ظاهرتا السباخ والإرساب الريحي غرب شط العرب
دراسة جيومورفولوجية
أطروحة تقدم بها
نميـر نذ ير مراد علي الخياط
إلى مجلس كلية الآداب / جامعة البصرة
وهي جزء من متطلبات الحصول على درجة دكتوراه فلسفة
في الجغرافيا الطبيعية
بإشراف
الأستاذ المساعد الدكتور
تغلب جرجيس داود
الأستاذ المساعد الدكتور
عبد المطلب حسون المرسومي
صفر 1423 هـ - نيسان 2002
محتويات الرسالة
المـوضــوع
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الصفحة
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المقدمة
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1
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(1) الهدف من الدراسة
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4
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(2) الدراسات السابقة
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5
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(2-1) الدراسلت الخاصة بظاهرة السباخ
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5
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(2-2) الدراسات الخاصة بظاهرة الغرساب الريحي
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7
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(3) تحديد منطقة الدراسة
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9
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(4) الدراسة الميدانية
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12
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الفصل الأول: العوامل الجغرافية التي ساهمت في تشكيل ظاهرتي السباخ والإرساب الريحي في منطقة الدراسة .
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16
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(1) : العوامل الطبيعية .
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16
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(1-1) : الوضع الجيولوجي
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16
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(1-2) : الوضع الجيومورفولوجي
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20
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(1-2-1) : مناطق كتوف الانهار الطبيعية
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20
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(1-2-2) : مناطق المنخفضات المجاورة
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20
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(1-2-3) : مناطق مسطحات المد والجزر
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22
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(1-3) : الخصائص المناخية
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25
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(1-3-1) : الإشعاع الشمسي ودرجات الحرارة
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25
|
(1-3-2) :
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28
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(1-3-3) : الريا ح
|
29
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(1-3-4) : التبخر
|
30
|
(1-5) : المياه الجوفية
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39
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(1-6) : النبات الطبيعي
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40
|
(2) : العوامل البشرية
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44
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(2-1) : الأسايب الزراعية
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44
|
(2-2) : مصدات الرياح
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45
|
(2-3) : الرعي الجائر
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45
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الفصل الثاني: السمات الطبيعية لظاهرة السباخ في منطقة الدراسة
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46
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(1) : التوزيع الجغرافي لظاهرة السباخ وخصائصها المورفولوجية
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47
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(2) : مكونات رواسب السباخ
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48
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(2-1) : محتوى المواد الكلسية والجبسية
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48
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(2-2) : محتوى المواد العضوية
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51
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(2-3) : المحتوى الرطوبي
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52
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(3) : التجوية الكيميائية في منطقة السباخ وتباينها الفصلي والمكاني
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57
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(3-1) : القشرة الملحية وخصائصها المورفولوجية
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58
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(3-2) : الأيونات الذائبة في الرواسب وأثرها في عملية التملح
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65
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(3-2-1) : التوصيلية الكهربائية
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71
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(3-2-2) : أس الهيدروجين
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72
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(3-3) : الظروف المائية وأثرعا في عملية التملح
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79
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(4) : تحديد أنواع السباخ وخصائصه الطبيعية
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85
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(5) : الدورة الجيومورفولوجية لظاهرة السباخ
|
93
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(6) : الآثار البيئية لظاهرة السباخ وسبل الحد منها
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96
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الفصل الثالث : السمات الطبيعية لظاهرة الإرساب الريحي في منطقة الدراسة
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103
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(1) : التوزيع الجغرافي لمظاهر الإرساب الريحي في منطقة الدراسة وخصائصه المورفولوجية
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104
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(2) : التحليل الحجمي للورواسب الرملية
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113
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(2-1) : الوسط الحسابي
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113
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(2-2) : الانحراف المعياري
|
115
|
(2-3) : الالتواء
|
116
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(2-4) : التفلطح
|
117
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(2-5) : المتوسط
|
118
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(3) : بيئة التعرية الريحية
|
119
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(3-1) : تحليل المعادن الثقيلة
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119
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(3-2) : شكل حبيبات الرواسب
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122
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(4) : بيئة الترسيب الريحي
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125
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(4-1) : الوسط الحسابي مقابل الانحراف المعياري الشامل
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127
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(4-2) : الوسط الحسابي مقابل التناظر
|
128
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(4-3) : الوسط الحسابي مقابل التفلطح
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128
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(4-4) : مخطط ستيوارت
|
128
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(5) : تقدير كمية الرواسب الريحية المنقولة وتباينها الفصلي والمكاني
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131
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(5-1) : القابلية المناخية لتعرية الرواسب
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135
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(5-2) : قابلية التربة للتعرية الريحية وتباينها المكاني
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139
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(6) : حركة الكثبان الرملية وتباينها الفصلي والمكاني
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151
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(7) : الدورة الجيومورفولوجية للكثبان الرملية
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155
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(8) : الآثار البيئية لظاهرة الإرساب الريحي وسبل الحد منها
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159
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الفصل الرابع : العلاقات الكمية للمتغيرات المؤثرة في ظاهرتي السباخ والكثبان الرملية
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165
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(1) : الارتباط البسيط
|
166
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(2) : الارتباط الجزئي
|
167
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الخلاصات والاستنتاجات
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189
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التوصيات
|
195
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المصادر
|
196
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الملاحق
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206
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Form of Sabakh and Eolian Deposits
East of Shatt -Al - Arab River
A Geomorphological Study
A Thesis Submitted By:
Nameer Nathir Murad Ali Al -Khait
To the council of the college of Arts, University of Basrah in
In Partial fulfillment of the Requirements of the
Ph. D. Degree in Geography
Supervised By:
Ass . Prof . Dr
Taghlub Jerjis Dawood
( First Supervisor )
Ass .Prof . Dr
Abdul-mutalib Hasson Al-Marsoumi
(Second Supervisor)
Form of Sabakh and Eolian Deposits East of
Shatt Al-Arab River
A Geomorphological Study
The present study sheds light on some factors that play an important role in the formulating the phenomenon of sabakh and eolian deposits in the studied area. The climate is among the basic factors that form these two phenomena where the arid season, which lasts from May to November has prominent effect in the process. Latitudes also determine intensity and duration of sun light, that reach the surface of the earth and rise its temperature and also increase rates of evaporation which is accompanied with little or no rain fall. On the other hand the hot dry winds which help for increases evaporation from soils and thus enhanced the existence of salt on the earth surface and formation of sabakh in the region of the flood plain of the area under study.
This also happens by the aid of some other factors like slope surface of the flood plain from the north-west to the south-east, movement of ground water towards south and transfer and accumulation of saline solutes in the area of the study which geomorphologically occupies the low lands of the river basins
Increase of clay and decrease of sand in the soil make the water content and the ability to raise water in the capillary fringes high.
The human action represented by employing classical away of irrigation also plays a role in increasing salinity of the soil .
During the rainfall season from December to March within the period of the study, low of temperature,low rate of evaporation and high rainfall causes the dissolution of salts .
The climate factors also play an active role in the process of erosion and deposits in the region of Al-Batin alluvial fan. These factors are represented by the increase of wind speed resulting from the flat surface , the high temperature , the low rainfall , the high rate of evaporation which lead to limited wet of the deposits . and its breaking during the dry season .There is also the effect of the human activities like exploiting lands in agriculture and movement of machinery in addition to the little natural plant cover .
The rainfall season, which is characterized by high rainfall with low temperature, which increase of wet content of the sediments which causes, high rate of soil aggregate and increase the density of natural plant cover help, in their turn, to consolidate the soil grains and consequently lessen the geomorphologic influence of wind in the region of Al-Batin alluvial fan.
All the above show that Sabakh areas are the most existing kind of geomorphological features in the region of the flood plain of the studied area, it is characterized by the hight lime content in comparison to gypsum content which works as cementing material that help to consolidates the sediment in the dry season. It contains low rate of organic material because of the high temperature that hastens decline of the organic materials. The clay loom constituents most of the sediments in the sabakh area and it makes a rate of 84.6 % of total studied samples.
The ground water movement was of two types. The first type is the down ward movement as the result of gravity during the rainfall season which cause desalinization, dissolving and moving of salts as solutes towards the bottom a matter which increase salt concentration in the ground water and increase electric conductivity on expense of decrease its concentration in the soil.
The second is represented by the upward movement of the ground water due to capillary fringes when the ground water reaches the critical depth in the dry season and this helps to transfer the ions as solutes toward the surface and to increase its concentration in the soil on expense of decrease of its concentration in the ground water which leads to existence of the white salt crust above the surface of the soil. This means dominance of the process of salinization during the dry season and desalinization during the rainfall season.
The sabakh area is characterized by the high level of groundwater, which causes its movement towards the sea according to the hydrulic gradient rule.
Variation of temperature, amount of rainfall in the two seasons of the study and other aiding factors made these sabakh undergo three stages an processes of salinization accompanied by crystallization and dissolving.
It is shown that the sabakh of the area of the study passes through three stages of the geomorphlogical cycle which are basically connected to the climatic and geomorphological conditions which were mentioned earlier.these are : the youth stage during the rainfall season , the mature stage during the transitional period between the two seasons of the study and the old stage at the end of the dry season . the most important phenomena on this stage is availability of the salt crust which is characterized by the polygons ,saucers and multiple thick salt layers .
As for the population variation in the area of sabakh, it is shown that there are two types of sabakh depending on the rate of calcium carbonate salts and variation of concentration of the ions of sulfate and magnesium. The first type occupies most lands that extend north-west of Basrah. The second type occupies all the lands extending from north Basrah to the Arabian Gulf in the south which was covered by sea water during the spring tide.
Application of some certain equations show that wind pressure depend on the factor of climate which is the force that controls the amount of the transferred sediments by means of the soil factor But this force increases during the dry months of June, July, August and September , due to increase of its speed in these months. This causes the increase of the amount of sediments that are transformed during the time of the dry season and to decrease of the amount of deposits that are transformed during the other months and its diminishing during the rainy months (December, January and February).
It's found a spatial variation in the degree of wind erosion. The sediments of the flood plain were with in the region of light erosion because of the high wet content of the sediments, which increase soil aggregate. Sediments of Al-Batin alluvial fan were within the class of the region heavy erosion because of its little wet content and disparity of its sediments.
There was also variation in the ability of the soil for erosion within the region of Al-Batin alluvial fan where this ability increases towards the north because of little lime content and the small size of the grains and the few soil aggregate in comparison with the other places.
It's shown that size of the Barchn sand dunes in the place of Artawi is bigger than those of Um Qasir and through applying one of the equations, it was shown that dunes of Um Qasir are faster than those of Artawi. Generally , the speed of the dunes increases during the dry season and decreases during the rainfall season.
The relative distribution of the heavy minerals. The shape and size of the grains and the content of clay and sand in the sediments showed that the suppliers of the dunes of Artawi are the new deposits of Euphrates that are transformed by the dominant north-westly winds. The suppliers of Um Qasier dunes are the rock components that are separated in Al-Dibdiba desert.
Some Barchan dunes in Artawi represent the youth stage. Others are within the mature stage of the geomorphological cycle of the Barchan dunes. This is because large amounts of sand come from the north of the area of the study . Um Qasir dunes are within the stable mature stage because insufficient amounts of sand come to the area. Beside, dunes of Nebak separate irregularly in the area of the study because of the variation of distribution of the density of natural plant cover and the amount of the transformed eolian deposits.
Studying the direction of the axis of the dunes besides the morphology of the ripple marks which indicate the direction of the wind (North Westly-South Eastly) and the relation between the ups and downs of the ripple -marks illustrate that they are originated as a result of the force and movment of wind .
The statistical correlation analysis of changes has shown that temperature has positive correlation with the wind speed,wind pressure and evaporation, and negative correlation with rain fall. These factors causes accumulation of saline solutes in region of flood plain.
The wind factor has more correlations with amount of transferred eolian sediments than correlation of temperature of that amount.
The rainfall has negative correlation with the amount of transferred eolian sediments and this lead to decrease of sand dunes movement in rainfall season.
The climate factor has more correlation with amount of transferred eolian sediments than correlation of soil factor with that amount.
It is showed after applying simple linear regression that some data represented with linear correlations and some other were none.
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