilient to climate change risks. The consideration of all publicly available GI in the analyses improved the M indicator by 0.62% in Łomża and 2.75% in Siedlce. The increase in the value of the M indicator translates into a higher number of people able to use the GI areas located within walking distance on a daily basis, i.e., by 385 people in Łomża and 2473 people in Siedlce.
GI accessibility indicator for Łomża and Siedlce
| 89.95 | 69.54 | 27.21 | 94.73 | 107.55 | 58.57 | |
| 90.57 | 72.29 | 29.04 | 67.81 | 111.10 | 59.68 | |
Spatial analyses of the M indicator made it possible to distinguish within Łomża and Siedlce residential areas with walking access to recreational GI sites and to identify those suffering from a deficit in GI (Figures 8–11). Outside the range of the M indicator buffer are the parts of the city deprived of green areas, which means a probable worse standard of living and consequently, a negative impact on the health of the inhabitants. These are areas with a higher risk in situations of extreme thermal and precipitation occurrences compared to areas rich in GI. Longer walking distance to green areas can be an obstacle for residents to freely enjoy leisure activities in contact with nature, especially for the disabled, elderly, and children (climate main sensitive groups). The spatial picture of accessibility of GI at the city scale, can serve in the planning of urban investments related to blue-green infrastructure, as a material to support the identification of residential areas. These GI-less city parts should be considered as sites for future green space-enriching interventions for social reasons, arising from the need to ensure equitable access to green spaces for most of the city residents.
Figure 8.
Range of the M indicator buffer in Łomża calculated in relation to public GI sites of ≥ 1 hectare
Figure 9.
Range of the M indicator buffer in Łomża calculated in relation to all public GI sites
Figure 10.
Range of the M indicator buffer in Siedlce calculated in relation to public GI sites of ≥ 1 hectare
Figure 11.
Range of the M indicator buffer in Siedlce calculated in relation to all public GI sites
The analyses of the accessibility of GI in the city are complemented by the S1 indicator, which determines the level of provision of GI to the population within close walking distance. The use of this parameter in the study supports the interpretation of the urban structure of the city in terms of the composition of residential areas with green areas. The results of the analyses are presented in Figures 12–15.
Figure 12.
Range of the S1 indicator buffer in Łomża calculated in relation to the place of residence. Includes elements of public GI of ≥ 1 hectare
Figure 13.
Range of the S1 indicator buffer in Łomża calculated in relation to the place of residence. Includes all public GI sites
Figure 14.
Range of the S1 indicator buffer in Siedlce calculated in relation to the place of residence. Includes elements of public GI of ≥ 1 hectare
Figure 15.
Range of the S1 indicator buffer in Siedlce calculated in relation to the place of residence. Includes all public GI sites
The S1 indicator, describes the area of green space per inhabitant within 300 metres calculated from the residences. It resulted in 29.04 m2 in Łomża and 67.81 m2 in Siedlce per resident for the variant including all public GI sites (Table 4). In the variant excluding GI areas less than 1 hectare, it reaches 27.21 m2 in Łomża and 94.73 m2 in Siedlce. The large discrepancies in the value of the S1 indicator between the two variants of the analysis are mainly due to the significant difference in the spatial distribution of the population with access to these areas and to the different spatial distribution of green areas in relation to the places of residence, depending on the assumptions adopted. The significant increase in the value of indicator S1 in Siedlce in variant two is mainly associated with a significant decrease by as much as 18% in the size of the city’s population between the variants under consideration, with a simultaneous decrease of 9.7% in the area of GI taken into account in the calculation of the indicator (Figure 16).
Figure 16.
Differences in the value of indicators between the two analysis variants [%] (author’s approach versus original)
The S1 indicator provides additional information on the potential load on green areas in close proximity to the building (300 m) resulting from their use by residents. Interpretation of this indicator can therefore provide an indication of the need to maintain at current levels or increase the area of green spaces closer to the residential zones in order to improve their recreational and leisure functions. In relation to the analysed cities, the twice lower value of indicator S1 in Łomża, compared to Siedlce, may indicate a much higher possible use of GI sites in this city. A second conclusion arising from the analysis is the potential need for an increase in the area of green areas in the immediate vicinity of residences in Łomża in the situation of maintaining the current population configuration in this city. In Siedlce, on the other hand, despite the significant value of the S1 indicator, the privilege of close access to green areas can be enjoyed by approximately only half of inhabitants. Increasing the dispersion of GI sites of various sizes in this city, including the smallest ones, may instead improve their accessibility to green areas in close proximity to residence for a greater number of the city’s inhabitants, as defined by the M indicator.
Additional information was obtained as a result of S1 index processing compared to the original method. It was possible to describe the structure of access to a number of different categories of GI facilities located within 300 meters of a building by their inhabitants. It could be called a multi-access to GI (Figure 17 and Figure 18). This is a measure that expresses the scope of residents’ access in their close surroundings, to a different number of GI facilities and categories. Multiple areas of access to GI shows the extent to which a city is rich with GI. Access to a greater number of green areas in close proximity creates a very favourable living environment, so it can be taken as another measure for assessing equality in access to ecosystem services in a city, determining the chance of residents choosing GI (CGIC
CGIC means chance of residents choosing GI
Figure 17.
Structure of accessibility of Łomża residents to different categories of GI (all sites of GI) within a distance of 300 m [%]
Figure 18.
Structure of accessibility of Siedlce residents to different categories of GI sites (includes all sites of GI) within a distance of 300 m [%]
Access to green areas in close proximity to the place of residence in the surveyed cities is provided to a large extent by an area of urban greenery (Figure 19). The majority of residents (nearly 90% in Łomża and over 60% in Siedlce) have access to this category of GI. Moreover, in the structure of accessibility of GI of different categories, forests and natural areas stand out in this respect in Siedlce.
Figure 18.
Residents of Lomża and Siedlce with access to different categories of GI (includes all GI)
The next indicator S2 (supplementary indicator) characterises the degree to which the city’s population is provided with green space on a general, city-wide scale. This overall indicator covers the total area of GI (as in the M indicator) related to the city’s population regardless of the locations of both actors. Comparing the M indicator values obtained in the studied cities, it is stated that this indicator is almost twice as high in Łomża as in Siedlce (Table 4). In Łomża there is an average of 107.55 m2 and 111.10 m2 per inhabitant depending on the analysed variant (GI only ≥ 1 hectare of green area and all public GI, respectively). In Siedlce, on the other hand, the area of green areas per inhabitant is approximately 60 m2 (the difference between the variants is up to 2%).
The significant role of GI in enhancing the resilience of the city to climate change, linked to its multifunctionality, is identified in many policy documents on local climate change adaptation. The development of GI planned in the face of climate change risks, such as heat stress, heavy rainfall or urban water scarcity, is identified as one of the main adaptation measures. GI is also recognised as a pathway for sustainable economic development and improved quality of life for people, with environmental, social and economic benefits resulting from its introduction into space. The critical factors for the functionality of GI are spatial distribution of green spaces and their accessibility to residents. Therefore, the research focused on analysing the accessibility of GI in residential areas as an indicator of quality of life, which could potentially also be considered as one of the indicators for assessing local adaptation to climate change.
The indicators used in the analyses of the accessibility of GI to the city’s residents capture the social aspects of ecosystem services and taken together they can help to assess matters of social justice in local climate change adaptation associated with GI solutions. The primary indicator, the M indicator (general availability of green space) shows the share of the city’s population that has access to green space within walking distance. This is complemented by two additional indicators. Indicator S1, which indicates the level of the green space provision and their burden in zones of close accessibility to residential areas, and S2 indicator, which is used to assess the accessibility of green space at the whole city scale. Together, they allow for a comprehensive characterisation of the city’s current or planned spatial structure in terms of accessibility and abundance of urban space concerning the GI perspective.
The assessment of spatial differentiation in the accessibility of GI for residents in the close vicinity of residential areas (within a 15-minute walk and direct access within 5 minutes) was examined in two case studies. The results indicated problem areas in Łomża and Siedlce that would require action to build GI resources to increase access to public GI and improve local climatic conditions in the places of residence. Insufficient spatial distribution of green areas to meet the nature-related needs of residents may cause social exclusion or lead to discrimination due to unequal access to nature. The central location of green areas in the city, but also access to scattered and small natural areas, can make these areas vulnerable to over-intensive recreational use, which contributes to a decline in the attractiveness of green spaces. The synthetic picture of the city that emerges from the spatial analysis of the accessibility indicators of GI can provide local authorities with information and guidance for planning new initiatives related to the development and revitalization of GI in the city in accordance with the principle of ensuring better living conditions for all city inhabitants.
The two different approaches used in the study to assess the accessibility of GI in Łomża and Siedlce allowed the role of small areas of GI in urban space to be demonstrated for the provision of ecosystem services related to residents’ recreational needs. These smallest areas constitute an important element of urban greenery, influencing the formation of climatic and health conditions in the city, modifying the local climate and thus improving the quality of life in the city.
The results of research on the accessibility of GI in Łomża and Siedlce allow one to indicate the possibility of using the method of synthetic indicators of GI accessibility to evaluate the effectiveness of adaptation activities related to GI in a specific city, group of cities, or even other settlements. Such activities are monitored and evaluated as part of the process of assessing the implementation of local adaptation and may constitute the basis for assessing a plan or action related to the development of GI.