Hamideh Afkhami; Mohammadreza ekhtesasi; Mozhdeh mohammadi
Volume 22, Issue 3 , November 2015, , Pages 570-582
Saeid Gharachelo; Mohamad reza Ekhtesasi; Mojtabah Zareian Jahromi; Mohamad bagher Samadi
Volume 17, Issue 3 , October 2010, , Pages 402-420
Abstract
Nowadays, desertification is one of the ecological crises of the world. To control desertification, having a clear understanding of its factors and processes is necessary. Khezr Abad-Hemat Abad region of Yazd with area of 242 Km2 was considered to evaluate current condition of desertification using ICD. ...
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Nowadays, desertification is one of the ecological crises of the world. To control desertification, having a clear understanding of its factors and processes is necessary. Khezr Abad-Hemat Abad region of Yazd with area of 242 Km2 was considered to evaluate current condition of desertification using ICD. Iranian Classification of Desertification (ICD) was presented by M. Ekhtesasi and S. Mohajeri in 1995. First of all, available data were collected and basic studies were done. The data were entered in GIS and basic maps were produced through interpretation of aerial photos and satellite images using Arcview and Ilwis software. Eight desert homogenous units were separated according to the studies and by overlaying geomorphology, land use and vegetation cover maps. In next stage, effective factors in desertification including three environmental factors, three anthropogenic factors, soil erosion index, resilience potential and reconstruction of ecosystem were scored in a range of 0-10. Afterward, according to the sum of scores and comparing with table of desertification severity index, final desertification map was produced. The result showed that 81.53% of the region was in middle class of desertification while 18.47 % was in severe class. The environmental factors were determined as the main factor in desertification of 81.53 % area of the studied region while 18.47 % of that was affected by anthropogenic factors. Most main criterion in desertification of this region was water degradation process
Mohammad reza Jamalizadeh Tajabadi; Ali reza Moghadam nia; Jamshid piri; Mohammad reza Ekhtesasi
Volume 17, Issue 2 , September 2010, , Pages 205-220
Abstract
Dust storms are common climatic events in arid, semi arid and desert regions of the world. These events impact human resources by foundation losses, every year. Accurate prediction of these events can be effective for decision support in environmental, health, army, and other related fields. An artificial ...
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Dust storms are common climatic events in arid, semi arid and desert regions of the world. These events impact human resources by foundation losses, every year. Accurate prediction of these events can be effective for decision support in environmental, health, army, and other related fields. An artificial neural network is a method which can predict nonlinear problems. In this study we attempted to predict dust storms and low visibility in Zabol city using synoptic data. Result indicates that this method is somewhat successful and appears that via identification of much more dust storm occurrence process, we can do more accurate prediction.
Hadi Memarian Khalilabad; Ali akbar Safdari; Mohammad reza Ekhtesasi
Volume 15, Issue 1 , January 2008, , Pages 26-41
Abstract
In wind erosion process, there are three areas: source area, transport area, and deposition area. The prevention of sediments movement in the source area is a fundamental task. In stabilizing source sediments of sand dunes, recognition of the taking regions is essential. In order to study the in order ...
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In wind erosion process, there are three areas: source area, transport area, and deposition area. The prevention of sediments movement in the source area is a fundamental task. In stabilizing source sediments of sand dunes, recognition of the taking regions is essential. In order to study the in order to study the source of eolian sediments in the Fadisheh region, a step-by-step method (Ekhtesasi-Ahmadi) was used. This study was done in two stages: direction finding and location finding. First, information about the direction of local winds was gathered by questionnaire. Then satellite image (ETM+, 2002) and field investigations, the erg morphological map was determined. By studying wind regime and wind rose drawing, the erosive winds were recognized. After recognition of source sector (southeast and east sector), the location finding phase was started. In this stage by geomorphologic studying of the source sector and sampling into facieses, the mineralogical and morphoscopical studies of sand dunes and source sector sediments were done. Finally, paying attention to other evidences as the direction of Barkhan dunes (Southeast-Northwest), high intensity of energy for East winds, the existence of heavy minerals as Hematit, Chamosite, Edenite and Sphalerite in sand dune and source area soil samples, average median of sand dunes sediment samples (~210micron), symmetrical shape of sand dunes sediments frequency graph, was found that the source of eolian sediments are in the middle distance relative to sand dunes and are as follows: damaged Haloxylon forests, non vegetative area, unutilized lands in the southeast sector of the clay plains, Microlithic pediments and non vegetative lands in the margins of Kal-e-Shoor and Kal-e-Shoor River bed.
Mohammad ali Meshkat; Mohammad reza Daneshvar; Mohammad reza Ekhtesasi; Kazem Dashtakian
Volume 13, Issue 1 , February 2006, , Pages 10-16
Abstract
Desertification is important for our country because it refer to land degradation in arid, semi-arid and arid sub - humid zones due to climatic and human agents. General and continuous study, local and exact investigation,and use of current quantitative models is necessary to better understanding of ...
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Desertification is important for our country because it refer to land degradation in arid, semi-arid and arid sub - humid zones due to climatic and human agents. General and continuous study, local and exact investigation,and use of current quantitative models is necessary to better understanding of land degradation process and desert development. In this research that is based on FAO/UNEP provisional methodology , some of the main desertification processes such as: vegetation destruction, wind erosion, and salinization were studied from two aspects:1) current status and 2) inherent risk. This area covers about 327700 hectars, extends to north of Yazd - Ardakan basin. Then, six maps were drawn for three processes and for two aspects which mentioned above, separately in 1:50000 scale, when the field observations and measurements were carried out. Finally two equal maps were provided by combination of six previous maps . Results of this investigation show that at the present time degrees of vegetation destruction, salinization, and wind erosion are ,, severe to very severe ,, ,,,medium to severe ,,, and,, slight to medium,, respectively . However, degrees of these processes from inherent risk aspect are ,, very severe ,, , ,, medium to severe,,, and,, medium to severe,, respectively. Although the FAO/UNEP methodology is the best model , however it has still some problems, such as: Non quantitative of some criteria; Non sensitivity of some indexes to slight changses ; Non measureable of some criteria; and Non equal the number of indexes in different processes.