LANDSLIDE ZONATION IN AREA OF PROVINCE ()

Shadi Khoshdoni Farahani, Assoc.Prof.Dr.Md Nor Kamarudin, Dr. Mojgan Zarei Nejad

Faculty of Geoinformation Science and Engineering, Universiti Teknologi Malaysia 81300 Skudai, Johor, Malaysia Email: [email protected]

Faculty of Geoinformation Science and Engineering, Universiti Teknologi Malaysia 81300 Skudai, Johor , Malaysia Email: [email protected]

GIS Center, Solvegatan 12, 223 62 Lund, Lund University, Sweden Email: [email protected]

ABSTRACT

Tehran province which encircles the capital of the Islamic Republic of Iran is highly momentous from the politico- socio-economic-cultural aspects. This significance has instigated the implementation of the geological, geographical and climatological studies in this state in a comprehensive and precise manner. Fasham district in the north eastern part of which is a geologically and geographically area has been opted out in this research for semi- detailed studies. the case studied in this research is the landslide in Fasham area. Iran is one of the highly landslide prone countries due to its particular geological, topographical and climatological conditions. Heavy financial lost are reported each year due to the landslide occurrence. The transpiration of these landslides occasionally brings about other death tolls and financial lost originating from earthquakes. Some of the factors affecting this phenomenon are as follows: the alteration of the slope amplitude, geotechnical and litho logical circumstances, earthquake and trembling, tectonics motions, structural alterations, pluvial effects and snow thawing, the extermination of the vegetation, land utilization alteration. The zone under studied is prone to landslide due to various reasons such as possessing special geological conditions and special geographical position. In this research with using of ArcGIS 9 software and Index overlay Method the landslide prone zones will be anticipated in Fasham area. A GIS-based geographical database is developed to identify landslide and can be used in any decision making in future.

KEYWORDS: Tehran, Fasham, Landslide, Geology, Geography, ArcGIS

INTRODUCTION

Iran is one of the highly slide prone countries due to its particular geological, topographical and climatological conditions. Heavy financial lost are reported each year due to the landslide occurrence. The transpiration of these landslides occasionally brings about other death tolls and financial lost originating from earthquakes. Some of the factors affecting this phenomenon are as follows: the alteration of the slope amplitude, geotechnical and lithological circumstances, earthquake and trembling, tectonics motions, structural alterations, pluvial effects and snow thawing, the extermination of the vegetation, land utilization alteration such as transformation of forest land into roads, express ways, the culture type recasting, the transfiguration of the steep regions to residential and industrial districts, etc. The zone under scrutiny in this study is prone to landslide due to various reasons such as possessing several aquifers and special geographical position. The landslide classification is momentous in the aforementioned district. This geographical region is selected because of its special climate and atmosphere, its location in central part of the

ASPRS 2012 Annual Conference Sacramento, California  March 19-23, 2012 , its slopes and special directions of slopes regarding the absorption of solar radiation, and its geological conditions with regard to types of stones and soil. The north eastern section of Tehran or Faham area has been highlighted due to various reasons such as possessing orchards, pleasant climate, being situated in the southern slope of the Alborz mountain ranges. Its vicinity to the capital Tehran and many of the population have immigrated to this area.

SCOPE OF RESEARCH

Tehran province which encompasses the capital of the Islamic republic of Iran is so crucial from the political, social, economic and cultural aspects. The province is located between 34 ◌ ْ and 36.5◌ ْ northern latitude and from ,to 53.0 ◌ْ eastern longitude (Figure 2.1). It is situated among the provinces of Mazandaran, Ghazvin, Central ْ ◌50.0 , and Semnan States. This province is one of the key tourist-bearing zones. According to the census in the 1996 the total population in this province was assessed to be about 10. 3 million and 35% of the whole expressways in Iran are situated in Tehran province. According to the latest statistics 40% of the total industrial units are situated in Tehran.

Figure 2.1. Study Area (Fasham) locations in Tehran Province.

DATA AQUISITION

As shown in Figure 2.2, there are several layers for data to be prepared as mention below: a. Topographical information topographical maps bearing 1:250000 scale of the army are plied to peruse the macro-scales. Cartography organization maps whose scale is 1:25,000 are utilized for semi-detailed probes. b. Geology organization maps at the scale of 1:100,000 which have to be digitized for modeling. c. Provision of the altitude model of the region. d. Provision of the acclivity map by means of a Digital Elevation Model (DEM) map of the region. e. The land use map f. Fault map g. Slope map h. Aspect map

ASPRS 2012 Annual Conference Sacramento, California  March 19-23, 2012 RESEARCH METHODOLOGY

The following methods have been applied in order to complete the research as explain in a flow chart and the relevant aims as shown in Figure 2.2. A brief explanation of the methodology is as follow: i) First using the extant layers to digitize some of the available maps data a. Utilization of the topographical maps in the scale of 1:250,000 and 1:25,000. b. Utilization of the geological cartography in the scale of 1:250,000 and 1:100,000. c. Utilization of the land use cartographical entities. d. Utilization of the Geographical Information System (GIS) and Remote Sensing (RS) software for modeling. ii) Making maps originating from basic data and the provision of new topical maps such as the declivity (slope) cartography, steepness direction, geomorphologic maps, isohyetal and isothermal maps, etc. iii) analyses and the producing of landslide hazard zonation map of Fasham area iv) finally, the Conclusion.

DATA ANALYSIS AND CLASSIFICATION (PROVIDING OF INDICATOR MAPS)

In this section the data analysis carried out as for providing maps such as geology map, Fault map, aspect map, land use map and slop map. To analyze the layers in ARC GIS software using the Index Overlay Method, bearing in mind the extent and level of collected data regarding the layers in the region, and to have precision in studies, all the layers used in this project were divided into five classes based on experts' views. In the first phase, data is labeled either as high risk or low risk in the attribute tables of each layer, with regard to its significant role in occurrence of landslides, and is assigned an even number between 2-10 (Stable-Unstable). This is shown in the legends of re-classed maps as the following table demonstrates:

Table 3.1. Base of data classification

Data classification Score Equivalent in the maps High risk 10 Unstable Relatively High Risk 8 Relatively Unstable Moderately Low Risk 6 Moderately Stable Relatively Low Risk 4 Relatively Stable Low risk 2 Stable

PROVIDING OF GEOLOGY MAP

The geology map of study Fasham area is classified into 5 groups which this are based on rocks strength of Fasham area. According to Table (3.2), rocks and stones are classified into 5 different groups and according to their stiffness and strength, per score is added to them. This is shown in map 3.1

ASPRS 2012 Annual Conference Sacramento, California  March 19-23, 2012 Table 3.2. Base of Geology Classification of Fasham area

Symbol on Group’s No. Rock Unit Score the map name legend Quaternary Unstable 1 Rocks and PIQC, S 10 Sediment 3 2 1 C K sh a m t sh Sedimentary M, M u, M u, M u, O 1, E N, E k, E k, E k, E k, E k, Relatively 2 m,s,s c 3 a 8 Rocks gy, PE f, PE f, PEv, P JS,pd, P j, CZ, Ebt Unstable Kd Kc Kb Ka K Kc Kb Ka Kt, Kc Ja, J Moderatly Calcareous u, u, u, u, 3, 2, 2, 2, 1, 1, 3 Jd, Rd Rl Rm.l Pn, Pr, Cm, Cd Cc Cb Ed PE- 6 Stable Rocks e, e, e, j, j, j, bt, ES Volcanic Relativly 4 Rv Dv , Eq, C , E Tr,MZa,d, Tda, Tb, Td,R 4 Rocks 3, j 1 1, Stable 5 Igneous Rocks Tgr, T8, Td, Tgb 2 Stable

In this classification, the most score belong to Quaternary rocks and sediments, that is, Quaternary rocks and sediments are more reliable to happen landslide. Because of the geologically reason Quaternary rocks and sediments are very young, not very stiff, and are unstable. The second group includes sedimentary rocks like Sandstones, Mudstones, Marl, Gypsum and shale. Geologically, the sedimentary rocks are not very strong and belong to unstable rocks group. The third group is calcareous rocks which are more strength than sedimentary rocks; this group includes Limestone and dolomite. The fourth group is volcanic rocks which are in the group of strongest rocks. This group includes Andesite, Andesite- Basalt, Pyroclasticm Quartz, Sandstone, Riolite, Dolerite and Lithic tuff. The fifth group, which is the most strength group of rocks, includes igneous rocks and so give the fewer score is added to this group. There is very little possibility that happen landslide in this group. This group includes Granite, Granodiorite, Siyenite, Diorite, Micro diorite and Gabbros. Finally, the classify map from original map which is vector file, is changes into raster or grid file. After preparing all the attribute tables for all the layers in ARC GIS software, and when the analysis process is complete, it is necessary that all the layers data be turned from Shape file or Vector format into Rater or Grid format for the final process so that they can be merged in ARC GIS software using Index Overlay Method and make the final map. Shape files can not be merged with each other.

Figure 3.1. Reclassed Geology Map.

ASPRS 2012 Annual Conference Sacramento, California  March 19-23, 2012 PROVIDING OF FUALT MAP

Faults of Fasham area can be classified into 3 groups according to original map of faults of Fasham and information presented in attribute table.  major faults  minor Faults  buried faults

According to this classification, the original map is separated in to 3 new maps. Then each map includes special group of faults showing 4 areas around faults like 200m, 500m, 1000m and 1500m of multiple ring buffer. Then, these maps compiled presented the major, minor and buried faults into one map. As a result, there show 3 types of fault to coincidence together are special in this map (map 3.2). These cross points for scoring are appropriate to high danger because, each type of faults in this area strengthens activity and their activities will cause landslide.

Figure 3.2. Reclassed Fault Map.

PROVIDING OF ASPECT MAP

To prepare a classification of a map for aspect the Azimuth used. According to geographical position of the study area, north, north-west and part of west received very little ray of sun which these sides are always wet. Then the, north, north-west and part of west are more reliable to occur landslide. The highest score which is 10 belong to this group. The east, south-east and south are less reliable to occur landslide because these sides are very dry and have less humidity. The map 3.3 shows the map for aspect. In order to prepare the Aspect classification map, the basic original Aspect map had been used.

ASPRS 2012 Annual Conference Sacramento, California  March 19-23, 2012

Figure 3.3: Reclassed Aspect map

PROVIDING OF LAND USE MAP

According to information presented in the land use map, land use for Fasham area is divided into 5 groups the Map 3.4 shows the land use include: forestation, bare land, dry farming, irrigated farming, range, rock, scattered dry farming and Urban. In preparing the classification map, the land use is divided into 5 groups (attention to the score) and related score is added to each group as show in table 3.3.

Table 3.3. Land use classification

Symbol on the map No. Land use type score legend 1 Irrigated Farming 10 Unstable 2 Dry Farming 8 Relatively Unstable Scattered Dry Farming 6 3 Moderately Stable Bare Land 6 forestation 4 4 Relatively Stable Range 4 Rock 2 5 Stable Urban 2

ASPRS 2012 Annual Conference Sacramento, California  March 19-23, 2012

Figure 3.4. Reclassed Land Use Map.

PROVIDING OF SLOPE MAP

Using the original map, the maximum and minimum slopes are determined and the slope between two groups are classified into 5 groups. Slope 0.003 degree to 8.05 degree, the lowest score is definite in stable area. Slope 32.21 degree to 40.26 degree, highest score is definite in unstable area. The map 3.5 shows the slope map. Also there are complete information and classification about the slope in the Fasham area in the table 3.4.

Table 3.4. Slope information and classification in Fahsam area

No. Slope ( Degree) Score Symbol on the map legend 1 0.0031 to 8.055 2 Stable 2 8.055 to 16.108 4 Relatively Stable 3 16.108 to 24.161 6 Moderately Stable 4 24.161 to 32.214 8 Relatively Unstable 5 32.214 to 40 .267 10 Unstable

ASPRS 2012 Annual Conference Sacramento, California  March 19-23, 2012

Figure 3.5. Reclassed Slope Map.

CLIMATOLOGY

Latitude, altitude and distance from the sea are among the chief climatological determinants. Tehran Province is situated in the median latitudes (between the equator and the boreal pole). It should have a moderate climate irrespective of other factors however altitude and distance from seas has made oodles of changes in Tehran climate. Altitude plays a key role in Tehran climatology. Two key climatological factors yclept pluvial precipitation and temperature vary due to Tehran elevation. Pluvial precipitation quantity is not the same in temporal and locodescriptive manners. Pluvial precipitation in Tehran province is affected by elevation. Thus as the elevation increases from the south northwards, the pluvial precipitation escalates proportionately. The rainfall quantity in the boreal elevations of this province for instance Station which is 500 meters above the sea level outstrips 500 ml. thus the rainfall increases or decreases based upon the highness. Since temporal distribution of the pluvial precipitations are unbalanced most of the rain occure in the cold seasons whereas it is so slight especially in torrid seasons. Tehran and Abali Stations receive respectively 74% and 68% of their rainfall during autumn and winter. Thus two third of the precipitation happens in cold seasons. The average annual temperature in Tehran and Abali Stations is respectively 16.5 and 8 degrees centigrade. The temperature increases from north to south as the elevation decreases. The glacial days increase from south to north due to elevation increase. FiroozKooh whose minimum temperature reaches -30 degrees centigrade is the chilliest town in this province. Tehran compass card demonstrates that occidental winds are dominant in this station. Occidental winds are the chief pluvial precipitation factors in this province. The south eastern winds which blow from the central playa region in Iran is in the 2nd priority. This wind transfers desert climate, dusty and polluted conditions to Tehran. The average monthly wind celerity never outstrips 20 knots in Tehran station nonetheless there may occasionally eventuate winds whose celerity is 130 kilometers per hour. Mountain-to-plain winds and plain-to- mountain winds blow usually diurnally. The quotidian blowing is from Tehran Plains towards Alborz Mounts and the nocturnal blowing is vice versa. The ensuing stations have been utilized in a 10-year statistical epoch (1993-2003) (Table 3.5).

ASPRS 2012 Annual Conference Sacramento, California  March 19-23, 2012 Table 3.5. Statistic of 10 climatology stations (1993-2003)

No Stations Statistical epoch 1 Tehran mehrabad 1993-2003 2 The boreal Tehran 1993-2003 3 1993-2003 4 Kan 1993-2003 5 Geophysic 1993-2003 6 Abali 1993-2003 7 Firozkooh 1993-2003 8 1993-2003 9 Sadabad 1993-2003 10 1993-2003

The region of our study was a high area at central Alborz. Some its climate features are semi mild summers and cold winters and its changes the slope which is lower than 1 degree. Effects of slope are perfectly obvious in this region. Earth slope is various from 5 to 51% and more complicated is Darkia… towns. Geographical directions are effective in eco system's quality and generally geographical directions from warm to cold slopes some of the altitude in the studied area are shown in table 3.6.

Table 3.6 Altitude of cities in the study area (Fasham area) form sub see depth

The and name Oshan Fasham Meygon Hajiabad Emame Zaygan of area Altitude 1900 2000 2350 1850 2200 2300 (m)

INDEX OVERLAY METHOD

The index overlay methodology has been selected in this project with regard to the extant layers and data. Overlay of indicators make indicators combination more flexible in comparing with Bulian logical operation. The score tables and map scales can be presented in a way that shows a professional’s opinion about practical use. Map scales can be positive or negative non-decimal numbers or integer numbers without limitation in numerical range. Because, scaling for output map classes are accessible by classification of turning-points. The weak point of this method is ambiguous logic which is similar to this method, but their combination rules are more flexible and have no linear increasing.

OVERLAYING OF INDICATORS WITH MULTICLASSES MAP

In this state, map classes on each map will be given different scores and different scales. It is better to define and determine features of each map. Some of GIS show special frame for input data in special table for combining map. So sum of score is:

n  SWij i i S  n  W i i S Sum of score (pixel, polygon) th Wi  Score of i in put map

ASPRS 2012 Annual Conference Sacramento, California  March 19-23, 2012 th th Sij = Score of i class of j map j is amount of calsses

Each map should have a list of scores for each class. The editor can insert scores into table to achieve modeling and then that table can be correct through work without any changes.

RESULT AND CONCLUSION

The final product of this research is Landslide Hazard Zonation map in Fasham area. The scale of this map is 1:100,000 and all the studies and surveys in this area have been done with 1:100,000 precision. Such information as classification of hazard zone, altitudes of the region, main roads and side roads, rivers and important cities in the region can be found in the legend of the map. This map is divided into five classes as follow: stable zones in blue, relatively stable zones in yellow, moderately stable zones in green, relatively unstable in light red and unstable zones in dark red. The light red and dark red zones are in fact landslide hazard zones. The altitude curves divide the region into three parts. The zones with the height of 1,067 meters and more are shown by red lines, the zones with the height of 2,615 meters and more are shown by purple lines, and the zones with the height of 4,022 meters and more are shown by black lines. As it can be seen on the map, the zones in light red and dark red that depict hazard zones are located in the regions higher than 2,615 meters in the northern region of the main towns. There are seven main towns and cities of the region are shown in the map. They are Tehran, Jajrood, Vasafjan, Boomehen, Dar-a, and Roodehen from west to east. The main and side roads connect most parts of the region facilitating access to urban areas and other main centers. Landslide hazard zonation map is very useful and important for several fields such as civil engineer, geologists and geographists. These groups of specialists can use the map to find the suitable area for making dam, bridge, residential areas and governmental projects decision making

Figure 4.1. Final Product (Landslide Hazard Zonation Map of Fasham Area in Tehran province.

ASPRS 2012 Annual Conference Sacramento, California  March 19-23, 2012 REFERENCES AND BIBLIOGRAPHIES

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ASPRS 2012 Annual Conference Sacramento, California  March 19-23, 2012