Showing 12 results for Storm
B. Ghahreman,
Volume 7, Issue 2 (7-2003)
Abstract
An intense storm occurred on June 6, 1992 in Mashhad city and its suburb, which caused a flood in the residential areas of Najafi, Chahar-cheshmeh and Nodareh. As a consequence of the abnormally huge flood, 25 people lost their lives and many structures were destroyed. Three recording rain gages located in Mashhad city (airport, College of Agriculture, and Water Authority) and one in the suburbs (Toroq dam) recorded the temporal distribution of the storm. Twenty five other nearby rain gages in the region also recorded the event. The rainfall hyetographs and rainfall amounts were analyzed.
The results of this survey showed that: a) maximum rainfall intensity over a 15-minute duration in the College of Agriculture station, one of the centers of the storm, was 112 mm/hr, b) temporal distribution of rainfall for all recording stations were nearly the same, c) these patterns were in close agreement with all historic storms, and d) a return period of 380 years was implied via comparing the maximum rainfall intensity with relevant IDF curves. As a consequence, although an intense storm had happened, it was simply an outlier.
S.h Sadeghi, S.h Pourghasemi, M Mohamadi, H Agharazi,
Volume 12, Issue 46 (1-2009)
Abstract
The use of suitable empirical models for estimation of soil erosion and sediment yield is essential because of nonexistence or shortage of associated data in many watersheds. In the present study, the applicability of the USLE and its different versions Viz. MUSLE-S, AOF, MUSLT, MUSLE-E, USLE-M and AUSLE in estimation of storm-wise sediment yield from standard plots installed in dry farming, ploughed and rangeland treatments was evaluated. To conduct the study, the entire input data were collected from plots installed in three replicates in each treatment in Khosbijan Natural Resources Research Station in Arak Township. The models’ estimates were then compared with the observed sediment data for 12 storm events. Contrary to high correlation among different models’ estimates, the models used in estimation of measured sediment data were found inapplicable. However, significant relationship (r=94.4%) and non-significant relationship with correlation coefficients less than 50% were found between MUSLE-E, and MUSLE-S and MUSLE-E estimates and measured data in rangeland, dry farming and ploughed treatments, respectively.
S. Mehrabi, S. Soltani, R. Jafari,
Volume 19, Issue 71 (6-2015)
Abstract
Since climate has a major impact on dust generation, it is essential to identify the climatic parameters affecting this phenomenon. In this study, climatic parameters including temperature, relative humidity, rainfall, maximum wind speed and direction were selected and their relationship with visibility data and also dust storm days (recorded at meteorological stations) was analyzed on monthly and yearly scales using multivariable linear regression. Results showed that the number of dust storm days has reached 366 days in the last five years. The minimum dust storm days occurred in autumn in all the stations of Khuzestan province including Abadan, Ahvaz, Omidiyeh, Dezful, and Masjed Soleiman and the maximum dust days for Abadan and Ahvaz stations and three remaining stations occurred in spring and summer, respectively. Results also showed that the highest frequency of dust storms in Abadan and Ahvaz stations did not coincide with summer season which has the lowest rainfall of the year. As a result, it seems that the main reason for this difference is the climatic characteristics of dust sources and deposition regions. The occurrence of dust events in the remaining stations in summer time indicated that the sources of dust storms might be local and within the study area. The regression analysis confirmed this issue as the number of climatic parameters which had significant correlations with visibility data increased from 8 to 16 from west to east in the region. Overall, the results showed that with the increasing distance from Arab countries such as Iraq and Saudi Arabia, dust sources were mostly local and provincial.
M. Jafari, M. Vafakhah, A. Tavasoli,
Volume 19, Issue 73 (11-2015)
Abstract
The rainfall-runoff process and flooding are hydrological phenomena that are difficult to study due to the influence of different parameters. So far, different methods and models have been provided to analyze these phenomena. The purpose of this study is evaluation of adaptive neuro-fuzzy inference system (ANFIS) for storm runoff coefficient forecasting. To that end, Barariyeh watershed was chosen in Neishabour and the data of 33 events were collected from 1952 to 2006. Factor analysis (FA) was used for determination of independent variables in storm runoff coefficient forecasting. Four variables were selected as independent variables, including average rainfall, third, first and fourth quartiles of rainfall intensity and also five other variables included &phi index and first to fourth quartiles of rainfall intensity. Other variables combined based on their hydrological role were considered as ANFIS inputs. The results revealed that the ANFIS inputs including first to fourth quartiles of rainfall intensity, &phi index, and total rainfall of five days before can predict storm runoff coefficient with R2=0.91, RMSE=0.02506, MAE=0.0666 and CE=0.87.
M. Montaseri, M. Hesami Afshar, O. Bozorg Haddad,
Volume 21, Issue 2 (8-2017)
Abstract
Nowadays, urbanization is a common process which replaces vegetation cover with impervious areas. This process increases urban stormwater. A new tendency in urban stormwater management endorses ‘source control’, whereby distributed water sensitive urban design systems are built throughout the subdivisions to alleviate the effects of land use changes. Various costs and functions are considered for different urban stormwater treatment measures methods. The present study introduced a legal optimization approach, to minimize the costs of urban stormwater treatment measures. For this purpose, the MUSIC model and Genetic Algorithm were combined in the Matlab environment. The Results of application of MUSIC-GA model, to optimize urban stormwater treatment systems, at 2.8 hectares of industrial areas near Rowzehchay River in Lake Urmia basin, showed that the developed MUSIC-GA model has an efficient performance for finding the optimal urban stormwater control. The results also indicated that the optimized treatment measure in the post development scenario decreased at least 45 percent of pollutants from urban stormwater runoff. Moreover, very small values of coefficient of variation (0.00007) among different results of multiple runs indicated that there was a high convergence between result of MUSIC-GA and the global optimal solution.
A. Vali, F. Roustaei,
Volume 21, Issue 4 (2-2018)
Abstract
Wind erosion is the most important geomorphic process and the main cause of the landscape change in arid and semi-arid areas. This paper focuses on the Dust Storm Index (DSI) with the aim of monitoring wind erosion in Central Iran using meteorology data. The trend of standardized DSI and its three factors which are sever dust storm, moderate dust storm and local dust events were studied using Man-Kendal non-parametric test. It was found that wind erosion is accelerating in recent years. Compared to primary 20 years (1965-1985) DSI rate has been three times more than 30 years ago (1985-2014). The central and southern parts of Central Iran show the highest severity of wind erosion and the severity of DSI decreases by approaching the north. Therefore, considering the sensitivity of these areas, in addition to taking into account prevention programs, they should also be considered in regeneration and control programs.
S. Ghorbani, R. Moddress,
Volume 23, Issue 3 (12-2019)
Abstract
The purpose of this study was to model the relationship between the frequency of dust storms and climatic variables in desert areas of Iran. For this purpose, climatic data of temperature (maximum and minimum), rainfall, wind speed (maximum and minimum), and their relationship with the number of days with dust recorded in 25 meteorological stations (statistical period since their inception until 2014) in summer using Pearson correlation coefficient and linear regression method multivariate was analyzed in SPSS software. Also, due to regional analysis, correlation coefficient between climatic variables and frequency of drought storms in desert areas of Iran, the mapping of these coefficients was prepared by method of Inverse distance weighting (IDW) in Arc GIS software. The results showed that the stations in the south and southwest of the study area have the highest dust incidence in the summer season. So that Zabul station with (3892 days) has the most frequent occurrence of dust storms. In most stations, there was a significant relationship between the frequency of dust storms and the variables of average wind speed and maximum wind speed. The highest correlation coefficient of the mean wind speed was related to the station of the Chabahar Konarak with correlation coefficient of 0.710 and Iranshahr station with a correlation coefficient of 0.65, showed the highest correlation with maximum wind speed. The maximum temperature variable at Qom station with a correlation coefficient of 0.398 shows a significant and positive relationship. Iranshahr station has a correlation coefficient of -0.620 with a mean temperature and Minab station has a correlation coefficient of -0.446 with maximum temperature. The results of temperature correlation with the frequency of dust storms indicate that ground low pressure is effective in creating the phenomena in the warm course of the year. Most stations have inverse correlation with precipitation. The highest correlation coefficients between precipitation and dust events were observed at -0.208 and -0.185 at east of Isfahan and Torbat Heidariyeh stations, respectively. Multivariate regression modelling between dust and climatic variables in summer also shows that the most important parameter in dust events are average wind speed, maximum wind speed and average temperature. Regression models show that, at the best condition, climate variables explain only 70% of the variation of dust frequency.
Y. Dinpashoh, E. S. Alavi,
Volume 23, Issue 4 (12-2019)
Abstract
Identifying the rainfall characteristics and understanding the rainfall-related processes is one of the key factors in the scientific management of water resources. Selection of the design storm is the first step in the estimation of the design flood. Determining temporal rainfall patterns is very important as one of the design rainfall properties in flood estimation and the design of drainage systems. This study was concerned with the pattern of rainfall depth during its occurrence at the Dez dam station. In order to plot Huff curves in the Dez dam station, the recorded data of the rain gauge was used. For this purpose, all 280 storms from 1972 to 2016 in different seasons were classified into the five distinct classes including i) 0-2 hours, ii) 2-6 hours, iii) 6-12 hours, iv) 12-24 hours, and v) more than 24 hours. Furthermore, for each class and in each of the seasons, the Huff curves were plotted using all storms information single class. Moreover, for the considered station, all recorded events were considered in a single class and the general Huff curve was plotted using the probability of 50%. In general, the highest number of storms in the Dez dam (about 32.9%) was grouped in the second quartile. However, it was about 55, 48.5 and 50.4 percent in the case of short storms (0-2 hours) for spring, autumn and winter, respectively. In contrast, low percentages were obtained for the rainfalls having long durations. The Logistic equation was extracted for all Huff curves. These curves would be useful in efficient water resources management. The value of the correlation coefficient between the amounts obtained from the Logistic model and the corresponding values extracted from the curves was more than 0.99, which was significant in 1 percent.
Z. Ebrahimikhusfi,
Volume 24, Issue 1 (5-2020)
Abstract
The purpose of this study was to analyze the temporal variations of dust phenomenon and its relationship with the climatic elements in Yazd city, located near one of the critical centers of dust production in the center of Iran. For this purpose, the Dust Storm Index was first calculated. After the standardization of precipitation, temperature, maximum wind speed, average wind speed, relative humidity and, dust storm index, the co-linearity effect between variables was calculated by using inflation variance factor. Then, several regression models were prepared based on the optimal Ridge parameter. The performance of the models was evaluated based on the determination coefficient, F value and Root Mean Square Error. Finally, by using the most accurate model, the impact of climate parameters on the dust events changes was determined. The results showed that the incidence of dust events in the spring was more than the rest of the year. Based on the optimal model (Model 12), it was found that the main factor influencing the dust storm index variations in different seasons was the surface winds speed. It was also shown that 39%, 25%, 46% and 31% of dust storm index changes in winter, spring, summer, and autumn were due to the interaction of the five climatic parameters studied in this study.
S. Zandifar, Z. Ebrahimikhusfi, M. Khosroshahi, M. Naeimi,
Volume 24, Issue 3 (11-2020)
Abstract
The occurrence of wind erosion and the spread of dust particles can be regarded as one of the most important and threatening environmental factors. Climate change and the frequency of droughts have played an important role in exacerbating or weakening these events. The primary objective of the present study was to investigate the trend of changes in four important climatic elements (precipitation, temperature, wind speed and relative humidity) and dust storm index (DSI) in Qazvin city using the Mann-Kendall pre-whitened test and to determine the relationship between them based on the multiple linear regression method. Assessment of the meteorological drought status based on two standardized precipitation index and standardized precipitation, as well as the evapotranspiration index and analysis of their effect on activity level of dust events, was the other objective of this study in the study area. For this purpose, after preparing and processing the climatic data and calculating the dust storm index, the trend of changes and the relationship between climatic parameters and dust events were investigated. The results showed that the changes of trend in the annual precipitation and relative humidity in Qazvin city were increasing, while the trend of annual changes in the wind speed and the mean air temperature was a decreasing one. Investigation of the monthly changes in the dust events also showed that there was a sharp decrease in the occurrence of wind erosion and the spread of domestic dust particles only in July. On a seasonal scale, with the exception of winter that has been reported without trends, in other seasons, the intensity of these events was significantly reduced. The effect of the meteorological drought on wind erosion was estimated to be 11% at the confidence level of 99%. In general, these findings indicate a decreasing trend of land degradation and desertification caused by wind erosion in Qazvin.
M. Motavallizadeh Naeini, R. Modarres,
Volume 25, Issue 4 (3-2022)
Abstract
Dust storms in arid and semi-arid regions have harmful impacts on the environment, the economy, and the health of local and global communities. In this study, the frequency of annual dust events in twenty-five stations and five climatic variables including rainfall, maximum annual wind speed, average annual wind speed, maximum annual temperature, and average annual temperature in arid regions of Iran up to 2014 were used to show the effects of climatic change on dust storms. Annual correlation coefficient time series between climatic variables and dust storms were first calculated based on monthly observations. Then, the trend in climatic variables, dust storm frequency, and their correlation were assessed using the Mann-Kendal method. Results indicated that the correlation coefficients had fluctuations in time and are both significant and insignificant in different years that reach from 0.6 to 0.9 for wind speed and temperature and -0.2 to -0.6 for precipitation. This trend in correlation has the same direction with climatic variables and shows co-movement between climatic change and dust storm fluctuations in central Iran. Results also showed that wind speed and temperature have a high impact on dust storm fluctuations and rainfall reduction has an increasing effect on dust storms.
A.r. Nourafar, A. Pahlavanravi, M. Nohtani, V. Rahdari,
Volume 26, Issue 1 (5-2022)
Abstract
Wind erosion is one of the most important natural processes in arid and semi-arid regions. Sistan plain has a hyper-arid climate and is one of the windy regions of the country. Due to the soil characteristics of the Sistan plain, wind erosion is very intense in this region. In this study, the relationships between some soil's physical and chemical properties and wind erosion were investigated in different land cover in a part of the central region of Sistan in 2018. A map of land cover in five classes was prepared using the results of field studies and the classification of satellite images. Fifty soil samples at a depth of 10 cm were collected to investigate the physical and chemical soil properties and the wind erosion threshold was determined at each location using a portable wind tunnel device. Also, the relationship between physical and chemical soil properties including soil texture, soil moisture, specific apparent weight, EC, SAR, ESP, Na+, k+, with the speed of wind erosion threshold was investigated. According to the results, the highest and the lowest threshold speed were 8.2 and 3.8 m s-1 and occurred in agricultural lands and hilly lands, respectively. The results of this study indicated that the velocity of wind erosion threshold in different lands adjacent to sandy areas is less than the average of that cover. Also, the soil texture, EC, and SAR have the most significant effect on soil wind erodibility at P <0.05 in the study area.
