Siavash Taei Semiromi; Hamidreza Moradi; Morteza Khodagholi
Abstract
Now a day, long-term prediction of climate variables is necessary for climate change impact studies. Currently Global Circulation Models (GCM) are powerful tools to generate climate scenarios. These models are limited to capture the local climate due to their low spatial resolution. So, they cannot be ...
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Now a day, long-term prediction of climate variables is necessary for climate change impact studies. Currently Global Circulation Models (GCM) are powerful tools to generate climate scenarios. These models are limited to capture the local climate due to their low spatial resolution. So, they cannot be directly applied for hydrological modeling in a catchment scale. In this research, first the trend of variables such as rainfall, radiation, maximum and minimum temperature were assessed for the base period with nonparametric Man-Kendall test. Second, these variables were downscaled by using the outputs of HADCM model and under three scenarios of A1, A2 and B1 which are accepted by IPCC(1971-2010) under three scenarios and their monthly changes were investigated for three periods of 2011-2030, 2046-2065 and 2080-2099 compared to the base predicted period of (1971-2010). All these scenarios showed almost similar results on precipitation shortage and increasing of solar radiation, minimum and maximum temperature over the future periods. As an example, the results of A2 scenario showed increasing of the annual mean, minimum and maximum temperature by 1.1, 3.2, and 4.6 °C, increasing of solar radiation by 0.07, 0.30 and 0.33 mJ m-2d-1 and decreasing precipitation by 16.4, 17.6 and 31.9 percent for these periods compared to the base period.
Morteza Khodagholi; Raziyeh Saboohi2
Abstract
The wind erosion is one of the most striking examples and the most devastating flow identifiers of desertification among the difficult obstacle of development in many countries. The rate of affected area by wind erosion in Iran is more than six times the global average. So, the purpose of this study ...
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The wind erosion is one of the most striking examples and the most devastating flow identifiers of desertification among the difficult obstacle of development in many countries. The rate of affected area by wind erosion in Iran is more than six times the global average. So, the purpose of this study is climatic zonation in west and south-west of Iran with emphasis on wind. In this study, 77 annually and monthly climate variables were selected within and adjacent areas of studied location from weather stations of the Weather Organization of Iran. To reduce the number of variables and determining effective factors, factor analysis with varimax relation was used, and then the spatial distribution of the factor score area plotted in Surfer Ver. 10. The result of the factor analysis identified six factors of heating temperature-precipitation, wind mean speed, prevailing wind speed, relative humidity, the fastest wind speed and solar radiation. These factors included 24.01, 19.78, 14.65, 12.66, 9.85 and 3.09 percent and in total 84 percent of the data variance. In this region seven climate zones were determined with Ward method that include moderate Mediterranean region with relatively fast winds, hot and semi-arid region with fast winds, hot and relatively arid region with calm air, extreme hot, arid and windy with fast winds, extremely hot, arid and windy, relatively hot and semi-arid with calm air, extremely hot and arid with relatively fast winds that extend on 17, 10.5, 15.1, 22.1, 7.9, 9.9 and 17.4 percent of the study area, respectively.
Javad mohammadi nejad; Morteza Khodagholi
Abstract
Dust is one of the drought consequences which during recent years has been emerged as one of the important factors affecting wheat growth and its production yield beside other climatic fluxions. In this research, the drought intensity has been studied at nine synoptic stations of Lorestan province, during ...
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Dust is one of the drought consequences which during recent years has been emerged as one of the important factors affecting wheat growth and its production yield beside other climatic fluxions. In this research, the drought intensity has been studied at nine synoptic stations of Lorestan province, during a ten years period of 2000-2009 and its dominant effects on dust frequency rate and its effects during seasons on the wheat cultivation performance rate, as one of the most important agricultural products sensitive to climatic variations,. The drought intensity analysis has been conducted by SPI index, for a six months’ time scales led to January and its relation with dusty day’s frequency distribution has been examined in horizontal sight less than 2000 m at the province stations. Also, the mutual correlation rates have been analysed using Pearson correlation test and multiple regression method with SPSS software and clustering was studied using Ward method in S-plus software. Results demonstrated that even during normal wet-spell, dust days happen and wheat performance in drylands falls below1000 kg ha-1 (2004, 2005 and 2007). Whereas, the dust days reached to zero and the wheat performance exceeded kg ha-1 (2006), when the wet-spell exceeds its normal rate and reaches to reduced domain. The frequency of dust days and wheat performance are directly correlated in most stations like Khoramabad, Koohdasht and Broojerd with a rate of 0.784, 0.626 and 0.933, respectively and completely adverse in Azna with a rate of -0.926.
Zahra Jaberalansar; Morteza Khodagholi; Masoud Borhany; Hossein Arzani
Abstract
Rangeland ecosystems in semi-arid regions are vulnerable systems to climatic changes specially precipitation. In such conditions droughts are predictable. In this study the relationship between rangeland production and spatial and temporal changes of precipitation was investigated. Therefore, rangeland ...
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Rangeland ecosystems in semi-arid regions are vulnerable systems to climatic changes specially precipitation. In such conditions droughts are predictable. In this study the relationship between rangeland production and spatial and temporal changes of precipitation was investigated. Therefore, rangeland production through 10 years data set (1377-1387) in steppic bioclimatic of Esfahan province (Alavije, Muteh, Kalahrood and Gardaneshadian) using Standard Precipitation Index (SPI), the relationship between SPI series of 3, 5 and 8 month time scales, and rangeland production of 10 years. Thus Anova and correlation matrix between production and SPI factors were formed. Results indicated that the most severe drought has occurred in 1387 simultaneously, with the least production. A harmony between change trend of production and SPI in the sites showed that in most cases maximum and minimum production have occurred simultaneously with maximum and minimum of SPI series. Also, the production correlated with SPI series of three, five and eight months' time scales with correlation coefficients more than 63 percent which were significant in 1% and 5% level. Due to efficacy of production from spring precipitation and soil depth less than 30 cm in the sites, it is proposed to use SPI series of three months scale to evaluate drought in similar rangelands.
Mohammad Reza Yazdani; Sattar Chavoshi; Morteza Khodagholi; Bahram Saghafian
Volume 1, Issue 3 , October 2009, , Pages 167-178
Abstract
Most parts of the Isfahan province are located in central arid land of Iran and are sensitive to drought occurrences. So it is required to study drought for prediction. There are many ways to define drought using different indicators. Climatology drought was evaluated using annual precipitation time ...
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Most parts of the Isfahan province are located in central arid land of Iran and are sensitive to drought occurrences. So it is required to study drought for prediction. There are many ways to define drought using different indicators. Climatology drought was evaluated using annual precipitation time series and different truncation levels including 30% 40, 50, 60, 70, 80, 90 and 95%. In this study 85 precipitation stations were selected in Isfahan province and around of it, in period of 1966-1998.Interpolation methods such as, kriging, Co-kriging, inverse distance weighted and TPSS were evaluated for interpolation of truncation levels and the error of each method was calculated. In the selected methods, Co-kriging method had minimum error and TPSS method had maximum error. Drought extension maps were drawn for each truncation levels using ILWIS software. Also water volume of probable precipitation is calculated for each truncation levels. Results showed about half of rainfall events occurred in 30 percent truncation level, whereas about 80 percent of the events are in 30 percent truncation level. Thus intense droughts occurred in the study area. Maximum frequency of drought occurrences in basis of truncation levels in study area are 30, 80, 60, 50, 40, 90, 70, 95%, respectively. Results indicated that truncation levels are suitable method for climatological drought evaluation in the studied area.
