تحقیقات کاربردی علوم جغرافیایی

تحقیقات کاربردی علوم جغرافیایی

تاثیر نوسانات سطح آب دریای کاسپین برتغییرات سواحل خلیج گرگان در بازه زمانی 1955-2021

نویسندگان
دانشگاه خوارزمی
چکیده
خلیج گرگان یک منظره زمین ریخت شناسی و محیط رسوبی ساحلی در جنوب خاوری دریای کاسپین محسوب می شود. هیدرودینامیک سواحل این منطقه تابع هیدرودینامیک عمومی دریای کاسپین می باشد. به واسطه توپوگرافی کم شیب این سواحل، کمترین تغییر در تراز آب دریا منجر به صدها متر جا به جایی در خط ساحلی این منطقه خواهد شد. تغییرات سطح آب دریای کاسپین یک مشکل زیست محیطی و مدیریت ساحلی است و امروزه روند رو به کاهش سطح آب دریای کاسپین در طی چند دهه اخیر باعث تاثییرات مخربی همچون خشکی زایی در سواحل خلیج گرگان شده است. به منظور برسی تاثیر تغییرات تراز دریای کاسپین بر سواحل جنوبی خلیج گرگان در بازه زمانی 66 ساله از گزارشات و مطالعات موجود استفاده و بررسی های میدانی صورت گرفته است و پایش خطوط ساحلی منطقه مورد مطالعه از طریق پردازش عکس هوایی سال 1955 و تصاویر ماهواره های لندست MSS،TM ، ETM و +ETM در سال های 1975-2021 در نرم افزار Arc GIS و ENVI انجام گرفته است.تغییرات ساحلی طی 4 دوره پردازش شد در این دوران تراز سطح آب دریای کاسپین بین 26.5- تا 28.7- در نوسان بوده است. بر اساس نتایج بدست آمده از تصاویر ماهواره ای و بازدید های میدانی خلیج گرگان1 مرحله افزایش سطح آب در بازه زمانی 1985-1995 به میزان 131 کیلومتر مربع و 3 مرحله کاهش سطح آب در سال های 1955، 1975-1985 و 1995-2021 به میزان 246 کیلومتر مربع را سپری کرده است.این افزایش و کاهش باعث مشکلات زیست محیطی عظیمی شده است به ویژه در در بازه زمانی 2015-2021 که خشکی زایی به وسعت 103 کیلومتر مربع موجب کاهش 172کیلومتر مربع از وسعت آبی خلیج گرگان و پدید آمدن گلزارها، باتلاق های شور، لجن‌زارها و نمکزار ها در قسمت باختری منطقه مورد مطالعه شده است.
کلیدواژه‌ها

عنوان مقاله English

The effect of Caspian Sea water level fluctuations on the changes of the coasts of Gorgan Bay in the period of 1955-2021

نویسندگان English

sara Kiani
raziyeh lak
babak najafi ha
ali ahmad abadi
Zahra Haftani
kharazmi University
چکیده English

Gorgan Bay is considered a geological landscape and a coastal sedimentary environment in the southeast of the Caspian Sea. The hydrodynamics of the coasts of this region is subject to the general hydrodynamics of the Caspian Sea. Due to the low slope topography of these beaches, the slightest change in the sea level will lead to hundreds of meters from place to place in the coastline of this area. Changes in the water level of the Caspian Sea is an environmental and coastal management problem, and today the decreasing trend of the water level of the Caspian Sea during the last few decades has caused destructive effects such as land formation on the coasts of Gorgan Bay. In order to investigate the effect of changes in the level of the Caspian Sea on the southern shores of Gorgan Bay in a period of 66 years, existing reports and studies have been used and field surveys have been used, and the coastlines of the studied area have been monitored through the processing of aerial photos from 1955 and Landsat satellite images. MSS, TM, ETM and +ETM have been carried out in the years 1975-2021 in Arc GIS and ENVI software. Coastal changes were processed during 4 periods. During this period, the level of the Caspian Sea water level fluctuated between -26.5 and -28.7 . Based on the results obtained from satellite images and field visits of Gorgan Bay, 1 stage of water level increase in the period of 1995-1985 by the amount of 131 square kilometers and 3 stages of water level decrease in the years 1955, 1985-1975 and 2021-1995 by the amount of It has covered 246 square kilometers.

کلیدواژه‌ها English

Reconstruction of fluctuations
advance and retreat of sea level
Gorgan Bay
southeastern shores of the Caspian Sea
sea level fluctuations
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