TENDENCIES AND FUTURE OF URBAN SPRAWL IN TWO STUDY AREAS IN THE AGGLOMERATION OF BUDAPEST ZSUZSANNA ILLYÉS

The Budapest agglomeration is a rapidly changing environment. Urban sprawl has been a prominent process in municipalities around the Hungarian capital, and its pace has significantly increased since the change of regimes. In our paper, we analyse the tendencies of urban development, the role of territorial protection and the types of land use mostly threatened by urban sprawl in two study areas within the Budapest agglomeration. A significant part of the Northern study area – located on Szentendre Island – is under territorial protection, while the Southern study area – located on Csepel Island – has a considerably lower amount of protected areas. We found that the settlements of the Northern study area have been expanding at a much slower pace than their Southern counterparts, where in the absence of effective restrictions, extensive areas – mostly former agricultural fields – have been converted into built-up areas. In addition, the Spatial Plan of the agglomeration allows the same tendencies to continue in both areas in the future as well. Received 20 March 2016, accepted in revised form 3 June 2016


Introduction
The concept of the environment as a potential built-up area, focusing on the monetary value of land was the typical point of view of the last century.However, in recent years the expansion of built-up and permanently altered areas on former agricultural and natural sites has created a demand for building regulations based on a new, different, conservation-based approach in several European countries.In our paper, we wish to reveal the local aspects, causes and spatial context of land-use change, along with the ecological conflicts they cause, on the example two settlement groups located in the Budapest agglomeration.
In historical times, population growth was the main factor in the growth of settlements.After the Turkish rule, the defensive role of walls and fences was diminished, which led to the first wave of urban expansion.Later, the appearance of new settlement types -farms, ranches, manors etc. -, due to intensive agriculture gaining land over extensive husbandry, allowed the network of built-up areas to expand even further.Data from Hungarian Central Statistical Office (KSH) shows that the proportion of cultivated land in Hungary was highest in the first third of the 20th century (Fig. 1), at that time non-cultivated land -which is essentially synonymous with built-up areascovered barely over 6% of the country's total area.In contrast, in 2013 non-cultivated land covered more than 22% -approximately the same area as Natura 2000 sites or forests.This means that by today, spatial structure contains an almost equal amount of ecologically important areas and significantly altered areas (settlements, infrastructure and mines), which generally have low ecological value or even cause ecological problems.
The background of non-productive land uses changed significantly in the second half of the 20th century.Hungary's population reached its peak around 1980, and has been decreasing ever since.However, since 1990, the proportion of non-cultivated areas has still grown from 11% to 20% (Fig. 2).This phenomenon can only partly be explained by the dramatic changes in lifestyle -the lower number of persons per household and the increase in the number of households.Another, perhaps even more prominent reason is the differences in -economic benefit between continuous agricultural land use and real estate development.
Naturally, the speed of this change has been different in each part of the country.It is significantly faster in urban agglomerations with increased property values, while in rural, depopulating areas forest cover is increasing.On a national scale, however, the growth of built-up areas still outweighs the growth of forest cover.This process is partly due to the decreasing amount of land necessary for the food supply of the same number of people, which, combined with the population decline, naturally causes the shrinking of agricultural areas.This would not raise environmental concerns in itself -ecological problems are not caused by the decrease in arable land, but by the dynamic expansion of land uses with even less ecological value.Construction sites, monoculture plantations of exotic species with low ecological value and spontaneous forests of invasive species occupy the place of grasslands, gardens, vineyards, reeds and marshlands, which has adverse effects on biodiversity and landscape diversity.Therefore, the questions are whether the network of areas with virtually no ecological value will overcome the system of traditional land use and whether the ecological system will remain sustainably functional in the changed spatial structure.It is very urgent to determine the characteristics and arrangement (?) of such spatial structure for the future that does not threaten the ecosystem within a specific region.
This paper focuses on two study areas located within the Budapest agglomeration, the spatial structure of these is regulated by the Spatial Plan of the Budapest Agglomeration (thereinafter BATrT).In 2011 the goal of the amendment of the BATrT was to control urban sprawl using regulatory instruments.For this purpose, proposals for building new apartment complexes and industrial facilities have been restricted, settlement coalescence has been prohibited (5 § (3)), and the designation of new developments is now restricted in a 200 meter wide zone around the administrative boundaries of the municipalities.The restriction of the growth of built-up areas (a limit of 2%) was aimed to increase the  Hungary (1990-2013) (KSH 2012a;KSH 2012b;KSH 2012c;KSH 2014) value of brownfields.Requirements have been imposed on some developments, while new regulatory procedures are being implemented.The BATrT, while restricting new developments in general, creates the possibility, named "land switch", for municipalities to change their previous, sites for proposed development and, according to a revised urban development concept, designate new sites of the same size in their amended Structural Plan.Land switch does not decrease new developments, but at least makes structural corrections possible.
Apart from influencing urban sprawl, another way to ensure a sustainable spatial structure is to conserve areas that are still in favourable ecological conditions.In the early 1990s EU member states had to recognize that the previous practice of nature conservation -based on species protection and the designation of protected areas -is not sufficient to ensure the survival of natural habitats.The shrinking and fragmentation of these habitats brought attention to the importance of ecologically less valuable, but widespread associations in the conservation of interconnected habitat networks.As a result, in 1993 in Maastricht the idea of a European Ecological Network was born.The main principle behind the development of the network was to surpass the previous dichotomy of "protected areas vs. nonprotected areas" and to protect habitats from further degradation and fragmentation together with their surroundings.
In 1995, on the proposal of the Council of Europe, all accessing states signed the Pan-European Biological and Landscape Diversity Strategy (PEBLDS) in Sofia, which set the development of the Pan-European Ecological Network (PEEN) as one of its main goals.The directive for setting up a unified network stated that the network is a coherent spatial system of natural and seminatural ecosystems, habitats and landscape elements, consisting of core areas, ecological corridors, buffer areas and restoration areas, which, following habitat restoration, may even join the network as core areas.
According to the original proposal, buffer zones would have protected core areas and ecological corridors in a continuous, wide belt.However, their designation often failed or their area was reduced due to the interests of urban development, agriculture, industry and mining (Nagy 2004).
In Hungary, the aforementioned restrictive protection system reached its full extension with the adoption of the National Spatial Plan (thereinafter OTrT) in 2003.Nevertheless, both the spatial structure and the content of conservation measures has changed a lot at several planning levels since then.Figure 3 shows the elements of the ecological network and built-up areas of regional level as designated by BATrT.Buffer areas (Fig. 3.) apparently do not meet the original principles of PEEN designation: not only do they fail to form a wide belt, but they are basically missing in most of the agglomeration area, which means that core areas and ecological corridors are often directly adjacent to residential areas without any buffer zone.

Study areas
The investigated settlement groups are located in a similar geographical environment, but they have had markedly different histories of settlement development (Fig. 4).They are both located within the Budapest agglomeration, near the capital.They are both located on islands on the Danube.However, there are key differences in their past and present that have significant spatial consequences as well.The Budapest agglomeration is a region particularly affected and threatened by the process of change.The Environmental Management Programme of the region drew attention to the predominance of greenfield investments, the resulting conflicts between nature conservation and investment purposes and the ongoing loss of natural green surfaces as far back as 2007 (Budapesti Agglomerációs Fejlesztési Tanács 2007).This process is especially prominent regarding small and already fragmented habitats and (semi-)  (Szirmai 2011) aspects.Authors stated, among others, that biologically active surfaces had been constantly shrinking in the Budapest agglomeration, while built-up areas had been steadily expanding.As the extent of non-productive land use had been expanding at an increasingly fast rate, by 2008 their proportions approached -and in the inner ring of the urban agglomeration even exceeded -the 1/3-2/3 ratio of built-up and non-built-up areas regarded to be the limit of regionally sustainable land use.The proportion of forested areas had also been decreasing, and with the expansion of paved surfaces, the runoff coefficient declined as well, resulting in a deterioration of drainage and water management conditions (Schuchmann 2008).
The main differences between the two study areas can be seen when comparing population dynamics and changes in land use, these, in turn, show the dynamics of settlement development and the characteristics of urban sprawl tendencies.
The settlements of the Northern study area Landscape & Environment 10 (2) 2016.75-88 (located on Szentendrei Island) had already been in existence before the 20th century, with a population between 1000 and 6000 -the same range as today.The population of almost all municipalities were stagnating until the change of regimes -and even though population has been growing since then, the growth rate is significantly lower than in the other study area.This stability is also reflected by land use proportions, the extent of non-cultivated land (the land use category including built-up areas as well) has only been growing at a moderate rate in the last two decades.The growing population is facilitated by more intensive use of builtup recreational areas but only partially by gardens, orchards or vineyards.The settlements of Szentendre Island have been moderately expanding (Fig. 5).
The municipalities located in the southern study area took their present form later, Szigethalom and Halásztelek only becoming independent in the second half of the 20th century.Their population shows a constant and dynamic growth, today they have between 10,000 and 40,000 residents.The population growth has been especially fast since the change of regimes and the construction of the M0 highway ring around Budapest.Changes in land use are proportional to population growth, the amount of non-cultivated land is growing rapidly.Gardens, vineyards and orchards formerly characteristic of the area have competely been transformed/replaced by built-up areas and the proportion of arable lands also have reduced.The settlements on Csepel Island are among the most intensively expanding settlements within the agglomeration (Fig. 6.).

Materials and Methods
Our analysis comprises of two distinctbut thematically connected -topics, which are as follows: • In order to determine the efficiency of regulations and restrictions as planning tools, we analyse the networks of different territorial protections on our study sites.Based on the history of protected areas we assessed their roles regarding not only in conservational ecologically important habitats, but in reducing urban sprawl.• The Corine Land Cover database-encompassing four surveys -allows to analyse and assess ecologically valuable areas and habitats destroyed on all studied municipalities by the expan-sion of urban areas between 1990 and 2012.The comparative analysis of the land cover data and the proposed land use designated by regional plans shows the valuable -but unprotected -areas threatened by land use changes and therefore allows us to predict the magnitude of possible future ecological loss.By this analysis we determined areas have mostly been eliminated from the ecological structure due to the lack of protection, and habitats expected to disappear in the future.Naturally, the proposed network of potential built-up areas will not necessarily be realized in the foreseeable future.However, it is indicative of the potential pace of development, and therefore the proportion of possible changes in the near future in the two study areas.By comparing the two study areas in both questions we wish to reach conclusions about the complex interactions among urban sprawl, population dynamics and regulatory measures.
Several territorial protection tools have been implemented to restrict development in planning practice.Protective zones, protected areas and land use categories preventing or restricting building-up/ construction/installation help controlling urban sprawl threatening intended land use or natural conditions.Nature conservation, aquifer protection and the designation of the National Ecological Network (OÖH) aim at protecting natural resources directly.However, there are several land uses (military areas, airports, etc.) restrict development not for the conservation of nature, it is merely a result of the restricted use.A common feature of the two study areas is that drinking water extraction from gravel terraces of the river Danube had an important part in the history of their land use.
In order to determine the efficiency of territorial protection and the effectiveness of property speculation strategies we analysed the parts of the ecological system that have been replaced or destroyed by urban development in the last 20-25 years, using the Corine Land Cover (CLC) database.Remote sensing and satellite imaging is considered an efficient tool of tracking changes in land cover, and they have been successfully used for monitoring urban sprawl as well (Nagyváradi et al. 2011).Using the database, the change of the land cover -and therefore the change of land use with ecological value -can be studied as well.We compared the changes in land use data of different CLC surveys (1990, 2000, 2006 and 2012) published so far on the survey areas, using ESRI ArcMAP 10 software, with special regard to areas turned into artificial builtup surfaces in order to monitor the scale of urban expansion.
We considered the following Corine land cover categories as built-up areas (Commission of the European Communities 1995): 1.1.1"Continuous urban fabric", 1.1.2"Discontinuous urban fabric", 1.2.1."Industrial or commercial units", 1.2.2."Road and rail networks and associated land", 1.2.3."Port areas", 1.2.4."Airports", 1.3.3."Construction sites", 1.4.1."Green urban areas", 1.4.2."Sport and leisure facilities".(We did not consider mineral extraction sites (1.3.1.)and dump sites (1.3.2) as built-up areas despite their artificiality.) Afterwards, we compared the latest (2012) land cover data with areas designated as built-up areas in the current Structural Plan of the Budapest Agglomeration (BATrT), which shows the amount of land use change and urban expansion allowed by the current regulation compared to the land cover of 2006, making it possible to determine the areas threatened by development.

Results and discussions
The role of territorial protection in nature conservation and in controlling urban sprawl

Northern study area
The expropriation of waterworks and the riverbanks -to ensure the water supply of Budapest -has been restricting the development of riverside (costal?) areas, but restrictions had been in place even before.The construction of the first row of wells on Szentendre Island started in 1899, and the presence of territorial protection on the island can be dated from this year (Károlyi -Tolnai, 2008).Since the 1980s, the conservation of the quality of vulnerable aquifers has become the centre of attention.The conservation of vulnerable water resources -like the bank-filtered aquifers of Szentendre and Csepel Islands -has been regulated by a Governmental Decree since 1997.Protective areas and zones (inner and outer areas, hydrogeological A, B and C zones) are designated for the protection of the water resources, based on the travel-time of the hypothetical pollution to the water extraction site (Liebe 2006).The prohibitions and restrictions regarding development, land use and access within the zones, even though these are not based or aimed at ecological purposes, contribute significantly to the conservation of the remaining alluvial habitats, as the designated ecological network contains these areas almost entirely (Fig. 7).
Several levels of protection ensure the conservation of natural values of Szentendre Island.The first protected area was designated in 1974 within the municipal boundaries of Tahitótfalu.By 1981, three other, smaller and isolated protected areas were designated.The largest area was designated in 1985 by a decree of the Pest County Council, extending the county-level protection to the entire island.
The council decree stated that the intention of protection was the conservation of the image of the island's landscape, the botanical, zoological, geological and cultural values within the area and the aquifer providing water supply for a significant amount of people.This protection was not really efficient in preventing urban expansion, but it drew the attention of municipalities to the importance of restricting certain land uses.
In 1990, the authority over county-level protection and the power to designate new protected areas was passed over to municipalities.In 1992, the municipalities of the island unanimously lifted the protection from the entire island and ensured the protection of areas of significant value -islets, alluvial forests, pastures -via municipal decrees.Upon creation of Duna-Ipoly National Park (DINP) in 1997, the municipal-level protected areas were lifted to the national level as part of the new National Park.The parts of the island with valuable wildlife that do not belong to the DINP is protected by the Natura 2000 network of the European Union.Two Special Areas of Conservation are designated on the island.One of these is "Duna és ártere" (HUDI20034), an elongated area stretching along the river Danube, touching many settlements apart from those on Szentendre Island, protecting mainly floodplain habitats.The other one is "Szigeti homokok" (HUDI20047), designated for the protection of the remaining sandy grasslands formed on the higher elevations in the centre of the island (European Union The core areas and ecological corridors of the National Ecological Network, designated in 2003, were based on DINP's areas and the elements of the Natura 2000 Network on Szentendre Island.Ecological corridors were designated chiefly on the inner and outer protection areas of water resources and protective forests of the hydrogeological "A" zone.Elements for the ecological corridor network were only designated without any previous protection South from Szigetmonostor, on a forested area with protective functions.Buffer areas were only designated on a few smaller plots, but even there without the originally described function of a "protective zone" around core areas.

Southern study area
Water extraction from the Csepel Island aquifers for Budapest began only in the 1980s -due to the high concentration of iron and manganese -when Szentendre Island has reached its full capacity, its wells completely constructed (Debreczeny -Jancsár, 1993).Protective zones were designated at the same time, therefore water resource protection could only contribute to the conservation of ecologically valuable areas in the last 30 years.Aquifer protection contributes to building restrictions and, partially, to the conservation of ecologically valuable areas here as well, although with lesser extent than in the northern study area.The Natura 2000 area "Szigethalmi homokbuckák" used to be a fenced, guarded, closed area as the protective zone for the waterworks of Csepel Works (a highly important industrial facility of the era).Its environmental value mainly consists of the remaining patches of forests and sandy grassland.Another example of a buffer area designated in connection with the protective zone of a technical facility is the radio tower of Lakihegy -the element of the ecological network is based on an earlier restriction in this case as well (Fig. 8.).
The National Ecological Network is mainly based on Natura 2000 areas on Csepel Island ("Duna és ártere" HUDI20034, "Szigethalmi homokbuckák" HUDI20045, "Ráckevei Dunaág" HUDI20042) (European Union 1995-2016).Building and land use restrictions for the elements of the ecological network are described in the National Spatial Plan.Development plots cannot be designated -only in exceptional cases -on core areas and ecological corridors.An exception from this restriction may be requestedthe settlements of the southern study area have submitted such a request based on existing recreational use, while the northern settlements have submitted similar requests for the same reason and also for harbour expansion.

Comparison
A common feature of the two areas that their ecologically valuable areas currently belonging to the National Ecological Network (OÖH) used to have (and often still have) some other protection or restriction that helped their survival indirectly by restricting land use.This phenomenon is almost exclusive on both study areas -virtually all areas protected by nature conservation are based on earlier types of territorial protection.
Table 1 shows the proportions of different protection types within the boundaries of each municipality.It shows that the proportion of areas affected by restrictions in the Northern study area is considerably higher than on Csepel Island.The data shows that National Ecological Network (OÖH) is the most extensive, integrational area, covering and connecting smaller areas, which are often affected by several different types of protection.There is a high level of correlation (?) between the ecological network and aquifer protection.The low proportion of buffer areas is also notable.

Northern study area
Between 1990 and 2000 very little changed in the studied land cover types of Szentendre Island.Only one formerly biologically active area was turned into a category considered as settlement area: the Magyar Golfing Club appeared in Kisoroszi to replace former agricultural land (Fig. 9).The golf course, covering just over 30 ha represents 0.33% of the combined area of the settlement group.The area affected by urban development on the northern study area was even smaller between 2000 and 2006 -four sites, with a total area of 17.2 ha, became built-up areas -a new horse ranch in Tahitótfalu and a new Danube bridge (Megyeri Bridge) near the southern end of the island.Less than 0.2% of the total area of the four municipalities were affected.Urban development has apparently become even slower between 2006 and 2012, as only one site, with an area of 5.39 ha (0.06%) was built up.It is also worth noting that a majority of the sites we considered to be transformed into non-productive areas are actually newly created recreational areas with considerable green surfaces.
The network of built-up areas designated in the most recent BATrT allows a relatively low amount of expansion on Szentendre Island compared to the built-up areas shown by the data of the 2012 CLC survey -urban sprawl is stagnating (Fig. 10).It is also worth noting that according to the Agglomeration Plan, the settlements of Pócsmegyer and Szigetmonostor (and also Surány and Horány, which are under their respective jurisdiction) could hypothetically merge, which would result a built-up area of considerable size in the centre of the island, occupying current fringe areas.Areas designated as parts of the National Ecological Network restrict the expansion of Pócsmegyer (and Surány) to the north and Szigetmonostor (and Horány) to the south, therefore their urban areas are approaching each other.As Kisoroszi is almost completely (at 90% of its fringe) surrounded by the ecological network, its built-up areas are almost completely unchanged since 2012 and this trend is not likely to change in the foreseeable future.Territorial protection effectively prohibits further development: all the place could be built up has already been built up.Potential built-up areas designated by the BATrT and built-in surfaces recorded by the CLC survey in 2012 in Tahitótfalu are also almost completely identical.However, this in this case not due to the ecological network, as the proportion of fringes between developed areas and parts of the OÖH is low -the ecological network does not cover the inner parts of the island.Potential built-up areas designated by the BATrT cover 14.5% of the total administrative area of the four municipalities of the island.

Southern study area
Between 1990 and 2000, five formerly undeveloped sites were changed into built-up land cover types, all of them within the administrative boundaries of Szigetszentmiklós and all the five are replacing arable land.The new land uses were residential, industrial and transportation (Fig. 11), covering a total area of 75.7 hectares (0.74% of the administrative area of the four settlements).Built-up areas of the four municipalities designated by the BATrT are significantly larger than the extent of artificial land cover in 2012 (Fig. 12).According to the Structural Plan, the creation of a continuous urban area is possible, with Tököl and Halásztelek the only two settlements without a direct connection to each other.Furthermore, the Agglomeration Plan allows a direct connection of Szigetszentmiklós and Budapest.The significantly lower proportion of areas protected by the National Ecological Network on Csepel Island compared to Szentendre Island has a role in the expansion of designated built-up areas -apart from the Danube and its floodplains, only six isolated sites of variable size represent the Ecological Network.Therefore, the elements of the National Ecological Network are unable to form a real network, which opens the gate for urban development.The designated built-up areas cover 44.6% of the area of the four studied municipalities, which means that almost half the southern study area can be considered as potential settlement area.This is almost three times higher than the corresponding data (14.5%) for the Northern study area.
In case the designated built-up areas were actually fully built-up in the future, the ecological network of the Csepel Island study area would be reduced to isolated elements with no connection to each other, increasing the threat of degradation of the remaining habitats.The spatial connection of the residential and industrial areas of Szigetszentmiklós would cut the connection between the Danube and its side-branch called Ráckeve Danube.Although presumably development will continue to occur on agricultural lands, the potential coalescence of the settlements poses a threat to the survival of remaining wildlife by itself.
When comparing the two study areas, it is evident that while the Northern study area can be characterized with a very low rate of land use change and a relatively stable ecological network, the Southern study area has been rapidly changing since 1990.These processes are allowed to continue by the BATrT as well.If the proposed network of built-up areas actually is realized, the remaining areas of significant ecological value cease to be a functioning networkas opposed to the long-term stability of the biologically active areas of Szentendre Island.

Conclusion
As sites within the study areas in an ecological condition worthy of protection have survived -or appeared -due to former land use restrictions, it can be stated that long-term restricted use has an important role in the conservation of the ecological system.
Analyses of two regions of the agglomeration of Budapest, an area critically affected with urban sprawl showed that mutual dynamic factors are an essential part of the spatial systems of both urban and ecological areas.High proportions of heavily restricted areas compared to the total municipal area result in a direct contact of built-up areas and areas with significant ecological value.A high proportion of territorial protection conservational leads to passing of problems instead of solving them.In contrast, a lower proportion of protected areas leads to the loss of ecological connections and the isolation of valuable sites.A low level of conservation as a weaker resistance attracts development.
In conclusion, the two situations hold different dangers for the ecological system: permanent disturbance on the fringe of the ecological network due to the proximity of built-up areas on the northern study area and isolation on the southern settlement group.
According to these two main results, the current spatial structure and functional units of the National Ecological Network (OÖH) are incapable of protecting ecologically important habitats in agglomerating regions.In order to prevent the complete coalescence of built-up areas, current arable lands have to be integrated into the ecological network as buffer zones, with continued agricultural land use -with restrictions.This can create a protective zone between the urban fabric and valuable habitats.

Fig. 3 .
Fig. 3. Built-up areas and the OÖH according to the Structural Plan of the Budapest Agglomeration (Pestterv 2011)

Fig. 7 .
Fig. 7. Water resource protection and nature conservation in the Northern study area

Fig. 8 .
Fig. 8. Water resource protection and nature conservation in the Southern study area

Fig. 9 .
Fig. 9. Changes in land cover in the Northern study area between 1990 and 2012 (Comission of the EC 1995)

Fig. 10 .
Fig. 10.Comparison of the potentially built-up areas in BATrT and the built-up surfaces in CLC 2012 in the Northern study area (Commision of the EC 1995; Pestterv 2011)

Table 1 .
Comparison of the extent of territorial protection types in the two study areas