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排序方式: 共有177条查询结果,搜索用时 156 毫秒
1.
Quantitative modeling of groundwater in Satluj River basin of Rupnagar district of Punjab using remote sensing and geographic information system 总被引:3,自引:1,他引:2
Chander Kumar Singh Satyanarayan Shashtri Amit Singh Saumitra Mukherjee 《Environmental Earth Sciences》2011,62(4):871-881
Water is a fluctuating resource making it difficult to measure in time and in space. To demonstrate the efficiency of the
geographic information system (GIS) for groundwater studies, information on the parameters controlling groundwater such as
lithology, geomorphology and lineament analysis were analyzed. LISS-III and Landsat satellite image of the area was used to
infer information on the geologic lineaments and geomorphology. To delineate linear features enhancement and direction, filtering
was performed on single bands of Landsat images. Thematic maps for geology, slope, geomorphology and lineament were prepared
and integrated in GIS by assigning the weights and ranking to various parameters controlling the occurrence of groundwater
to generate the groundwater potential map for the study area. The results indicate that the floodplain of river and its adjoining
areas have very good groundwater potential, whereas the steeply sloping area in the northern part having high relief and slope
possesses poor groundwater potential. 相似文献
2.
Since the early 1980s, the Dead Sea coast has undergone a near catastrophic land deterioration as a result of a rapid lake-level
drop. One conspicuous expression of this deterioration is the formation of sinkholes fields that puncture the coastal plains.
The evolution of sinkholes along nearly 70-km strip has brought to a halt the regional development in this well-known and
toured area and destroyed existing infrastructures. Great efforts are being invested in understanding the phenomena and in
development of monitoring techniques. We report in this paper the application of airborne laser scanning for characterization
of sinkholes. We demonstrate first the appropriateness of laser scanning for this task and its ability to provide detailed
3D information on this phenomenon. We describe then an autonomous means for their extraction over large regions and with high
level of accuracy. Extraction is followed by their detailed geometric characterization. Using this high-resolution data, we
show how sinkholes of 0.5 m radius and 25 cm depth can be detected from airborne platforms as well as the geomorphic features
surrounding them. These sinkhole measures account for their embryonic stage, allowing tracking them at an early phase of their
creation. 相似文献
3.
Shantanu Joshi Amit Prashant Arghya Deb Sudhir K. Jain 《Soil Dynamics and Earthquake Engineering》2011
Presently available simplified analytical methods and semi-empirical methods for the analysis of buried pipelines subjected to fault motion are suitable only for the strike-slip and the normal-slip type fault motions, and cannot be used for the reverse fault crossing case. A simple finite element model, which uses beam elements for the pipeline and discrete nonlinear springs for the soil, has been proposed to analyse buried pipeline subjected to reverse fault motion. The material nonlinearities associated with pipe-material and soil, and geometric nonlinearity associated with large deformations were incorporated in the analysis. Complex reverse fault motion was simulated using suitable constraints between pipe-nodes and ground ends of the soil spring. Results of the parametric study suggest that the pipeline's capacity to accommodate reverse fault offset can be increased significantly by choosing a near-parallel orientation in plan with respect to the fault line. Further improvement in the response of the pipeline is possible by adopting loose backfill, smooth and hard surface coating, and shallow burial depth in the fault crossing region. For normal or near normal orientations, pipeline is expected to fail due to beam buckling at very small fault offsets. 相似文献
4.
Amit Kumar Arvind Chandra Pandey Najmul Hoda A. T. Jeyaseelan 《Journal of the Indian Society of Remote Sensing》2011,39(2):213-224
The present study analyzes the built-up expansion of Ranchi urban agglomeration over a period of about 8 decades from 1927–2005.
Satellite images and topographical maps were used to evaluate land use dynamics during these periods. Built-up growth of 473.7%
during 1927–2005 was primarily at the expense of agricultural land along with reduction of natural water bodies reflects negative
impacts of built-up expansion, which increased many folds in recent decades. The built-up growth is also analyzed with reference
to population growth, land consumption rate and land transformation. The land loss due to increasing built-up growth of Ranchi
were compared with other capital regions and cities along with population increase to provide insight into the possible scenario
of built-up expansion in Ranchi urban area. 相似文献
5.
Praveen Gupta Amit Kumar Dubey Nandita Goswami Raghvendra Pratap Singh Prakash Chauhan 《Marine Geodesy》2015,38(3):614-625
In the absence of many gauging stations in the major and mighty river systems, there is a need for satellite-based observations to estimate temporal variations in the river water storage and associated water management. In this study, SARAL/AltiKa application for setting up hydraulic model (HEC-RAS) and river flow simulations over Tapi River India has been discussed. Waveform data of 40 Hz from Ka band altimeter has been used for water levels retrieval in the Tapi river. SARAL/AltiKa retrieved water levels were converted to discharge in the upstream location (track-926) using the rating curve available for the nearby gauging site and using linear spatial interpolation technique. Steady state simulations were done for various flow conditions in the upstream. Validation of river flow model was done in the downstream location (track-367) by comparing simulated and altimeter retrieved water levels (RMSE 0.67 m). Validated model was used to develop rating curve between water levels and simulated discharge for the downstream location which enables to monitor discharge variations from satellite platform in the absence of in situ observations. It has been demonstrated that SARAL/AltiKa data has potential for river flow monitoring and modeling which will feed for flood disaster forecasting, management and planning. 相似文献
6.
Glacierised basins are significant sources of sediments generated by glacial retreat. Estimation of suspended sediment transfer from glacierised basins is very important in reservoir planning for hydropower projects in Himalaya. The present study indicates that storage and release of sediment in proglacial streams may categorise the pattern of suspended sediment transfer from these basins. Assessment of suspended sediment concentration (SSC), suspended sediment load (SSL) and yield has been undertaken for Dunagiri Glacier basin located in Garhwal Himalaya (30o33'20”N, 79o53'36”E), and its results are compared with the Gangotri and Dokriani glaciers sharing close proximity. Out of the total drainage basin area, about 14.3 % of the area is glacierised. Data were collected for five ablation seasons (1984–1989, barring 1986). The mean daily SSCs for July, August and September were 333.9, 286.0 and 147.15 mg/l, respectively, indicating highest concentration of mean daily suspended sediment in July followed by August. SSL trends were estimated to be 93.0, 57.0 and 21.3 tonnes. About 59% of the total SSL of the melt period was transported during the months of August and September. Sediment yield for the study basin was computed to be 296.3 t km?2 yr ?1. It is observed that the cumulative proportion of SSC precedes the discharge throughout the melt season except in the year 1987. Release of SSL in terms of total load is less in the early part of melt season than in the later stage as compared to that of discharge. Diurnal variations in SSC reach their maximum at 2400 h, and therefore, SSC was found to be high during night (2000–0400 h). There was a good relationship between SSC and SSL with discharge for the ablation seasons (1988 and 1989). Mean monthly SSC and mean monthly SSL provide a good exponentional relationship with mean monthly temperature. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
7.
8.
Rivka Amit Ori Simhai Avner Ayalon Yehouda Enzel Ari Matmon Onn Crouvi Naomi Porat Eric McDonald 《Quaternary Science Reviews》2011,30(3-4):312-323
The time at which deserts established their current arid or hyper-arid conditions remains a fundamental question regarding the history of Earth. Cosmogenic isotope exposure ages of desert pavement and welded, calcic–gypsic–salic Reg soils that developed on relatively flat alluvial surfaces ~2 Ma ago in the Negev Desert indicate long geomorphic stability under extremely dry conditions. Over a short interval during their initial stage of development between 1–2 Ma, these cumulative soils are characterized by calcic soils reaching maximum stage III of carbonate morphology. This interval is the only period when calcic soil horizons formed on stable abandoned alluvial surfaces in the southern Negev Desert. Since ~1 Ma pedogenesis changed toward more arid soil environment and the formation of gypsic–salic soil horizons that were later followed by dust accumulation. The dichotomy of only moderately-developed calcic soil (stages II–III) during a relatively long time interval (105–106 years) indicates an arid environment that does not support continuous development but only occasional calcic soil formation. The very low δ18O and relatively high δ13C values of these early pedogenic carbonates support soil formation under arid climatic conditions. Such an environment was probably characterized by rare and relatively longer duration rainstorms which occasionally allowed deeper infiltration of rainwater and longer retention of soil moisture. This, in turn enabled the growth of sparse vegetation that enhanced deposition of pedogenic carbonate. At ~1 Ma these rare events of slightly wetter conditions ceased and less atmospheric moisture reached the southern Negev Desert leading to deposition of soluble salts and dust deposited in the soils. The combination of long-term hyperaridity, scarcity of vegetation and lack of bioturbation, salts cementation, dust accumulation and tight desert pavement cover, has protected the surfaces from erosion forming one of the most remarkably stable landscapes on Earth, a landscape that essentially has not eroded, but accumulated salt and dust for more than 106 yr. 相似文献
9.
10.
Climate change is likely to adversely affect many countries throughout the world, but the responses of different countries to this threat vary widely. Attempts to explain the differences in countries’ mitigative policies have been largely deficient. This study seeks to assess the degree to which vulnerability may improve the level of explanation of adopted mitigation policies, studying over 90 countries between 1990 and 2011. Vulnerability is defined to be comprised of two basic factors: impacts (expected damages due to climate change) and adaptive capacity (the ability to adjust to these damages). As there may be a gap between declared and implemented policies, these components of mitigation policy are examined separately. In addition, other variables which mediate between these ‘extreme ends’ of mitigation policies are tested.The effect of vulnerability on climate change mitigation policies is examined by multiple regressions, incorporating a wide range of control variables. The results indicate that climate impacts do not affect mitigation policies. Adaptive capacity has a positive effect on the level of declared policy, but this effect becomes insignificant once implemented policy is examined. However, other tests suggest a possible transition from declarations to actions by high adaptive capacity countries. This finding suggests that high adaptive capacity countries do not view mitigation and adaptation as substitutes. Further analyses indicate that the insignificancy of impacts is caused by the uncertainty in their assessment. 相似文献