Reza Bayat; Bagher Ghermez Cheshmeh; Hoseingholi Refahi
Abstract
The rate of soil erosion and sediment yield depends on different factors. Vegetation cover is more variable factor effecting occurrence of soil erosion in comparison to the other factors in a given watershed. The main purpose of this study was to investigate the role of canopy cover resulting from land ...
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The rate of soil erosion and sediment yield depends on different factors. Vegetation cover is more variable factor effecting occurrence of soil erosion in comparison to the other factors in a given watershed. The main purpose of this study was to investigate the role of canopy cover resulting from land management on sediment yield. Taleghan watershed was selected as a study area due to the availability of sufficient data. Necessary information was provided for MPSIAC model and was made in GIS environment and all needed calculations were done for preparing sediment yield map. The result of the comparison of the calculated and the estimated sediment yield indicated similarity of them (i.e. 98.3% similarity). For impact assessment of vegetation cover effect on sediment control, canopy cover was changed in a range of ±5 to 25% percent with 5% interval in both good and bad conditions. The effect of these changes was applied to bare soil percentage as well. The related thematic maps were prepared and sediment yield was determined. The result showed that sediment yield varied because of changing canopy cover. The increase and decrease of canopy cover by 25%, affected the sediment yield to change by -29.6% and 26.8% respectively.
Maral Khodadadi; Mohammad Sadegh Askari; Fereydoon Sarmadian; Hossein Gholi Refahi; Ali Akbar Norouzi; Ahmad Heidari; Hamid Reza Matinfar
Volume 1, Issue 2 , July 2009, , Pages 99-110
Abstract
Salinity is the major factors of soil degradation in semi arid and arid regions. The main aim of this study was to evaluate the capability of Landsat ETM+ data for soil Salinity mapping in the selected part of the Qazvin plain, an area of arid environment. In this study spectral classes carried out on ...
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Salinity is the major factors of soil degradation in semi arid and arid regions. The main aim of this study was to evaluate the capability of Landsat ETM+ data for soil Salinity mapping in the selected part of the Qazvin plain, an area of arid environment. In this study spectral classes carried out on remotely sensed data and with the help of field observation and soil analysis were regrouped to soil salinity classes to prepare soil salinity map.. Soil sampling was implemented using stratified random sampling method, depending on landscape complexity and homogeneity as well as on the representativeness of Landsat ETM+ data. Also in each soil map unit at least one profile was studied for subsoil salinity variations. Field samples taken by using augur and profiles were analyzed in laboratory for Na+ , Ca2+ , Mg2+ cations, as well as soil texture, ECe and pH. We have analyzed the effectiveness of additional data such as digital elevation model to improve the accuracy of classification. Also NDVI, SRVI, PVI, SAVI, SI, BI and NDSI indices, PCA and Tasseled cap were analyzed. Soil salinity map of each selected bands produced and with ground truth map crossed. The results indicated that combination of DEM with ETM+ bands has highest accuracy. This study addressed that thermal band of ETM+ can increase the classification accuracy which illustrated its effective role to classify the soil salinity. Tasseled cap and other indices had almost high accuracy among studied image processing techniques. The SI and BI indices had the highest correlation with EC and could distinguish the saline and non saline soils while the optimum index factor had overall low accuracy.
