چکیده:
بارش یکی از عناصر و فرایندهای اصلی اقلیم هر منطقه است که در برنامهریزیهای شهری و روستایی، مکانیابی صنعتی، معماری، کشاورزی، صنایع، و ... نقش تعیینکننده دارد. ازاینرو، در تحقیق حاضر تلاش شده است تا مقدار، فراوانی، و شدت بارشهای سالانة ناحیة خزری ارزیابی شود. بدینمنظور، از دادههای روزانة 385 ایستگاه همدید، اقلیمشناسی، و بارانسنجی سازمان هواشناسی کشور و ایستگاههای بارانسنجی وزارت نیرو طی بازة زمانی ۱۹۶۶-2016 استفاده شده است. با برازش مدل رگرسیون خطی به روش پارامتری، روند مقدار، فراوانی، و شدت بارش سالانه بررسی شد. نتایج حاصل از این پژوهش که در دیگر مطالعات مشهود نبوده است بیانگر این است که میانگین بارش سالانه و فراوانی آن بهترتیب در 4/61درصد و 1/47درصد از پهنه دارای روند افزایشی است. شدت بارش سالانه در همة پهنه دارای رفتار ایستاست. روند ضریب تغییرات میانگین بارش سالانه نشان داد که گسترة تحت حاکمیت روند ایستا بیشتر است؛ بهطوریکه در همة خط ساحلی و بخشهایی از ارتفاعات البرز توزیع بارش در گذر زمان در طی فصلهای مختلف سال تغییری نکرده است. بخشهای شرقی ناحیه، ارتفاعات البرز (جنوب دریای خزر)، بخشهایی از ارتفاعات البرز غربی، و بخش بسیار کوچکی از غرب ناحیه روند کاهشی در ضریب تغییرات میانگین بارش سالانه دیده میشود.
Precipitation is one of the most important climatic elements in every given region that plays a decisive role in urban and rural planning, industrial location, architecture, agriculture, industry, and so on. Accordingly, the present study attempts to evaluate the amount, frequency and intensity of annual precipitation in the Caspian coastal region in which the economical planning is fundamentally based on precipitation. To this end, the daily data of 385 stations, under Meteorological Organization and the Ministry of Energy's supervision have been used for the period of 2016-1966 (51 years). Then, the amount, frequency and intensity of annual precipitation were studied and finally, the trend was verified by fitting the linear regression model by using parametric method. The results showed that the annual precipitation in 61.4% and the frequency of precipitation in 47.1% of the under investigation area has an increasing trend. The annual precipitation is also stationary in all under study area. The trend of the coefficient of variation in the month- to- month precipitation indicated that the stationary trend is overcome in the majority of the area. Precipitation is one of the most important climatic elements in every given region that plays a decisive role in urban and rural planning, industrial location, architecture, agriculture, industry, and so on. Accordingly, the present study attempts to evaluate the amount, frequency and intensity of annual precipitation in the Caspian coastal region in which the economical planning is fundamentally based on precipitation. To this end, the daily data of 385 stations, under Meteorological Organization and the Ministry of Energy's supervision have been used for the period of 2016-1966 (51 years). Then, the amount, frequency and intensity of annual precipitation were studied and finally, the trend was verified by fitting the linear regression model by using parametric method. The results showed that the annual precipitation in 61.4% and the frequency of precipitation in 47.1% of the under investigation area has an increasing trend. The annual precipitation is also stationary in all under study area. The trend of the coefficient of variation in the month- to- month precipitation indicated that the stationary trend is overcome in the majority of the area. Consequently, precipitation throughout the coastline and parts of Alborz mountain chain has not changed during the year. Some parts of the area including the eastern parts, the Alborz mountain (south of the Caspian Sea), parts of the western Alborz, and a very small part of the west have experienced declining trend in the coefficient of variation in the annual rainfall. Precipitation is one of the most important climatic elements in every given region that plays a decisive role in urban and rural planning, industrial location, architecture, agriculture, industry, and so on. Accordingly, the present study attempts to evaluate the amount, frequency and intensity of annual precipitation in the Caspian coastal region in which the economical planning is fundamentally based on precipitation. To this end, the daily data of 385 stations, under Meteorological Organization and the Ministry of Energy's supervision have been used for the period of 2016-1966 (51 years). Then, the amount, frequency and intensity of annual precipitation were studied and finally, the trend was verified by fitting the linear regression model by using parametric method. The results showed that the annual precipitation in 61.4% and the frequency of precipitation in 47.1% of the under investigation area has an increasing trend. The annual precipitation is also stationary in all under study area. The trend of the coefficient of variation in the month- to- month precipitation indicated that the stationary trend is overcome in the majority of the area. Consequently, precipitation throughout the coastline and parts of Alborz mountain chain has not changed during the year. Some parts of the area including the eastern parts, the Alborz mountain (south of the Caspian Sea), parts of the western Alborz, and a very small part of the west have experienced declining trend in the coefficient of variation in the annual rainfall. Precipitation is one of the most important climatic elements in every given region that plays a decisive role in urban and rural planning, industrial location, architecture, agriculture, industry, and so on. Accordingly, the present study attempts to evaluate the amount, frequency and intensity of annual precipitation in the Caspian coastal region in which the economical planning is fundamentally based on precipitation. To this end, the daily data of 385 stations, under Meteorological Organization and the Ministry of Energy's supervision have been used for the period of 2016-1966 (51 years). Then, the amount, frequency and intensity of annual precipitation were studied and finally, the trend was verified by fitting the linear regression model by using parametric method. The results showed that the annual precipitation in 61.4% and the frequency of precipitation in 47.1% of the under investigation area has an increasing trend. The annual precipitation is also stationary in all under study area. The trend of the coefficient of variation in the month- to- month precipitation indicated that the stationary trend is overcome in the majority of the area. Consequently, precipitation throughout the coastline and parts of Alborz mountain chain has not changed during the year. Some parts of the area including the eastern parts, the Alborz mountain (south of the Caspian Sea), parts of the western Alborz, and a very small part of the west have experienced declining trend in the coefficient of variation in the annual rainfall.