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Showing 4 results for Alijani
, Dr Bohlool Alijani, Mr Hadi Donyadoost,
Volume 17, Issue 58 (9-2017)
Abstract
Instability of Synoptic severe along with abundant moisture has a major role in flood event. At the present study, the synoptic situation of the Sarbaz flood basin has been investigated. For this purpose, two databases were needed. First one contains daily discharge data of Pirdan hydrometric station and daily rainfall census in neighbor stations of basin and second database include maps of ground surface and 500hp level in confine of latitude 10° till 60° N and longitude 10° till 90° E that are prepared from the National Oceanic and Atmospheric Administration (NOAA). Because of the flood type of this watershed in the summer and winter season, strongest floods for each season are selected. Thus, provided maps are belonging to two days before flood, start day of flood and maximum of flood. 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 500hp 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 500hp 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.
Mr Mehdi Taghiloo, Proff. Bohloul Alijani, Proff. Hossein Asakereh,
Volume 19, Issue 68 (4-2019)
Abstract
Introduction: The climate of the earth has begun to warming since 1980’s which has created very serious problems for the human living and natural environment. As a result the study of the global warming and its solutions has become the focal point of the climate change research all over the world. The climatologists are trying to understand, predict and finally give solutions to it. Many different models have been developed to predict and project the future climate conditions among which the Regional Climate Model is to some degree has lower values of uncertainty. The impacts of climate change is relatively higher in the
naturally dry climate of the Middle East including Iran. Here the main parameters of the climate that is temperature is increasing and precipitation decreasing. As a result the projection and understanding of these two elements are very important for the region and Iran. For this reason this studyhas focused on the efficiency of the Regional Climate Model in projecting the future climate of the region and Iran.
Data and Methods: In order to test the efficiency of RegCM 4.3the monthly temperature and precipitation
Data were extracted for the window 24N-40N and 43E-64E from the ECMWF database with spatial resolution of 2.5 degrees. These data were compared and corrected with the station data of Bandar Anzali, Bandar Boushehr, Mashad, Tehran, Yazd, Zahedan, Khorramabad and Zanjan . The simulated model data for RegCM 4.3were extracted for the same period and area with the same spatial resolution. Both data were transported into the Matlab environment and compared.
Results and Discussion: Results of simulated RegCM 4.3data were compared withobserved data of eight stations. The temperature data were slightly (about 2 degrees C) more than observed data. But the precipitation projections were somewhat complicated. The values of rainy stations such as Anzali were overestimated ( about 257 mm) while that of most dry stations such as Zahedan were underestimated (about 58 mm). But the RegCM 4.3 simulations were the same as the observed data inthe normal stations such as Zanjan. The results showed that the RegCM 4.3is suitable for projecting temperature data more than the precipitation. This is in agreement with the findings of many other studies.
Mahmoud Roshani, Mohammad Saligheh, Bohlol Alijani, Zahra Begum Hejazi Zade,
Volume 20, Issue 69 (5-2020)
Abstract
Probability distributions and different mixed regression models are used to study of wet and dry spells. In this study, eight stations on the southern coast of the Caspian Sea were used for 55 years (1960 to 2015). One and two day wet spells are the most frequent in the area. Also, four and higher days wet spells in the western region is more than the east. The best probability distributions of wet spells are two-parameter gamma, two parameter normal log, two parameter logistic log, four-parameter generalized gamma, generalized three parameters gamma, two-parameter gamma, three-parameter gamma and a three-parameter logistic log. Also, the dry spells of the region are better fitted with generalized Parto, generalized logistics and generalized extreme value distributions. Due to the random behavior of the annual wet and dry spells, the best generalized linear mixed model for wet spells is the negative binomial log, Log Poisson, log normal and gamma logarithmic, also the Log Poisson, log normal and the negative binomial distribution was determined for the annual dry spells.
Masoumeh Soufi, Behlul Alijani, Reza Borna, Farideh _asadian,
Volume 21, Issue 75 (10-2021)
Abstract
One of the most significant and obvious effects of dams on nature is the change in the type of use of surrounding lands. The construction of the dam reservoir contributes to converting pasture lands into agricultural lands and industrial plants, and dryland farming to the irrigated cultivation of crops. The main purpose of this study is to predict possible land repurposing in the Urmia Lake Basin based on hydroclimatology and remote sensing data. In order to evaluate the efficiency of the classification algorithm for the land use map of Urmia Lake Basin, two Landsat satellite images taken at the same month with a time interval of 15 years were selected. In addition, Landsat satellite images taken by ETM+ (Landsat 7) and OLI (Landsat 8) sensors were used. According to the predicted land use plan over the next 20 years, poorly vegetated rangelands, salt marsh lands, and bare lands will increase by 19%, 42%, and 17%, respectively. On the other hand, garden land areas, farming lands, rural residential areas, densely vegetated rangelands, moderately vegetated rangelands, and water zones will decrease by 16%, 11%, 1.11%, 3%, and 24%, respectively. This land repurposing forecast by 2038 indicates that the reduction in water zones and the increase in salt march areas will be very high. The land use prediction map for the Urmia Lake Basin by 2038 indicates that bare lands, poorly vegetated rangelands, and salt marsh lands will increase by 1668, 7257, and 4497 square kilometers from 2018 to 2038. In contrast, farming lands, rural residential areas, densely vegetated rangelands, moderately vegetated rangelands, and water zones will decrease by 18356, 6622, 5578, 2974, 535, and 2911 square kilometers over a 20-year time period.
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