mahdieh soltani Gerdfaramarzy; gholamali mozafari; Shahab Shafie
Abstract
Extended Abstract Introduction Droughts are one of the most common climatic changes that occur in many arid and semi-arid regions of the world with high intensities every few years. In many years, the occurrence of droughts is also unknown for a while, therefore, the identification of drought itself, ...
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Extended Abstract Introduction Droughts are one of the most common climatic changes that occur in many arid and semi-arid regions of the world with high intensities every few years. In many years, the occurrence of droughts is also unknown for a while, therefore, the identification of drought itself, is considered as a valuable finding for managing the water resources in areas such as Iran, most of which are formed by arid and semi-arid regions. Precipitation is the most important determinant variable in drought conditions among climatic variables. Rainfall is the most important variable whose variations are directly reflected in soil moisture and surface runoff, variations in underground water reservoirs and others. The purpose of this research is to investigate the best method of drought interpolation in the Yazd-Ardakan plain, to identify areas at risk of this phenomenon and to identify its spatial distribution, and also to investigate the relationship between drought and the salinity of groundwater and the spatial distribution of saline water in the Great Plain of Yazd – Ardakan. Materials & Methods In this research, regarding the lack of long-term statistical period of some stations and considering the distribution of stations in this basin, the annual precipitation data of meteorological stations of Yazd - Ardakan plain during 2 long term period of 7 meteorological stations (1346-1391), and short term precipitation and salinity period of 41 meteorological stations and 47 underground water wells (1375 to 1391) have been used all together. The standardized drought index for the determining drought condition and descriptive statistics methods in SPSS software has been used to describe the state of groundwater salinity using Excel software. The Pearson, Man-Kendhal, and Spearman correlation analyses were also used to determine the relationship between drought and the state of salinity of groundwater. Finally, the Geographic Information System (GIS) was also used to map the zoning of groundwater salinity. Results & Discussion The results of the assessment showed that in the correlation analysis with all 3 Pearson, Man-Kendhal, and Spearman statistics, a negative trend along with inverse correlation is observed between the precipitation (SPI) and salinity based on the Z grade,, in none of which the significant level is observed. The existence of a strong correlation between these two parameters with a one year delay was among the other results of this research. Using GS+ and GIS, the best variogram model was selected and the maps of drought, groundwater salinity and salinity variations were also drawn. Generally, in most stations with negative precipitation trend, a positive trend of underground water salinity is observed, and groundwater quality has also changed more strongly in areas with more drought outbreak and its salinity has also increased. Conclusion The occurrence of droughts, on the one hand, increasing water demand in the area, on the other hand, exacerbate the shortage and need for water. Therefore, the monitoring of future droughts and wet years should be considered very important in terms of management strategies of the region. Passing such crises require the efficient management of water resources under present conditions, especially during drought periods. Usually, during such a period, the region’s water shortage, are provided from the groundwater resources and through increasing the water extraction from wells, to meet basic needs such as drinking. Therefore, in such cases, the quality issue of the extracted water from these wells becomes more important. The available statistics show that the water quality in the Yazd-Ardakan plain (electrical conductivity) is a function of annual precipitation (as the most important feature of droughts in the region), and with the annual precipitation increasing and decreasing, the groundwater quality also undergoes changes. In general, the results of the analysis of the studied parameters indicated that the climate of Yazd-Ardakan plain was associated with a rainfall reduction trend, which is one of the important factors of drought, so that, its consequences have also affected the level and quality of water resources. It has been observed in this research, that droughts have had a considerable effect on the salinity of groundwater in most of the areas. Therefore, it is generally stated that the groundwater quality has changed more strongly in areas with more drought outbreaks and its salinity has increased.
Seyyed Hossein Mousavi; Zahra Heydari Monfared; Shahab Shafie
Abstract
Extended Abstract
Introduction
Identifying the patterns and synoptic models that create instability and precipitation in the region is necessary. If the systems that come into the area, contain the appropriate thermodynamic structure, i.e. of high volatility, with appropriate heat and humidity, make ...
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Extended Abstract
Introduction
Identifying the patterns and synoptic models that create instability and precipitation in the region is necessary. If the systems that come into the area, contain the appropriate thermodynamic structure, i.e. of high volatility, with appropriate heat and humidity, make good rainfall in the region. Thunder storms along with subsidiary phenomena arising from them, such as hailstones, are one of the violent manifestations of nature. In the North West of the country due to geographical conditions in addition to synoptic systems (front cold low pressure systems), instability of local causes urinals (in this instability rising moist air causes rain too) and sometimes because of both the (synoptic system and local instability) heavy showers and hail occur. Thus, in the present research, in order to obtain hailstone risk management in north western part of the country and to reduce damages deriving from it, the evaluation of this destructive phenomenon has been taken into consideration using instability indices.
Materials and methods
The data used in this study included daily information related to hail of the country's North West region from 25 synoptic stations. Codes of hail (27, 90, 87, 93, 94, 96 and 99) of 100 Codes of Group VII (ww air now) were extracted from the data of the listed stations. In order to detect thermodynamic conditions of the occurrence of this phenomenon during a 18 year statistical period (1992-2009), instability indices, 230 cases of the occurrence of Skew T log P, and glacial levels of PWC, T.T, V.T, C.T, KI, SW, LI, SI hailstone atmospheric climatic diagrams of Tabriz and Kermanshah provinces’ stations to thorough covering of the region were extracted from the Wyoming University website of the United States of America and were studied.
Findings
Evaluating and comparing the instability indices of days of hail in the North West with the above table, the following conclusions emerged: the values of SI on all days of sampling except on 22 April 1994, 22 April and 29 May 2003, 27 January 2004, 19 May 2005 and 21 November 2009, about 9/73% of the days selected are larger than 4. LI values greater than zero on all days have been evaluated. It means the observed figures on the proposed figure of 100% are contrary to international indicators. SW values in all the days to the days of April 22, 1994, February 11, 2003, April 27, 2005 and November 21, 2009, about 6/82 are less than 150% of study days. Index values are less than 43 days T.T on December 18, 1993, February 11, 1997, January 16 and 6 March and 4 May 1998, 18 February 1998, 23 January and 27 April 2005, respectively. In other words, it can be noted that about 8/34% of observation days is contrary to the global indices. Days of less than 15, KI includes 30.4% of the studied days. it means on December 18, 1993, February 11 and March 8, 1997, January 16 and 6 March and 4 May 1998 and 23 January 2005, CT values of about 39% of studied days on December 18, 1993, April 22, 1994, February 11 and 3, 1997, January 16 and 6 March and 4 may 1998, 8 February 1999 and 29 may 2003 were lower. V.T index also includes amounts less than 25 days of December 18, 1993, February 11, 1997, January 16, 6 March 4, 1998, February 8, 1999, is April 4, 2002 and January 23, 2005. In other words, about 8/34% of studied days are incompatible with global indices figures.
Conclusion
The results obtained from all of the aforementioned indices were compared with the atmospheric instability standards and were evaluated. In this study, some contradictions between observatory and predicted values were discerned and finally, instability indices of the region were determined as follows:
SI ≤ 20.71, LI ≤ 16.63, SW≤ 19.99, KI ≤ 14.30, CT ≤ 11.50, V.T≤ 24.70 and T.T ≤ 41.80
Moreover, it was observed that atmospheric instability of the region has aggravated in recent years, so that SI and LI indices have approached zero in the past few years and other indices have each ascended one millimeter towards their maximum thresholds. Additionally, glacial level in the hailstone days under study fluctuates between 850 to 650 Hectopascal, i.e. between the altitude of 1393 and 3788 meters. This level increases in the hot months of the year.
Gholamali Mozafari; Shahab Shafiei; Zahra Taghizade
Abstract
Over the past few decades, the increase in the temperature of the Earth has caused the disruption of climatic balance of the Earth, causing widespread climatic changes in most parts of the planet, which is referred to as climate change. The aim of this study is to predict climatic changes of Sistan-va-Baluchestan ...
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Over the past few decades, the increase in the temperature of the Earth has caused the disruption of climatic balance of the Earth, causing widespread climatic changes in most parts of the planet, which is referred to as climate change. The aim of this study is to predict climatic changes of Sistan-va-Baluchestan Province using statistical downscaling in which the A2 scenario data of ECHO-G atmospheric general circulation model is implemented.To assess, the climatic changes and the drought in Sistan and Baluchestan Provincewere downscaledby the LARS-WG model during the statistical period of 2012 to 2031.In this study, the data of minimum temperature, maximum temperature, radiation, and precipitation of ECHO-G model, and the actual data of 7 stations in the province, including the Chabahar, Iranshahr, Khash, Saravan, Zabol, Zahak and Zahedan have been used. The overall results of the surveys for the aforementioned period indicate an 8 percent increase in precipitation in the province and a decrease in the number of glacial days and an annual average increase of about 0.3 degrees Celsius. The highest monthly increase in wintertemperatureis at 0.9 degrees Celsius. Moreover, the number of dry days increases in Saravan city and decreases in other cities, and in general, the droughts in this province decrease in the period of 2012- 2031.
Seyyed Hosein Mir Moosavi; Shahab Shafiei; Zahra Taghizadeh
Volume 23, Issue 89 , May 2014, , Pages 81-87
Abstract
Studying the influence of climatic elements on residential environments is an applied subject in meteorology, which has recently received a significant importance in synchronizing buildings and residential environments with dominant climatic situations due to the high costs of energy. The present study ...
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Studying the influence of climatic elements on residential environments is an applied subject in meteorology, which has recently received a significant importance in synchronizing buildings and residential environments with dominant climatic situations due to the high costs of energy. The present study use data collected from different climatic parameters (humidity, minimum temperature, maximum temperature) in an hourly basis. Data was analyzed using Ecotect and One Square software. Moreover, day degree, temperature adaptability index, climatic-environmental situations of the designed building in Mehr-Abad station were investigated. Results indicate that climatic comfort in winter (January, February, and March) and December equals zero. In other words, some of the necessary situations for climatic comfort inside buildings should be achieved using mechanical systems, while others must be achieved by appropriate climatic designing of buildings. Comparing comfort level in and outside of buildings indicates that some of necessary situations for climatic comfort were provided naturally in March. This shows the role of correct designing in reducing the need for mechanical systems. Moreover, temperature adaptability index in different points inside the building indicated 0.94 which shows a completely appropriate situation in the designed building. Finally, Tehran bioclimatic graph was extracted which shows that there is just a 7 percent climatic comfort around the year and Tehran climatic situation is out of comfort range for the other 93 percent of the year.
