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. الأخطار الجيومورفولوجية للسبخات وأثرها على الإنسان وأنشطته الاقتصادية

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Abstract

السبخات مسطحات ملحية تحتوى على أحياء الاسترماتوليت والروابي الجبسية في مناطق البرك شديدة الملوحة ،وعادة ما ترتكز المسطحات الملحية Salt flats فوق تكوينات من الصلصال والغرين والرمال وغالباً ما تغطى بقشور ملحية . تهدف الدراسة إلى رصد خصائص السبخات والتغير فى بيئتها باستخدام تقنيات الاستشعار عن بعد ونظم المعلومات الجغرافية، وانتاج نموذج لتوضيح نشأة السبخات ،ودراسة اثر الانسان على بيئة السبخات وأثر بيئة السبخات على الانسان، كما أهتمت الدراسة بانتاج خرائط أخطار السبخات ووضع حلول ومقترحات لمواجهة اخطار السبخات . استخدم فى هذه الدراسة مرئيات فضائية ETM ,TM, land sat لأعوام متتالية بدقة 30م و15م. ومرئيات SPOT لأعوام متتالية بدقة 20م و10م. ،ومرئيات IKONOS بدقة 1م. ومرئيات الرادار،و خرائط طبوغرافية مقياس 25000:1 و50000:1.وخرائط جيولوجية. والدراسة الميدانية والأساليب الاحصائية والتحليلات المعملية.كذلك تم استخدام بعض ادوات التحليل وتشمل التحليل الثلاثى الابعاد 3D analysisوتحليل السطحsurface analysis فى اعداد نماذج الارتفاعات الرقميةDEM وخرائط الانحدار Slope mapواتجاهات الانحدار Aspect mapللتعرف على مورفولوجية سطح السبخات فى منطقة الدراسة والتصنيف المراقبsupervised classification لتحديد النطاقات المورفولوجية للسبخات والتحليل الطبقى Overlay analysisوتحليلات رصد التغير Change Detectionلرصد التغيرات التى تطرأعلى السبخات. وانتهت الدراسة بعرض نموذج نشأة السبخات وطرق انتاج خرائط الأخطار كما تم عرض حلول ومقتراحات لمواجهة أخطار السبخات.
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Salt flats 
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
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open system

 ( ،ليعامسإ2006)

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
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

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2002
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
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







60



ETM ,TM,land sat

SPOT 
IKONOS 





3D analysissurface analysis 
DEM Slope
mapAspect map
supervised classification
Overlay
analysisChange Detection









 
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 






























62


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
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



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

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




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














Sass, et al ,1971,p.21) 






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
 
 



 Salt Hydration






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





71




















Landsat) 
SPOT
DEMElevation
Band




DEM
72
Slopes
Aspects
3Ds



Reclassification 
Raster format  Vector format


IKONOS 



73




74





















Geographic lat /Lon 
UTMSubset 
Inquire Box 
ERDAS Imagine 9.1
Enhancements 
Filters 

Stretching Histogram 
Contrast 



(Band)
75
(Bands)


Supervised Classification

(Thematic Maps)
(Raster)
(Vector)ArcGIS 9.2
Feature Class
Geodatabase 
Overlay Analysis 
ArcGIS 9.2





76






77























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

78







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

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









Salt cycle









79




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



Gray crustBlack Crust

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
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
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
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
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80
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81
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82
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83
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Arc GIS v. 9.2 
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




 proximity analysis





85


      





      
        

       

        

  

      

  
       
.


          
        
        
86

.
     
Preloading
. 


       
       
       
         

.
Chemical Stabilization 

        

  .    

 Geotextiles
      

.
    



Hydrophobic Albond
        
87


      


        



       







        

      
      

       


       
     

88






       





       
    

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
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ResearchGate has not been able to resolve any citations for this publication.
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Salt weathering is a negative aspect that causes marked deterioration and hazards in Siwa Oasis. Salt weathering primarily results from both mechanical and chemical deterioration of rocks. In recent years many parts of Siwa Oasis have suffered immensely from salt weathering activities such as archaeological sites, roads, cultivated and urban areas. Human activities are a main cause for secondary salinization particularly in the last decades as a result of unplanned development programs. LAND SAT- TM, SPOT, IKONOS and QUIKBIRD images in addition to GIS techniques were apply to record the varying degrees of development of salt weathering. They were used to detect, analyze and assess the negative environmental features of salt weathering. Cartographic representation of this feature was produced from multi-dates data, digital maps and field investigation. A comprehensive map of such hazards is produced and represents a contribution in this connection.
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السبخات مسطحات ملحية تحتوى على أحياء الاسترماتوليت والروابي الجبسية في مناطق البرك شديدة الملوحة ،وعادة ما ترتكز المسطحات الملحية Salt flats فوق تكوينات من الصلصال والغرين والرمال وغالباً ما تغطى بقشور ملحية . تهدف الدراسة إلى رصد خصائص السبخات والتغير فى بيئتها باستخدام تقنيات الاستشعار عن بعد ونظم المعلومات الجغرافية، وانتاج نموذج لتوضيح نشأة السبخات ،ودراسة اثر الانسان على بيئة السبخات وأثر بيئة السبخات على الانسان، كما أهتمت الدراسة بانتاج خرائط أخطار السبخات ووضع حلول ومقترحات لمواجهة اخطار السبخات . استخدم فى هذه الدراسة مرئيات فضائية ETM ,TM, land sat لأعوام متتالية بدقة 30م و15م. ومرئيات SPOT لأعوام متتالية بدقة 20م و10م. ،ومرئيات IKONOS بدقة 1م. ومرئيات الرادار،و خرائط طبوغرافية مقياس 25000:1 و50000:1.وخرائط جيولوجية. والدراسة الميدانية والأساليب الاحصائية والتحليلات المعملية.كذلك تم استخدام بعض ادوات التحليل وتشمل التحليل الثلاثى الابعاد 3D analysisوتحليل السطحsurface analysis فى اعداد نماذج الارتفاعات الرقميةDEM وخرائط الانحدار Slope mapواتجاهات الانحدار Aspect mapللتعرف على مورفولوجية سطح السبخات فى منطقة الدراسة والتصنيف المراقبsupervised classification لتحديد النطاقات المورفولوجية للسبخات والتحليل الطبقى Overlay analysisوتحليلات رصد التغير Change Detectionلرصد التغيرات التى تطرأعلى السبخات. وانتهت الدراسة بعرض نموذج نشأة السبخات وطرق انتاج خرائط الأخطار كما تم عرض حلول ومقتراحات لمواجهة أخطار السبخات.
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Salt weathering is a negative aspect that causes marked deterioration and hazards in Siwa Oasis. Salt weathering primarily results from both mechanical and chemical deterioration of rocks. In recent years many parts of Siwa Oasis have suffered immensely from salt weathering activities such as archaeological sites, roads, cultivated and urban areas. Human activities are a main cause for secondary salinization particularly in the last decades as a result of unplanned development programs. LAND SAT-TM, SPOT, IKONOS and QUIKBIRD images in addition to GIS techniques were apply to record the varying degrees of development of salt weathering. They were used to detect, analyze and assess the negative environmental features of salt weathering. Cartographic representation of this feature was produced from multi-dates data, digital maps and field investigation. A comprehensive map of such hazards is produced and represents a contribution in this connection.
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Provides a thorough, broad-ranging account of the theory and practice of GIS, which is suitable for students who are serious about mastering the subject. Numerous and diverse real-world examples, with clear explanations of methodology, demonstrate the usefulness of GIS to solving practical problems and foster enhanced understanding. End-of-chapter summaries, questions, and further reading allow students to check their understanding and explore the subject further. An Online Resource Centre features additional resources for students and lecturers, enhancing the educational value of the text.
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Radar satellite images could be used to produce digital elevation model (DEM) of certain areas by processing a couple of images, covering the same area, obtained at two different angles. In this study, the DEM generated from the Canadian RADARSAT stereoscopic data for a north western area of the Gulf of Suez, Egypt, is compared to the DEM generated from the topographic contour maps, scale 1:50,000. An evaluation and assessment of the results were conducted. The study shows that the DEM derived from RADARSAT data has a high precision as compared to the one generated from the topographic maps. It is also accurate enough to provide information where other sources of digital elevation are not available.
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The sink as a geomorphological feature can modify a spatial distribution of soil moisture due to the water stagnation in the flood-plain region or spatial distribution of air temperature and humidity (air confluence effect) as well as soil depth in the karstic region. A new variable based on digital terrain model, depth in sink, is introduced as an environmental estimator. The ability of the new variable to explain spatial distributions of the relative presence of dominant tree species is tested in the case study for a karstic region (Europaean Silver Fir, Common Beech, Norway Spruce and Mountain Pine) and for a flood-plain region (Pedunculate Oak and Narrow-leaved Ash), both in Croatia. The general linear modelling method was used. Depth in sink was the significant estimator of the spatial distribution for all tested tree species.
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WEATHERING of rocks as the result of pressures exerted by the crystallization of salts from solutions in confined spaces has been recognized for many years. Studies of crystal growth pressures have been summarized by Buckley1. The roles of such pressures in rock weathering have been described by Birot2, and analysed by Wellman and Wilson3, who stated that for rocks of equal mechanical strength those with large pores separated from each other by microporous regions are most liable to salt weathering. The process is pronounced in desert and coastal areas. It is likely to be most effective (i) in the humid deserts of western littorals where the supply of salts from fogs and chemical weathering is accompanied by frequent wetting and drying of the surface, and (ii) around the margins of playas and along channels in desert areas where salts tend to be concentrated and wetting and drying is most frequent. We accept the effectiveness of salt crystallization pressures, the Salzsprengung of German authors, but we suggest that there are two additional factors associated with salts which may lead to the disintegration of rock: (i) stresses exerted by the expansion of many salts in confined spaces as they are heated, and (ii) stresses caused by hydration of certain salts in confined spaces.
The Sabkha Soil in the Kingdom of Saudi Arabia and its Engineering Problems, Almuhandis (Saudi Arabia
  • Al-Amoudi Naggger
  • Z Asi
AL-Amoudi, o., El-Naggger, Z., and ASI, I., (1991): The Sabkha Soil in the Kingdom of Saudi Arabia and its Engineering Problems, Almuhandis (Saudi Arabia) vol.6, issue 2.
Using Arc GIS TM 3D analyst" Environmental System Research, United sates of America
  • B Bob
Bob, B., (2000): "Using Arc GIS TM 3D analyst" Environmental System Research, United sates of America.
Geomorphological Hazards in Arid land: present and future
  • A Goudie
Goudie, A (2003): "Geomorphological Hazards in Arid land: present and future" Bull soc. Geo. Egypt.