Journal of Spatial Analysis Environmental Hazards
تحلیل فضایی مخاطرات محیطی
Journal of Spatial Analysis Environmental Hazards
Literature & Humanities
http://jsaeh.khu.ac.ir
1
admin
2423-7892
2588-5146
10.61186/jsaeh
fa
jalali
1394
7
1
gregorian
2015
10
1
2
3
online
1
fulltext
fa
تحلیل فضایی مخاطرات ژئومورفولوژیکی توسعهی شهر در حریم رودخانهی خشک کلانشهر شیراز
Spatial Analysis of Geomorphological Hazards of Urban Development in the Banks of Khoshk River in Shiraz, Iran
تخصصي
Special
پژوهشي
Research
<p dir="RTL" style="text-align: justify;"><span style="font-family:nasimyw;"><span style="font-size: 14px;"><strong>توسعهی شهرنشینی و گسترش مناطق اسکان جمعیت</strong> <strong>در حریم رودها مستلزم</strong> <strong>مطالعات دقیق دربارهی شرایط سیلگیری محدودهی مورد نظر برای توسعه است. بیشتر خسارات واردهشده به شهرها ناشی از وقوع سیل به دلایلی نظیر تخطی در بستر و حریم رودخانهها، پایین بودن ظرفیت پلها و معابر حرکت آب، ناپایداری سیلبندها، ساخت و ساز در مسیر سیلها و کاهش پوشش گیاهی اراضی مشرف به شهرهاست. بر اثر این اقدامها هر ساله صدمات جبرانناپذیر مالی و انسانی به مناطق گوناگون کشور وارد میآید. در این پژوهش کلانشهر شیراز از لحاظ مخاطرات ناشی از فرایندهای ژئومورفیک رودخانهای بررسی شده است. مطالعهی این مخاطرات در دو قسمت صورت گرفت. در یک قمست مخاطرات ناشی از فرسایش رودخانه و آبراههها (تخریب، حمل و رسوبگذاری) و مخاطرات ناشی از طغیان آب و سیلاب مطالعه شد و در قسمت دیگر تحلیل و بررسی نقش عوامل انسانی تشدیدکنندهی مخاطرات رودخانهای انجام گرفت. روش تحقیق در این پژوهش کتابخانهای ـ میدانی است.</strong> <strong>نخست از عکسهای هوایی و تصاویر ماهوارهای برای بررسی حوضهی آبریز رودخانهی خشک و پهنههای سیلخیز استفاده گردید. سپس، بازدیدهای میدانی و برداشت نقاط زمینی با استفاده از </strong><strong><span dir="LTR">GPS</span></strong><strong>، تفسیر عکس هوایی و کاربرد </strong><strong><span dir="LTR">GIS</span></strong><strong> نقشهی مناطق در معرض خطر حاشیهی رودخانه و فاصله از رودخانه ترسیم شد. در نهایت مشخص شد که از یک طرف بخش شرقی کلانشهر شیراز به دلیل قرارگیری بر روی دشت سیلابی از طرف آبراههها و رودخانهی خشک و از طرف دیگر با تعرض به حریم رودخانه، ابعاد و ارتفاع نامناسب پلها، احداث کنارگذرها و... در معرض مخاطرات محیطی ناشی از فرآیندهای رودخانهای وعوامل انسانساخت قرار دارد.</strong></span></span></p>
<p style="text-align: justify;"><span style="font-size:14px;">The process of urbanization and development in high-risk areas such as river banks has increased the vulnerability of urban communities to environmental hazards. The banks of Khoshk River in Shiraz is one of these areas. These hazards are two parts : hazards resulted from river and waterways erosion (destruction, transportation and sedimentation) and the hazards resulted from floodings over the surrounding urban areas.</span></p>
<p style="text-align: justify;"><span style="font-size:14px;">In order to prepare the literature review for this study, the various books, theses and articles were applied. Also, in order to determine the spatial position of this section, the Satellite Images and Google Earth pictures were used. The Global Positioning System (GPS) was also applied for the field observations such as collecting spatial data, extracting the kind of formations, Geological structures and faults. ArcGIS and Global Mapper 16.2 were also used for data processing and mapping.</span></p>
<p style="text-align: justify;"><span style="font-size:14px;"> The geomorphological hazards in Khoshk River bank were evaluated in two parts:</span></p>
<ol>
<li style="text-align: justify;"><span style="font-size:14px;">The evaluation and analysis of the role of river and flooding processes in creating the environmental hazards for Shiraz.</span></li>
<li style="text-align: justify;"><span style="font-size:14px;">The evaluation and analysis of the role of humans as the intensive factors of riverine and floods hazards in city.</span></li>
</ol>
<p style="text-align: justify;"><span style="font-size:14px;"> The evaluation of longitudinal profile in the river indicates that when the stream is entered to plain, the water moves with more speed because of faults and high steepness over the Drake alluvial fan. One indication of this process is the presence of coarse sands and angled gravels. In this part, the erosion of riverbank is much higher than the erosion of river bed. In this section, the longitudinal profile of the river has a regular trend of concave and convex sections due to the erosion in convex parts and sedimentation in concave parts. In addition, there is a balance between deposition and digging process. The erosion is very intensive in regions where arc meander is close to the flooding plain of the bank and causing the destruction of all facilities.</span></p>
<p style="text-align: justify;"><span style="font-size:14px;"> The longitudinal profile in the river indicates that the height and slope of river has been reduced from North West to Maharloo River. The average slope of the river is 2.40%.</span></p>
<p style="text-align: justify;"><span style="font-size:14px;"> In order to determine the role of flooding in creating risks for Shiraz, the floodwater discharge data were collected from Regional Water Organization. Furthermore, in order to understand the role of maximum discharge values, various experimental relations were used in the basin. The un- ordered development of urban areas especially in the north west, destruction of natural areas intensified the amount of runoff and reduction of vegetation cover.</span></p>
<p style="text-align: justify;"><span style="font-size:14px;"> The pick values of maximum discharges in Khoshk river with the return periods of 50 and 100 years waere estimated 115m<sup>3</sup>/s to 131.4m<sup>3</sup>/s respectively which may result in overflowing of water on the streets. The human factors include the construction of bridges on the river, fencing river with stones and construction of beach, construction of bypasses for public transportation and reducing the traffic in the riverbed and trespassing to the river bed in Shiraz caused the overflowing of water from the river. The last floods in Shiraz occurred in 1987 and 2002 that caused major losses to the houses and commercial places close to Khoshk River. In order to analyze parts of river that are close to the town and have more important influences on the hazards and disasters, the satellite images of khoshk river basin in the town were taken and the river was classified in three sections with regard to risks level, river morphology and river classification based on its hazards for close areas as high risk (Maali abad Bridge limits to Fazilat Bridge and Sardkhaneh Bridge to Maharloo River), low risk(Tange sorkh to Maali abad Bridge) and medium risk (Fazilat Bridge to Sardkhaneh Bridge).</span></p>
تحلیل فضایی, مخاطرات ژئومورفولوژیک, توسعه, شهر, شیراز.
Spatial analysis, Geomorphological hazards, Development, City, Shiraz.
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http://jsaeh.khu.ac.ir/browse.php?a_code=A-10-3-26&slc_lang=fa&sid=1
Mesysam
jamali
میثم
جمالی
jamali_mir93@yahoo.com
1003194753284600773
1003194753284600773
Yes
Ebrahim
Moghimi
ابراهیم
مقیمی
1003194753284600774
1003194753284600774
No
Zeynolabedin
Jafarpour
زین العابدین
جعفرپور
1003194753284600775
1003194753284600775
No
Parviz
Kardovani
پرویز
کردوانی
1003194753284600776
1003194753284600776
No