بالاترین بارش محتمل24 ساعته و تاثیر آن در مخاطرات هیدرولوژیکی منطقه جنوب غرب خزر

مطالعه بارش محتمل جهت ارزیابی و برآورد سیل برای طراحی سازه های هیدرولوژیکی شهری، از قبیل کانال آبیاری، تعیین بیشترین میزان آبی که وارد مخازن و یا سایر تاسیسات می شود ضروری است. سیلاب ها بالاترین نرخ تلفات جانی را به همراه دارند و به لحاظ وسعت تاثیر بعد از خشکسالی دومین بلای طبیعی محسوب می شوند. مفهوم بیشترین بارش محتمل (pmp) به لحاظ نظری بیشترین ارتفاع بارش در یک مدت مشخص برای یک دوره معین از سال که از نظر شرایط فیزیکی خاص در محدوده توفان و یک محدوده جغرافیایی می تواند ببارد اطلاق می شود. هدف از این تحقیق برآورد pmp در منطقه جنوب غرب خزر به روش سینوپتیک است. روش کار پس از بررسی آمار 30 ساله ایستگاه های باران سنجی و کلیماتولوژی موجود در منطقه ، 4 طوفان شدید و فراگیر انتخاب شدند. که از 4 طوفان انتخاب شده، جهت محاسبه pmp به روش سینوپتیک پس از تحلیل نقشه های ارتفاعی هوا و رطوبت و صعود قائم هوا، و تعیین دهانه ورودی توفان از داده های سرعت باد، دمای نقطه شبنم و فشار مربوط به ایستگاه های سینوپتیک بندر انزلی، رشت، رامسر، اردبیل و پارس آباد استفاده شد. نتایج نشان داد مقادیر بیشترین بارش محتمل با تداوم 24 ساعته برای منطقه مقدار آن برابر با 95/276 می باشد. و متوسط دبی حاصل از آن با در نظر گرفتن ضریب جریان، عدد 66/21797 متر مکعب بر ثانیه است.این مقدار آب یک تهدید جدی برای مخاطرات سیلاب در منطقه می باشد.

The impact of daily Probable Maximum Precipitation (PMP) on the hydrological hazards of the south west region of Caspian Sea

Understanding the climate of a region as a first step and most immediate action is considered research for development projects Climatic phenomena such as floods every year irreparable damage to the soil, pastures, forests, urban and rural facilities, human and animal import Climatic phenomena such as floods every year irreparable damage to the soil, pastures, forests, urban and rural facilities, human and animal import. The first factor in causing flood is rainfall intensity that occurs at a certain time. Therefore necessary infrastructure projects, and one of the main issues in hydrological and hydroclimate is awareness of the occurrence and amount of rainfall, most likely for different periods. In order to implement the model of Synoptic convergent in this research and estimated probable maximum precipitation in the South West region of the Caspian 1: The 1:50,000scale Digital Mapping the location of all stations in the study area, Climatology, rainfall and hydrometric surveys in selected were identified on the map. 2: The maximum instantaneous discharge rate of the highest daily rainfall stations selected surveys (19762011) are also studied. 3: collection of the highest daily rainfall statistics selected stations, monthly and annual precipitation data for the period (1986200),Facts about the daily atmospheric phenomena (cloud, wind speed, dew point temperature, air pressure) with an interval of 3 hours to 3 hours, Statistics continuing 12hour maximum dew point of the surface (in degrees Celsius) and wind speed times (NAT) for the stations of Anzali, Rasht, Astara, Ramsar, Ardabil, Pars Abad For the first 10day period, 10day and 10day return period for calculating the 50yearold third, 80year and 100year and monthly statistics on the average pressure of the selected stations establishment station. 4: Select the desired storm rainfall in 24 hours and 48 hours to obtain a return period of 50 years, 80year and 100year 12hour maximum dew point and wind speed persistence for long periods, the separation of each month, and the resolution of each decade, through software SMADA and HYFA. 5: Purvay of Rain maps and DAD chart is also the main stages of this work. 6: Finally, weather maps, humidity maps and omega air maps at ground level, 700 level and 850 hp prepared from Days prior to completion until the day of rain showers in the stormy period from the NCEP / NCAR site and was ready in GRADS software environment. In order to realize the adiabatic saturation warmest period of the most intense storms in 13551390The maximum instantaneous rate of discharge and daily rainfall statistics, the most comprehensive and stations on their occurrence in the previous chapter, was studied.So the four pervasive hurricane was selected. Then, rain storms map were plotted in the GIS software environment and use of IDW method and Using data from the windy days selected on rainfall stations in the study area. In order to obtain the rainfall in the whole region,were regressed between the two parameters: precipitation and elevation; and was estimated average of rainfall in the cumulative area and rainfall amount in during of the storm days. Based on the height area tables of ​​each storm separately, DAD curves was drawn based on average rainfall in columns cumulative and cumulative area. Then we reviewed and interpreted weather maps at ground level, elevation Maps, humidity maps and omega maps at 850 hPa level. Survey maps showed Tongue of immigrant anticyclons in North West Europe that usually is deployed on the Black Sea will advection cold air from the above widths on the Caspian sea and is transmited very wet weather to the south and West south Caspian Sea. After analyzing weather maps, the next step is obtain to water for showers.To calculate the rain water the best way is getting the hottest adiabatic saturation that occurs with the maximize the dew point temperature and wind speed. After obtaining the maximum dew point and wind speed factor, we would like to calculate the coeffcient storm. After obtaining the coefficients of the storm,obtained its P.M.P by multiplying the amount of rainfall for each storm. According to the obtained PMP,was adopted rainfall continued for 24 hours with the numbers 276/95. PMP obtained showed that the storm dated 2/10/2001 of 24hour duration, has been most intense and pervasive from the two other samples.