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1997
10ème Colloque Européen de Géographie Théorique et Quantitative, Rostock, Allemagne, 6-11 septembre 1997
52

Soil pollution in an urban area : a GIS approach

Daniel Delahaye, Pierrich Folligne, Yves Guermond, Jean-Pierre Vapaille et Renaud Zambeaux

Texte intégral

1The southern bank of the river Seine, in the urban area of Rouen, was an important industrial suburb in the 19th century and during the first half of the 20th century up to the urban rehabilitation which began around the seventies. The main industries were foundries and mechanical engineering plants, and later, in the harbour districts, oil factories and naphtha refineries. During the "reconstruction" period, after the second world war, and at the time of the "rehabilitation" , a lot of residential compounds, schools and playgrounds have been established, regardless of the nature of the soils.

2A great amount of the ancient industries were replaced by other plants, or by derelict land ; so the sequence of the different industrial uses and the nature of the chemical products involved, which have been stored or rejected cannot be easily defined.

3The studied area extends on three administrative districts : the left bank of Rouen city area, to the north, and two suburban districts, respectively Petit-Quevilly, to the west, and Sotteville, to the east.

Defining soil pollution

4The objective cannot go further than a mere estimation of the risks. The level of risk may be estimated on the one hand by the nature of soils, and on the other hand by the former location of the polluting activities (industrial or commercial), by the nature of these activities, and by the migration rate of the pollutants.

5The soil of the studied area is a uniform covering of a clayish and stony alluvial soil about 20 meters deep.

6The nature of the activities may be linked to pollution as shown by the following table :

(from BRGM 1995)

Table 1 : Chemical products used by different industries according to their activities

7This table 1 allows the creation of a technical data base, affecting a theoretical "index of risk" to the different activities, as shown in table 2.

A

B

C

D

E

F

G

H

I

J

Degree of solvability

2

1

1

2

2

2

2

3

2

3

Degree of danger

3

3

2

3

3

2

2

3

2

3

Solvability x Danger

6

3

2

6

6

4

4

9

4

9

Chemical products

ACTIVITIES

round average=

Index of risk

mineral chemistry

3

2

6

6

4

4

9

34

3

organic chemistry

6

3

2

4

9

4

9

37

4

plating

6

2

6

4

9

27

3

woodwork

3

4

9

9

25

3

thermo-processing

6

2

6

4

9

9

36

4

leather - textile

3

4

9

4

9

29

3

petroleum

6

3

6

4

9

4

9

41

4

metal work

3

2

6

4

4

9

4

9

41

4

ore exploitation

6

9

15

2

legend : A hydrocarbons

B acid and base

C alkaline metals

D cyanide

E phosphorus

F chloral and organic compounds

G halogenic compounds

H mineral grease

I sulphide

J heavy metals

Table 2 : Potential risk of different activities

Locating the potential risk on a broad scale

8We have used the investigation method initiated by Frederic OGE (1994). The archives of the local administration keep record of all the dangerous activities, declared as such according to a law dating back from 1810. The archives have been studied from 1810 to 1936 - after that date, the preservation of the so-called "industrial secret" forbids public consultation of the archives -, and recorded in a historical data base.

9For each declared activity the name of the operator is given, as well as the nature of the activity, the full address, and the date of the administrative decree giving (or refusing) the licence to carry on the activity.

10From the second half of the 19th century onwards, and increasingly so as one comes nearer to contemporary times, the declarations are accompanied by diagrams and blue-prints showing more precisely the location of the workshops. For some important plants, it is sometimes possible to determine the location of the waste yard - more often a little quarry, at a short distance from the workshops and offices of the firm, which may be, incidentally, mentioned on the plan.

11A precise topographical chart is required to plot this information. The most efficient means to do so is to resort to the present day cadastral survey. For the three studied boroughs the survey dates from 1972, and has been more or less revised when needed, since that date. Unfortunately the digitalisation of the survey, recently established for the needs of the landed property tax, is not yet obtainable for the whole area for research purposes.

12The traditional survey is available in the format of 75 x 70.5 cm sheets for each "sector" at variable scales ( from 1/5,000 to 1/500 ), depending of the dimension of the sector. For each of the three boroughs, there is an aggregation map at the scale of 1/10,000.

13The system of co-ordinates used for the survey differs from the Lambert projection currently used in the maps produced by the IGN ( National Geographic Institute), notably the newly edited "Geo-Routes" data base, which gives all the streets of the French urban areas of more than 100,000 inhabitants. After we have digitalised the aggregation maps, an adjustment of this survey has been made according to the street pattern provided by "Geo-Route". This will be our reference map.

14The location of the former activities on the reference map is made difficult by the lack of precision in the geocoding of the traditional paper-survey. The complexity is increased by the evolution of the urban structure since the middle of the 19th century. An important change on this formerly agricultural suburb, heavily transformed by 19th century industrialisation, has occurred both in the built areas and the layout of the streets.

15The old survey maps of 1837 are not comparable to the present survey, and they must be complemented by blueprints of the boroughs, drawn by the services of the three city-councils around the end of the 19th century (but at different scales). The precise location of the polluting activities must be based on control points between these different maps, but complete and accurate similarity between the different topographical layers is, of course, not obtainable.

16The precision obtained is quite sufficient for the first aim of the GIS, which was to give - at a wide scale for the whole left bank of the urban area - a general outlook of the different levels of occurrence of a potential soil pollution. On the "vulnerability layer" the activities recorded from the inventory of the archives ("historical data bank") have been located (manually on the topographical reference map) and distinguished according to the index of risk given by the "technical data bank" (extract on table 2).

17The main profit of the GIS approach is to allow the overlay of these potential sources of soil pollution on the present day land use pattern. A land-use layer has been digitalised on Arc-Info on the same reference map, using different administrative and city-planning documents (fig. 1). The overlay illustrates clearly the possible soil pollution in dwelling areas, school premises, sport grounds, and green areas, for instance in Petit-Quevilly, on the western part of the meander.

18The polluting activities may be differentiated according to their dates of implementation (fig. 2).

19The first locations appeared on the main road in the centre of the meander, around the initial villages. In the middle of the 19th century, these activities consisted in transforming animal by-products, mainly grease, for the fabrication of soap and candles. Formerly scalded, this butchery waste was subsequently treated with sulphur acid.

20The textile industry involved the development of industrial chemistry : soda and sulphur acid were employed for the bleaching and dyeing of cloth. An important production of sulphur acid was obtained by the combustion of sulphur with saltpetre (sodium nitrate), which was soon replaced by lead-chambers, which induced an important increase of production.

21It appears from figure 2 that at the first stages industrialisation was immersed in the dwelling areas, but in later periods (since 1920), it grew mainly outside them, to become concentrated in industrial estates along the river, to the north (sea-harbour) and to the east (river-harbour).

A more detailed view at a narrow scale

22The target of the first stage of the GIS was the production of a tool for city planners to locate the places where chemical investigations were required before any new implementation of housing or public equipment (mainly for children). The GIS may be useful also at this second stage, provided that a complementary information could be obtained at a narrow scale. A zoom on the surroundings of the main street (fig. 3) offers 4 layers overlaid :

  • - the "Geo-Routes" network (reference system),

  • - the present constructions, according to the cadastral survey, located on the Geo-Routes system,

  • - the initial constructions, as revealed by the 1837 cadastral survey,

  • - the industrial areas, digitalised from the application forms for the licence of producing or storing dangerous substances, whenever the archives include a rough chart locating the industrial constructions, the yards, and even, sometimes, the exact places where the polluting products are stored.

23Of course the zooming procedures are only relevant for the areas presenting a higher risk of soil pollution, due to the high density of polluting industries or workshops, the high level of danger of some of the substances employed, the vulnerability of the soil or of the ground waters, or also the nature of the projected schemes of urban development.

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Bibliographie

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B.J. ALLOWAY (1990) Heavy metals in soils. London. Blackie
DOI : 10.1007/978-94-011-1344-1

BRGM (Bureau de la Recherche Géologique et Minière) 1995 Gestion des sites pollués

M.GULEA (1996 La pollution des sols en milieu urbain : Petit-Quevilly.Rouen. Département de Géographie. 60 p.

F. OGE (1995) Guide méthodologique Paris. Ministère de l´Environnement. 80 p.

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Table des illustrations

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Pour citer cet article

Référence électronique

Daniel Delahaye, Pierrich Folligne, Yves Guermond, Jean-Pierre Vapaille et Renaud Zambeaux, « Soil pollution in an urban area : a GIS approach », Cybergeo : European Journal of Geography [En ligne], Dossiers, 10ème Colloque Européen de Géographie Théorique et Quantitative, Rostock, Allemagne, 6-11 septembre 1997, document 52, mis en ligne le 19 mars 1998, consulté le 19 décembre 2014. URL : http://cybergeo.revues.org/1575 ; DOI : 10.4000/cybergeo.1575

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Auteurs

Daniel Delahaye

ddelah@osiris.univ-rouen.fr

MTG - University of Rouen. France

Articles du même auteur

Pierrich Folligne

MTG - University of Rouen – France

Yves Guermond

MTG - University of Rouen. France

Articles du même auteur

Jean-Pierre Vapaille

MTG - University of Rouen – France

Renaud Zambeaux

MTG - University of Rouen – France

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Droits d’auteur

© CNRS-UMR Géographie-cités 8504

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