Risk Analysis of Sands Movement on the Settlements of the West of Lut Desert (Case study: Hojjat Abad Village - East of Shahdad)

جغرافیا و مخاطرات محیطی

Article 4, Volume 1, Issue 1, January 2012, Pages 83-96   

Document Type: Research Article

DOI: 10.22067/geo.v1i1.16534

Authors

Mehran Maghsudi^{* 1}; Said Negahban¹; Sajad Bagheri²

¹Tehran University

²University of Tehran

Abstract

Introduction
Dominant process in arid and semi-arid region is dynamic of wind that carries the sand and caused damage to several facilities and human settlements. There are many human settlements with low population and mostly small and scattered in different parts of Foothills of Dasht-e Lut (Lut desert), especially in mountainous margins of alluvial fans. Residential and cultivation area of this settlements are mostly affected by sand movement and over time a very large impact of this move are accepted. This study tries to examine the risk assessment of the sand dune movement at Hojjat Abad village located on the west of Lut desert (East Shahdad).
Methodology
Study area is located at Kerman province in the West of Lut desert and East of Shahdad City. In this study, descriptive analyses were used base on fieldwork and librarian study. At first, study area confined with satellite imagery. With three days fieldwork all parts of Erg were studied. Also different parts of Hojjat Abad village that by sand, were observed and area that invaded by wind and sand were identified. For identification of wind regime and the direction of sand movement, wind data were collected from synoptic station of Shahdad. In this study for comparing of Erg movement during the times, aerial photographs from different time were used. Aerial photos of 1:55000 (1955), 1:20000 (1969), 1:4000 (1998) and Google Earth image (2009) were used for determination of Erg displacement during 54 years. According to above mentioned, aerials photographs and satellite images, area and displacement of Hojjat Abad Erg was measured. At the next step, using ArcGIS software, shifting and other morphometric characteristics of Erg were measured in the different period of the time. Finally, based on population data of the village in different census, population growth and diminish were analysed and compared with displacement of Hojjat Abad Erg.
Results and Discussion
Based on periodic diffrent aerial photographs and Google earth images, Results shows the changes and displacement of Erg Between 1955 to 2009. In fact, Displacem of Erg was accompanied with changes of area in Hojjat Abad Erg during the 54 years. At the first stage in 1955, area of Erg was 237 ha and about 13 years later, the area of Erg increased to 245 ha. Therefore, we encounter to eight ha increase the area of the Erg. At the second stage between 1969 and 1998 the area of the Erg increased from 245 to 293 ha, (46 ha increase of Erg area). At the third stage between 1998 and 2009, the area of the Erg increased about 22 ha. Overall, between the first stage in 1955 and the final stage in 2009, area of Hojjat Abad Erg increased about 78 ha. In the other hand, Increase of area of the Erg was accompanied with displacement of the Erg to the south east of the region. According to the measurement, 1050 meters displacement accrued during 54 years, between 1955 and 2009. Between 1955 and 1969, displacement was 350 meter and between 1969 to 2009 displacement was about 700 meter. In the first stage, the Erg displaced from 550-meter distance from Hojjat Abad village to 200-meter distance. In the second stage that covered 29 years, Erg passed east of village, affected and harmed the cultivation area around the village and some part of residential area. This has led to a large volume of agricultural land of Hojjat Abad village affected by sand movement and buried under the sand, and consequently the area of habitat was reduced. Results of the study of population of Hojjat Abad village shows that during the period from 1955 to 1375 census, the population shows an ascending mode and from this year onwards there is descending mode due to sand movement and risk Erg displacement. In fact, frequency, direction and intensity of prevailing wind and sand transportation from north west are most important reason of Erg movement to the south east in this area.
Table 1 Displacement of Erg in the period of study
Scale Area (ha) Displacement (m) Year
1:55000 237 - 1955
1:20000 245 350 1969
1:4000 293 700 1998
- 315 - 2009
Conclusion
In this study, we investigate the sand sea displacement and risk of sand movement in Hojjat Abad region near the Shahdad city and West of Lut Plain (Lut Desert). Our study shows that the study area has been encountered with sand movement for many years. Especially in recent year with invaded of Erg to near of Hojjat Abad village, some cultivation area buried by sand and caused the migration of people from this village to other areas. Aerial photos from different periods of time and satellite image of 2009 shows the displacement of Erg from north west to the south east of the region as well as increasing of area of the Erg from 1955 to 2009. Results show that the village did not affected by sand movement during 1955 to 1969 but the Erg approached to 200 meters distance from the village. In the second stage, sand movement covered part of agricultural area of the village. In the third stage, sand effected some part of residential area of the village and cultivation area and Erg passed from east of village. Results of population census show that until 1996 population in Hojjat Abad village increase while from this time, population decrease. In fact, main reason for population decrease is sand movement in this area and damage of cultivation area by displacement of Erg. In feature two methods of live or biological and none live methods or mechanical methods can be used to prevention of sand movement to the residential and agricultural part of this area.

Keywords

Erg; Sand hazards; Lut Desert; Shahdad; Hojjat Abad

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