Drought is a major problematic phenomenon mostly for semi-arid areas of Iran. During drought periods, reduction in vegetation levels causes such problems as soil erosion, surface runoff, flood risk, etc. Therefore, the assessment of drought effects on plant covers is the most important issue. This research was conducted in 2015 using the extracted vegetation indices from Moderate Resolution Imaging Spectroradiometer (MODIS) sensor data during 2000-2008. In Esfahan province, monthly rainfall data from 25 stations were used to derive the Standardized Precipitation Index (SPI) at 3 month scale, March to September. SPI was used to validate three index results in drought estimation. The result of calculating SPI showed that droughts occurred in 2000, 2001 and 2008. The result of Pearson correlations between SPI and Vegetation Indices showed thatthe highest correlation was related to VCI index and the lowest correlation was related to TCI index. The result of NDVI index in 2000, 2001 and 2008 indicated that the poor vegetation cover was increasingly occurred. Based on the results of this study, it can be concluded that the NDVI and VCI indices concerning MODIS sensor can be a good alternative for estimating the drought with respect to meteorological indices and consequently can give a better idea on drought conditions in the study area. It was shown that remote sensing data can be practically useful in analyzing the drought events in Esfahan province. پرونده مقاله

Dust storms are known as hazardous problems in western part of Iran. Iraq is one of the main sources for dust storm arriving to the western part of Iran. The Radial Basis Function Network model (RBFN) has been used to assess wind erosion hazards in the source area of dust storms over several western Iranian cities. Normalized Difference Salinity Index (NDSI) was used to determine the changes in the source area salinity over the studied years. The RBFN model has been used to assess the wind erosion severity of all land uses in the source area. Generally, NDSI values of all land uses in 2003 were higher than those in 2013. The maximum and minimum mean NDSI values were seen in severely dissected plains and mountainous lands, respectively. The observed differences in the wind erosion hazard maps of 2003, 2005, 2007, 2009, 2011 and 2013 were due to the changes in vegetation percent. Soil salinization caused the source area vegetation degradation and wind erosion exacerbation. So, the occurrences of dust storms in Western parts of Iran have become more frequent. The in situ observations showedthat there were two, five, five, twelve and nine records of pervasive dust storms in western parts of Iran in 2003, 2005, 2007, 2009 and 2011, respectively. پرونده مقاله

Soil erosion is a serious problem especially in northern parts of Iran. One themost important side effects on soil erosion may be the decline in qualities of soil refers toagricultural productivity. So it is very important to assess the soil erosion risk for thesustainable development of agriculture. This study outlines ways undertaken to provide anew tool to manage water erosion from physical and economical perspectives. KashidarWatershed in north of Iran is used as a case study. The focus of this study is on exploringthe economic and physical impacts of eight land use-based scenarios for water erosionmanagement as well as conducting a trade-off analysis using the Multi-Criteria DecisionMaking (MCDM) technique. This involves developing a modeling system to assist decisionmakers in formulating scenarios, analyzing the impacts of these scenarios on water erosion,interpreting and suggesting appropriate scenarios for implementation in the area. This studywas conducted with object of modeling and assessing soil erosion risk in KashidarWatershed with the application of IMAGE\LDM. Rainfall erosivity index, relief index, soilerosivity index and land cover index were four basic factors used in IMAGE\LDM. Soilerosion risk can be divided into six groups. Furthermore, the spatial distributioncharacteristics were also analyzed with the application of GIS in the view of elevation, landuse types. Among 8 scenarios for water erosion management, most appropriate ones thathave minimum proportion of high water erosion hazard classes, maximum gross marginand minimum establishment cost were chosen as best scenarios. پرونده مقاله

Information on different rangeland plants’ nutritive values during variousphonological stages is of importance for the rangelands management. This information helpsrangeland managers to choose proper grazing times to achieve higher animal performancewith no detrimental effects on the rangeland vegetations. Effects of various plant parts’phenological stages and vegetation types on reserve carbohydrates and forage qualityindicators were investigated during 2009 and 2010 in Sabzkooh rangelands at Charmahalprovince, Iran. Plant samples were collected based on a Completely Randomized Design(CRD) at 3 phonological stages (seedling, vegetative and flowering) with 5 replications. Thespecies included grasses (Secale montanum and Festuca ovina), forbs (Lotus corniculatus andSanguisorba minor) and shrubs (Kochia prosterata and Salsola rigida). Aerial plant parts’samples were harvested and oven-dried at 80oC for 24 hours; then, they were analyzed fordetermining the amounts of Water Soluble Carbohydrates (WSC), Crude Protein (CP), AcidDetergent Fiber (ADF), Dry Matter Digestibility (DMD) and Metabolic Energy (ME). Resultsshowed that forbs contained more WSC as compared to the other two vegetation types(grasses and shrubs). For other forage quality traits (CP, DMD, and ME), there weresignificant differences between species over two years and higher and lower forage qualitieswere obtained for forbs and shrub, respectively. For WSC, Sanguisorba minor and Lotuscorniculatus had the highest values while Secale montanum and Salsola rigida had the lowestWSC content. پرونده مقاله