Shahram Yousefi khanghah; Damoon Razmjuee; Somayyie Dehdari; Nasim Arman
Abstract
To better managing of rangeland the vegetation map is one of major factors, because plant communities is planning units of rangeland management and vegetation map shows the current status of plant communities. This research was conducted to produce vegetation type's map using Landsat 8 image classification ...
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To better managing of rangeland the vegetation map is one of major factors, because plant communities is planning units of rangeland management and vegetation map shows the current status of plant communities. This research was conducted to produce vegetation type's map using Landsat 8 image classification in Behbahan, Khuzestan province. Rangelands of the study region is warm semi steppe and winter grazing. Geometric correction of satellite image was performed by ground control points with an error of less than one pixel. Atmospheric correction of existing data using the dark object subtraction was done. Field visits for vegetation type's border controlling and sampling training area was conducted. Eight supervised classification algorithms included Parallelepiped (PP), Minimum Distance to mean (MD), Mahalanobis distance (MAH), Maximum Likelihood (ML), Neural Net (NN) and Support Vector Machine (SVM) was performed. The results showed that ML algorithm has the highest overall accuracy (87.5 percent) and kappa (0.867) and PP algorithm has the lowest overall accuracy (67.1 percent) and kappa (0.571). It is suggested that, along with digital methods of classification of satellite images, visual interpretation should be used to clarify the boundary of the obtained vegetation types map.
ayoub moradi; Ali Nakafinejad; Majid Ownagh; Choghi Bairam Komaki; mehrangiz foladi mansouri
Abstract
Indiscriminate land utilization methods, forest and rangeland degradation, land abandonment and development of residential areas contribute to the changes in flow intensity, erosion rate and sedimentation. Therefore, having knowledge on the effect of land use changes on discharge flow and sediment yield ...
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Indiscriminate land utilization methods, forest and rangeland degradation, land abandonment and development of residential areas contribute to the changes in flow intensity, erosion rate and sedimentation. Therefore, having knowledge on the effect of land use changes on discharge flow and sediment yield has been found necessary. The present research aims at investigating the effects of these factors by means of the semi-distributed Soil and Water Assessment Tool (SWAT) in Galikesh watershed, Golestan province (as a tributary of the River Gorganroud), in an area covering approximately 39000 hectares. This model was used in a 27-year period for simulation, calibration, validation and optimization of the parameters affecting flow and sediment yield. Land-use maps were prepared form the Landsat imageries dated 1987, 2000 and 2013. The SUFI2 model was used for model calibration and validation. Nash-Sutcliffe (NS) index was used as the objective function during model calibration (1990-2007) for the simulation of discharge and suspended load, which resulted in 0.63 and 0.61 that could be interpreted as satisfactory compared to the standards set in previous research. To evaluate the effect of land use changes on runoff and sediment yield, all model inputs, other than land use, were assumed constant. The results demonstrated that land use changes since 1987 to 2013 have led to an increase in annual runoff height by 1.40 mm and annual sediment concentration by 2 t.ha-1.
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
