Hazard Management in the Eastern Attica

NATIONAL TECHNICAL UNIVERSITY OF ATHENS SCHOOL OF RURAL & SURVEYING ENGINEERING CENTRE FOR THE ASSESSMENT OF NATURAL HAZARDS AND

PROACTIVE PLANNING

“Developing a Decision Support System for the Management of Natural and Man-Made Hazards in the Eastern Attica Prefecture. An Initial [Spatial] Inventory. ”

APRIL 2006

Table of Contents 1. The Scope of the Project. A brief introduction 2. The GIS environment and the Digital Map output

3-6 7-11

3. Seismological Data within the frame of a GIS for the area of Eastern Attica

12-22

4. Landslide Hazard

23-31

5. Flood Hazard Estimation

32-36

6. Documentation for the Data Layers contributed by the Laboratory of Remote Sensing, School of Rural and Surveying Engineering

37-40

7. Using GIS to create Hazard Maps for The Assessment of Cultural Heritage. The case of Eastern Attica

41-46

APPENDIX Map Map Map Map Map Map Map Map Map Map Map

1.1: 1.2: 1.3: 1.4: 1.5: 2.1: 2.2: 2.3: 2.4: 2.5: 2.6:

Topography, road network, hydrographic network Vegetation 2000 – Forest fires 1985 - 1992 Population 1951-1961 Buildings’ construction period Buildings’ main uses Soil erosion hazard Desertification hazard Landslide hazard Flood hazard Earthquake catalogs Peak Ground Acceleration – Seismicity zones (EAK)

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1. The Scope of the Project. A brief introduction.

The Centre for the Assessment of Natural Hazards and Proactive Planning undertook a project focusing on the “development of a decision support system for the management of natural and man-made hazards” in the Prefecture of East Attiki.

It is well established in the relevant research and policy community that Natural RiskDisaster management is a multifaceted process which requires the development of a comprehensive and integrated governance system. Detailed recommendations for the development of such a system however, lie outside the scope of this project. In this first stage the project has focused on the creation of an initial inventory of natural hazard data, an inventory of elements and structures under threat, as well as an inventory of the cultural heritage sites, in the study area. This inventory utilizes fully the capabilities of advanced technology techniques, namely that of Global Positioning Systems, Remote Sensing and Geographical Information Systems.

More specifically, the project reported here has focused on the following goals / actions: 1. Identification of the natural hazards that threat the study area in a permanent, seasonal or periodical basis, categorization and organization of them into groups & level. The main hazards investigated were: Earthquakes, Floods, Landslides, Forest Fires, Soil erosion, Desertification.

In addition to cultural heritage sites the series of elements and structures under threat and /or lifelines registered were: Transportation Network, Vegetation, Resident population, Buildings-Build up Space. The later two elements/structures can also be considered as Risk Factors.

2. Identification and location of the cultural landscapes that are situated in the study area, categorization and organization of them into groups & levels.

According to international conventions and national decrees, the cultural heritage includes the artefacts and mentifacts, even the ecofacts that exist within a specific area: a. Monuments b. Clusters of buildings c. Sites d. Mobile Objects e. Archival Material and Scientific Works f. ‘Non - material’ human creations relating to ‘memory procedures’ g. Remains

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h. Natural Features i. Geological & Physiographical Formations k. Natural Sites (specific areas highly valued) 3. a. Development of a GIS environment that will form the basis for the production of hazard maps related to the cultural sites within the authority limits of Eastern Attica Prefecture b. Development of a Personal Geodatabase intergrating all the available spatial and descriptive data The latest (2001) census data show that the study area of Eastern Attica Prefecture, which is located east of the city of Athens, covers a surface of c. 1.800 square kilometres and has a resident population of 410.000 inhabitants. It is the fourth biggest prefecture in Greece, with 20 municipalities and 26 communities. The Prefecture is considered as the fastest growing area in Greece. Apart from the large scale

infrastructure

elements

(e.g.

International

Athens

Airport

‘Eleftherios

Venizelos’, motorway ‘Attiki Odos’), two significant commercial ports (Rafina

and

Lavrio), services companies, energy production installations, five industrial zones and tourism sites along the 160 km of tourist coasts, the study area could be characterized as one of the richest location of cultural landscapes in Greece. Its proximity to Athens and its tourist development potential increase the necessity for a proactive disaster planning system.

Natural hazards are geological and environmental phenomena occurring at irregular intervals and at varying intensity. Some regions and/or locations are more at risk than others, depending on factors such as geology, topography and proximity to hazard sources. Disaster risk arises when hazards interact with physical, social, economic and environmental vulnerabilities. Today, scientific knowledge and advanced technologies are being applied for hazard risk reduction, including among others, innovative mitigation and risk communication techniques.

The various Laboratories of the School of Rural and Surveying Engineering - the Laboratory of Geography and Spatial Analysis, the Laboratory of Reclamation Works & Water Resources Management, the Remote Sensing Laboratory, the Laboratory of Structural Mechanics & Technical Works- and the Geodynamic Institute of the National Observatory of Athens have collaborated under the auspices of the Centre for the Assessment of Natural Hazards and Proactive Planning in order to

4

elaborate spatial and descriptive data and to integrate them in an initial inventory utilizing GIS technology.

Details for the various data and methodologies used can be found in the following sections of this report.

Section 2 outlines the GIS environment, the digital data structures and the Digital Map output of the project. The report was prepared by Professor K. Koutsopoulos, A. Zervakou, Geologist, PhD student and Dr. Th. Hadjichristos, Dr. Engineer, members of the Geography and Spatial Analysis Laboratory.

Section 3 describes the Seismological Data and the methods used to intergrate them in a GIS environment. The report was prepared by Dr. I. Kalogeras, Seismologist, Senior researcher at the Geodynamic Institute of the National Observatory of Athens.

Section 4 discusses the Landslide hazard history and describes the methodology used for the zoning of the hazard the report was prepared by the members of Structural Mechanics & Technical Works laboratory the Professor M. Sakellariou, Dr. M. Ferentinou, geologist, post-doc research and S. Karanasiou, postgraduate student In Section 5 the details of Flood Hazard estimation are presented and the data and methodology employed are analyzed. The section was prepared by Prof. G. Tsakiris, Panagiotis Siwras, MSc, Pistrika Aimilia, MSc, PhD student all members of the Centre for the Assessment of Natural Hazards and Proactive Planning.

Section 6 provides a through documentation for the Data Layers contributed by the Laboratory Of Remote Sensing. In particular it documents the data and the methodology for the Forest fires 1985-1992, Garbage, Urban areas, Forest areas, Mountains, Vegetation and Vegetation grouped and CORINE Land Cover data layers that can be found in the Personal Geodatabase of the project. The documentation was prepared by the members of the Remote Sensing Laboratory, Professor D. Argialas, P. Kolokoussis and Α. Tzotsos, Phd students.

Section 7 discusses the issues, problems and prospects in using GIS to create hazard maps for the assessment of cultural heritage with a particular focus on the case of Eastern Attiki. The Report was prepared by Dr Amanda Laoupi, Environmental Archaeologist – Archaeology of Natural Disasters, researcher at the Centre for the Assessment of Natural Hazards and Proactive Planning.

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The above mentioned members of staff, researchers and research students took part in the Research team of the project and provided the data and the expertise for its completion. As the project coordinator I would like to thank all the colleagues who have participated in this project and Dr. D. Zegginis the General Secretary of the East Attica Prefecture for their valuable cooperation for the duration of this project.

John Sayas Lecturer Project coordinator

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2. The GIS environment and the Digital Map output The Laboratory of Geography and Spatial Analysis of the School of Rural and Surveying Engineering of the National Technical University of Athens under the supervision of its director Professor K. Koutsopoulos was responsible for the following tasks:

2.1

Provision of digital data for the study area regarding the following: • • • • •

2.2

Hypsometric Contours (base map: topographic map of the Geographic Military Service (GMS), scale: 1:50.000) Hydrographic network (base map: topographic map of the GMS, scale: 1:50.000) Transportation network (base map: topographic map of the GMS, scale: 1:50.000) Primary roads network (base map: topographic map of the GMS, scale: 1:50.000 Local Authoritiy areas of the Attiki Prefecture (Metro Development Study, 1997)

Elaboration of a Geographical Information System.

The ArcGIS 9x, ArcInfo version, software was used for the development of the specific GIS application.

The project comprised the following stages.

• • • •

Input of Vector data Heads Up Digitizing Correction of Geometric and Descriptive data Correction and amendment of data through digitization

2.3

Data Management

2.3.1 Elaboration of a Personal Geodatabase: Geodatabases are a new form used for the storage of spatial data specially designed for ArcGIS. They consist of a set of Feature Classes. A Personal Geodatabase can be utilized by a multitude of users but only one user-administrator can modify it. The spatial and descriptive data are stored in Microsoft Access tables.

For the specific application a customized Personal Geodatabase has been developed using the ΕSGΑ87 projection system. The geodatabase contains all the initial and final (corrected) data layers classified in Feature Datasets groups and single tables containing additional information.

The table 2.1 below shows all the contents of EAST_ATTICA.mdb geodatabase. That is the Feature Dataset groups and Tables as well as the information entities (Feature classes) that they include.

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Table 2.1 Personal Geodatabase contents

Feature Datasets

Feature classes archaeological sites

cultural heritage

memory institutions monuments remains

earthquakes

acc gimb gimb2005 int int_max int_quake mdl papap seismo_zones1 seismo_zones2 B_KATF CORINE Forest_areas Forest_fires-85_92 Garbage

environment

NPR_EGSA87_masked Urban_EGSA87 Vegetation_1991 Vegetation_1991_grouped Vegetation_2000 Vegetation_2000_grouped Cones Geol_lines

geology

Geol_points Geol_polygons Malakasa_landslide (point) Malakasa_landslide_polygon DES_EGSA87_masked

hazards

Flood_hazard Hzone_polygon RSE_EGSA87_masked Hydrographic Metrostation

hydrology

Streams Watershed_polygons Watershed_polylines

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Table 2.1 Personal Geodatabase contents (Continued)

Attica_municipalities East_Attica_municipalities municipalities

East_Attica_municipalities_buildings_age East_Attica_municipalities_buildings_uses East_Attica_municipalities_islands East_Attica_municipalities_buildings_population contours Main_roads

topography

mountains Provincial_roads trans

Tables codes int_frq pinfage_dk pinmat pinuses_dk population streams watersheds

2.3.2 Geometric-descriptive data management: • • •

Creation of Polygons Addition of new Data Layers Pre-analysis processes

2.4

Cartographic Output

A series of digital maps (mxd files, using the ArcMap software) has been created in order to present the available spatial data.

The following table includes the digital maps created and the figure presents a sample of the cartographic output.

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Table 2.2 Digital Map catalogue

Digital maps

Scale

Map 1.1: Topography, road network, hydrographic network

1:100.000

Map 1.2: Vegetation 2000 – Forest fires 1985 - 1992

1:100.000

Map 1.3: Population 1951-1961

1:100.000

Map 1.4: Buildings’ construction period

1:100.000

Map 1.5: Buildings’ main uses

1:100.000

Map 2.1: Soil erosion hazard

1:100.000

Map 2.2: Desertification hazard

1:100.000

Map 2.3: Landslide hazard

1:100.000

Map 2.4: Flood hazard

1:100.000

Map 2.5: Earthquake catalogs

1:300.000

Map 2.6: Peak Ground Acceleration – Seismicity zones (EAK)

1:100.000

In addition to the above a map file (mxd) including all the seismological data has been created (see section 3).

A detailed description of the methods and data used for the elaboration of the respective hazards is presented in sections 3-… below.

Figure 2.1: Flood hazard map (scale 1:100.000)

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2.3

The ΑrcReader software

The digital maps produced can be accessed only through the use of the ArcGIS software. Taking into account the high cost of this software, as well as the fact that its utilization requires specialized and experienced personnel, it was decided to convert the projects’ digital map output to pmf files. These files can be accessed by the freely available (through www.esri.com) and user-friendly software ArcReader.

More specifically the ArcReader software allows the final maps to be accessed, moved and magnified, map units can be identified, descriptive data can be queried.

Finally, the maps can be printed without any quality loss.

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3. Seismological Data within the frame of a GIS for the area of Eastern Attica, Greece 3.1 Introduction The modern urban environment is strongly depended on the continuous and reliable operability of the transportation networks, the fuel pipelines, the harbors and the airports, the power supply and the communications. In case that one or some of these, so called lifelines, systems lose their continuation for some reason, the losses appear in human or financial level. The possibility of these losses is increased in seismically active areas.

These systems generally share three common characteristics: a) Geographical dispersion: They are geographically dispersed over broad areas, thus they are exposed to a wide range of seismic and geotechnical hazards. b) Interconnectivity: They are interconnected and interdependent, since each lifeline system is composed of many interconnected facilities and is influenced by the performance of other lifeline systems. c) Diversity: Each system is related to many diverse components, since most lifeline networks have been built over many years and function with parts produced according to different construction and manufacturing techniques, standards and design procedures.

Earthquakes can cause significant damage to both the man made and the natural environments. The impact of these types of events can destroy entire ways of life. In addition to structural damage, seismic events can affect significantly the infrastructure that is vital to the function and well being of the community, can cause significant monetary losses, casualties and disease and can inflict long-term economic hardship on the local or regional economy.

The system earthquake – lifelines is characterized by complexity, since the operability of the lifelines depends on various factors, which are being participated at the same time and since the earthquakes usually affect more than one lifeline at the same time. For example, damage on a major transportation line would possibly delay the response of rescue or repairing teams.

The risk of a region to a seismic event is connected directly to the vulnerability of the region to damage, losses and casualties. The magnitude of the damage and losses depend not only on the seismic hazard, but also upon the density of the population, the location and type of building exposure, the socio-economic makeup of the region and their spatial relationship to the hazard. If an earthquake occurs in a sparsely populated region, there will be little to no effect on regional infrastructure and little likelihood of loss of life. However, if the same earthquake were to occur near a large city, the results could be described by very high losses. Regions with inexpensive constructions are more vulnerable and can expect heavier damage, than regions that

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have large numbers of new buildings that are designed and constructed to modern earthquake resistant codes. Local economies that are highly dependent on one or two types of businesses or industries that are destroyed by the event, unemployment can be almost complete and recovery very slow.

Seismic zonation leads to an improvement of the seismic hazard estimates for design by taking into account the effects of local site conditions. Seismic zonation involves treatment of the spatial variability of seismic excitation, geotechnical conditions and the characteristics of the build and structure environment and of the communities affected by the earthquakes.

The complexity of the above mentioned systems can be well described within the frame of a Geographical Information System (GIS), which is defined as “a set of tools for the input, storage and retrieval, manipulation and analysis, and output of spatial data� (Marble et al., 1984).

GIS can be used in risk assessment, even in the very beginning of the risk assessment process, which is the identification of the hazards themselves, or to determine new hazards through the overlay of hazard datasets (for example landslides due to an earthquake affecting the transportation network).

Finally, regional planners and government agencies require sophisticated risk assessment tools in order to plan for disaster mitigation as well as, disaster monitoring and rescue in the event of a disaster. GIS can deliver not only data on hazards in a region, information on structures and critical facilities, but can also contain built-in risk assessment programs that allow the planner to simulate disaster scenarios and graphically view the potential damage and affected areas, as well as plan rescue operations.

The above mentioned incorporate the necessity for the definition of three terms: a) Hazard is an extreme natural or technological event concentrated in space and time that poses risks to human activities. b) Risk is the potential losses associated with a hazard defined in terms of expected probability and frequency. c) Vulnerability is a measure of the damage that the hazard can cause to the built environment (structures, infrastructure, utilities).

As a first step for combining the lifelines, the seismic hazard and a multilayered Geographical Information Systems, an effort is made within the frame of this study to collect the seismological data, which could be useful for the district of Eastern Attica.

3.2 Area under investigation – Seismotectonic regime Attiki is located within an extensional domain of the Aegean broader area, where normal faulting is dominating. Northern and Eastern Attica are dominated by the mountains of Parnitha, Pendeli and Hymitos, which are bounded by shallow NW-SE and NE-SW Neogene basins. Parnitha

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together with Aegaleo are consisted by the oldest rocks in the region, that is Triassic limestones of Pelagonian zone. Penteli and Hymitos are parts of metamorphic rocks to the north and to the east of Athens, respectively. This metamorphic mass is extending past Marathon to the opposite coasts of Evia and it belongs to the Attic-Cycladic metamorphic belt, consisting of schist and marbles.

Although Thiva basin to the north and South Gulf of Evia to the east have experienced at least 10 earthquakes of M > 6.0 during the last 300 years, the Athens region remained quiet throughout this time, until the recent strike of the September 7th, 1999 Ms=5.9 Athens earthquake, which affected the broader area. Prior to this destructive event, no late Quaternary faults had been identified as potentially active in that region (Pavlides et al., 1999; Tselentis & Zahradnik, 2000). Although the historical seismicity of Central Greece is imperfectly known due to various reasons, there is no historical or instrumental evidence, so far, that any of the earthquake occurred exceeded the magnitude of 7.0. (Ambrasseys & Jackson, 1990). Nevertheless, the seismogenic areas of East Gulf of Corinth and the South Gulf of Evia host earthquakes that affected already or could affect the broader area in the future.

East Gulf of Corinth (fig. 3.1) is part of the 100km elongated asymmetric graben characterized as the most rapidly extending region in Greece. The East Gulf of Corinth opens with a rate of 6-8 mm/year (Clarke et al. 1997; Briole et al. 2000), reflected to high seismicity, with earthquakes of magnitude Ms = 6.0 – 6.8 during the last 300. East of the Gulf of Corinth the faulting and earthquakes continue in a diffuse zone through the Thiva basin, the South Gulf of Evia and the Mt. Parnitha.

The morphology of the southern coasts of the South Gulf of Evia is controlled by E-W faults. The South Gulf of Evia is an elongated WNW-ESE basin, which is extending from Chalkis to the Stira Island. The orientation of these tectonic lines is represented in Fig. 3.2 (Goldsworthy et al., 2002).

Fig. 3.3 and fig. 3.4 are taken from the work of Ganas et al. (2005) and represent the seismotectonic regime of the area, namely the historical seismicity, the focal mechanism of the earthquakes occurred and the faults defined.

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Fig. 3.1. Tectonic lines concerning the East Gulf of Corinth (Goldsworthy et al., 2002).

Fig. 3.2. Tectonic lines concerning the South Gulf of Evia (Goldsworthy et al., 2002).

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Fig. 3.3. Focal mechanism representation of various earthquakes from the broader Attiki region.

Map taken from Ganas et al. (2005), after the interpretation of the works by Ambraseys & Jackson (1997, 1998), Papadopoulos et al. (2000) and Taymaz et al. (1991).

Fig. 3.4. Interpretation of 60-m relief model of Attiki (Ganas et al. 2005). Red lines represent fault segments, blue lines represent rivers. Among others fault segments, APFS stands for Agioi Apostoloi, OFS for Oropos, MR for Maliza, PEFS for Pendeli, AFFS for Aphidnes and AVFS for Avlona.

3.3 Seismological Data Under the term “seismological data” we mean earthquake parameters from catalogues, strong motion data, seismic station locations and macroseismic data. a) The used earthquake catalogues were chosen according to their completeness for the respective period of time: Till 1900 Papazachos & Papazachou (1989) 1901 – 1910 Makropoulos et al. (1989) M>=6.5

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1911 – 1949 Makropoulos et al. (1989) M>=5.2 1950 – 1963 Makropoulos et al. (1989) M>=4.8 1963 – 1987 Makropoulos et al. (1989) M>=4.5 1988 – 2004 Monthly bulletins G.I. 2005

Monthly bulletins G.I.

M>=4.0 M>=3.5

In order to extract the earthquakes concerning the area under study from the above mentioned catalogues, the extreme points of the area were taken into account, namely to the north 38.34Ν 23.69Ε, to the west 38,21Ν 23.62Ε, to the south 37.64Ν 24.03Ε and to the east 38.16Ν 24.08Ε. Then, the earthquakes included in a spatial window defined by these points plus 100 km from each side are being selected, namely to the north 39.24Ν 23.69Ε, to the west 38.21Ν 22.72Ε, to the south 36.74Ν 24.03Ε and to the east 38.16Ν 24.98Ε.

The file, which includes the earthquakes according to the respective catalogue is the CATEPI.xls. b) For the macroseismic observations, that is the effects of the strong earthquakes from the broader area to the municipalities and the communities of East Attiki, the macroseismic database of the National Observatory of Athens was used, including data from its monthly bulletins. The file including the macroseismic observations is the CAT-INT.xls c) The only strong motion station, which is located within the district of East Attiki, is the one of Rafina. Nevertheless, and for reasons of the sample enrichment, data from other strong motion stations of the broader region of Athens were included too (Neo Psychiko, Agia Paraskevi, Sepolia etc.). The stations, the data from which can be used in this study, have been included in the file CAT-ACC-STA-IN-MBR.xls. d) Furthermore, the seismicity zones proposed by Papazachos and Papaioannou (1997) were included in the GIS. The division of an area to zones of seismicity is significant not only for theoretical reasons (better understanding of geodynamic regime of the area), but also for applied reasons (the estimation of the seismic hazard of the area and the long term prediction). The criteria used for this division are the spatial distribution of the seismic foci, the orientation of the fault segments, the direction and the dip of the P and T axes of the faults, the type of the seismogenic faults, the seismicity rate, the values of b of the Gutenberg-Richter scale, geological criteria, macroseismic observations and the rate of the seismic moment release.

3.4 Seismological Geographical Information System All the above mentioned data have been incorporated in a Geographical Information System, after their transformation to the EGSA87 projection system.

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For each earthquake catalogue different categorization was made according to the focal depth and according to the magnitude, while different color was assigned for each catalogue. As examples, fig. 3.5 shows the historical earthquakes (till 1900) from the Papazachos and Papazachou catalogue (1989), while fig. 3. 6 shows the epicenters of 2005 earthquakes from the GI monthly bulletins having different symbols according to their focal depth.

For strong earthquakes, for which strong motion data (values of peak ground acceleration) and macroseismic data exist an independent source was established showing the epicenter with a star, the sites with circles of different color according to the observed intensity and the strong motion stations with triangles. Figure 3.7 shows the epicenter of the earthquake of July 26th, 2001 (Northern Sporades) and the sites within the district of Eastern Attica having different color according to the observed macroseismic intensity. The opened informative window shows details for the site of Avlona (earthquake parameters, site-coordinates in φoN and λoE and in EGSA87, site population, macroseismic intensity observed, epicentral distance and azimuth.

Fig. 3.8 shows the epicenter of the September 7th, 1999 Athens earthquake and the sites of the accelerograph stations at the area of Athens, that recorded the main event. The opened window shows details concerning the site of Rafina (coordinates of the station, epicentral distance, and the peak values of acceleration, velocity and displacement for the three components).

Figure 3.9 is like fig. 3.8, including also the observed macroseismic intensities for the mentioned earthquake and from sites of Eastern Attica.

Fig. 3.5. Historical earthquakes (till 1900) from Papazachos and Papazachou catalogue (1989).

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Fig. 3.6. The epicenters of 2005 from the monthly bulletins categorized according to their focal depth.

Fig. 3.7. Details about macroseismic intensities observed at sites of Eastern Attica from the July 26th, 2001 Northern Sporades earthquake.

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Fig. 3.8. The September 7th, 1999 Athens earthquake and the sites of strong motion stations of the Athens area recorded the main shock.

Fig. 3.9. The September 7th, 1999 Athens earthquake, the sites of strong motion stations of the Athens area recorded the main shock, and the sites for the observed macroseismic intensities, represented by circles of different color according to the value of intensity.

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Fig. 3.10. The seismicity zones surrounding the area of Eastern Attica according to the study of Papazachos and Papaioannou (1997)

REFERENCES Ambraseys, N. and Jackson, J. (1990). Seismicity and associated strain of Central Greece between 1890 and 1988. Geophys. J. Int., 101, 663-708.

Briole, P. et al. (2000). Active deformation of the Corinth rift, Greece: Results from repeated Global Positioning System surveys between 1900 and 1995. J. Geophys. Res., 105, 25605-

25625.

Clarke, P. et al. (1997) Geodetic estimate of seismic hazard in the Gulf of Corinth. Geophys. Res.

Lett., 24, 1303-1306.

Ganas, A., Pavlides, S. and Karastathis, V. (2005). DEM-based morphometry of range-front escarpments in Attica, Central Greece, and its relation to fault slip rates.

Geomorphology, 65, 301-319.

Geodynamic Institute Monthly Bulletins (1988 – 2005).

Goldsworthy, M., Jackson, J. and Haines, J. (2002). The continuity of active fault systems in Greece. Geophys. J. Int., 148, 596-618.

Makropoulos, K.C., Drakopoulos, J. and Latoussakis, J. (1989). A revised earthquake catalogue since 1987. Geophys. J. Int. 98, 391-394.

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Marble, D. F., H. W. Calkins, and D. J. Peuquet, Basic Readings in Geographic Information

Systems, SPAD Systems Ltd., Williamsville, NY, 1984.

O.Rourke, T. D. and S.-S. Jeon, .Factors affecting the Earthquake Damage of Water Distribution Systems., Proceedings of the 5th US Conference on Lifeline

Earthquake Engineering, Seattle, WA, ASCE, Reston, VA, August 1999, 379-388.

Papazachos, B.C. and Papaioannou, Ch. A. (1997). A seismic hazard in Greece based on new seismotectonic data. Abstr. 29th IASPEI General Assembly, Thessaloniki, 18-28Aug.,

294.

Papazachos, B.C. and Papazachou, C. (1989). Earthquakes in Greece. Editor Ziti, Thessaloniki (in

Greek with English abstract).

Papadopoulos, G.A., Drakatos, G., Papanastassiou, D., Kalogeras, I., Stavrakakis, G., 2000.

Preliminary results about the catastrophic earthquake of 7 September 1999 in Athens, Greece. Seismological Research Letters 71, 318–329.

SCHENKOVA, Z. KALOGERAS, I., KOUROUZIDIS, M., SCHENK, V. and STAVRAKAKIS, G. (2004).

Macroseismic observation in Greece: Development of a database for extraction of new knowledge. XXIX ESC General Assembly,SCA-0 Seismicity of the European –

Mediterranean Area (poster), 12-17 September, Potsdam, Germany.

Taymaz, T., Jackson, J., McKenzie, D., 1991. Active tectonics of the north and central Aegean Sea.

Geophys. J. Int. 106, 433– 490.

THEODULIDIS, N., KALOGERAS, I., PAPAZACHOS, C., KARASTATHIS, V., MARGARIS, B., PAPAIOANNOU, Ch. and SKARLATOUDIS, A. (2004). HEAD v.1.0: A unified Hellenic Accelerogram Database. Seismological Res. Lett., V. 75, No 1, 36-45 .

Tselentis, G. & Zahradnick, J., 2000. Aftershock monitoring of the Athens earthquake of 7 September 1999, Seis. Res. Lett., 71, 330–337.

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4. Landslide Hazard 4.1

Introduction

4.1.1 Scope - Methodology The scope of the current study is to present an inventory of the hazards that menace the district of Eastern Attica. In the field of landslide hazard in order to assess the hazardous regions the investigation comprised the following stages: ¾ Thorough search of the relevant documentation, including geological topographic and soil maps, technical papers and records so as to develop a preliminary ground model of the area. ¾ Historical search. A wide range of sources can provide useful information on the past occurrence of events, including aerial photographs, topographic maps, satellite imagery, public records, consultants reports, scientific papers etc. ¾ Aerial photograph interpretation, provided an exact and complete record of the ground surface at a given time. The time limit that was selected was February 1995, were Malakassa landslide occurred.

4.2

Regional geological and tectonic setting

In figure 4.1, Higgins M.(1996) presents, the general geological setting of Attika.

The main geological units that dominate are: the non-metamorphic formations of Mts. Parnitha and Egaleo and the metamorphic autochthonous system of Hymitos and Pendeli (Lepsius, 1893, Kober, 1929, Marinos et al 1971; Katsitsaktos et al., 1976, 1986.) The metamorphic unit which is the bedrock of the study area is overthrusted by the non metamorphic unit, and consists of marbles, dolomites, schists and gneiss - schists of thickness more than 2500m. The age of these formations is considered to be Triassic to upper cretaceous. The neogene, sediments that cover the alpine bedrock, are mainly formations of lacustrine phase, accompanied mainly by fluviolacustrine and lacustrine terrestrial deposits. They occupy, almost entirely, the north half of Athens basin and continue, on the north, towards the uppermiocene formations of the big lacustrine basin Thives – Tanagra – Oropos and on the east, towards the uppermiocene lacustrine formations of Messogia area. Upper Tertiary formations of fluvio- lacustrine origin, are also encountered in the area, consisteing mainly of fine grained alluvial deposits, old

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scree and talus cones frequently overlain in places by unconsolidated material from younger talus cones and screes.

Figure 4.1 : Attica Geological Map, Higgins R.

The tectonic texture of the Subpelagonic zone comprises major normal faults on an E-W direction and minor ones on a NE–SW direction (see, seismological data section).

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4.3

Landslide Hazard

Landslides are common in Greece but are generally quite small or surficial.

However about 500 villages have been relocated during the last 30 years as a result of actual or potential landslide hazard. During the last decade the landslide activity is relatively high as a result of increased urbanization and construction development (transportation routes, dams and reservoirs, industrial and urban activities) even in landslide prone areas, continued deforestation and climate change. Landslide occurrence is principally controlled by three factors: climate, relief and local geology.

Many landslides are triggered by rainfall human activities and earthquakes.

A systematic inventory of data concerning landslides in Greece, was initially attempted by, Koukis and Ziourkas (1991). The landslide inventory progressively covered the period (1950-2004), trough extensive studies undertaken from the Department of Geology of Patras University and the Institute of Geology and Mineral Exploration (IGME), (Koukis et al, 2005). In the current preliminary approach of regional scale demand, published data, were assembled from national scale maps (Ziourkas, 1991), KIFISSIA sheet geological map 1:50.000 IGME, aerial photos, in order to estimate landslide hazard in East Attica district.

The whole area is characterized as low hazard area 0-1 landslides per 100km2 (Koukis et al, 2005). Malakassa event which occurred on the 18th of February 1995, is the most only important event in the study area mainly associated with human activity. It is considered as the largest and most destructive landslide that ever occurred in Greece. The result of that landslide was the destruction of the main railway and motorway axes of Greece, which link the Capital (Athens) to the Central and Northern Greece. A section of the Railway Line, which links Athens to Thessaloniki and a section of the Motorway, both affected by the landslide area, were destroyed. The perception of precursory phenomena on the motorway began on the 16th of February 1995, while on the railway line on the 3rd of January 1995.

4.4

Malakassa Landslide

On February 18th 1995 an extended landslide took place at the area of Malakassa, 36 km north of Athens. The number of vehicles, using everyday this section of the Motorway, comes up to 35.000 for both directions. This number increases drastically, during holidays and weekends.

25

Figure 4.2 : Aerial view of Railway Line failure

This landslide, one of the most destructive landslides in Greece, was of 310m maximum length, 240m maximum width and 31m maximum depth. The slide mass was of the order of 1.500.000 m3.

Figure 4.3 : Aerial view of the landslide (2.21.1995)

The landslide in its bigger part moved from South to North with a small divergence to Northeast of approximately 7m horizontally. Particularly, the upper part of the landslide (head) was located above the Railway Line, while its lowest part (toe) was located on the branch towards Athens of the Motorway. The part of the landslide next to the Motorway was substantially narrow. There is an exception in its Southwest edge, which shows smaller movement and more intense inclination towards Northeast that proves that the part of this edge was drifted by the landslide and had a semi-autonomous movement.

26

The movement of the toe had also an important vertical component (elevation).

The following pictures depict the movement of the toe wall and its failure.

Figure 4.4 :Movement of toe wall

Figure 4.5 : Failure of the toe wall nearby the Motorway Re-establishment Works (immediate and permanent measures)

In response to the problems generated by the landslide, re-establishment works were constructed. The stabilization works were not only immediate measures but also permanent.

The first category of stabilization works was that of the immediate measures.

They resisted in a new destabilisation and increased the stability of the landslide area until the second category of stabilization works (permanent) was materialised.

The immediate measures were undertaken during 1995 and functioned with very positive results. The aim of these works was to use vertical pumped wells to lower the water table under the landslide. A total of 46 pumped wells were installed and became operational in January 1996. After 6 months of wells operation (in July, 1996), the groundwater surface had been drawn down an average of 10m.

The evaluation of the monitoring results showed that the stability of the region increased due to the immediate measures. After the completion of the technical final measures through out the mass of the landslide, the stability factor was increased.

27

So these results led to the final decision of the measures to be taken in the area of the landslide in order to rehabilitate the part of the Motorway which was destroyed. Consequently, the second category of re-establishment works is about the permanent works, in which the immediate measures were also incorporated.

The basic design of the permanent measures included works of which the main purpose was to lower the water table (drainage), to decrease driving forces by excavations on the top (head) of the landslide area and to increase resisting forces by fillings at the toe of the landslide, close to the Motorway.

Analytically, the drainage system was conducted consisting of seven adits of 1.470m total length. The main drainage adit extends from North to South under the slide surface, 365m long.

Figure 4.6 : Drainage system and drainage adit section

Figure 4.7 : Typical cross section of South-North direction where the stratigraphy, the slip surface and the drillings next to it appear

Six more vertical branch-adits of 1.100 m total length connected to the main adit complete the drainage adits. Their cross-section is "horse-shoe" type with a 3m diameter. From the interior of the adits drainage, boreholes were drilled every 10m (Vandalia form). Also every 10m, well drains (30cm diam.) were drilled, vertically

28

from the surface level down to the top of the adits. The slide mass is draining to the adits through these drain drilling holes due to the gravity force.

Furthermore, the works done to reconstruct the Motorway were designed in such way to increase the resisting forces by filling the area where the toe of the landslide was located. For this purpose within the landslide area the left branch of the motorway was elevated for about 2m, although the axis of the pavement in the horizontal level remained in its initial position. The adaptation of the new elevated pavement grade to the existing conditions was of 1.200 m length.

Figure 4.8 : Cross section of left - right branches

However, the different level between the left and the right branch required the construction of a retaining wall next to the existing axis of the Motorway. Along with the construction of the left branch of the Motorway, a new parking space was also constructed in order to provide access to the landslide area. The right branch of the Motorway (towards Thessaloniki) remained in its existing position.

As it was mentioned, a landslide toe counterweight was constructed. More specifically, in the upper part of the Motorway's left branch (direction to Athens), a counterweight with a slope 2 : 3 was constructed up to a level of +301m.

In order to avoid the interruption of the natural surface water flow and the underground water flow, the upper surface was regraded to a flatter angle, especially where there were cracks and other local ground irregularities.

As supplementary works, excavations were made to smooth the surfaces and to unload the head of the landslide, in the area above the railway. Finally the "secondary" landslides above the railway line were stabilized.

Regarding monitoring, a network of 46 piezometers and 23 inclinometers was installed throughout the landslide area. Measurements are taken systematically at specified periods of time. The evaluation of the measurements proves that all the

29

permanent measures taken are satisfactory and the stability of the slope has been assured.

REFERENCES Γεωργόπουλος Ι., Βαρδουλάκης Ι. (2001), «Μελέτη της κατολίσθησης της Μαλακάσας της 18-02-1995 μέσω μηχανισμών αστοχίας κινηματικής αλυσίδας εκ στερεών σωμάτων»,

Πρακτικά

4ου

Πανελλήνιου

Συνεδρίου

Γεωτεχνικής

και

Γεωπεριβαλλοντικής Μηχανικής, Αθήνα. Παντελίδης Π., Καβουνίδης Σ. (1997), «Αναλύσεις ευστάθειας κατολίσθησης Μαλακάσας», Πρακτικά 3ου Πανελλήνιου Συνεδρίου Γεωτεχνικής Μηχανικής, Τ.Ε.Ε., Πάτρα.

Geomechaniki Ltd, Gamma-4 Ltd (1996), “Final design of permanent measures for the confrontation of Malakasa landslide”, Athens.

Higgins M.D, Higgins R., 1996, Ageological Companion to Greece and the Aegean, Duckworth Katsitsaktos G., Mercier, J., Vergely, P.., 1976. La fenetre d’ Attique – Cyclades et les fenetres metamorphiques des Hellenides internes Grece. C.R. Acad. Sci. Paris 283D, 1613-1616.

Katsitsaktos G., Migiros G., Triantaphyllidis, M., Mettos, A., 1986. Geological Structure of internal Hellinides E. Thessaly – S.W. Macedonia, Euboa – Attica – N. Ccyclades islands and Lesvos. IGME Geol. Geophys. Res. Special Issue, Athens, 191 – 212.

KIFISSIA Sheet , IGME, Katsikatsos G., 1998 Kober, L. 1929, Beitrage zur Geologie von Attica. Sitzungsb. Akad. Wiss. Mat- Nat, K1 138, 229-327.

Koukis G., Ziourkas C, (1991), Slope instability phenomena in Greece: a statistical analysis. Bull IAEG 43:47-60.

Koukis G., Sabatakakis N., Nikolaou., Loupasakis C., 2005, The First General Assembly and The Fourth Session of Board of Representatives, of the International Consortium on Landslides, 12-14 October 2005, Keck Center of the National Academy of Sciences, Washington D.C., USA Lepsius R., 1893, Geologie von Attica. Zeischr. Prakt. Geol. 4, 196 (S. karte 1:25.000, Berlin).

30

Marinos G., Katsikatsos, G., Georgiadou – Dikeoulia E., Mirkou, R., 1971. The Athens’ schist formation I. Stratigraphie and Structure. Annales Geologiques des Pays Helleniques, La serie XXIII, 183-216.

Marinos P., Sotiropoulos E., Yannatos M., Cavounidis S. (1997), “Increasing the stability of a failed slope by pumping, Malakasa landslide, Athens, Greece”, Proceedings Symposium Engineering Geology and the Environment, Balkema.

Polakis A, Alevra E. (2004), “Landslide in Malakasa area: encountering works and rehabilitation of P.A.TH.E. – Motorway”, Geotechnics in Pavement and Railway Design and Construction, Gomes and Loizos, Milpress, Rotterdam.

31

5. Flood Hazard Estimation 5.1 Objective The aim of the study at this preliminary phase is to estimate the river sections under potential hazard due to flooding especially at threatened areas of high residence where streams are under capacity stress.

5.2 Study Area Eastern Attica Prefecture, the study area, is located east of the city of Athens, covers a surface of 1.800 km2 with a population of 410.000 inhabitants (last census). Fourth among the biggest prefectures in Greece, with 20 municipalities & 26 communities, the Prefecture is considered as the most developing area in our country. Apart from two significant commercial ports (Rafina & Lavrio), services companies, energy production installations, five industrial zones and tourism enterprises along the 160 km of tourist coasts, dynamic infrastructure works (e.g. International Athens Airport ‘Eleftherios Venizelos’, motorway ‘Attiki Odos’) have been constructed in the recent years and thus the study area could be characterized as one of the richest and most promising cases of cultural landscapes in Greece.

Furthermore, the area has experienced natural disasters, such as earthquakes (e.g.

Parnitha 1999 ; Oropos 1938), wild land fires, continuous threat of the industrial risks, and last but not least the area has suffered from severe floods that repeatedly during the last decade have destroyed transport lines and properties. Additionally area’s vicinity to Athens and its potential of touristic development multiply the necessity of identifying the flood hazard zones at least in the main river basins of the area.

In the framework of SIPROCI project the main (in terms of capacity) and the most known tributaries of the whole area of the Eastern Attica Prefecture were identified and registered whereas at the most of them their downstream cross sections were in situ visited and measured by advanced technology (GPS etc). When the overall view of the Prefecture in hydrographic terms was accomplished, the research team focused mainly on three river basins that according to the historic records and the last year events present an increased frequency of severe flooding with baneful consequences for the socioeconomic and environmental conditions of the area. The three under study river basins are: a) the basin of Rapentosa river and b) the basin of Rafina river and c) the basin of Erasinos river and constitute the basins where the flood hazard was identified.

32

5.3 Data Data used for the following analysis are:

1.

2.

3.

4.

Maps of 1:50.000 scale (source: Geographical Military Service) Maps of topography and hydrographic network in GIS platform Review of relative hydrological studies Meteorological data

Supplementary Actions

5. In situ visits / fieldwork 6. Measurements by advanced technologies (GPS, Laser- scanner)

5.4 Work Flow – Methodology Due to the economic and temporal restrictions of SIPROCI project the research team defined the following workflow for the flood hazard identification in the two case studies 1. Definition of the boundaries of the river basins in GIS platform 2. Selection of the under study tributaries 3. Selection of the appropriate criteria for the flood hazard identification 4. Estimation of flood peaks for return period T = 50 years 5. Estimation o f discharge capacity of the selected tributaries 6. Production of flood hazard map The crucial criteria that indicated the method of the flood hazard identification are based on:

Historical Records In situ visits Estimation of discharge flow of return period Q50 Comparison of the discharge Q50 to stream capacity Qo

and resulted in the above classification:

Qo > 1.25 Q50 Q50< Qo< 1.25 Q50 0.75 Q50< Qo< Q50 Qo< 0.75 Q50

if

area not at long term flood hazard (green color) area not at direct flood hazard (yellow color) area at potential flood hazard (orange color) area at direct flood hazard (red color)

Finally for the estimation of the Q50 discharge the following factors were taken into account:

time of concentration idf curve for T=50 yrs CN soil conservation service (SCS) estimation of outflow hydrograph of each sub basin flood routing via river section final outflow hydrograph (peak discharge, total volume)

33

and correspondingly for the estimation of stream flow capacity Qo the following factors were taken into account:

geometry of cross sections stream gradients hydraulic calculations of discharge

5.5 Conclusions Based on the above data and methodology the identification of certain flood hazard sites along the main tributaries was achieved. For the identification of the potential flood hazard sections of the tributaries a separate layer was produced in GIS environment.

References 1. Ναλμπαντης Ι. και Λαζαριδης Λ. (2004), « Αντιπλημμυρική προστασία λεκάνης ρέματος Ραφήνας», Ημερίδα ΤΕΕ « Αντιπλημμυρική Προστασία Αττικής».

2. Μπεσσανσων Α. και Παπαλεξοπουλος Β. (2004), « Αντιπλημμυρική προστασία λεκανοπεδίου ρέματος Ερασινου», Ημερίδα ΤΕΕ « Αντιπλημμυρική Προστασία Αττικής».

3. Τσακιρης Γεώργιος (1995) « Υδατικοί Πόροι: Ι. Τεχνική Υδρολογία », Εκδόσεις Συμμετρία 4. HEC-RAS User’s Manual , Technical Reference Manual, Haestad Methods 5. AFORISM: A comprehensive forecasting system for flood risk mitigation and control, Ανάδοχος: University of Bologna, 568 σελίδες, Department of Water Resources, Hydraulic and Maritime Engineering - National Technical University of Athens, Bologna, April 1996.

6. Labadie G. (1992), “Flood waves and flooding models”, Coping with floods, pp.

177-218. Pre-proceedings of the NATO A.S.I. held at Erice, Italy.

Research Team 1. Prof. G. Tsakiris 2. Panagiotis Siwras, MSc 3. Pistrika Aimilia, MSc, PhD student

34

APPENDIX Table 5.1. Registration of main Tributaries and historic flood peaks

code

name

classification Strahler

Q50 (m3/s)

1

Rapentosa

3

2

Kimpitougios

1

3

Vagias

1

4

Ν. Μakris

2

23.4

5

Zuberi

2

14.9

6

Ag. Andreas

2

11.1

7

Kokkino Limanaki

2

13.3

8

Rafinas

3

514

9

Ag. Paraskevis

1

10

Valanaris

2

11

Likorema

2

12

Megalo

3

13

Viglo

1

14

Krioneri

2

15

Panagitsas

2

16

Leontariou

1

17

Erasinos

3

18

Ag. Georgiou

2

19

Kaliviwn

1

20

Kouvara

1

21

Maleksi

1

22

Ag. Annas

1

23

Markopoulou

2

24

Strogilis

1

25

Charadros

3

26

Ag. Stefanos

3

27

Loutsas

3

128

Q=650 (considering longterm land use)

26.2 131.5 35.6

Q50 = 140 ( deviation discharg Q= 650 (at the outfall of Vravronas gulf) Q=460 (Τ=20 yr - at the outfall of Vravornas gulf ) Q=420 (upstream of the confluence with Ag. Georgios River) Q=200 ( at confluence with Erasinos River)

35

Table 5.2. Registration of River Basins

code

name

Α (km2)

1

Rapentosa

33.9

2

3

Rafina

Erasinos

150

115

Length of main channel (km)

Geomorphological characteristics

Technical works

13,2

Hilly area with intense terrain of high density of hydrographic network

Control dam of Rapentosa river

25

The natural watercourse of the stream under study differentiates: upstream the cross sections are generally well defined but downstream their boundaries become unclear. The area at a certain point of the downstream section of the tributary mostly includes agricultural land.

1. Deviation of the tributary of Podoniftis river in the tributary of Rafina 2. Not clearly defined section

8,7

1. Outfall not well defined – wetland 2. mainly flat or hilly area 3. outflow receptor of central (Spata, Peania, Koropi municipalities) and southern areas (Markopoulo, Kouvaras) of Mesogeia.

Outfall of flood preventing receptor of Mesogeia areas

Olympian Equine Center

4

Ag. Georgiou

70

7

1. small slopes of watercourse 2. extended cultivated areas 3. watercourse degradation in 4.5 km distance before the confluence with Erasino river

5

Kaliviwn

17

4

1. bosky cultivation and vineyards 2. non existent watercourse

Technical work of stormwater receptor at the Lavrio’s motorway

6

Kouvara

20

5.2

1. well defined watercourse along the whole tributary 2. locally woodland

Significant technical works int the transport field

Charadrou

70

16,8

Mountainous terrain

Lake of Marathonas

8

Ag. Stefanou

6,9

5,5

Mainly high residence area

Lake of Marathonas

9

Loutsas

6,7

3,9

10

New Makri

6,6

6

Outfall in the Rafina Bay

11

Zouberi

3

4,8

Outfall in the Rafina Bay

12

Ag. Andrea

2,97

4,68

Outfall in the Rafina Bay

13

Kokino Limanaki

1,4

3,4

Outfall in the Rafina Bay

7

36

6. Documentation for the Data Layers contributed by the Laboratory of Remote Sensing, School of Rural and Surveying Engineering •

Forest fires 1985-1992

Forest fires (from 1985 to 1992). From data provided by the Ministry of Agriculture to the Laboratory of Remote Sensing of the N.T.U.A. •

Garbage

Garbage deposition areas. From data provided by the Ministry of Agriculture to the Laboratory of Remote Sensing of the N.T.U.A. •

Urban areas

Map of urban areas. It has been generated by photointerpretation of SPOT imagery with 10m ground resolution. Apart from the built-up areas, those areas which seem to be included in the town plan (delimitated blocks) have also been characterized as urban areas.

•

Forest areas

Map of forested areas. This map has been generated by classification of LANDSAT 5 TM image (acquired in 1993). It contains only areas with trees and dense bushes.

•

Mountains

This layer has been generated by automatic extraction of mountains, foothills and valleys from the Digital Elevation Model of the area using Geomorphological Feature Extraction. The basic concept of the method is the creation of photointerpretation knowledge base using object oriented programming in multiple analysis levels utilizing fuzzy logic.

The classified objects have been vectorized and entered into the GIS (Argialas D. and Α. Tzotsos, 2003).

•

Vegetation and Vegetation grouped

Many vegetation indices have been tested for their accuracy in estimating vegetation density (NDVI, SAVI, MSAVI2, Tasselled Cap Greenness, WDVI, PVI). Among them MSAVI2, which is an improved version of SAVI, was selected as the best performing vegetation index.

SAVI (soil adjusted vegetation index) is calculated by the following relation: Soil Adjusted VI:

SAVI =

ρNIR − ρred (1+ L) ρNIR + ρred + L

where L is a soil dependant parameter ranging from 0 to 1 according to vegetation density. Usually L is set to 0.5. This vegetation index gave better vegetation density estimations than NDVI in sparsely vegetated areas.

MSAVI2 is given by: Modified Soil Adjusted VI:

MSAVI2 =

2 ρNIR +1− (2*ρNIR +1) 2 −8( ρNIR − ρred ) 2

This is a self adjusting version of SAVI. Its advantage compared to other indices is that there is no need for external parameters which are possible sources of errors.

37

The satellite images have been classified using Object-Oriented Image Analysis which does not classify single pixels, but rather image objects which are extracted in a previous image segmentation step (Argialas D. and P. Derzekos, 2003).

The concept behind Object-Oriented Image Analysis is that important semantic information necessary to interpret an image is not represented in single pixels, but in meaningful image objects and their mutual relationships. The classified image oblects may be vectorized and entered into a GIS. Object-oriented classification for vegetation density has been carried out using LANDSAT TM images acquired in 1991 and 2000. Before enetering the maps into the GIS the classified image objects were grouped in:

â&#x20AC;˘

i.

three classes (layer Vegetation): (1) dense vegetation, (2) sparse vegetation and (3) no vegetation

ii.

two classes (layer Vegetation grouped): (1) vegetation and (2) no vegetation.

CORINE Land Cover

For this layer, map composition has been carried out according to the CORINE Land Cover Legend in 5 and 44 classes. sources:

â&#x20AC;˘

Hellenic Mapping and Cadastral Organization European Environment Agency: http://reports.eea.eu.int/COR0landcover/en CEH: http://www.ceh.ac.uk/data/index.html#CORINE FIMK: http://imk-msa.fzk.de/MSA-Datasets/geo/landcovercorine/legend.htm

Natural regeneration potential, soil erosion risk, desertification risk

Maps for natural regeneration potential, risk of soil erosion and desertification risk after forest fires.

An experimental model for predicting natural regeneration potential and risk of soil erosion has been generated by the National Agricultural Research Foundation (NARF, Greece). The model consists of three simple rules which are based on the experience of our forestry expert colleagues.

The first rule takes into consideration the soil depth class (related to soil water storage capacity) and the aspect of a site and gives five classes of natural regeneration potential based on the following assumptions: -

Deep soils store more water and usually carry denser and taller vegetation than shallow soils.

The origin of soil parent material (surface geology) is indirectly manifested through soil depth.

-

Vegetation in areas facing South is usually sparser and shorter than similar vegetation which is in areas facing North. This happens because areas facing South receive larger amount of solar energy and thus tend to be drier.

Soil depth >30cm >30cm 5-30cm 5-30cm <5cm <5cm

Aspect North South North South North South

Natural regeneration potential No Limitation Slight Limitation Slight Limitation Moderate Limitation Strong Limitation Severe Limitation

The second rule considers three factors (permeability, soil depth and inclination) and determines five classes of soil erosion risk. The third rule determines the risk for future desertification as a 38

function of the natural regeneration potential and the risk of soil erosion. The following premises comprise the base of the soil erosion risk rule: -

Soils on permeable rocks are less sensitive to erosion than soils on impermeable rocks.

Similarly, deep soils, due to their larger water storage capacity, are less sensitive to erosion than shallow soils.

-

The erosion risk is higher in slopes that are steep than in slopes that are flat.

Permeability Bare rocks Permeable Permeable Permeable Permeable Impermeable Impermeable Impermeable Impermeable Impermeable

Soil depth >30cm >30cm 530cm 530cm >30cm >30cm >30cm 530cm 530cm

Slope (%) <20 >21

Soil erosion risk No - Slight No - Slight Slight

<20

Slight

>21 <20 21-40 >41

Moderate Slight Moderate High

<20

High

>21

Very High

The above model ignores weather conditions (mainly rainfall) which affect the regeneration process and erosion due to rain. It is assumed though that there has been sufficient rain and that the whole area has received rainfall with the same characteristics in terms of intensity and distribution pattern. Furthermore, the proposed model ignores human factors (mainly animal grazing) which proved to be quite important to be left aside.

The functionality of the described model depends on the availability of the data necessary. Data on aspect, slope, soil depth, surface geology are necessary to use the proposed model. Aspect and slope layers may be produced easily using DEMs of the study areas. Data on permeability may be obtained by digitising of the existing geological maps. The depth of soil may be obtained from detailed soil maps, which, unfortunately, are usually not available or not detailed enough for most Mediterranean regions. As an alternative, soil depth could be estimated indirectly using satellite images. In arid and semiarid regions, in the dry season, the amount of green biomass depends mainly on the quantity of water available to the plants. Thus, soil depth (related to the water storage capacity of a soil), in the dry season, is highly related to the density of vegetation in the area, while it should be related less than 50% to the type of vegetation. Such a strong relationship between soil depth and vegetation density is encountered when the maximum possible amount of vegetation is present in the study area.

For the given area soil depth was estimated using the maximum vegetation density, which has been calculated using maximum MSAVI2 values from three LANDSAT MSS images acquired before the forest fire events (1984, 1981 and 1977).

Thus, maps for natural regeneration potential, risk of soil erosion and desertification risk have been successfully produced for the study area. (Rokos. D. et al, 2004, 1996, 1995). â&#x20AC;˘

Landsat 321-RGB

Geometrically corrected LANDSAT ETM+ satellite image acquired in 1999 with ground resolution 30m.

39

References Argialas D. and Α. Tzotsos (2003), “Geomorphological Feature Extraction from a Digital Elevation Model Through Fuzzy Knowledge-based Classification”, in Remote Sensing for Environmental Monitoring, GIS Applications, and Geology II. M. Ehlers (Editor) Proceedings of SPIE International Conference on Remote Sensing, Vol. 4886 (2003), 23-26 September 2002, Agia Pelagia, Crete, pp. 516-527.

Argialas D. and P. Derzekos (2003), “Mapping Urban Green from IKONOS Data by an ObjectOriented Knowledge-base and Fuzzy Logic”, in Remote Sensing for Environmental Monitoring, GIS Applications, and Geology II. M. Ehlers (Editor) Proceedings of SPIE International Conference on Remote Sensing, Vol. 4886 (2003), 23-26 September 2002, Agia Pelagia, Crete, pp. 96-106.

Rokos D., Kolokoussis P. (2004), "Natural Regeneration Potential and Soil Erosion Risk after Forest Fires in Typical Mediterranean areas", Local Land & Soil News No. 10/11/II/III/04, European Land and Soil Alliance ELSA e.V. 2004.

Rokos D., Kolokoussis P., (1996), “The Use of Remote Sensing in the Evaluation of the Natural Regeneration Potential, Erosion Risk and Desertification Risk after Forest Fires”, Advances in Remote Sensing, Vol. 4, No. 4, pages: 106-116, EARSeL. Rokos D., Halaris G., Andronis V., Kolokoussis P., (1995), “A GIS Decision Support System for the Prevention of Desertification Resulting from Forest Fires - Final Report”, ENVIRONMENT ECProgramme, EV5V-CT91-0025, N.T.U.A., Athens.

Research Team Professor D. Argialas P. Kolokoussis Α. Tzotsos

40

7. Using GIS to create Hazard Maps for The Assessment Of Cultural Heritage. The case of Eastern Attica.

7.1 Introduction Consistent with its purposes and perspectives, the Centre has already embraced the interdisciplinary methodology used by a variety of scientific fields which study the disturbances, the adaptation and the resilience in socio-ecological systems (SES).

The Archaeology of Natural Disasters defines the identity, the impact and the dynamics of natural hazards into the evolution of human civilization (biological, ecological, environmental, socio-economic, political, technological, geographical, & cultural results), b) tries to find and analyse the kinds, frequency & magnitude of natural hazards that are hidden in the ‘archaeological landscapes’, c) searches for the adaptation process in past human societies and the ‘unfamiliar landscapes’ formed after natural disasters.

On the other hand, The Risk Management of Cultural Heritage Landscapes includes: a) the definition of cultural heritage (monuments, groups of buildings, man-made sites, mobile objects, archival material, scientific works, ‘memory landscapes’, palaeontological & paleoanthropological remains, natural features, geological & physiographical formations, natural sites), b) the categorisation of natural and man – made risks & disasters, c) the a priori prediction/assessment for a natural hazard to take place and, also, the a posteriori quantification of the consequences of such a disaster and its long term effects, d) the inventory of current situation in heritage sites, e) the permanent observation and monitoring of these sites, f) the development and promotion of peak technologies applied to the protection of these sites, h) the integrated management of heritage sites in a framework of environmental planning, sustainable development, disaster prevention and cultural heritage impact assessment, i) the co-operation with a variety of archaeological sub-fields (e.g. Rescue/Salvage/Crisis Archaeology, Public Archaeology, Virtual Archaeo- logy).

Within this scope, a cartographic information system has been created offering digital spatial information, risk maps of the study area and availability of cultural targets. This project promotes the co-operation between scientific community and local social structures. The final proposal was submitted by the end of 2005, through the Centre for the Assessment of Natural Hazards and Proactive Planning, NTUA. The data that built the d-bases of the produced maps were provided and analysed by scientists who work at the Institute of Geodynamics (National Observatory of Athens) and various laboratories of NTUA (Laboratory of Reclamation Works & Water Resources Management, Laboratory of Remote Sensing, Laboratory of Structural Mechanics & Technical Works, Laboratory of Geography and Spatial Analysis). Special mention deserves the GIS team which realised this specific sub-field of the project, and included Dr. Thomas Chatzichristos & candidate Dr. Alexandra Zervakou (Laboratory of Geography and Spatial Analysis, NTUA).

7.2 The Study Area

According to the reports of Eastern Attica Prefecture (September 2004), the study area, which is located east of the city of Athens, covers a surface of c. 1.800 square kilometers with a population of 410.000 inhabitants (last census). Fourth among the biggest prefectures in Greece, with 20 municipalities & 26 communities, the Prefecture is considered as the most developing area in our country. Apart from the dynamic infrastructure works (e.g. International Athens Airport ‘Eleftherios Venizelos’, motorway ‘Attiki Odos’), two significant commercial ports (Rafina & Lavrio), services companies, energy production installations, five industrial zones and tourism enterprises along the 160 km of tourist coasts, the study area could be characterized as one of the richest and most promising cases of cultural landscapes in Greece. Its vicinity to Athens and its potential of touristic development multiply the necessity for a GIS management of the cultural heritage.

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Furthermore, the area has been experienced natural disasters, such as earthquakes (e.g.

Parnitha 1999 ; Oropos 1938), landslides, wild land fires (e.g. repeatedly during the last decade), severe floods (every few years), snowstorms (once or twice every decade), continuous threat of the industrial risks, even climatic & coastal hazards. All things considered, the whole area needs immediately a risk management of cultural landscapes.

7.3 Goals Of The Project This specific sub-category of the project focused on the following briefly mentioned actions: a. Define the targets, categorize them and organize them into groups & levels b. Map the high risk areas and their zones of responsibility in reference to the cultural targets c. Coordinate and supervise the existing structures & capabilities in the cultural landscapes d. Ensure the maintenance & function of institutions that ‘manage’ the cultural heritage of the study area e. Promote new operational centers in high risk locations f. Mobilize the public services and the local communities.

Generally speaking, the chosen targets were experimental covering medium-term goals, in order to test the applicability, usability and flexibility of the automated products in the real life working conditions. In fact, this was the first, very significant, step to the realization of a wider digital cartographic background in the Prefecture of Eastern Attica.

7.4 Work Flow The work went through specific phases.

Firstly, three main categories had been recorded: a. the problems concerning the production of digital maps that incorporate cultural information, b. the natural phenomena & the environmental parameters which may act as potential hazards in the area or may affect it and c. the cultural landscapes (‘targets’).

Secondly, cultural information had been collected and classified in a d-base.

Then, maps had been produced in a digital format. The version Arc GIS 9.0 was the main tool, with special reference to specific, advisory maps for the layers concerning the cultural landscapes (Hiking Map of North Hymettos, Topo 10, 1.2 Greece – Attica, Anabassi Maps & Guides, Athens, ISBN 960-8195-12-8 & Attica Egina and Salamina, Updated 2004, Road Editions, Athens, ISBN 960-8481-88-0).

The entries of the d-base were organized into data-sets, in order to create thematic maps & different layers in a GIS conceptual basis. The Cultural Heritage data-sets consist of six (6) layers that could be transformed into six (6) thematic maps. Each layer of the d-base contain relevant attributes. The above digitized data were treated similarly, while a number of symbols were used for mapping the cultural landscapes (symbology sets).

The Layer no. 1 is called ‘Monuments’ and includes the following categories of data : architectural works, inscriptions, karst forms, works of monumental sculpture & painting, elements & structures of archaeological nature (temple, church, house, tomb/ burial monument, wall remain, other). The attribute table includes the following columns : dating, categories, coordinates, altitude, depth, perimeter, state, form, interest, information, distance from sea, above sea-level, specific date, building types. The entries include : the caves of Kitsos, Koutouki, Lion, ‘Nympholyptos’ or ‘Archedamos’ & Oinoe B’, the ‘Polyandrion’ or Tumulus of Marathon and the Church of Saint Petros & Pavlos at Spata.

The Layer no. 2 is called ‘Archaeological Sites’ and includes some of the following categories of data : groups of buildings, settlement, harbours, communication network (e.g. bridge, road), supply system (e.g. drainage), works (e.g. dam, wells, walls), cemeteries, sacred areas, mining industry, quarry, archaeological stratigraphy. The attribute table includes the following columns : dating, categories, coordinates, altitude, depth, perimeter, state, form,

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interest, information, distance from sea. above sea-level, specific date, size, number of inhabitants, stratigraphy type, characterization, use. The entries include : the Mining Complex of Kamariza, the archaeological sites of Sounion, Thorikos, Brauron, Rhamnous & Amphiareion, the ancient ports of Sounion, Thorikos, Marathon, Delphinion & Rhamnous.

The Layer no. 3 is called ‘Memory Institutions’ and includes the following categories of data : mobile objects, archival material, scientific works. The attribute table includes the following columns : dating, categories, coordinates, altitude, depth, perimeter, state, form, interest, information, distance from sea, above sea-level, specific date, material. The entries include : the Archaeological Museums of Brauron, Lavrion & Marathon and the Mineralogical Museum of Lavrion The Layer no. 4 is called ‘Remains’ and includes the following categories of data: palaeontological remains, palaeoanthropological remains. The attribute table includes the following columns : dating, categories, coordinates, altitude, depth, perimeter, state, form, interest, information, distance from sea, above sea-level, specific date. . The entries include : the site of Pikermi, area with enormous palaeontological interest.

There is also the prospect to create two additional layers. The Layer no. 5 will be called ‘Mentifacts’ and will include the following categories of data: ancient administrative boundaries, oral traditions, social structures, traditional customs & habits, mythical landscapes, language, sacred landscapes, other. The attribute table will include the following columns: dating, categories, coordinates, altitude,specific date. As an example of a specific category could be the elaboration of the geographical & political boundaries of Eastern Attica during the Classical Era in a GIS application, in order to provide a comparative tool for the modern geopolitical & socioeconomic situation.

According to the political reform of athenian Kleisthenes (507 / 6 B.C.), Attica with its 2.650 km2 during the period of maximum expansion, was divided into 10 tribes (phyles), 3 geographical departments (Paralia = coastal areas, Mesogaia = inland areas, Asty = city) & 30 trittyes (administrative units of racially related demes). Paralia had 10 trittyes, as Mesogaia and asty did also. So, each tribe included 3 trittyes (one from Paralia, one from Mesogaia and one from Asty).

The lately acquired areas (Oropos, Salamis, Lemnos) were not included to this system. In the case of Oropos, the whole area was distributed to the attical tribes.

Although the population levels in the classical demes were constantly fluctuated, there was a standard per deme, perhaps of 65 men and of 130 - 1.500 inhabitants in average. N.E. Attica contained 13 demes, eastern cost 9, Mesogaia 15, S.E. Attica 7, SW. Attica 6, plain S. of the city of Athens 6, city inside the walls 5, city outside the walls 9, lower plain of Athens 15, Upper plain of Athens13, plain of Eleusis 9. There is also a number of demes of ambiguous location (?20).

The Layer no. 5 will be called ‘Natural Sites’ and will include the following categories of data: geological & physiographical formations, areas of aesthetic value, specific protected areas.

The attribute table includes the following columns : dating, categories, coordinates, altitude, depth, perimeter, state, information, distance from sea, above sea-level, specific date, type, size, exploitation rates, activity, period of function, specific date.The entries will include : The Vouliagmeni Lake, the vineyards land at Mesogaia, the National Park of Sounion, the Pentelikon Mountain, the eastern slopes of Mountain Hymettos, The national park of Parnitha, and the wetlands of Brauron & Schinias.

Finally, the risk maps that were produced separately (landslides, hydrological phenomena, earthquakes, landfires, desertification rates, man-induced hazards), can be combined with each thematic layer of the Cultural Heritage Map, in order to : a) give a broader idea of the environmental factors which exist in the ecological, socioeconomic & cultural landscapes and b) to form a clear view of the facts concerning the future (problems, hazards, solutions, trends) of the cultural landscapes within the territory of Eastern Attica Prefecture.

Given that a digitized inventory of the cultural sites is absent – or dispersed and practically difficult to be retrieved in our country, having as a result the urge need for elementary registration of cultural targets using GIS, the present work phase should be titled : «Creating the methodological background for the application of GIS technologies in cultural heritage’s hazard management within the boundaries of Eastern Attica Prefecture».

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7.5 Conclusions - Suggestions

Not surprisingly, digital archaeological spatial d-bases are today acknowledged as significant contributors to the effective use, management and protection of natural & cultural resources.

For the first time, cultural targets within the geopolitical units of Eastern Attica’s Prefecture had been selected accordingly to various geo-database criteria, creating interactive fields and covering a wide spectrum of groups, in the framework of a synthesis of different levels of analytical tools & layers of information input. The user can ‘play’ with alternative layers and synthesize new ones having as operational framework the six (6) produced maps of the area : 1.

Topographic information (elevation contour & hydrological background combined with main roads network & elements of urban development) and sites of cultural heritage, 2. Flood hazards and sites of cultural heritage, 3. Earthquakes and sites of cultural heritage, 4. Landslide hazard and sites of cultural heritage, 5. Forest fires / vegetation indices and sites of cultural heritage, and finally, 6. Erosion estimation and sites of cultural heritage.

This step has already opened a new doorway to information, education and training in the study area. It has also created the basis for a future 24h / day monitoring of the targets, thus, it has reinforced the decentralization and the tourist development of the region, by the awareness of local communities and the promotion of the applied research in sectors of prevention.

Lacking time and possibility, because this phase was a pilot effort, this project do not contain digitized geo-spatial information (GPS measurements, panoramic photographs, field surveys & plans of archaeological sites, evaluation or monitoring based on field work).. This disability highlights the vast gap between the existing maps and, generally, the usual d-bases that incorporate cultural information now available by different sources in Greece (e.g. ephorates of antiquity, institutions, local agencies & authorities), and the digital products made in GIS platforms. When a ‘cultural target’ is located in space (given the exact coordinates and other specialized measurements), apart from the meta-data (images & photos, accompanying information), various z values can be added (e.g. elevation data & contour interval, distance from the coast, bathymetric curves, pollution markers, distance from the communication network). So, the user may choose between alternative scenarios and operational options in the framework of many ‘optimization’ tools operating within ArcGIS 9x applications.

Moreover, 3-D models may be produced in order to enhance the ‘visualization’ of the parameters analyzed by the user. Finally, the possibility of creating ‘virtual landscapes’ could be a rather convenient tool for exhibiting the cultural heritage. ‘Virtual tourism’ & ‘virtual museums’ are examples of user- and environment- friendly kinds of sustainable development, that supports a proper social profile (e.g. information’ availability to various groups and for various reasons, such as persons with health’s problems, communities or people isolated from the sociocultural procedures, alternative strategies for long-term investment on sustainable tourism).

Consequently, further analysis in a future research program, could – and will - combine different technologies & data, for example, historical data (statistical data, digital maps, images, e.t.c.), real-time data (images, reports, sensor data, e.t.c.), various mathematical models, technological solutions (d-bases, networks, e.t.c.), mobile technologies & communication means, presentation techniques and even software solutions, creating an integrated package of GIS applications on the management of cultural landscapes. The development of friendly methodologies & technologies concerning the potential hazards within the cultural landscapes detects the interdependency of the arisen problems and offers tangible and not too expensive solutions.

The ultimate challenge for this rich in cultural values area of Eastern Attica, would be the steady development of a continuously updated geographical information index in an interactive mode of real time monitoring.

The very next step to be taken is the definition and detailed categorization of these cultural targets within the study area, and, secondly, the specification of the relevant criteria matrix. This matrix will contain the specific cultural targets as rows and the thematic criteria as columns. More specifically, these thematic criteria will consist of the following aggregate variables:

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predictability and reversibility of the hazard, duration of exposion to the hazard, distance from the main ‘centre’ or the influence sphere of hazard, impact assessment on the cultural targets, severity of consequences, levels of damage, accessibility of the ‘site’, level of preparedness, recuperative potential (economic, social, other) within the areas including the targets. The above-mentioned process of categorization will also include archaeoenvironmental profiles of the relevant sites. This extremely useful but also neglected aspect of hazardous physical & man-induced phenomena, their historical background (temporal variation), can be provided through the methodological tools and the existing studies of the scientific fields of Environmental Archaeology & Disaster Archaeology.

Finally, a multi-dimensional analysis of the ‘sites’ characteristics (e.g. geographical, social, economic & environmental analysis of the landscapes) will be intergrated in the sociospatial ‘clustering’ of hazards and sites.

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APPENDIX