Monitoring wetland as one of the important parts of the global ecosystem is necessary for conservational programs. But, usually, collecting in situ data is restricted in these areas because of their remote locations, vast area and dynamic conditions. Remote sensing provides a cost effective tool to investigate hydrological patterns and the seasonal trend of changes in wetlands. In this paper, Land-use/land-cover change during water inundation period of Hamun wetland was investigated in order to determine change trend during this period. Hamun wetland is an unsustainable ecosystem, and monitoring this wetland is essential for conservation goals. This trend is critical for decision makers in order to plan the conservational scheme in all unsustainable ecosystems. To reach this objective, the land-use/land-cover maps during inundation period of Hamun were produced using Landsat 8 time series images. The results of accuracy assessment showed the classification of water and vegetation have the highest accuracy (94% and 93%, respectively). And the accuracy of plants in the water classes was the lowest (water–veg?=?89.9%, veg–water 1?=?88.8%, veg–water 2?=?87.6%). This means the higher misclassification is in determining the vegetation in the water. Then, the changes in the land-cover classes in relation to wetland inundation were investigated. Results of land-use/land-cover change illustrate the regions that were suitable for water birds but lost their suitability when the wetland dried out. These areas are crucial for water bird’s conservation. Satellite data determined these areas with acceptable accuracy. 相似文献
Water Resources - Monitoring and reviewing vegetation changes are one of the important strategies for multi-year planning in an area regarding the environmental problems of the last decade. The... 相似文献
Mine planning is influenced by many sources of uncertainty. Significant sources of geological uncertainty in mine planning include uncertainty in layout of geological domains and uncertainty in metal grades. These two sources of uncertainty cannot be modeled separately because the distribution of the grade is controlled usually by geological domains. Two approaches exist for combining these two sources of uncertainty: the joint simulation approach and the cascade approach. In this paper, these two approaches were compared using a real case study. To this end, uncertainty in iron grade (quantitative variable) and ore zones (qualitative variable) was modeled using both approaches. There were some considerable differences in the results obtained by each approach, which confirm the importance of choosing the most appropriate approach with consideration of the dominate features of a deposit.
In this study, we calculate accurate absolute locations for nearly 3,000 shallow earthquakes (≤20 km depth) that occurred from 1996 to 2010 in the Central Alborz region of northern Iran using a non-linear probabilistic relocation algorithm on a local scale. We aim to produce a consistent dataset with a realistic assessment of location errors using probabilistic hypocenter probability density functions. Our results indicate significant improvement in hypocenter locations and far less scattering than in the routine earthquake catalog. According to our results, 816 earthquakes have horizontal uncertainties in the 0.5–3.0 km range, and 981 earthquakes are relocated with focal-depth errors less than 3.0 km, even with a suboptimal network geometry. Earthquake relocated are tightly clustered in the eastern Tehran region and are mainly associated with active faults in the study area (the Mosha and Garmsar faults). Strong historical earthquakes have occurred along the Mosha and Garmsar faults, and the relocated earthquakes along these faults show clear north-dipping structures and align along east–west lineations, consistent with the predominant trend of faults within the study region. After event relocation, all seismicity lies in the upper 20 km of the crust, and no deep seismicity (>20 km depth) has been observed. In many circumstances, the seismicity at depth does not correlate with surface faulting, suggesting that the faulting at depth does not directly offset overlying sediments. 相似文献
Finding a coupling model between a hydraulic parameter such as permeability and a mechanical parameter such as damage is the key element for several recent engineering problems. A review of the technical literature reveals that several mechanical constitutive laws exist which allow determining a damage tensor for a damageable porous material under loading. But the present work develops a method to deduce the permeability change due to the damage propagation. 相似文献
The objective of this paper is to estimate water seepage from the upper reservoir of Azad pumped storage power plant, based on combined geotechnical investigations and geostatistical methods. In order to select the optimum water tightening alternative, such as clay blanket, concrete cover (or concrete lining), geomembrane, asphalt cover, etc., estimation of water seepage from the reservoir is essential. Six exploratory boreholes were drilled at the pumped storage reservoir area and permeability tests (Lugeon tests) were conducted in all of them. Records at the boreholes have been considered as the main source for seepage calculations. Due to expansion of upper reservoir and a few boreholes, distribution of permeability and permeability changes in the reservoir area is not an indicator for reservoir. In this research using geostatistical method (Kriging), Lugeon values have been estimated for walls of reservoir. According to correspondence between estimated permeability distribution and geological conditions, the estimated values are acceptable. In addition, results show that in about 60% of tests, permeability is very high and potential of water seepage is very dangerous. Afterward, seepage was estimated for reservoir by using both analytical (Vedernikov method) and numerical method. Results from both methods are very close together and the average seepage is around 280,000 m3/day according to analytical and numerical results. Regarding results and general geological considerations, seepage is concentrated at fault zones. Results show that using appropriate permeability distribution, the estimated values of water seepage are acceptable and reliable. Due to the high amount of water seepage and economical value of water in this region, water tightening is necessary. 相似文献