پديد آورندگان :
آرمش، محسن دانشگاه سيستان و بلوچستان , عليجاني، بهلول دانشگاه خوارزمي تهران - گروه اقليم شناسي , دنيادوست، هادي دانشگاه آزاد واحد اسلامشهر - آموزشكده فني و حرفه اي سما
چكيده فارسي :
ناپايداري هاي همديدي شديد همراه با رطوبت فراوان نقش زيادي در رخداد سيلاب دارند. در اين مطالعه شرايط همديدي سيلاب در حوضه آبريز سرباز بررسي شد. بدين منظور دو پايگاه داده مورد نياز است، گروه اول، شامل داده هاي دبي روزانه ايستگاه هيدرومتري پيردان و آمار بارش ايستگاه هاي مجاور حوضه و گروه دوم نقشه هاي سطح زمين و تراز 500 هكتوپاسكال در محدوده 10 تا 60 درجه عرض شمالي و 10 تا 90 درجه طول شرقي سازمان مطالعات جوي و اقيانوسي امريكا مي باشند. بخاطر رژيم سيلابي تابستانه ـ زمستانه اين حوضه دو مورد از شديدترين سيلاب ها براي هر رژيم سيلابي انتخاب شد. همچنين نقشه هاي تهيه شده متعلق به دو روز قبل از سيلاب، آغاز و اوج سيلاب مي باشند. نتايج نشان داد در رژيم تابستانه در سطح زمين استقرار دو مركز كم فشار روي خليج فارس و پاكستان و گسترش زبانه كم فشار خليج فارس به سمت جنوب شرق ايران و ورود هواي گرم و مرطوب آن به كم فشار پاكستان همراه با عميق تر شدن ناوه غرب درياي خزر و قرارگيري كم فشار پاكستان در جلوي اين ناوه سبب ناپايداري مي شود. در تراز 500 هكتوپاسكال استقرار سامانه پرارتفاع روي ايران و گسترش زبانهاي از آن به صورت پشته بلندي تا شمال درياي خزر و تشكيل ناوه عميقي بين پرارتفاع ايران و كم ارتفاع غرب هند سبب ناپايداري در جنوب شرق ايران شده كه جلوي اين ناوه قرار گرفته است. در رژيم زمستانه در سطح زمين زنجيره اي از كم فشارها از شرق آفريقا تا شمال شرق پاكستان با جهت جنوب غربي ـ شمال شرقي شكل گرفته است. ناوه ناشي از پرفشار درياچه آرال و ناوه ناشي از زبانه پر فشار غرب درياي خزر نقش اساسي در ناپايداري و كنترل مسير اين زنجيره دارد. در سطح 500 هكتو پاسكال استقرار ناوه عميقي در غرب و مركز ايران و قرارگيري سامانه هاي كم فشار سطح زمين جنوب شرق ايران در جلوي اين ناوه سبب تشديد ناپايداري مي شود.
چكيده لاتين :
The most important climate hazards in arid areas, the flood event_ Showery
precipitation with poor vegetation cover these areas are due to destructive floods_ In
southeast Iran 1;he Sarbaz River only permanent river of Baluchestan every year
overflowed and their fertile coastal areas remained under water. This basin due to
large area, large volumes of water to collect and occurrence of floods is severe.
Recognition of the area synoptic situation before and start flooding was helps
properly managed to reduce flood damage. Therefore, this study will examine the
flood basin of the synoptic view.
Materials and Methods
In order to study the ruling system during torrential rainfall was used from
environmental to circling approach. In this method, according to the climatic conditions in the earth's surface will be discussed to identify patterns upper
atmosphere. For this purpose, the daily data flow Pirdan hydrometric station from
Mehr 1360 to Shahrivar 1388 {28 years}, daily rainfall stations nearby Sarbaz basin,
including daily precipitation data stations Sarbaz, lranshahr, Saravan, Khash, Konarak
and Chabahar during the same period and maps re-analyzed sea level pressure and
500 hPa height in the range of 10 to 60 degrees north latitude and 10 to 90 degrees
east longitude of oceanic and atmospheric studies organization, United States of
America was used.
Discussion and Conclusion
The survey data of River flow and station precipitation of nearby Sarbaz basin showed
that the river has flooded the regime's summer and winter. Thus, two choices were
analyzed of each flood regime. In the summer regime, were selected torrential
rainfalls of 31 Tir to 3 Mordad 1374 with maximum daily discharge 308.46 cubic
meters per second and 13 to 15 Mordad 1387 with maximum daily discharge 1922
cubic meters per second and in winter regime, were selected torrential rainfalls of 11
to 12 Esfand 1376, with maximum daily discharge 1078 cubic meters per second and
6 to 7 Dey 1383 with maximum daily discharge 432 cubic meters per second. In the
summer flood regime, extensive thermal low pressure is causing instability on the
surface of the Persian Gulf and southeastern Iran. The pressure difference between
this low pressure and pressure on the Indian Ocean caused the suction the flow of
hot and humid Indian for regions of southeastern Iran. The Tibetan high pressure
boost and a lot of pressure gradient are created. Dispatch this tab high pressure to
the West expansion Pakistan low-pressure to the southeast of Iran. Relatively deep
trough at 500 hPa level is made in western Iran and placed eastern regions of Iran in
front of the trough has been unstable. In winter flood regime, at ground level continuum of low pressure from east Africa to
north-east of Pakistan was formed with southwest-northeast direction. The system
crossed from the warm waters of the Red Sea, Oman Sea and the Persian Gulf and
increased instability caused by heavy rainfall in the central cities of Baluchestan. Deep
trough is formed at 500 hPa on the Red Sea, which the beginning of the rainfall has
been moved to Iran. Axis trough's on Iran a lot to become skewed, so that until
Khuzestan afoul is axis skewed. Located of the Sudanese low pressure in the front
trough is due to aggravate the instability of the system.
Conclusions
Results showed that in the ground surface of summer type, establishment of two low
pressure centers on Persian Gulf and Pakistan, spread of Persian Gulf low pressure
flow to south-east of Iran and entrance of its warm and wet air into the low pressure
of Pakistan, deepening of west troughs of Caspian sea and presence of low pressure
pitch of Pakistan in front of this troughs were causing instability. establishment of
high system of Iran and spread of its prongs, as rich, to north Caspian Sea and
forming of deep troughs between high systems of Iran and low pressure in the west
of India at SOOhp level has caused instability in south-east of Iran that is located in
front of troughs. In the ground surface of winter type, continuum of low pressure
from east Africa to north-east of Pakistan with southwest-northeast direction was
formed. Troughs that are emanated from the Aral Lake high pressure and prongs of
high pressure in west of Caspian Sea have main roles in instability and control of this
continuum path. In SOOhp level, establishment of deep trough in west and center of
Iran and presence of low pressure systems of ground surface of southeast of Iran in
front of this trough have intensified instability.
