Nahid Moshtagh; Reza Jafari; Saied Soltani; Nafiseh Ramezani
Abstract
Land surface temperature (LST) is an essential parameter in ecological, hydrologic, climatic, and related studies. The objective of this study was to evaluate the performance of Artis and Sobrino algorithms for retrieving LST from 2009 Landsat TM thermal infrared band in Damaneh region of Isfahan province. ...
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Land surface temperature (LST) is an essential parameter in ecological, hydrologic, climatic, and related studies. The objective of this study was to evaluate the performance of Artis and Sobrino algorithms for retrieving LST from 2009 Landsat TM thermal infrared band in Damaneh region of Isfahan province. The accuracy of LST extracted from geometrically corrected image was then assessed against field-based LST data recorded at 10 meteorological stations using linear regression analysis. The results showed that both algorithms were able to map LST spatial distribution in the region and they were significantly correlated (R>0.97), but the Artis algorithm performed slightly better than Sobrino one. This algorithm explained up to 72% of the variation in the field measurements of LST. According to this algorithm, bare lands and highly vegetated agricultural and rangeland areas had the highest (328k0) and lowest LST (291k0) in the region, respectively. As the results indicated here the decrease in vegetation cover corresponds with increase in temperature values, therefore, remotely-sensed LST information with their extensive coverage can have a key role in ecosystem management.
vahid chitsaz; Aliakbar Nazari Samani; Saeed Soltani; sadat feiznia
Abstract
Sediment and erosion are two natural phenomena in watersheds. Due to irregular recording and sampling difficulties, daily data are not available for sediment records. Therefore, decision makers and researchers have to apply interpolating methods to estimated sediment yields. In this study, 30 watershed ...
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Sediment and erosion are two natural phenomena in watersheds. Due to irregular recording and sampling difficulties, daily data are not available for sediment records. Therefore, decision makers and researchers have to apply interpolating methods to estimated sediment yields. In this study, 30 watershed characteristics including physiography, geomorphology, vegetation, climate conditions in 69 watersheds located in the Karoon and Karkheh basins were used to statistical analysis. Based on the principle component analysis, eight characteristics including area, perimeter, river length, relief, mean of elevation at 85% upstream and 15% point of longest flow path and the number of landslide events were selected. Then using Cluster Analysis, six homogenous regions were identified and multiple regression models were applied. Due to constriction of large dames on the studied watersheds, access to the reliable data is a challenges for sediment yield analysis. Based on the sediment-precipitation double-mass curves 29 out of 35 stations were influenced by upstream dam. Results indicated that the effects of large reservoir dams can influence the downstream sediment yield along 98 Km of river length. The results show that in each group a particular combination of variables influence the sediment yields of the watersheds. According to the validation indices (NS and R2) the obtained models have the high performance (R2 = 0.71 and NS=0.72). In general, the physiographic characteristics of the watershed such as length, area, main flow path and relief are more important than other climatic, vegetation and geological factors. The total explain variance by the mentioned variables is 87.3%.
Sadat Feiznia; Rabbaneh Roughani; Saeed Soltani
Abstract
Particulate matters (PM) has a negative effect on human health especially in industrial and urban areas due to their great potential of reaching the furthest parts of human lungs. Therefore, it is essential to conduct continuous monitoring of PM in order to assess their spatial and temporal trend in ...
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Particulate matters (PM) has a negative effect on human health especially in industrial and urban areas due to their great potential of reaching the furthest parts of human lungs. Therefore, it is essential to conduct continuous monitoring of PM in order to assess their spatial and temporal trend in ambient air. This study aimed to assess the spatial and seasonal variations of PM2.5, PM10, total suspended particles (TSP) concentration and evaluating their correlations with meteorological parameters in surrounding regions of Isfahan city, Iran. PM2.5, PM10 and TSP concentrations (24-hours) were measured by gravimetry method with low volume air sampler for one-year period (July 2015-July 2016) at three stations located on western, eastern and southern part of Isfahan. The overall daily mean concentrations of PM2.5, PM10 and TSP were 73, 101 and 134 µg/m3 in east; 50, 86 and 103 µgr/m3 in the south; and 23, 45 and 53 µgr/m3 in west stations, respectively. This study identified that PM2.5 concentrations were above the US Environmental Protection Agency (EPA) guideline at all stations. The daily mean concentration of PM2.5, PM10, and TSP showed a negative correlation with humidity, while a positive correlation was observed between daily average temperature and all pollutant concentrations. A weak positive correlation was observed in case of wind speed. This study found that the meteorological condition has the highest impact on fluctuating PM2.5 concentration over the monitoring period. Pollution rose analysis indicated that westerly and north-westerly wind increased PM2.5 concentration at all sites.
shahin mohammadi; Hamidreza karimzadeh; saeid pourmanafi; Saeed Soltani
Abstract
Soil is one of the most important production factors that has a great impact on human socio-economic life and the process of soil erosion is one of the environmental issues that threatens the environment, natural resources and agriculture. Spatial and temporal information of the soil loss and soil erosion ...
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Soil is one of the most important production factors that has a great impact on human socio-economic life and the process of soil erosion is one of the environmental issues that threatens the environment, natural resources and agriculture. Spatial and temporal information of the soil loss and soil erosion on the land has a significant role in influencing management practices, soil erosion control and watershed management. Therefore, this study was conducted with the aim of studying the spatial and temporal estimation of soil erosion during 1994, 1999, 2008 and 2015 in the sub-basin of Menderjan with an area of 21100 hectares located in the west of Isfahan province using RS and GIS. In the present study, while conducting field studies, various data and information including the digital elevation model, satellite images, soil, and statistics on rain gauge stations were used as a research tool. Estimation of soil erosion in the study area was carried out using RUSLE Model. The results of this study showed that the amount of soil erosion in 1994, 1999, 2008 and 2015 was 0.001 to 233, 0.001 to 297, 0.001 to 231 and 0.001 to 215 "ton/”ha.year”. The topography factor in the study area with the correlation coefficient of 80% had the greatest effect on the estimation of annual soil erosion by the RUSLE model. This research corroborate the effectiveness of modern GIS technologies and remote sensing in temporal simulation for quantitative, exact, and point-to-point estimates in the whole area to obtain soil erosion content.
Mohsen Sarshad Ghahfarrokhi; Seyed Alireza Mousavi; Saeed Soltani; Saeed Pourmanafi
Abstract
Natural resources are valuable capitals for all nations. Rangelands as the most extensive natural ecosystems in Iran provide numerous services, including fodder production and red meat supply, soil conservation and water regulation. Although uncontrolled exploitation of these resources has imposed much ...
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Natural resources are valuable capitals for all nations. Rangelands as the most extensive natural ecosystems in Iran provide numerous services, including fodder production and red meat supply, soil conservation and water regulation. Although uncontrolled exploitation of these resources has imposed much pressure and caused many losses within the ecosystems. Impacts of overutilization of nomadic livestock on Semirom rangelands from runoff control perspective has been the core objective of this study. Considering the utilization conditions, vegetation cover was measured within the vegetation types before and after livestock grazing during 2013 grazing season. Curve Number method was selected to evaluate the runoffs originating from rainfalls with different return periods before and after livestock grazing and the difference was considered as the grazing impact. This externality was valuated using replacement cost method. Results showed that utilization pressure is extremely more than grazing capacity which has distorted water regulation function of the rangelands, e.g. it has increased the runoff volume from a rainfall with 2-year return period from 1660884 to 2600487 m3. In other words, it has diminished the potential of rangelands in controlling water runoffs. Economically speaking, the external damage to water regulation function of rangelands was calculated at the rate of 25391 million Rial/year. This information on the externalities of nomadic livestock will provide the useful basis for economic appraisal of the utilization process and adjustment or rectification of economic activities which entail social costs on their way towards private profits.
Fatemeh Hadian; Reza Jafari; Hossein Bashari; Saeed Soltani
Abstract
Because soil moisture condition affects vegetation changes hence, monitoring of drought and vegetation changes are among valuable management tools in these ecosystems. Nowadays, satellite images are used as a low-cost and fast method for vegetation study in different scales. Vegetation change is assessed ...
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Because soil moisture condition affects vegetation changes hence, monitoring of drought and vegetation changes are among valuable management tools in these ecosystems. Nowadays, satellite images are used as a low-cost and fast method for vegetation study in different scales. Vegetation change is assessed using vegetation spectral characteristics. This study aimed to analyze and monitor the vegetation cover changes in 4 rangelands and one forest type site in south of Isfahan and southeastern of Chaharmahal and Bakhtiary province during 1997-2009 ّField sampling were used for measuring the percentage of canopy cover in all vegetation types using step-point method in radial direction (6000 points per vegetation type). Regression analysis technique was used to ensure if vegetation cover can be measured properly using a Landsat images from 2009. Then NDVI indices were derived from 12 Landsat images between 1997 to 2009 (all images were taken from 22th of May to 5th of Jun each year) to monitor vegetation changes. According to results, there was significant correlation between NDVI indices and canopy cover in all vegetation types. Evaluating the canopy cover changes indicated that the precipitation had various effects on different vegetation types based on their plant form and ecological condition. T
Leila Bakhshandehmehr; Saeid Soltani; Adel Sepehr
Abstract
According to the UNCCD definition, “Desertification” is land degradation in arid, semi-aridand dry sub-humid areas resulting from various factors, including climatic variations andhuman activities. It has been recognized as a major economic, social, and environmentalproblem in many countries ...
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According to the UNCCD definition, “Desertification” is land degradation in arid, semi-aridand dry sub-humid areas resulting from various factors, including climatic variations andhuman activities. It has been recognized as a major economic, social, and environmentalproblem in many countries of the world. The MEDALUS methodology is a practical approachto assess the present status of desertification and evaluate the desertification risk. In this study,a regional model has been developed to desertification assessment and mapping in the SEGZIplain (Eastern Isfahan) based on the MEDALUS methodology. At first step, seven criteriaincluding climate, soil, vegetation cover, ground water, water erosion, wind erosion and policyand management were recognized according to the local condition. Each criterion includedseveral indicators accounting as factor quality determination. These indicators quantified basedon their influences on desertification process. For each indicator a score ranging from 100 to200 were assigned and desertification weighting was finally extracted. The weight of eachfactor and the weight of desertification status was calculated by geometric mean. Ultimately,desertification status was classified in four levels including low, moderate, severe and highsevere. At last the maps of these results was produced by geographical information system.Results showed that 2% of the study area was classified as moderate class, 35% classified assevere and 63% involved high severe class. Climate, policy and management are the mostimportant factors have led to desertification process in this region.
S. Saadati; S. Soltani; S. eslamian
Volume 62, Issue 2 , October 2009, , Pages 257-270
Abstract
Drought is universal phenomenon that can occur everywhere and can cause harmful impacts on human beings and natural ecosystems. Thus, it is very important to study drought character ristics part of for water resources management. In this study, the Standardized Precipitation Index (SPI) is used for drought ...
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Drought is universal phenomenon that can occur everywhere and can cause harmful impacts on human beings and natural ecosystems. Thus, it is very important to study drought character ristics part of for water resources management. In this study, the Standardized Precipitation Index (SPI) is used for drought frequency analysis in Isfahan province. After collecting the precipitation data in the province stations and removing those stations with incomplete data, frequency analysis of drought was carried out by 12-month SPI time series scale end of March. Then, the maps of drought return periods were prepared and analyzed by SURFER software. These maps show that moderate and severe drought with long return period mainly in the west the province and extreme drought events in the east and north east of the province with short return periods which indicate high sensitivity and the necessity for suitable managing programs to deal with the problem of drought.
