Climate-proof cities: City of Tallinn, Estonia

Surface Permeability

Surface permeability is regarded as one of the key indicators of climate resilience.

Two time scales have been selected for assessing the surface permeability in the city of Tallinn: current situation (contemporary permeability) and future permeability. It was assumed that greenery areas have good surface permeability and that greenery ratios (percentage of greenery set for each land use type in district comprehensive plans) are equivalent to such permeability.

Contemporary permeability

Base map: Land cover layer of Tallinn City TAR

Methodology: Different surface types in Tallinn City TAR were divided into two groups:

1. Permeable surfaces:

1. Wood
2. Flintstone
3. Gravel
4. Sand
5. Cobblestone
6. Soil
7. Limestone
8. Artificial lawn

2. Impermeable surfaces:

1. Asphalt
2. Concrete
3. Rubber
4. Tar paper

The percentage of permeable surface of each map polygon was calculated. The percentages were classified into four classes: Class 0: 0-10% permeability (in red colour), Class 1: 11-40% (in orange), Class 2: 41-70% (in yellow) and Class 3: 71-100% (in green) and represented on the map.

Summary of the contemporary map (2653 polygons in total):

Class 0 – 103 polygons, 4% (in red)

Class 1 – 395 polygons, 15% (in orange)

Class 2 – 779 polygons, 29% (in yellow)

Class 3 – 1376 polygons, 52% (in green)

Currently, the lowest share of surface permeability (Class 0 and Class 1) covers about 20% of the polygons, while more than half of the polygons has the maximum share of permeability (Class 3) (Table 1 and 4).

Table 1. Current surface permeability in Tallinn districts

District	Area (ha)/ Permeability cover class
	Class 0: 0-10%	Class 1: 11-40%	Class 2: 41-70%	Class 3: 71-100%	Total
Haabersti	12	39	406	1599	2056
Kesklinn	78	560	317	1180	2135
Kristiine	19	158	386	196	759
Lasnamäe	26	663	951	1084	2724
Mustamäe	18	158	487	138	801
Nõmme	29	190	433	2109	2761
Pirita	1	58	233	1539	1831
Põhja-Tallinn	43	334	615	464	1456
Total	226	2160	3828	8310	14524

Future permeability

Base map: Land use maps of 7 district comprehensive plans. In the case of City Centre District (Kesklinn) the thematic plan of green areas in Tallinn was used.

Methodology: Planned greenery ratios per land use type for each map polygon were taken from the district comprehensive plans and assumed to represent future permeability in each polygon. Comprehensive plans of 8 city districts, where the greenery ratio is set as follows:

Table 2. Proposed greenery ratios per land use type in district comprehensive plans in Tallinn

District	Land use type	Proposed greenery ratio
Haabersti	Forest town	50%
	Park town	40%
	Garden town	30%
	Mixed function	20%
	Industrial facilities	15%
	Centre	30%
Kesklinn (City Centre)	Forest town	50%
	Park town	40%
	Garden town	30%
	Mixed function	15%
	Public facilities	15%
	Industrial facilities	15%
Kristiine	Public facilities	20%
	Business and industrial facilities	10%
	Apartment houses	30%
	Multiple-family houses	40%
	Mixed function	20%
	Business facilities	15%
Lasnamäe residential areas	Public facilities	20%
	Public facilities and apartment houses	40%
	Business facilities	20%
	Business facilities and apartment houses	20%
	Business and industrial facilities	15%
	Mixed function	20%
	Apartment houses	40%
	Apartment houses and business facilities	30%
Lasnamäe industrial areas	Business facilities	15%
	Business and industrial facilities	15%
	Business, industrial facilities and apartment houses	15%
	Apartment houses and business facilities	20%
	Single-family houses	40%
Mustamäe	Multiple-family houses	40%
	Apartment houses	40%
	Apartment houses with open space between houses	40%
	Mixed function	20%
	Public facilities	20%
	Business facilities	15%
	Special facilities	15%
	Health facilities	10%
	Apartment houses and public facilities	15%
	Apartment houses and business facilities	10%
	Public and business facilities	10%
	Industrial and/or business facilities	10%
	Multiple-family houses and business facilities	10%
	Centre	10%
Nõmme	Public areas	50%
	Business and industrial facilities	15%
	Apartment houses	40% or 50%
	Apartment houses and business facilities	40%
	Single-family houses	50%
	Multiple-family houses	50%
	Multiple-family houses and business facilities	40%
	Mixed function	20%
Pirita	Mixed function	15%
	Existing single-family houses	75%
	Multiple-family houses	75%
	Apartment houses	15%
	Perspective single-family houses	70%
	Multiple-family houses with trees	85%
	Public facilities	15%
	Business facilities	15%
	Industrial facilities	10%
	Technological facilities	will not change
Põhja-Tallinn (North-Tallinn)	Public facilities	40%
	Business facilities	15% or 20%
	Apartment houses	30% or 40%
	Single-family houses	40%
	Technological facilities	15%
	Mixed function	20%
	Industrial areas	15%
All districts	Green areas	Same as nowadays
	Transportation areas	Same as nowadays

Based on the greenery ratios set in district comprehensive plans, the future soil permeability

Table 3. Future soil permeability in Tallinn districts

District	Area (ha)/ Permeabilty cover class, percentage
	Class 0: 0-10%	Class 1: 11-40%	Class 2: 41-70%	Class 3: 71-100%	Total
Haabersti	0	1083	239	734	2056
Kesklinn	68	873	181	1013	2135
Kristiine	107	465	174	15	760
Lasnamäe	4	1480	445	795	2724
Mustamäe	202	356	136	107	801
Nõmme	0	327	1252	1182	2761
Pirita	10	173	197	1451	1831
Põhja-Tallinn	3	931	146	376	1456
Total	226	2160	3828	8310	14524

If the greenery ratios proposed in the district comprehensive plans would be implemented to the full extent (Table 2), the surface permeability would decrease (Table 3). The most significant reduction would be in Class 3: from 52% to 20% and in Class 1, where the number of polygons with greenery ration between 11 and 40% will almost equally increase (Table 4).

Table 4. Surface permeability classes today and in the future in Tallinn

Surface permeability class	No of polygons today	No of polygons in the future
Class 0: 0-10	103, 4	58, 2
Class 1: 11-40	395, 15	1437, 54
Class 2: 41-70	779, 29	636, 24
Class 3: 71-100	1376, 52	522, 20
	2653, 100

Map 2: Surface permeability in Tallinn today (left) and in the future (right), if the comprehensive plans would all be put into action. 

The comparison between the contemporary and future permeability map indicates that the number on polygons in the lowest permeability class (Class 0) will decrease (from 4% to 2%), which seems a positive development (Table 3 and 4; Fig.2., map on the right), alluding that the worst areas of surface permeability will improve. However, the number of polygons in Classes 2 and 3 will also decrease and most of the polygons (54%) will fall into Class 1, having the second lowest permeability ratio (between 11% and 40%) of the polygons (Table 4). Today, 52% of the polygons are in good permeability condition (Class 3: 71-100% of permeability).

While looking at the future surface permeability scenario across districts, 5 districts out of 8 would experience rather significant reduction in surface permeability if the proposed greenery ratios in comprehensive plans would be strictly followed (Table 5). The most pronounced changes may take place in Haabersti district, since the number of polygons in Class 0 and 1 (the least surface permeability) could increase by 10-fold compared to the contemporary situation (from 5,4% to 54,9%). Also Kristiine, Lasnamäe, Mustamäe and Põhja-Tallinn may experience significant surface permeability reduction resulting from greenery ratio reduction in polygons, but at different scales.  The least changes in the future compared to today’s situation would occur in Nõmme, Pirita and Kesklinn, where the greenery ratio has already been set high in comprehensive plan. For example, in Nõmme the suggested greenery ratio ranges from 40 to 50% and in Pirita even as high up to 75-85%. While the greenery ratio in Kesklinn (City Centre) has not been set particularly high, ranging from 15 to 40%, and in city forests up to 50%, the future scenario would not considerably differ from the today’s situation. One of the reasons may be the fact that the land use in City Centre has already taken shape and the objective is to maintain the green areas rather than to reduce them.      

However, in five districts the surface permeability in Tallinn could decrease significantly, if the district comprehensive plans become fully implemented.  

Table 5. Possible future surface permeability in districts and per permeability class

District	No on polygons\ Permeability cover class				Total
	Class 0: 0-10%	Class 1: 11-40%	Class 2: 41-70%	Class 3: 71-100%
Haabersti	0	101	18	66	185
Kesklinn	8	168	23	43	242
Kristiine	20	274	4	12	310
Lasnamäe	2	206	14	61	283
Mustamäe	22	81	5	17	125
Nõmme	1	125	544	105	775
Pirita	1	66	16	136	219
Põhja-Tallinn	4	416	12	82	514
Total: %	58 2.2%	1437 54.2%	636 24.0%	522 19.7%	2653 100%

Canopy cover

Canopy cover percentage (also canopy overlay) is regarded as one of the indicators of urban climate resilience. Canopy cover plays an important role in reducing high temperature (heat wave) impacts on citizens and slows down the stormwater runoff by allowing more retention time to either infiltration of the water into the soil or flowing into stormwater collectors, and by that reducing the risk of flooding.

Canopy cover (overlay) in Tallinn

In this study, the tree canopy cover is expressed as the percentage of the ground area shaded by tree canopies relative to the total open area. No quality criteria were applied.

Only the contemporary situation was analysed in this study. The possible future canopy cover ratios in polygons depend on the implementation of the district comprehensive plans (if the greenery ratios proposed in these plans are strictly followed) and on the potential increase of construction pressure and associated tree cover loss. On the other hand, tree cover ratio may increase in some polygons that are currently brownfields with some greenery. If those underdeveloped areas are left aside for decades the tree canopy cover percentage may improve naturally. All these assumptions need additional analysis.

The following results were obtained.

Contemporary canopy cover

Base map: LiDAR-based vegetation elevation model of Tallinn.

Methodology: The vegetation elevation model contains 10x10 m cells with information of vegetation height in each cell. Cells where the vegetation height was between 5 and 30 m were extracted from the model. Cells with lower vegetation height were discarded because either they do not indicate trees or the trees are too small to offer proper ecosystem services. Cells with higher vegetation height were discarded because they contain more likely classification errors. 

Percentage of canopy cover of each map polygon was calculated. The percentages were classified into four classes: Class 0: 0-10%, Class 1: 11-40%, Class 2: 41-70% and Class 3: 71-100%. The colours of the classes are represented on the map (Map.3.).

Map 3: Current canopy cover in Tallinn, percentage classes

Table 5. Contemporary canopy cover in Tallinn districts, no of polygons per canopy cover class

District	No on polygons\ Canopy cover class				Total
	Class 0: 0-10%	Class 1: 11-40%	Class 2: 41-70%	Class 3: 71-100%
Haabersti	31	60	40	54	185
Kesklinn	35	127	60	20	242
Kristiine	25	194	79	12	310
Lasnamäe	114	135	29	5	283
Mustamäe	21	62	31	11	125
Nõmme	10	123	287	355	775
Pirita	7	75	56	81	219
Põhja-Tallinn	93	245	150	26	514
Total: %	336 12,7%	1021 38,5%	732 27,6%	564 21,3%	2653 100%

As described in Table 5, there are big differences between the Tallinn districts in canopy cover classes. The largest contemporary canopy cover among the Tallinn districts is in Nõmme, where 87% of Class 2 and 3 polygons are located, whereas Lasnamäe holds 2,6% of Class 2 and 3 polygons only.

Since the canopy cover and surface permeability depend on the greenery ratio, it is crucial for the city planners to maintain the ratio of greenery at current level since it provides good prerequisites for climate resilience. Any reduction would lead to the reduced climate resilience and associated wellbeing of citizens. 

Access to public green areas

Access to public green areas has been regarded as essential for quality of life and wellbeing of local residents. Local authorities have an important role to ensure the public access to green areas via planning process.

Access to public green areas in 250m distance in Tallinn

In the current study, firstly, the availability of green areas of at least 0,75 ha (7500 m²) in size, secondly, the population in 100x100 m cells and thirdly, the number of residents living within 250 m radius of the green areas was mapped.

The following steps were taken.

Base map: Thematic plan of public green areas and a map of inhabitants in 100x100m cells. 

Green public areas are green areas for public use. It should also be noted that Tallinn City has green areas of private use (e.g. relatively large private gardens in the districts of Pirita, Nõmme, Kristiine). Thus, the access to green areas describes only the accessibility of citizens to public green areas, while the accessibility to green areas is much better if private green areas are also taken into account. But, in this study, only public green areas are considered.

Methodology: The map of inhabitants in Tallinn consists of 100x100 m quadrate cells with population data. As of 1 January 2018 there were 427 201 inhabitants in Tallinn.

The map of public green areas of Tallinn contains 197 polygons larger than 0.75 ha (Table 6; Fig.4.). 41% of the polygons are up to 2.5 ha large. The second size class (2.5-10 ha) covers 58 polygons (29%). There are also 23 polygons that cover more than 50 ha of public green areas. These are protected areas, such as Natura 2000 sites and water protection zones covered by forests.

Table 6. Number of polygons across size classes of public green areas in Tallinn 

Area class of green area	No of polygons
Class 1: 0,75 – 2,5 ha	80
Class 2: 2,5 - 10 ha	58
Class 3: 10 - 50 ha	36
Class 4: >50 ha	23
Total:	197

Map 4: Current access to public green areas in Tallinn, dependant on green area size class 

There are 5490 by 100x100m cells across Tallinn city (Table 7). Population density in the city is rather low, since majority of the cells (65%) have less than 50 people. The population density is higher in districts with apartment houses, such as Mustamäe, Haabersti, Lasnamäe and North-Tallinn (Table 8; Map 5.).

Table 7. Citizens’ density in 100x100 m cells in Tallinn

Number of citizens classes	Number of cells
<= 50	3593
51-100	601
101-200	700
201-500	527
>=501	69
Total:	5490

Map.5 

Map 5: Number of Tallinn citizens in cells (5 classes).

Table 8. Number of 100x100 m cells and number of citizens per population size class

	No of 100x100 m cells per size class						No of citizens per size class
Size class (no of citizens) District	≤ 50	51–100	101–200	201–500	≥ 501	Total	≤ 50	51–100	101–200	201–500	≥ 501	Total
Haabersti	645	40	57	61	6	809	9397	3023	8344	18839	3676	43279
Kesklinn	305	144	148	65	1	663	5746	10786	20897	17018	2921	57368
Kristiine	307	90	56	28	4	485	7150	6489	8007	7900	2731	32277
Lasnamäe	77	56	111	177	47	468	1205	4332	16676	58510	34273	114996
Mustamäe	34	33	111	124	8	310	409	2642	16720	38525	6806	65102
Nõmme	1275	79	35	6	1	1396	25548	5422	4889	1995	1131	38985
Pirita	831	30	10	3	0	874	13706	2200	1251	738	-	17895
Põhja-Tallinn	119	129	172	63	2	485	2432	9608	24112	17584	3563	57299
Total:	3593	601	700	527	69	5490	65593	44502	100896	161109	55101	427201

Table 9. Access to public green areas by citizens in districts, up to 250 m and further distance 

District	No of citizens in districts	% of citizens living in 250 m radius of a public green area	% of citizens living further than 250 m radius of a public green area
Haabersti	43279	77.6	22.4
Kesklinn	57368	87.9	12.1
Kristiine	32277	44.9	55.1
Lasnamäe	114996	81.7	18.3
Mustamäe	65102	71.3	28.7
Nõmme	38985	82.7	17.3
Pirita	17895	97.3	2.7
Põhja-Tallinn	57299	85.6	14.4
Total:	427 201	79.0%	21.0%

A 250 m buffer was constructed around the public green areas and population cells were differentiated based on whether their centroid was inside or outside of the buffer. According to the analysis, 79% of the population of Tallinn lives in a distance of 250 m or less to a public green area with at least 0.75 ha size (Table 9-11; Fig.6.).  The best access to public green areas appears to be in districts of Pirita, Kesklinn and Põhja-Tallinn, where 85 to 97% of the people in these districts have access to a public green area closer than 250 m. The district of Lasnamäe outstands the other districts, since the citizens have the least access to a public green area in their closest vicinity:  55% of the district population have access to a public green area further than 250 m of home (Table 10).   

Table 10. Access to public green areas by citizens 

Cell class of the number of citizens	Number of cells, hosting public green areas closer than 250 m
<=50	3108
51-100	484
101-200	550
201-500	400
>=500	62
Cell class of the number of citizens	Number of cells, hosting public green areas further than 250 m
<=50	485
51-100	117
101-200	150
201-500	127
>=501	7

Map 6: Access to public green areas closer and farther than 250 m in Tallinn.

Table 11. Citizens’ distance from public green areas in districts

	No of citizens in cells less than 250 m from nearest public green areas						No of citizens in cells further than 250 m from nearest public green areas
Size class (no of citizens) District	≤ 50	51–100	101–200	201–500	≥ 501	Total	≤ 50	51–100	101–200	201–500	≥ 501	Total
Haabersti	8484	2395	6051	12972	3676	33578	913	628	2293	5867	0	9701
Kesklinn	4927	9751	18189	14636	2921	50424	819	1035	2708	2382	0	6944
Kristiine	3085	2647	3155	3933	1661	14481	4065	3842	4852	3967	1070	17796
Lasnamäe	979	3512	13650	47665	28102	93908	226	820	3026	10845	6171	21088
Mustamäe	296	1964	12768	27557	3854	46439	113	678	3952	10968	2952	18663
Nõmme	21622	4756	3717	1017	1131	32243	3926	666	1172	978	0	6742
Pirita	13224	2200	1251	738	0	17413	482	0	0	0	0	482
Põhja-Tallinn	2228	8664	20440	14157	3563	49052	204	944	3672	3427	0	8247
Total:	54845	35889	79221	122675	44908	337538 79.0% of total Tallinn population	10748	8613	21675	38434	10193	89663 21% of total Tallinn population

In conclusion, the study results demonstrate that majority of the residents of Tallinn city (about 80%) has a rather good access to public green areas (of at least 7500 m² large) in their closest vicinity of 250 m. In addition to the access to public green areas also privately owned gardens in the districts of Kristiine, Nõmme and Pirita play an important role in providing recreational and climate resilience services to the citizens.