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Human impact on topography in an urbanised mining area: Pécs, Southwest Hungary

Impact anthropique sur la topographie d’un territoire minier urbanisé : Pécs, Hongrie du Sud-ouest
Dénes Lóczy et Péter Gyenizse
p. 287-300

Résumés

La ville de Pécs, de taille moyenne à l’échelle de l’Europe centrale, est située dans la partie sud-occidentale de la Hongrie. L’impact de l’Homme sur la topographie environnante s’est exercé au long de deux millénaires : il s’agit de la mise en place des constructions, des mesures de gestion des eaux, de l’agriculture (principalement la viticulture) et du développement du réseau routier associé à ces activités. Au cours des derniers siècles, l’essor industriel et l’exploitation intensive du charbon (souterraine et à ciel ouvert) ont joué un rôle capital dans la transformation du paysage. L’intégration dans un SIG de données relatives à la croissance urbaine historique et aux impacts humains associés a permis de mettre en évidence l’existence de processus relevant de la géomorphologie anthropique, en lien avec l’urbanisation. L’approche holistique (caractérisation des paysages historiques) utilisée ici pour identifier les changements topographiques induits par les sociétés, permet d’obtenir une vue générale de l’effet cumulatif des différentes activités humaines. Une classification des Unités Descriptives Paysagères en fonction des impacts anthropiques est également proposée.

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Notes de la rédaction

Article soumis le 10 novembre 2009, accepté le 15 juin 2010

Texte intégral

Texte intégral en libre accès disponible depuis le 01 octobre 2012.

The financial support from the History of Pécs Foundation is gratefully acknowledged. Thanks are also due to the reviewers, Richard McIntosh (university of Debrecen) for correcting the English version of the paper, and Marie-Françoise André (university Blaise-Pascal Clermont-Ferrand 2) for correcting the French texts.

Introduction

1The immediate environs of major settlements with a long history are usually particularly good examples of historic landscapes. Historic landscape is defined in the European Landscape Convention (Council of Europe, 2000) as “an area, as perceived by people, whose character is the result of the action and interaction of natural and/or human factors”. Historic landscapes incorporate the evidence of past human activities in a complex fashion, through the combination of their direct and indirect impacts (discerned in the modified operation of biophysical processes). Human impact related to urbanisation, coupled with other human-induced transformations, is often clearly manifested in topography (Goudie, 2006). For instance, settlements are gradually extending over areas previously under agricultural land use and topographic and hydrological conditions adjusted to the purposes of cultivation influence housing developments. The manifold impacts of human activities on topography in Hungary reached their peak in the 20th century and have been intensively studied recently. Today, anthropogenic geomorphology is an integral part of geography curricula at most universities (Lóczy and Sütő, 2010 ; Szabó et al., 2010). A map of direct human impact has been prepared recently covering the whole country (Lóczy and Pirkhoffer, 2009).

2In the less densely inhabited outskirts of Pécs, a Southwest-Hungarian city of medium size by Central European standards (fig. 1) traces of agricultural land use are preserved in urban areas, while locally large-scale hard coal mining (both underground and opencast extraction) has become the decisive landscape-forming influence. The present paper relies on a range of previous studies (including Czigány et al., 1997 ; Nagyváradi, 2000 a and b, 2001 ; Pirkhoffer, 2005 ; Lóczy et al., 2005, 2006 ; Ronczyk and Trócsányi, 2006 ; Ronczyk and Wilhelm, 2006 ; Lóczy, 2008 ; Gyenizse et al., 2008, 2009 ; Gyenizse, 2010) on human impact affecting the landscape in the study area. The research has practical applications as it either promotes the preservation of historic landscape character or helps to find best practice for landscape rehabilitation, the most urgent tasks in the environmental policy of the local government of Pécs today. Regional planning is founded on the survey of the legacy of mining activities and the elimination of deleterious impacts as well as the preservation of the valuable legacy of viticulture. Through the careful design and implementation of land rehabilitation measures, new spaces are created for urban development and the quality of the urban environment can be improved (Toy and Hadley, 1987).

3The paper intends to provide a comprehensive picture of topographic changes in an urban landscape with their environmental implications. Answers are sought to the following questions : what kinds of human activities have shaped the landscape during the history of Pécs ? What cumulative human impact arises from their interactions and to what extent does it modify natural geomorphic processes ? How can this impact be mapped and assessed using a GIS system ? How to typify landscape dynamics driven by human action and how to represent them on a map ? In the first part the impacts of various human activities are surveyed individually and then an attempt is made at their integration. The identification of the nature of changes and their interactions allows a classification of overall landscape dynamics.

Fig. 1 – Location of Pécs in Europe and in Hungary.
Fig. 1 – Situation de Pécs en Europe et en Hongrie.

Fig. 1 – Location of Pécs in Europe and in Hungary.Fig. 1 – Situation de Pécs en Europe et en Hongrie.

Methods

4There are useful holistic methodological approaches to the evaluation of landscape change, including Historic Landscape Characterisation (HLC, in England; Clark et al., 2004) or Historic Landscape Assessment (HLA, in Scotland; Fairclough and Macinnes, 2003; Rippon, 2004). Historic Landscape Characterisation (HLC) is a framework devised to record past impacts in the contemporary setting and to document historic landscape features as parts of the modern environment, particularly for landscape conservation purposes. Instead of rural landscapes, a method based on the HLC approach is applied here to urban and suburban landscapes, including agricultural and forested areas located within the administrative boundary of the city. Human impact on the landscape is usually classified (Lóczy and Sütő, 2010) as : occurring during construction or operation activities ; temporary or long-term ; being intentional or accidental ; direct or indirect ; having single or cumulative effects ; reversible or irreversible. According to the HLC concept (Fairclough and Macinnes, 2003), landscape change analysis (here restricted to the study of topographic change) should focus on : present-day landscape character as created by past (human) action (an historical perspective) ; mapping of the distribution of impacts, areas affected by change ; all implications of (topographic) change to the landscape. A relevant precedent for the historic evaluation of human impact on the landscape can be found in the United Kingdom. The pilot study of Stratford Town’s Urban Edge is carried out for policy planning purposes by the Warwickshire County Council (2005) in collaboration with the Living Landscapes Project. The study identifies Landscape Description Units (LDU) and renders grades of landscape sensitivity (the capacity of each individual LDU to accept change) to them based on fragility and visibility indicators. Aesthetic impacts have also received increased attention in landscape change studies in Eastern Central Europe recently (for instance, Sklenička and Kašparová, 2008).

5In the present study, the spatial distribution of topographic impacts resulting from various human activities is surveyed in the field and supplemented by information from archive and present-day map sources. For the spatial distribution of anthropogenic interventions, GIS modelling was applied in Idrisi Kilimanjaro program. A series of digital historical maps of the same resolution are produced for each type of human impact and their combinations in the administrative area of Pécs as presented in tab 1. The temporal resolution of the survey was adjusted to the main sources of spatial information, i.e. the archive maps of the Hungarian military surveys. Aerial photographs (Székely, 2001) were interpreted for land cover identification and build-up density estimation, corrected by field checking. The vector-system base maps are converted into grid maps and the mapped information is reclassified according to the scoring system shown in tab 1. Rating is based on the degree the given human impact controls landscape character (score 5 means highest degree and 1 means minimum intervention, inevitable to occur in the neighbourhood of a city). Landscape Description Units are identified on the basis of maps of historical urban expansion (fig. 2) and according to the extent of cumulative human impact on the landscape. Partial scores for each human impact traceable in the unit are added up to produce a score of cumulative impact. Based on international literature [such as Highways Agency (UK), 2007, 2009], the great diversity of landscape transformation processes is reduced to the most significant types. The spatial distribution of the types of cumulative human impact and the classification of Landscape Description Units by their dynamics are shown in fig. 12. Below we provide a brief introduction to the history of human impact on the territory of Pécs (162.61 km²), a memoir to the map representations in the figures. In the next step interrelationships between various human impacts are assessed.

Fig. 2 – The urban growth of Pécs between the late 18th century and the late 20th century reconstructed from maps of the Military Surveys.
Fig. 2 – Reconstitution de l’expansion urbaine de Pécs entre la fin du XVIIIe siècle et la fin du XXe siècle d’après les cartes d’état-major.

Fig. 2 – The urban growth of Pécs between the late 18th century and the late 20th century reconstructed from maps of the Military Surveys.Fig. 2 – Reconstitution de l’expansion urbaine de Pécs entre la fin du XVIIIe siècle et la fin du XXe siècle d’après les cartes d’état-major.

Urbanisation and its impacts

6Human settlement in the area dates back to ca. 2000 BC but urbanisation only began in the 4th century AD, under the Romans. The Roman city of Sopianae was located southwest of the present-day centre of Pécs, while its cemetery was to the north. Among the physical potentials which promoted settlement, the Mecsek Mountains is rich in building stone, karstwater, wood and game and the swamps of the Pécs Basin were also abounding in wildlife (Gyenizse, 2010). The most valuable monuments from Roman times, the 4th-century early Christian tombs and grave chambers, are included in the UNESCO World Cultural Heritage list. The first descriptions and map representations of the built-up area of Pécs date from the 11-13th centuries, when the city developed as an Episcopal centre and the distribution of church buildings and properties governed urban growth. Rather exceptionally among the medieval cities of Hungary, no congested structure emerged as the bishop’s lands intercalated between built-up areas could not be developed for housing. The city suffered war damage on several occasions. After the Mongol Raid of AD 1241-1242, city walls were erected to encircle the Bishop’s castle as an inner fortification and a walled city of 697,000 m2 area as an outer fortification. Although the city was never besieged, further destruction followed particularly in the first and last periods of the Ottoman Occupation (1543-1686). At the same time, the Hungarians driven out from the city had to settle on the footslopes of the Mecsek Mountains, which had been an agricultural land until then. Intense economic development only started in 1780, when Pécs became a Free Royal Town, where food, wood, leather and ceramic industries based on local resources emerged. Industries were concentrated around karst springs in the valleys of the Mecsek foothills. The 1 :20,800 scale map of the First Military Survey (drawn in 1783-84) is the first reliable source for the reconstruction of urban development (Gyenizse, 2010). Digitising and statistically evaluating this map, it is estimated that the total built-up areas of Pécs and the villages which now belong to the city amounted to 2 km2 at that time (fig. 2). In the 19th century, workers lived in the close neighbourhood of their working places. On the mountain footslopes, northeast of the city centre, miners’ colonies were spread. Industrial plants occupied agricultural areas and urban expansion in an east to west direction was also considerable. By the time of the Second Military Survey (1856-60) the city area reached 3.3 km2 and by the time of the 3rd survey (1880-81) 4.4 km2 (Gyenizse, 2010 ; fig. 2). In the densely built-up areas the landfill of garbage, ash and slope deposits reached up to 1.5 m depth (Erdősi, 1987). To this, another 0.5-1 m of rubble was added during the 20th century. Urban soils are usually strongly compacted, their aeration and biological activity are poor and infiltration capacity is low (at present, construction rubble is disposed in a nearby sand quarry under regulated conditions).

7In the early 20th century large-scale land drainage in the south, in the Pécs Basin, also created reclaimed surfaces for urban development. The expansion of sealed surfaces along the streams of the Mecsek foothills has brought about changes in hydrological conditions. As urbanisation proceeded, physical interventions, like stream diversion, channelization and conduct of runoff in pipes became increasingly common (fig. 3) and this relocated flooding and erosion problems downstream into more densely built-up areas with higher vulnerability. Surface sealing and pipelined runoff in densely built-up areas contributes significantly to flash flood hazards (Czigány et al., 2009). The deposits washed down by flash floods from hillslopes to the city centre often hinder transport. In a city without any river deteriorated water quality and poor ecological functioning of streams have serious consequences. As more and more vineyards were converted to building plots, new roads had to be built to access more remote areas and earthworks (terrain levelling and macro-terracing) became necessary to make plots suitable for construction (for their analysis see the section on viticulture). Under socialism Pécs as a coal-mining centre acquired further administrative functions and experienced population growth and spatial expansion. The GIS-aided interpretation of topographic maps from the 1950s shows a built-up area of 13.1 km2 (Gyenizse et al., 2009). Subsequently, both hard coal and uranium ore mining exerted a decisive influence on the economic and social life and even on the urban morphology of the city of Pécs (Lovász and Nagyváradi, 2000). The demand for labour force called for an expansion of housing estates : to the south of the centre, the ’Garden City’, accommodating 60,000 people at its peak, and the ’Uranium City’ for ca 10,000 uranium mine workers and family members (Pirisi and Trócsányi, 2006). Number of city population has reached 185,000 by the end of the 20th century in a built-up area of 27.2 km2 but after mine closures it dropped to 161,000 (in 2009, the number of population was 156,974). However, council housing stopped with the change of the political system at the end of the 1980s. Further, housing development took place in the 1960s and 1970s along the roads to the villages which were earlier administratively annexed to the city and around the turn of the millennium in former vineyards.

Fig. 3 – Hydrological impacts of urbanisation in Pécs.
Fig. 3 – Impacts hydrologiques de l’urbanisation à Pécs.

Fig. 3 – Hydrological impacts of urbanisation in Pécs. Fig. 3 – Impacts hydrologiques de l’urbanisation à Pécs.

1: once waterlogged area, drained in the 19-20th centuries; 2: artificial lake; 3: stream in artificial channel, canal; 4: covered stream bed; 5: spring dried or with considerably reduced yield; 6: built-up area.
1 : secteur marécageux drainé aux XIX-XXe siècles ; 2 : lac artificiel ; 3 : écoulement dans un chenal artificiel, canal ; 4 : lit de cours d’eau enfoui ; 5 : source asséchée ou à débit considérablement réduit ; 6 : zone construite.

8The variations in dwelling density created zones in the city structure (Gyenizse, 2010). Maximum surface sealing is typical in the city centre (70-80 %), which can be regarded an ’anthropogenic desert’ with urban soils on thick landfill and an extreme microclimate. The densely built-up residential-industrial-commercial zone has typically 50-60 % paved surfaces. Land levelling and hydrological changes also affected this zone. In the family home areas of former agricultural land (mostly in vineyards), 10-30 % of the surface is sealed. Here, traces of surface modifications by agriculture are still found.

Viticulture and its impacts

9On the southern slopes of the Mecsek Mountains, grapes and wine production dates back to Roman times, more exactly to the rule of Emperor Probus (276-282 AD), when plantations were permitted in the province (Majdán and Pálfi, 2008). The first impact of grape plantation was the clearing of woodlands on southerly slopes, a land use change with far-reaching environmental consequences, among others, regarding soil erosion. In Mediaeval times, vineyards surrounded the built-up areas, where the surface was gradually modified (slopes were terraced and drainage structures were built). As attested by the descriptions of Turkish travellers and taxation documents, in Mediaeval times wine production was the main source of income for most of the inhabitants. It is estimated that in the 1680s the area of vineyards amounted to ca. 137 ha (Szabó, 1958). Further estimates for vineyard area can be made from the military survey maps. However, at the end of the 19th century, the phylloxera epidemic led to the decline of viticulture. Most of the vineyards were abandoned and sold as building plots (see above).

10On slopes of 10-12 % inclination, terraces (fig. 4) were common practices of erosion control in traditional vineyards (Zanathy et al., 2002). In addition to terraces built across the slope, downslope terraces along field boundaries were also established. Micro-topography was fundamentally transformed by the terraces, which had an average riser height of 0.5-1 m (exceptionally more than 2 m). Distribution of terraces regarding elevation (fig. 5) and slope inclination (fig. 6) shows striking similarities. Terraces (of all kind, undistinguished whether established for construction or for vineyard cultivation) are most abundant at the elevation of 170-260 m and on slopes of 10-30 %. When distinguishing among terraces of different functions (constructional or viticultural) and focusing on large terraces (with risers higher than 2 m and flats wider than 10 m), however, a different spatial distribution was found. Constructional terraces dominate below an elevation of ca. 160 m and on slopes less than 5 %. Vineyard terraces appear at elevations between 160 m and 210 m and on 5-10 % slopes becoming predominant above 210 m and on slopes steeper than 10 %.

Fig. 4 – Agricultural and constructional terraces in Pécs. 1: major terraces; 2: built-up area.
Fig. 4 – Terrasses agricoles et construites à Pécs. 1 : principales terrasses ; 2 : zone construite.

Fig. 4 – Agricultural and constructional terraces in Pécs. 1: major terraces; 2: built-up area. Fig. 4 – Terrasses agricoles et construites à Pécs. 1 : principales terrasses ; 2 : zone construite.

11Related to the highly developed traditional viticulture, there is an extensive multi-storey system of wine cellars with storage and shelter functions under the city centre. Cellars were usually cut into unconsolidated Upper Miocene-Pliocene sandy deposits at 6-10 m depth below the surface (Balázs and Kraft, 1998). Under the Ottoman occupation (1543-1686 AD), this maze of galleries was vital for the survival of the population. The expansion of the cellar network continued up to the phylloxera epidemic of the late 19th century. In the 19th century the number of the cellars under the city amounted to 1300, their total length to more than 50 km and they had a total volume of 280,000 m3 (Sallay, 2006). Because re-plantation after the phylloxera was only partially successful on the one hand and the slopes of the Mecsek began to be developed for housing on the other hand, the demand for wine storage facilities dropped and most of the cellars became abandoned. They turned into a geomorphological hazard when increased load from housing and traffic as well as from infrastructural (public utility) development induced a series of collapses and inundation of cellars. Surveyed in the 1970s, some cellars were backfilled but new ideas for utilisation also emerged. The champagne factory established by Lőrinc Littke in 1853 now owned by a Swedish company, disposes a 5-storey cellar system of 2.5 km total length down to 15 m below the surface. A minor proportion of wine cellars has been restored and equipped with modern facilities for catering and cultural purposes.

Fig. 5 – Distribution of the area of major terraces by elevation above sea level.
Fig. 5 – Distribution spatiale des principales terrasses en fonction de l’altitude au-dessus du niveau de la mer.

Fig. 5 – Distribution of the area of major terraces by elevation above sea level. Fig. 5 – Distribution spatiale des principales terrasses en fonction de l’altitude au-dessus du niveau de la mer.

1 : all terraces ; 2 : constructional terraces ; 3 : viticultural terraces.
1 : totalité des terrasses ; 2 : terrasses construites ; 3 : terrasses viticoles.

Fig. 6 – Distribution of the area of major terraces by slope inclination.
Fig. 6 – Distribution spatiale des principales terrasses en fonction de la pente.

Fig. 6 – Distribution of the area of major terraces by slope inclination. Fig. 6 – Distribution spatiale des principales terrasses en fonction de la pente.

1 : all terraces ; 2 : constructional terraces ; 3 : viticultural terraces.
1 : totalité des terrasses ; 2 : terrasses construites ; 3 : terrasses viticoles.

Transportation and its impacts

12As with other historic landscapes, road cuttings and embankments have significantly transformed topography in the surroundings of Pécs as well. The resulted fragmentation is remarkable in several areas. Historically, transportation lines can be studied since the First Military Survey (fig. 7). This kind of information is represented on military maps fairly accurately since roads are essential infrastructural conditions for the design of army manoeuvres (the map sheet, however, only shows major traffic routes). Even some hollow roads are depicted on the map, hollow roads necessarily developed along cart tracks leading from the city to vineyards over sloping terrains of weathered or unconsolidated rocks (Gyenizse, 2010). South of the Pécs Basin, in the Baranya Hills, a dense network of hollow roads were cut into loess while, in the eastern outskirts, the Miocene sand surface was dissected by a road network since the 18th century. Some of them are still in use today but others disappeared with the decline of viticulture at the end of the 19th century. In the swampy Pécs Basin, embankments had to be raised for roads even centuries ago. The railway connections were built in the second half of the 19th century.

Fig. 7 – Engineering geological sketch of the city centre of Pécs with location of cellars (after Sallay, 2006).
Fig. 7 – Schéma géotechnique du centre ville de Pécs avec localisation des caves (d’après Sallay, 2006).

Fig. 7 – Engineering geological sketch of the city centre of Pécs with location of cellars (after Sallay, 2006). Fig. 7 – Schéma géotechnique du centre ville de Pécs avec localisation des caves (d’après Sallay, 2006).

1: Palaeozoic metamorphic rocks; 2: Miocene-Pliocene sands; 3: Quaternary sands and sandy silt; 4: Quaternary sands with gravels and debris; 5: Quaternary clayey debris; 6: anthropogenic landfill; 7: cellar; 8: mean groundwater table.
1 : roches métamorphiques primaires ; 2 : sables mio-pliocènes ; 3 : sables et limons sableux quaternaires ; 4 : sables et graviers quaternaires ; 5 : argiles quaternaires ; 6 : remblais d’origine anthropique ; 7 : cave ; 8 : niveau moyen de la nappe phréatique.

13The expansion of the road network can be followed from military survey maps (fig. 8). A GIS analysis was applied to reveal relationships between road network density and elevation (fig. 9) as well as road density and slope inclination (fig. 10) for the end of the 18th century and today. For the study of spatial distribution, the width of the surface modified by road construction was taken to be 10 m as an average and total areas were computed. On both diagrams the roads of the basin running on embankments are distinct from hollow roads typical on higher (above ca. 140 m above sea level) and sloping surfaces (above 5 % inclination). Most of the hollow roads, which were formed in the 18th century, led up to the vineyards of the Middle Pliocene marine terraces (160-250 m above sea level) bordered by 10-30 % slopes. In the 18th century, the road network did not encroach onto higher and steeper slopes (except for a main road leading to the north across the mountains). Only in the late 20th century, when family homes were built on such slopes, access roads were cut in larger numbers at this level.

Fig. 8 – Roads running in cuts and on embankments in Pécs.
Fig. 8 – Voies de communication empruntant des tranchées et des digues à Pécs.

Fig. 8 – Roads running in cuts and on embankments in Pécs. Fig. 8 – Voies de communication empruntant des tranchées et des digues à Pécs.

1: railway lines with embankments and cuts; 2: major hollow roads and road cuts; 3: built-up area.
1 : voies ferrées sur digues et tranchées ; 2 : routes principales situées dans des dépressions et tranchées routières ; 3 : zone construite.

Fig. 9 – Distribution of roads in cuts and on embankments by elevation above sea level in the late 18th and late 20th centuries.
Fig. 9 – Distribution spatiale des routes installées dans des tranchées et sur des digues en fonction de l’élévation au-dessus du niveau de la mer à la fin des XVIIIe et XXe siècles.

Fig. 9 – Distribution of roads in cuts and on embankments by elevation above sea level in the late 18th and late 20th centuries. Fig. 9 – Distribution spatiale des routes installées dans des tranchées et sur des digues en fonction de l’élévation au-dessus du niveau de la mer à la fin des XVIIIe et XXe siècles.

Fig. 10 – Distribution of roads in cuts and on embankments by slope inclination in the late 18th and late 20th centuries.
Fig. 10 – Distribution spatiale des routes installées dans des tranchées et sur des digues en fonction de la pente à la fin des XVIIIe et XXe siècles.

Fig. 10 – Distribution of roads in cuts and on embankments by slope inclination in the late 18th and late 20th centuries. Fig. 10 – Distribution spatiale des routes installées dans des tranchées et sur des digues en fonction de la pente à la fin des XVIIIe et XXe siècles.

Mining and its impacts

14The modest beginnings of the long history of coal mining (Szirtes, 1994) meant the manual working of surface outcrops started in 1782. As the coal reserves became known from geological exploration, however, shafts for underground mining were opened (the first by German entrepreneurs in 1846). At first, large-scale extraction served the purposes of the First Danube Steam Shipping Company (DDSG) and then the Hungarian State Railways (MÁV). For the whole of the coal basin, 100 Mt of workable reserves were explored. Underground mining was typical between the World Wars and the number of new shafts grew rapidly, mostly in the immediate vicinity of built-up areas (fig. 11). At that time, spontaneous combustion was not an uncommon phenomenon on the spoil heaps of shafts and air quality soon deteriorated over the miners’ settlements, which were naturally built next to the shafts. In the 20th century, hard coal was also used for gas manufacturing (for street lighting) and electricity generation. The mines suffered no damage worth mentioning in World War II. After 1950, coking coal was supplied for the iron and steel industry of Dunaújváros on the Danube. At the time of the peak of coal production (in the late 1950s and early 1960s), a huge plume of air contaminated with sulphur-dioxide could be detected over several kilometres along the northern margin of the residential areas in the city of Pécs. By the 1980s, coal mining became unprofitable and underground mines were closed one after the other. Similarly to other mining areas (e.g., Hannan, 1995), the most remarkable impact of underground mining was the accumulation of mining waste in numerous scattered spoil heaps. Their total area amounts to 150 ha. According to model predictions (TOTAL Kft., 1997), the compaction of spoil heaps is expected to cease within 5-6 years. Even within this time span, rising groundwater levels may lead to slope instability and minor slumping may occur (Haigh, 1978). Spoil heap rehabilitation was achieved partly through spontaneous processes and partly by means of planned reclamation measures (Lóczy et al., 2007).

Fig. 11 – Impacts of mining in Pécs.
Fig. 11 – Impacts de l’activité minière à Pécs.

Fig. 11 – Impacts of mining in Pécs. Fig. 11 – Impacts de l’activité minière à Pécs.

1: landfill by rubble, spoil or sludge; 2: area of wine-cellars; 3: undermined area, ground subsidence < 10 m; 4: damage to buildings by rising groundwater table; 5: built-up area.
1 : décharge de gravats, déblais et eaux usées ; 2 : secteur des caves à vin ; 3 : zone de sapement, subsidence < 10 m ; 4 : dommages aux bâtiments par remontée de la nappe phréatique ; 5 : zone de construction.

15A less direct but hardly avoidable accidental impact of underground mining is surface subsidence. By the 1970s, deep shafts and galleries represented a significant mass deficit at depth, which extended gradually upwards to the ground surface. The deeper the shafts reached, the larger the radius of possible ground surface subsidence could grow. The scientific study of this process was the first achievement of ’anthropogenic geomorphology’ in Hungary (Erdősi, 1987). Erdősi’s investigations revealed the mechanisms of compaction and the surface expressions of mining hollows. The conditions of the revegetation and surface stabilisation of spoil heaps has been also examined (summarised in Lehmann, 2008). The impact of mining on the built-up environment is described in an engineering geological study (Balázs and Kraft, 1998), where zones of land subsidence in the northern areas of the city are identified. The largest subsidence trough extends over an area of 13.5 km2 with a maximum surface-level drop of 27 m (fortunately, no residential area is directly affected by movements on this particular site). According to surveying data, step-like vertical displacements are locally accompanied by horizontal movements amounting to 1 m over 130 years (Balázs and Kraft, 1998). They are particularly dangerous for transmission pylons. As opposed to ground subsidence, thousands of dwellings are affected by horizontal displacements but only relatively few of them (ca. 300), those built upon fault-lines, have been cracked so seriously that they became uninhabitable. However, structures which had been built according to the building regulations have survived the movements without major damage, possibly suffering some tilting only. According to F. Erdősi (1987), in the vicinity of the Mecsek Mountains, 135 Mm3 of earth was moved by mining activities, most of it by opencast mining, since World War II. The biggest, almost 200-m deep, opencast pits are now being reclaimed at Vasas (an eastern suburb) and in the Karolina Valley of Pécs.

16Opencast mining operations in the Karolina Valley began in 1968 (Szirtes, 1994). The gradually expanded mine pit reached a length of 1200 m and a width of 600 m, from where ca. 15 Mm3 of hard coal had been extracted before it was closed down in 2004. Ca. 13 Mm3 of waste were removed and stored next to the pit, in two spoil heaps (TOTAL Kft, 1997). A maximum relief of more than 250 m was created from the floor of the pit to the highest point of the spoil heap. There is hardly sufficient spoil to fill in the pit, which collects surface and underground waters from a catchment area of 12.5 km2. The natural drainage areas are changed as streams were diverted. The broader hydrological impacts of mining are also remarkable. Altogether, 420 wells and 25 springs ran dry as a result of mining activities, while the discharge was considerably reduced in the case of 38 springs, while mine water inflow increased the discharge of other streams. After the mines were closed, a spectacular rise in groundwater table followed. Beginning with 1997 lawsuits started to attain compensation for wetting damage in houses. Until 2001, damage was confirmed in 113 such cases. The inundation of cellars and water-meter pits became common and septic tanks fill at increased rates. In the case of the Karolina pit, since mine closure the pit is gradually filling up with water and a pond soon appeared. After the exceptionally rainy year of 2005 (when annual precipitation approached 900 mm as opposed to the long-term annual average of 750 mm) water table rose to ca. 145 m (Lóczy et al., 2006). Pumping of water out of the pond into the closest water-course started but this raises further environmental problems since the dissolved salt content of pond water is above the tolerable limit. Partial landfilling and slope drainage and stabilisation could amend the situation. In the future, the reclaimed pit can be utilised for recreational and cultural purposes. Basic reclamation is an urgent task. The continuous retreat of gullies around the pit and on spoil tip surfaces is already a warning sign for geomorphologists. Naturally, the wide expanses of derelict land are also detrimental from a landscape ecological aspect. Biologists are worried about the favourable conditions they present for the spreading of invasive plants like ragweed (Ambrosia artemisiifolia). Closely associated with mining, the operation of the Pécs Power Plant (built between 1955 and 1959) also resulted in substantial changes in the landscape : fly-ash was deposited in sludge reservoirs (half a million tonnes per year). Its disposal represented large-scale landfill in the Tüskésrét local depression area of the basin floor, created surfaces to be reclaimed and demanded stream diversions. When all coal mines closed down in 2004, the power plant was converted to biomass fuelling and land rehabilitation measures were also launched at the sludge reservoirs, where wind erosion reached a considerable extent (Lóczy et al., 2006).  

Conclusions

17The basic types of environmental impact above were assessed individually, grouped by the human activities (housing and transport development, vineyard cultivation or coal mining) from which they originated (fig. 3, fig. 4, fig. 8 and fig. 11). Through superimposing the spatial distribution of individual impacts, a cumulative assessment is made (fig. 12). Fig. 12 shows that there are considerable spatial overlaps between the various impacts. The mere spatial superposition (or even only juxtaposition), however, supports the assumption that the impacts interact, feedbacks may exist between them, including positive ones, and they jointly influence ’natural’ (biophysical) geomorphic processes in the study area (tab. 1). However, a more appropriate, as yet less elaborated approach would be to regard human action as part (and locally the decisive factor) of the geomorphological system (Urban, 2002 ; Lóczy and Sütő, 2010).

Fig. 12 – Cumulative impact of human activities on the administrative territory of Pécs.
Fig. 12 – Impacts cumulatifs des activités humaines sur le territoire de Pécs.

Fig. 12 – Cumulative impact of human activities on the administrative territory of Pécs.Fig. 12 – Impacts cumulatifs des activités humaines sur le territoire de Pécs.

Greyscales show the scores of human impact (ranging from 0 to 25); for explanation, see tab. 1 column 3. Landscape Description Units by the dynamics of human impact : 1 : static conditions ; 2 : composite change ; 3 : dynamic change ; 4 : radical change.
Les échelles de gris montrent les valeurs exprimant l’intensité de l’impact humain (de 0 à 25) ; pour les explications, voir tab. 1 colonne 3. Unités paysagères descriptives en fonction de la dynamique de l’impact humain : 1 : conditions statiques ; 2 : changement composite ; 3 : changement dynamique ; 4 : changement radical

Tab. 1 – A typology of human impact in the administrative area of Pécs.
Tab. 1 – Typologie de l’impact humain dans le district administratif de Pécs.

Human activity

Major human impact

Landscape unit affected

Combined/ cumulative geomorphic impact

Influence on landscape change

Proposed mitigation

nature

rating (1 to 5)

housing development

surface sealing

3 to 5

historical city core, housing estates

altered runoff/ infiltration ratio

urban soil formation, extreme microclimate

replacing concrete and asphalt surfaces with stone paving

urban land-filling

3 to 4

historical city core

raised, loose surface

urban soil formation

reinforcing foundations

macro-terracing

4

housing estates, industrial-commercial zone

increased relief, surface instability, altered runoff routing

aesthetic damage, altered microclimate

supporting walls, buttressing, draining facilities

industrial and mining activities

opencast pits

5

mining zone

obliteration of all previous impacts, surface instability

major landscape scars, ponding, altered microclimate

landscaping, land reclamation, revegetation

shafts and galleries

2 to 3

mining zone

ground subsidence

altered drainage routing

backfilling, landscaping

spoil heap accumula-tion

5

mining zone

unnatural slope shapes, surface instability, erosion

surface desiccation, altered microclimate

landscaping, land reclamation, revegetation

industrial plot

4

industrial zone

surface levelling and sealing

air, water and soil pollution, vegetation loss, altered microclimate

after closure land reclamation, re-vegetation

sludge storage

5

power plant sludge reservoirs

landfilling and runoff modification

dust storm hazard

land reclamation, revegetation

transport

roads in major cuts and on embank-ments

4

within and outside built-up areas

surface sealing, new runoff routes, surface dissection, gully erosion

habitat fragmentation

grassing and shrubing slopes

agriculture

vineyard  terraces

4

old vineyards now with family housing

reducing erosion

soil/soil moisture conservation

cultural landscape conservation

cellar cutting in bedrock

2

historical city core

potential ground subsidence, caving in

none

backfilling or restoring for cultural or catering use

water management

stream diversion, regulation

3

historical city core, housing estates

artificial channels/pipes

loss of ecological corridors

stream restoration

swamp drainage

5

residential areas on basin floor

new drainage lines (ditches)

soil desiccation, loss of wetland habitats

none

Ground-water table reduction

1

housing estate

gradual ground subsidence

soil desiccation, compaction, vegetation loss

stone paving to increase infiltration

forestry

clear-cutting

3

undeveloped mountain slopes

runoff concentration, gully erosion and accumulation

soil desiccation, drier microclimate

selective clearance, afforestation

forest hiking

1

undeveloped mountain slopes

trampling

soil compaction, vegetation degradation

maintenance of marked foot-paths

meadowing

drainage

3

basin floor in the outskirts

-

loss of natural vegetation

-

arable farming

-

4

slopes and flats in the outskirts

levelling micro-topography

loss of natural vegetation and landscape pattern

optimising field pattern

18According to the spatial distribution and combination of human impacts, Landscape Description Units (Warwickshire County Council, 2005) can be delineated (fig. 12 ; for the sake of a complete land cover, tab. 1 and fig. 12 also includes forest and arable units, where human impact is minimal.) The most typical combination occurs in the old vineyards (orchards). Before human settlement these southerly slopes had been almost uniformly forested. Recently, however, following another major land use change in the 20th century, the long-established vineyard terraces were widened or locally replaced by macro-terracing for family home housing. At the same time, stream diversion and conduct in pipes were also often employed here. In undermined areas ground subsidence is often combined with modified runoff routing, while in residential districts surface sealing modifies runoff conditions. Broadly speaking, the extent of cumulative human impact is proportional to the duration of human use of landscape units on the one hand and to the frequency of land use changes on the other.

19On the basis of the reconstruction of the landscape changes induced by human activities,a holisticassessment seems to be to the purpose. In literature, landscapes are classified according to their dynamics in the following categories [modified after Highways Agency (UK), 2007, 2009] :

  • Static conditions (Class 1, fig. 12). In such areas no major land use change or human intervention has occurred over recent centuries. The forested southern slopes of the Mecsek Mountains, rising north of the city retained their seminatural vegetation type (oak and beech forests, karst shrub forests). Although forestry is practised here, the topography is not transformed to a considerable degree. The sensitivity of this static landscape to topographic change is low.

  • Composite change (Class 2, fig. 12). This type refers to areas where land use change has been infrequent but had considerable extents and proved to be enduring. Later changes are nested within the earlier landscape, preserve some of its characteristics and provide a palimpsest character to the landscape as the impacts of different land use classes are often superimposed upon each other. On flat surfaces of the Pécs Basinextensive (once forest- or shrub-covered) areas are used as arable land. The foothill forests were cut long ago to create space for vineyards, which recently acquired residential functions (family homes). Present-day landscape sensitivity is highest in this foothill zone of former vineyards, where extensive surfaces are exposed to erosion. One reason for this is the increase of relief as the walls of terraces created for housing development are much higher than in the case of agricultural terraces. Some former swamps and bogs in basin position were drained and converted into (still wet) meadows.

  • Dynamic change (Class 3, fig. 12). In this case, human impacts are constantly accumulating and keeping the landscape in the condition of permanent change. Urban development, for instance, involves constant relief alterations. Starting with landfill and various methods of surface sealing, construction activities brought about major transformations in the historical centre of the city. The spreading of built-up areas (housing estates and family home zones) involves a rapidly expanding belt of dynamic change around the centre. The instability of landscape conditions and thus landscape sensitivity are relatively high.

  • Radical change (Class 4, fig. 12). In radically transformed areas subsequent changes have removed most of the evidence of earlier stages in landscape evolution. In the environs of Pécs, hard coal mining (and previously stone and sand quarrying), the filling of the sludge reservoirs of the thermal power plant and some industrial developments resulted in fundamental topographic changes. Although land rehabilitation efforts in mining areas are underway, the impacts of human activities of this kind are often irreversible. Sensitivity (to erosion) is particularly high during the reclamation stage.

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Annexe

Version française abrégée

L’implantation de la ville de Pécs a bénéficié de conditions naturelles favorables. Les forêts riches en bois et gibier et les zones marécageuses riches en animaux aquatiques se trouvaient pratiquement sur place. Les côtes méridionales des Monts Mecsek assuraient un climat agréable, les sources apportaient suffisamment d’eau potable. Les matériaux de construction (bois, pierre) étaient également abondants. Dès la fin du XIXe siècle, l’exploitation du charbon et l’industrie et le commerce associés ont constitué la base de l’économie même si les sources des revenus les plus importantes de la ville étaient alors la viticulture et le commerce de vin. Les industries traditionnelles reposaient sur les matières premières et la main d’oeuvre locales. A partir des années 1850, l’importance de l’activité houillère a beaucoup augmenté. Ce fut la période de la construction des premières lignes ferroviaires qui s’est accompagnée du développement du commerce. A la fin du XIXe siècle, l’activité agricole (notamment viticole) de Pécs a été rejetée à l’arrière plan à cause du phylloxéra après lequel le commerce du vin a lui aussi décliné. A cette époque, l’évolution économique s’est accélérée, on a construit des briqueteries, brasseries, minoteries, usines de vin mousseux, ganteries et porcelaineries. La grande industrie s’est développée après la 2ème guerre mondiale.
On a construit la centrale thermique de Pécs de 1955 à 1959 dans la partie sud-est de la ville. Les cendres produites par son activité se sont accumulées dans des dépôts de schlamm (résidus du lavage du charbon) situés dans la partie la plus profonde du Bassin de Pécs. La surface de ces dépôts dépasse 230 ha. Les dépôts et les autres remblais ont modifié le relief d’origine. C’est la raison pour laquelle on a détourné les ruisseaux vers de nouveaux lits artificiels. La matière cendreuse et scoriacée des dépôts est caractérisée par son grain grossier et sa perméabilité élevée, ce qui provoque l’infiltration rapide des eaux pluviales et un contact permanent avec la nappe phréatique. Les sédiments sont très sensibles à l’érosion et notamment à la déflation à cause de leur nature meuble. Le boisement de ces espaces et la stabilisation des sols s’imposaient donc comme une nécessité. Les premières cartes et descriptions du centre de la ville datent de la période allant du XIe au XIIIe siècles. A l’époque, la structure de la ville était déterminée par la géographie des domaines ecclésiastiques, églises, monastères et paroisses.
Le premier lever cartographique militaire de Pécs et de ses environs a été effectué de 1783 à 1784 au 1/28 800. Cette carte représente clairement le centre entouré par les murailles, la ville extra muros ainsi que les rivières ou les ruisseaux et les routes indispensables à la vie quotidienne de la ville. La principale forme d’agriculture était alors la viticulture proche de la ville. L’expansion de la ville s’opéra au XIXe siècle en direction des zones industrielles, conservant la structure traditionnelle E-W. Des colonies minières étaient établies sur les pédiments situés au nord-est de la ville. Au cours de la première partie du XXème siècle, les banlieues ont complètement entouré le centre. La rivière Pécsi-víz fut aménagée et l’on a drainé les marais de la plaine alluviale. Dans la partie sud du bassin de Pécs, ces travaux ont abouti à la formation d’un quartier de maisons particulières relativement séparé de la ville. La ville s’est étendue également en direction des vignobles. Dès les années 1970 a commencé la construction de bâtiments de type HLM de 4 à 10 étages et d’édifices publics associés dans la partie sud de la ville.
Nous avons analysé l’effet simultané des processus de géomorphologie anthropique provoqués par l’agrandissement de la ville en utilisant un SIG. Nous avons déterminé les changements multitemporels de l’ évolution de la ville, des zones viticoles, de l’activité houillère,, des lignes de transport ainsi que les modifications du relief provoquées par ces activités humaines, en utilisant les cartes des trois levers cartographiques militaires et les cartes modernes. Une approche holistique (Caractérisation du Paysage Historique), utilisée ici pour identifier les changements du relief provoqués par les sociétés humaines, permet également d’obtenir une vue générale de l’effet cumulatif des activités anthropiques. Nous avons synthétisé dans un tableau l’intensité des divers impacts anthropiques et leurs combinaisons dans les différentes unités d’occupation du sol de la ville. Ce tableau dresse l’inventaire des conséquences des impacts anthropiques et rappelle les possibilités d’atténuation des dommages.

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Table des illustrations

Titre Fig. 1 – Location of Pécs in Europe and in Hungary.Fig. 1 – Situation de Pécs en Europe et en Hongrie.
URL http://geomorphologie.revues.org/docannexe/image/7989/img-1.jpg
Fichier image/jpeg, 248k
Titre Fig. 2 – The urban growth of Pécs between the late 18th century and the late 20th century reconstructed from maps of the Military Surveys.Fig. 2 – Reconstitution de l’expansion urbaine de Pécs entre la fin du XVIIIe siècle et la fin du XXe siècle d’après les cartes d’état-major.
URL http://geomorphologie.revues.org/docannexe/image/7989/img-2.jpg
Fichier image/jpeg, 412k
Titre Fig. 3 – Hydrological impacts of urbanisation in Pécs. Fig. 3 – Impacts hydrologiques de l’urbanisation à Pécs.
Légende 1: once waterlogged area, drained in the 19-20th centuries; 2: artificial lake; 3: stream in artificial channel, canal; 4: covered stream bed; 5: spring dried or with considerably reduced yield; 6: built-up area.1 : secteur marécageux drainé aux XIX-XXe siècles ; 2 : lac artificiel ; 3 : écoulement dans un chenal artificiel, canal ; 4 : lit de cours d’eau enfoui ; 5 : source asséchée ou à débit considérablement réduit ; 6 : zone construite.
URL http://geomorphologie.revues.org/docannexe/image/7989/img-3.jpg
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Titre Fig. 4 – Agricultural and constructional terraces in Pécs. 1: major terraces; 2: built-up area. Fig. 4 – Terrasses agricoles et construites à Pécs. 1 : principales terrasses ; 2 : zone construite.
URL http://geomorphologie.revues.org/docannexe/image/7989/img-4.jpg
Fichier image/jpeg, 216k
Titre Fig. 5 – Distribution of the area of major terraces by elevation above sea level. Fig. 5 – Distribution spatiale des principales terrasses en fonction de l’altitude au-dessus du niveau de la mer.
Légende 1 : all terraces ; 2 : constructional terraces ; 3 : viticultural terraces.1 : totalité des terrasses ; 2 : terrasses construites ; 3 : terrasses viticoles.
URL http://geomorphologie.revues.org/docannexe/image/7989/img-5.jpg
Fichier image/jpeg, 228k
Titre Fig. 6 – Distribution of the area of major terraces by slope inclination. Fig. 6 – Distribution spatiale des principales terrasses en fonction de la pente.
Légende 1 : all terraces ; 2 : constructional terraces ; 3 : viticultural terraces.1 : totalité des terrasses ; 2 : terrasses construites ; 3 : terrasses viticoles.
URL http://geomorphologie.revues.org/docannexe/image/7989/img-6.jpg
Fichier image/jpeg, 124k
Titre Fig. 7 – Engineering geological sketch of the city centre of Pécs with location of cellars (after Sallay, 2006). Fig. 7 – Schéma géotechnique du centre ville de Pécs avec localisation des caves (d’après Sallay, 2006).
Légende 1: Palaeozoic metamorphic rocks; 2: Miocene-Pliocene sands; 3: Quaternary sands and sandy silt; 4: Quaternary sands with gravels and debris; 5: Quaternary clayey debris; 6: anthropogenic landfill; 7: cellar; 8: mean groundwater table.1 : roches métamorphiques primaires ; 2 : sables mio-pliocènes ; 3 : sables et limons sableux quaternaires ; 4 : sables et graviers quaternaires ; 5 : argiles quaternaires ; 6 : remblais d’origine anthropique ; 7 : cave ; 8 : niveau moyen de la nappe phréatique.
URL http://geomorphologie.revues.org/docannexe/image/7989/img-7.jpg
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Titre Fig. 8 – Roads running in cuts and on embankments in Pécs. Fig. 8 – Voies de communication empruntant des tranchées et des digues à Pécs.
Légende 1: railway lines with embankments and cuts; 2: major hollow roads and road cuts; 3: built-up area.1 : voies ferrées sur digues et tranchées ; 2 : routes principales situées dans des dépressions et tranchées routières ; 3 : zone construite.
URL http://geomorphologie.revues.org/docannexe/image/7989/img-8.jpg
Fichier image/jpeg, 260k
Titre Fig. 9 – Distribution of roads in cuts and on embankments by elevation above sea level in the late 18th and late 20th centuries. Fig. 9 – Distribution spatiale des routes installées dans des tranchées et sur des digues en fonction de l’élévation au-dessus du niveau de la mer à la fin des XVIIIe et XXe siècles.
URL http://geomorphologie.revues.org/docannexe/image/7989/img-9.jpg
Fichier image/jpeg, 152k
Titre Fig. 10 – Distribution of roads in cuts and on embankments by slope inclination in the late 18th and late 20th centuries. Fig. 10 – Distribution spatiale des routes installées dans des tranchées et sur des digues en fonction de la pente à la fin des XVIIIe et XXe siècles.
URL http://geomorphologie.revues.org/docannexe/image/7989/img-10.jpg
Fichier image/jpeg, 116k
Titre Fig. 11 – Impacts of mining in Pécs. Fig. 11 – Impacts de l’activité minière à Pécs.
Légende 1: landfill by rubble, spoil or sludge; 2: area of wine-cellars; 3: undermined area, ground subsidence < 10 m; 4: damage to buildings by rising groundwater table; 5: built-up area.1 : décharge de gravats, déblais et eaux usées ; 2 : secteur des caves à vin ; 3 : zone de sapement, subsidence < 10 m ; 4 : dommages aux bâtiments par remontée de la nappe phréatique ; 5 : zone de construction.
URL http://geomorphologie.revues.org/docannexe/image/7989/img-11.jpg
Fichier image/jpeg, 260k
Titre Fig. 12 – Cumulative impact of human activities on the administrative territory of Pécs.Fig. 12 – Impacts cumulatifs des activités humaines sur le territoire de Pécs.
Légende Greyscales show the scores of human impact (ranging from 0 to 25); for explanation, see tab. 1 column 3. Landscape Description Units by the dynamics of human impact : 1 : static conditions ; 2 : composite change ; 3 : dynamic change ; 4 : radical change.Les échelles de gris montrent les valeurs exprimant l’intensité de l’impact humain (de 0 à 25) ; pour les explications, voir tab. 1 colonne 3. Unités paysagères descriptives en fonction de la dynamique de l’impact humain : 1 : conditions statiques ; 2 : changement composite ; 3 : changement dynamique ; 4 : changement radical
URL http://geomorphologie.revues.org/docannexe/image/7989/img-12.jpg
Fichier image/jpeg, 448k
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Dénes Lóczy et Péter Gyenizse, « Human impact on topography in an urbanised mining area: Pécs, Southwest Hungary », Géomorphologie : relief, processus, environnement, 3/2010 | 2010, 287-300.

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Dénes Lóczy et Péter Gyenizse, « Human impact on topography in an urbanised mining area: Pécs, Southwest Hungary », Géomorphologie : relief, processus, environnement [En ligne], 3/2010 | 2010, mis en ligne le 01 octobre 2012, consulté le 26 novembre 2014. URL : http://geomorphologie.revues.org/7989 ; DOI : 10.4000/geomorphologie.7989

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Auteurs

Dénes Lóczy

University of Pécs - Institute for Environmental Sciences - Ifjúság útja 6 - H-7624 Pécs - Hungary (loczyd@gamma.ttk.pte.hu)

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Péter Gyenizse

University of Pécs - Institute of Geography - Ifjúság útja 6 - H-7624 Pécs - Hungary (gyenizse@gamma.ttk.pte.hu)

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