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Geomorphological hazard map along Southwestern Sinai Coast El-Tur area using GIS.

Introduction

Along the coast of the Gulf of Suez Egypt, geomorphological hazards are the main threat as the greatest natural danger to life and construction and even marine life. The study area is located southwestern Sinai and located entirely within the catchment area of the Gulf of Suez. It is bounded from the West by the Gulf of Suez and from the East by wadis firan Dahab, kid basins (Fig. 1). It is elongated and covers an area of about 6665 km2. Flash floods are one of the most costly disasters in terms of both property damage and human casualties.

Since the blueprint paper flood modeling has greatly improved in recent years with the advent of Geographic Information Systems (GIS), radar- based, high-resolution Digital Elevation Models (DEM).

Methodology

In order to achieve the study objectives, the following data sources have been used:

1 ETM images produced in 2001 (3 bands) which give details smaller than 30m, and some images of a band of panchromatic spot which give details to give details smaller than 10 m lengths

2 Topographic maps scale, 1: 50.000 and geologic maps scale,

1: 500.000 and second source of geological data are three sheets of geological maps of Sinai scale 1:250000 which have produced by Egyptian General Survey Authority in 1994. They have more details about lithology and structure of the study area.

3 Climatic and hydrologic data. There are 3 meteorological stations in and around the study area. Their climatic data recorded until 2010 were used. During the record periods, there is a lack at the time.

4 Intensive fieldwork at the area, to determine and check the risk sites by using GPS.

All primary data were imported in a Geographical Information System in the MapInfo environment. Thus a GIS database was developed and updated with data deriving from different sources. Data were analysed quantitative and qualitative, while different aged thematic maps were created.

Physical Characteristics of the study area

Geological study area

The Sinai Peninsula occupies a portion of the foreland shelf of the Arabo-Nubian massif that dips gradually northward toward the Mediterranean Sea (Said, 1962, 245). Its morphology, stratigraphy, and structures are strongly interrelated and have a great bearing on the groundwater potential (Issar et al., 1972, 82). To understand the general geology of the study area, knowledge of background geology of the Gulf of Suez region is essential. A simplified map of geology of the study area and its surroundings is shown in Fig. 2. A brief the regional geology of the study area.

a. Basement rocks: the basement rocks are distributed in the southern and eastern part of the study area which can be represented as:

The oldest rock unit is represented by Firan--solaf gneiss rocks which composed of coarse medium grained banded hornblende gneiss intercalated by migmatites and crossed by dykes metagabbroic rocks contain coarse to medium gruined metagabbric, which variably deformed and locally banded Diorite rocks crop out sporad cally over the area (EL-Masry et al. 1992, 54) These rocks consist of course to medium--grained quartz diorite and hornblende--biotite granodiorite, (Geological Survey of Egypt, 1994).The granite rocks Composed of coarse to medium grained alkaline granite [+ or -] riebekite and monzogranite locally mega crystic and foliated (fig. 2) the volcanic rocks cover about 221.61 [km.sup.2] for about 3.3 % of total area and composed mainly of basic rocks.

b Sedimentary rocks: are more prevalent in the region and consist of the limestone, sandstone, Siltstone and sabkha. These sediments are dominated usually by carbonates, evaporates, fluviatile, aeolian and marine debris and are sometimes cemented with carbonate or gypsum (Cookl et. al 1973, 132) Alluvial deposits distributed in areal extent in the area.

2. Climatic conditions

The climatic conditions of the Sinai Peninsula are similar to those, which characterize desert areas in other parts of the world. They include extreme aridity, long hot and rainless summer months and a mild winter. During the winter months, some areas of Sinai experience brief but intensive rainfall that makes wadi beds overflow and sometimes cause severe flash floods damaging the roadways and, sometimes, human lives (JICA, 1999, 65). The minimum and maximum temperatures of the Sharm El-Sheikh Station are 20.9-30.1C and for EL-Tur and 17.5-28.3C and for St. Catherine 8.9 -24.3 C.

Average rainfall is relatively low with amean of about 6.2 mm/year at EL-Tur, 14.1 mm/ year at Sharm El-Sheikh and relative humidity varies between 29 % and 59% at St. Catherine and EL-Tur respectively.

Evaporation in the study area is very important because it is much higher than precipitation; the values of evaporation depend on some factors such as temperature, relative humidity, wind speed, the plant cover and solar radiation and average evaporation varies between 9.9 mm in EL-Tur and 17.9 mm in Sharm El-Sheikh.

Generally, the prevailing climatic conditions in the south Sinai include low rainfall, high temperatures, strong wind, high evaporation and low relative humidity.

Accuracy Enhancement Using Satellite Image and GIS to Automate Drainage Networks

Combining the remote sensing data in terms of satellite images with topographic maps of lower scale would noticeably enhance the accuracy of maps outputs. Overlying the digitized networks on satellite images is considered as a good routine to enhance the accuracy of output networks and minimize the errors in the basin calculations. Another advantage of using the satellite images is getting high resolution and updated view of the drainage pattern, (El-Behiry, 2005, 21). Geographic information systems (GIS) are computer-based systems for storing, retrieving, manipulating and displaying spatial data (Sabins, 2000, 85) In the present study, the DEM file contains both contour lines and the spot heights from topographic maps of scale 1: 50,000 The automated drainage networks of the area created from the available hydrologic data is shown in Fig (3) and Fig (4).

Morphometric analysis of drainage basins and (dem)

Morphometric parameters were calibrated with the remotely sensed and ground truth data to study the lithology of the study area.

The drainage systems, of different wadis threaten the Gulf of Suez coast El-Tur area, as well as the roads and crossing the area, are external, well developed, they are significantly controlled by geological structure and lithology. These basins originate mainly in mountainous highland of basement rocks. The area consists of drainage basins and these wadis flow the Gulf of Suez with its Villages, urban areas. The drainage net of the study area is well developed, integrated and fairly dense but is not consistent all over the area (Fig. 3). The degree of the uniformity of the drainage lines and their angles of juncture differ from one place to another. The main channels and their large tributaries are mostly oriented and show high degree of control. Qualitatively, the common types of drainage patterns along the basement highland are coarse dendritic to subdendritic parallel to subparallel and radial drainage and less common types are trellis. In order to evaluate the hazard probability of the different basins, some of the morphometric parameters were used these morphometric parameters include drainage density, drainage frequency and bifurcation ratio. Drainage density is a measure of the total network lengths of the basin to the total area of this basin (Melton, 1958, 35). Drainage frequency is the ratio of total number of all stream segments in the basin to the total area of the basin (Horton, 1945, 56). The following (Tables 2) show the drainage basin and network morphometric analysis.

El-Shamy (1992) has established empirical diagrams according to his work in the Egyptian drainage basins (Figs. 5). He divided his diagrams into three zones, the first zone (A) is characterized by high possibility for flash floods and low possibility for the groundwater aquifer recharging, the second zone (B) is characterized by moderate possibility for flash floods and moderate possibility for recharging the groundwater aquifer, and the third zone (C) is characterized by less possibility for flash floods and high possibility for recharging the groundwater aquifer.

Fig. 5 a and b show these approaches with zones A, B, C. The data from both diagrams used to determine the overall hazard degree. If a basin plotted in zone B in the first diagram (Moderate possibility of flash floods) and located in zone C in the second diagram (High possibility for flash floods) the overall hazard degree for this basin will be high possibility for flash floods which represents the more "conservative" situation.

1. Flash flood hazard map

Flash-flood-prone wadis (dry channels cut into the terrain) were delineated and assessed using GIS to determine the hazard of flash floods between wadi El-Aawag and wadi El-Mahash. For the creation of the hazard map, the data extracted from El-Shamy's model (Table 2) have been applied for each drainage basin in the study area. The overall hazard degree which determined by comparing the hazard degree resulted from bifurcation ratio versus drainage frequency and bifurcation ratio versus drainage density (Table 3) indicate that one basin high possibility for flash floods and Three basins have moderate possibility of flash floods and two basins have low possibility of flash floods. The overall hazard degree was added to the GIS database to assist in constructing the drainage basin hazard map for the most hazardous basins and is shown in Fig. 6. This hazard map was overlaid by the infrastructure facilities (road), urban areas, touristic villages, and industrial areas.

2. Susceptibility maps of areas and roads

Landslide hazard maps provide information that can be used to identify different levels of risks due to landslides, which in turn facilitates implementation of appropriate structural and non-structural loss reduction strategies for both existing and future development. In the present study the most susceptible zones have been performed using a subjective and qualitatively method. Susceptibility maps for both the areas along the coast and the road have been generated and shown in. (Fig. 7), the most susceptible zones that will be more prone to be damaged by flash floods have been determined only along the moderately hazard basins. The intersections between the perpendicular wadis with road are the most areas that are susceptible to be damaged due to erosion by flash floods. The final results of this analysis are shown as susceptibility maps.

Flood hazard and risk mapping has shown a great deal of importance for suitable urban developments. The results shown in this paper can help the developers, planners and engineers for afforestation and land-use planning. However, one must be careful while using the models for specific site development. This is because of the scale of the analysis where other causative factors need to be considered. Therefore, the models used in the present study are valid of generalized planning and assessment purposes.

Mass deposition hazard assessment

Slope gradient has a great influence on the susceptibility of a slope to landsliding on a slope of uniform, isotropic material increased slope gradient correlates with increased likelihood of failure. However, variations in soil thickness and strength are two factors which vary over a wide range for both failure and non-failure sites. To quantify the relative frequency of landslides on different slope gradients, it is necessary to consider the distribution of the slope gradient categories using the available digital elevation model (DEM). Examination of landslide frequency with the corresponding slope gradient categories Shows an increase with slope gradient until the maximum frequency is reached in the 35-40_ category, followed by a decrease in the >45_ category.

The results were integrated into the geographic information system (GIS) environment for identifying the development distribution and the slope instability hazard zones on large scale. On the other hand, field trips have been conducted to investigate most of the rock cuts and cliffs in the study area. The study included identifying and measurement of the different features along the unstable cliffs and slopes, as well as identifying the factors affecting the slope instability. Previous studies have amply demonstrated that landslides are predictable if terrain characteristics are available. The factors generally attributed to causing landslides are lithology, slope angle geomorphology, structures, and land use (Fig. 8). However, the seismic activities; and man-made factors such as over-steep (Ahmed M. 2011, 617). To mitigate the geomorphological hazard level it is necessary to determine the most susceptible hazard zones and above all, to reduce the mass wasting problems and flash flood hazards.

Places and degrees of risk

Through the previous model possible to arrive at risk scores according to the address that was using the Spatial Analyst in ArcGIS 9.2 (Fig. 9).

Coastal Erosion

Development activities along the eastern coastal plain of the Gulf of Suez and adjacent zones subjected coastal erosion. Spatial data was linked with descriptive information about the classified features on a map. The topographic maps of the study area were converted into digital format using Arc GIS 9.2. The Landsat TM scenes acquired in year 2000 were processed using ERDAS IMAGINE 8.7. Projection parameters for these datasets Universal Transverse Mercator, Zone 36, and WGS 84 Datum) were used to register the datasets.

Shoreline change evaluations are based on comparing historical shorelines derived from processed ertical aerial photography. Historical shorelines generally represent the period of the last 76 years, through analysis of satellite image and maps for years 1934-2010 has been monitoring several changes to as follows (Fig. 8)

The rates of erosion range 110.24 m with annual rate of about 1.45 m/yr, while the rates of accretion range 222m with annual rate of about 2.9 m/yr.

Seismicity maps in Gulf of Suez

The Sinai Peninsula has been recognized as a subplate of the African plate, located at the triple junction the Gulf of Suez Rift, the Aqaba-Levant transform fault (the southern part of the Dead Sea--Jordan transform) and the Red Sea Rift (Ben-Menahem, 1976, 24). And spread on the Gulf of Suez group of seismic stations as in the form of (Fig 10)

And increase the Seismicity of the Gulf of Suez in study area during the period from 1900-2010 (Fig. 11) several geological and seismological studies show that the area surrounding the Gulf of Suez displayed in the past, extensional tectonics with large deformation rate.

Sayed and Dahy (2010, 12) concluded that:

--The seismic activity in the Gulf of Suez takes a NW trend coinciding with the main trend of the opening of the rift and the activity markedly decreases from south to north.

--The focal depths of almost all events observed in the Gulf of Suez by the records of ENSN range mainly from 4 to 25 km

The influence of earthquakes on the movement of materials on the slopes, and the movement of these materials in the direction of the roads, leading to accidents and disasters, perhaps, and this change may cause earthquakes, displacement in the development of cracks, which affect the region on the roads and cause geomophological hazards.

Conclusion

Cartographic modeling provided a multi-disciplinary approach to explore land constraints. In this study, the use of cartographic modeling produced a land risk map. Such risk map can be useful as guidelines for more detailed studies in environmental impact assessment and environmental management plans. It can be useful in establishing and reviewing building codes for construction in the various zones. It is also helpful in land suitability analysis and land allocation in urban planning decisions. Flood protection is essential. It complements other preventive tools like the effective planning of the growth of cities by creating a computerized GIS database for the flood-prone areas. Detailed flood risk assessment location maps are required to minimize the harmful effects of these problems. The flash floods are concentrated along the main channels especially in the mountainous area of the investigated basins which are characterized by steep slope and narrow channel; the risk in these areas is strongly limited at the main streams. By contrast, some basins such as Wadi El-Aawag basin have wide channels and contain some large valleys with broad valley bottoms where Bedouin villages and cultivated areas are found. Consequently, these cultivated areas and villages often have been destroyed during flash floods.

Mitigation measures should be taken for flood and mass deposition protection. It complements other preventive tools like the effective planning of the growth of cities by creating a computerized GIS database for the flood-prone and mass deposition-prone areas, for the flash flood hazards in the study area.

REFERENCES

Abo-Ali, Nadia (2010), "GPS measurements of current crustal movements along the Gulf of Suez," Egypt Journal of Geology, 67 322-51.

Ben-Menahem, A., A. Nur and M. Vered (1976), "Tectonics Seismicity and Structure of the Afro-Eurasion- Junction the Breaking of an Incoherent. Plate. Phys." Earth Plant. Int., 12: 1-50.

Conoco (1987), "The Egyptian General Petroleum Corporation," Geological Map of Egypt 1:500 000,

Cooke, G., A. Warran (1973), Geomorphology in Deserts. London: Batsford, 394.

El-Behiry M. G., A. Shedid A. Abu-Khadra, M. El-Huseiny (2005), "Integrated GIS and Remote Sensing for Runoff Hazard Analysis in Ain Sukhna Industrial Area, Egypt." Earth. sci. Vol., 17-42.

El Masry, N. (1992), "Reconsideration of the Geologic Evolution of Saint Catherine Ring Dyke, South Sinai," Geol. Sinai Develop., Ismailia, Egypt, 229-238.

EL Shamy, I. (1992), Hydrogeologic Assessment of Saint Catherine Area, south Sinai, Geol. Sinai Develop., Ismailia, Egypt, 71-76.

Horton, R. E. (1945), Erosional Development of Stream and Their Drainage Basin: Hydrological Approach to Quantitative Morphology: Bull, Geophys. Soc. Am., v. 56, 275-370.

Melton, M. A. (1958), "Correlation Structure of Morphometric Properties of Drainage Systems and Their Controlling Agents," Journal Geology 66, 442-60.

Mahmoud M. Ashour (2002), "Flash Floods in Egypt (A Case Study of Durunka Village--Upper Egypt)," Egyptian Geographical Association. Vol. 75, 114.

Said, R. (1962), The Geology of Egypt. Elsevier, Amsterdam, 377.

Sabins, F. F. (2000), Remote Sensing: Principles and Interpretations. New York: W.H. Freeman and Company, 188.

Stickler, M., S. S. Feinstein, B. Kohn, P. L. L. Lavier and M. Eyal (1998). Pattern of Mantle Thin-Ning from Subsidence and Heat Flow Measurements in the Gulf of Suez: Evidence for the Rotation of Sinai and along--Strike Flow from the Red Sea," Tectonics 17: 903-920

Issar A., A. Bein, and A. Michaell (1972), "On the Ancient Water of the Upper Nubian Sandstone Aquifer in Central Sinai and Southern Israel." Hydrogeol. 17:353-374.

Youssef S., H. Sheref (2008), Flash Floods and Their Effects on the Development in El Qaa Plain Area in South Sinai, Egypt, A Study in Applied Geomorphology Using GIS and Remote Sensing Universtat Mainz.

*** Geological Survey of Egypt (1994), Geological Map of Sinai, Arab Republic of Egypt (sheet No.1) scale 1: 250000, Ministry of Industry and Mineral Resources.

*** Japan International Cooperation Agency, (JICA) (1999): South Sinai Groundwater Resources Study in the Arab Republic of Egypt, Main Report, Pacific Consultations International, Tokyo in association with sandy consultation. Tokyo.

MOHAMED FOUAD ABD EL AZIZ

mi_me46 @yahoo.com

El Arish, Suez Canal University, Egypt

Table 1. Climatic data from 1934 up to 2010 for the study area

Station         Max T   Min T     Annual        Aver       Average
                (_C)    (_C)     Rainfall    evaporation   humidity
                                in one day      (mm)         (%)
                                 (mm/in2)

ST. Catherine   24.3     8.9       10.5         11.6          29
EL-Tur          28.3    17.5       6.2           9.9          59
Sh. El-Sheikh   30.1    20.9       14.1         17.9          40

Source: the Egyptian meteorological authority from 1934 to 2010.

Table 2.  Morphometric parameters of the drainage basins

Name                A          L      W       P       TL
               ([Km.sup.2])   (Km)   (Km)   (Km)     (Km)

w. El-awag         1985       45.4   31.3   228.6   5409.4
w. Araba          3342.5      12.7   12.4   123.9   710.5
w. Asla           605.4       41.8   12.2   152.3   1236.6
w. Timan          402.3       37.8   8.4    118.4   662.5
w. El-Mahash      329.7       37.7   8.2    110.9   887.3

Name           TDN    Rb     f         D
                                      Km/
                                  [km.sup..2]

w. El-awag     5426   4.2   2.7       2.7
w. Araba       572    4.6   5.8       2.1
w. Asla        1059    4    1.7       2.1
w. Timan       998    5.7   2.4       1.7
w. El-Mahash   925    3.9   2.7       2.7

W. = Wadi, A = area, L = length, W = width, P = perimeter,
TL = total length, TDN = total drainage number, Rb =
Bifurcation ratios, D = Drainage density

Table 3. Hazard degree analysis following
El-Shamy's (1992) approach

Name           HD2   HD1   FHD

w. El-Aawag     M     M     M
w. Araba        L     L     L
w. Asla         M     L     M
w. Timan        L     L     L
w. El-Mahash    H     H     H

HD1 = hazard degree Br vs. F, HD2 = hazard
degree BR vs. D, and FHD = Final hazard
degree from HD1 and HD2. L: low hazard (low
possibility for flash floods); M: moderate
hazard (moderate possibility for flash
floods); and H: high hazard (high
possibility for flash floods).
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Title Annotation:Geographic Information Systems
Author:Aziz, Mohamed Fouad Abd El
Publication:Geopolitics, History, and International Relations
Article Type:Report
Geographic Code:7EGYP
Date:Jul 1, 2013
Words:3444
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