Payam Ebrahimi; mehdi Eslah; Maryam Azarakhshi
Abstract
One kind of the mass wasting which takes much toll and leaves much damage in the world and many locations in Iran is landslide. Landslide susceptibility mapping allows recognizing susceptible areas to be considered in environmental programs. Present research is aimed at Landslide susceptibility mapping ...
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One kind of the mass wasting which takes much toll and leaves much damage in the world and many locations in Iran is landslide. Landslide susceptibility mapping allows recognizing susceptible areas to be considered in environmental programs. Present research is aimed at Landslide susceptibility mapping in Hafshejan watershed in Chaharmahal-o-Bakhtiari province using Spatial Multi Criteria Evaluation (SMCE) method via geographic information system (GIS) and ILWIS software and AHP technic. Therefore, regarding the sites where landslides occurred, comparative studies, and the findings of other scholars, eight informational layers were identified for this research. Then, the tree of factors and restrictions was designed in ILWIS software. All layers were standardized and were evaluated and weighted applying AHP model. Last but not least, upshot model and landslide hazard zonation map were prepared and presented for the relevant study area. It was found out that from among effective factors, distance from road, distance from fault and distance from stream of 0.4047, 0.2239 and 0.1302 weight respectively are the most important factors triggering landslide in study area. According to the presented model, about 1.32 percent of watershed area (1013900 square meters) is extremely high risk and 9 percent (6909800 square meters) is high risk. The results of accuracy evaluation of the presented model are indicative of ascendantal trend of landslide index from very low hazard zone to very high hazard zone and they are indicative of sufficient precision of this model.
jalil farzadmehr; payam Ebrahimi; mehdi Eslah
Abstract
Predicting the hydraulic behavior of the river and flood zone determination to reduce probable damages, are among measures which in recent years has been the attention of many researchers. Mazandaran province, especially the city of Neka, each year is affected by the floods with different return periods; ...
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Predicting the hydraulic behavior of the river and flood zone determination to reduce probable damages, are among measures which in recent years has been the attention of many researchers. Mazandaran province, especially the city of Neka, each year is affected by the floods with different return periods; therefore, land use changes and the role of these changes were evaluated in flood zones. In this study, with integration of river system analysis, GIS and Remote Sensing, images of the years 2000 and 2011 were processed and Neka river hydrological response was determined in specified return periods. The results showed Pearson type 3 distribution, roughness coefficient determined by Cowan’s method and IRS image in comparison with ETM+ image, have good accuracy. With determining land use changes in the years 2000 and 2011, the area of each land use class was specified in GIS, and then attached to the HEC-GeoRAS. By determining two flood maps with return periods of 2 to 200 years, the difference of each layer was determined. Many studies determined land use only; but according to the results of this study and impact of the 14.60-percent increase in flood area, the role of changes is noticeable. This study suggests that in the flood zone determination, addition to land use designation, we should pay special attention to its changes and hydrological response of the total area to these changes, and its role in the flood zones. The simulation of river bed and flood zone in forest areas depends on land use, and deforestation in this river is one of the most important factors.
Maryam Azarakhshi; Jalil Farzadmehr; Mahdi Eslah; Hossein Sahabi
Abstract
Climate change is defined as long term and irreversible changes in the climatic behaviorof a region. Many studies have been conducted in different regions of the world on climatechange. The results of these studies show considerable changes in climatic factors especiallyin precipitation and temperature. ...
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Climate change is defined as long term and irreversible changes in the climatic behaviorof a region. Many studies have been conducted in different regions of the world on climatechange. The results of these studies show considerable changes in climatic factors especiallyin precipitation and temperature. In this research, the trend of changes in annual and seasonalrainfall and temperature in 24 synoptic stations over a 50-year data period (1956-2005) wasinvestigated in Iran. The Mann- Kendall test and linear regression technique were used to analyzethe trend of changes in climatic factors. The results showed both increasing and decreasingtrends in annual rainfall at various regions of Iran. Annual rainfall in northern slopes of Alborzand western slopes of the Zagros Mountain as well as in eastern and southeast parts of Iran hada decreasing trend while in the central of Iran the trend of changes was increasing. In southernregion of Iran the rainfall had an increasing trend. The results also showed that temperature inmost of the studied stations over the considered period was increasing. The highest and lowestchanges in temperature were seen in the mean temperature of summer and winter, respectively.Ahwaz and Khorramabad stations had a decreasing trend and over all seasons would go towardmore cooling. The temperature trend in Oromiye was decreasing in autumn and summer whileShahrekord and Bandar abbas had the same trend in summer and winter.
