Geomorphology
Shahram Roustaei; hasan Ahmadzadeh; mohammadreza nikju; maryam dehgani
Abstract
Abstract To reduce vulnerability of some villages to natural hazards, shifting their location is inevitable. The rural relocation and resettlement is a plan to determine the optimum establishment and activity site for the study of villages by studying the causes of displacement, evaluating social and ...
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Abstract To reduce vulnerability of some villages to natural hazards, shifting their location is inevitable. The rural relocation and resettlement is a plan to determine the optimum establishment and activity site for the study of villages by studying the causes of displacement, evaluating social and economic characteristics of villagers and environmental and physical assessment are of options for a new location. Googerd village due to its vulnerability to landslides was studied which several times was displaced and finally a place is specified for the displacement. If this site itself be vulnerable to natural hazards, it will cause the collapse of the physical, economic and social environment of villages. Vulnerability assessment in relation to natural hazards requires precision tools with applications in the spreadsheet spatial level. Therefore, in this study, in order to evaluate the rate of stability of the chosen site for displacement and relocation of Googerd village, at first the rate and range of displacement during the period from 2003 to 2010 were derived using 25 ASAR ENVISAT radar images and SBAS differential radar interferometry (D-InSAR) technique. The results showed that the stability of the selected sites does not have the favorable conditions and experience on average 12 cm line of sight (LOS) displacement. In order to conduct survey on the hillside of study area against mass movements and assessment of environmental stability and optimized understanding of them, displacement time series plots was drawn for six points around the selected site. These figures indicate that there is variable line of sight (LOS) rate of downward motion between 14-8 cm in all sides of selected site.
Jamshid Yarahmadi; Mohammadreza Nikjoo
Volume 16, Issue 39 , May 2012, , Pages 151-169
Abstract
The present work aims to assess the effects that landuse change has induced on the flood frequency regime. Study area covers upstream of Alavian Dam (250 km2) in the Sofi Chai basin. The torrential periods (in terms of flood event frequency and duration) has been carried out by comparing each daily discharge ...
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The present work aims to assess the effects that landuse change has induced on the flood frequency regime. Study area covers upstream of Alavian Dam (250 km2) in the Sofi Chai basin. The torrential periods (in terms of flood event frequency and duration) has been carried out by comparing each daily discharge with the base flood. Here, the base flood (flood with 2 years return period) was calculated from maximum annual discharge based on fitting various distribution models, and then the best fit model was chosen by considering RSS criteria. The results indicate that flood events and their duration tended to be abated on the last decade.
In this research, landuse/cover changes have been detected by interpretation of remotely sensed data based on object oriented method. The results indicated that the positive changes of crop patterns (overdeveloping of orchards as well as dry farming increasing) were occurred in the study basin.
HEC-HMS model was applied for simulation of rainfall-runoff process and assessment of the effects of landuse changes on the flood frequency. HEC-HMS simulated results based on corresponding CN derived from 2000 to 2005 satellite images show 36% abated of flood event respectively.
It should be noticed that the construction of a part of mechanical watershed management operations can reduce the flood events by reserving the surplus runoff.
