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Volume 8, Issue 6 (1-2009)
Abstract
Majid Vazifedoust, Nima Fayaz, Shahab Araghinejad,
Volume 15, Issue 37 (9-2015)
Abstract
Variation of snow cover area (SCA) in small to large scale catchment can be studied using MODIS snow products on daily to montly time step since the year 2000. However, one of the major problems in applying the MODIS snow products is cloud obscuration which limits the utilization of these products. In the current study, variation of SCA was investigated in Karoun basin, western part of Iran, using MODIS 8-day snow cover product (MOD10A2). More over in order to overcome the cloud barrier in application of snow cover products, a simultaneous employment of the images from both MODIS optical sensor and AMSR-E microwave sensor was recommended. Meeting our target, the combination of MODIS and AMSR-E daily images was exercised to accomplish snow cover area in daily interval and afterwards, a comparison was made between the result and those which had been obtained by the sole utilization of either of them while the weather had been either cloudy and not been overcast. Validation of snow cover gained by combined images was additionally compared with the discharge of one of the catchments existing in Karoun basin. The results demonstrate that regardless of the fact that microwave data, featuring a coarse spatial resolution, can penetrate the cloud cover, on average, AMSR-E images approximately show 16% more snow cover in comparison to MODIS images. The results also illustrate that the correlation existing between snow cover rate of AMSR-E and MODIS images during cloudless days, the difference of average snow cover area decreases from 16% to 5%. Moreover, the upshot of validation by the exercise of daily discharge data indicates that by possessing a correlation coefficient of 0.66, the correlation of snow cover and discharge in combined images features a higher accuracy in comparison to MODIS images with a correlation coefficient of 0.55.
Asadolah Hejazi, Zahra Heidari,
Volume 23, Issue 68 (4-2023)
Abstract
In recent years, population growth and consequently the shortage of drinking water resources have increased the importance of studying the areas of caries Regarding the importance of the subject, in the present study, the evaluation and monitoring of the developed karstic areas and the potential of contamination of Cartesian resources in the Ravensar basin have been addressed In this study, 7factors were used to evaluate the factors of Karst development in Ravansar basin as well as two methods of OWA and ANP. The method of work is that after the necessary processing, using the OWA method and applying weights obtained through the ANP model, the zoning is done After designing the zoning map, using the satellite imagery of 2007 and2015, the development of human development areas in the developed karstic areas has been evaluated The results of this study indicate that most of the studied basin, especially in northern and western areas of the basin, are highly and relatively developed in the class, The calculation of the area of man-made areas suggests that in2007, about 2.6 km of occupied areas of man-made industrial zones have been occupied which, according to the growing population, increased to 3.8 km in2015, human-made areas have been extracted in developed artisanal areas
