排序方式： 共有31条查询结果，搜索用时 296 毫秒
1.
Mukesh Gupta Kamini Kanta Mohanty Devendra Kumar Ramanuj Banerjee 《Environmental Earth Sciences》2014,71(6):2875-2883
This paper investigates surface elevation changes that occurred during 1996–2004 in the Jharia coalfield through the digital elevation model (DEM) generated using synthetic aperture radar interferometry (InSAR) using ERS-1/2 (European Remote Sensing Satellite) tandem and RADARSAT-1 data. The comparison of elevation values derived from the InSAR DEM and topographic height data shows a bias of 23.08 m with root-mean-square error of ±2.31 m (5.8 %). The accuracy of the DEM was investigated by comparing the elevation profiles with the digitized elevation contour data at four different locations. The profile comparison shows a mean bias of 22.68 m. Local topography shows changes in elevation up to ±40.00 m due to mining activities on the 8-year time period. The results of InSAR-derived heights and topographic heights were comparable and well-matched except at a few locations where topographic data were unavailable. DEM generated using InSAR due to its high spatial details is ideal for the detection and estimation of surface elevation changes in mining areas. 相似文献
2.
D. A. Robinson A. Binley N. Crook F. D. Day‐Lewis T. P. A. Ferré V. J. S. Grauch R. Knight M. Knoll V. Lakshmi R. Miller J. Nyquist L. Pellerin K. Singha L. Slater 《水文研究》2008,22(18):3604-3635
We want to develop a dialogue between geophysicists and hydrologists interested in synergistically advancing process based watershed research. We identify recent advances in geophysical instrumentation, and provide a vision for the use of electrical and magnetic geophysical instrumentation in watershed scale hydrology. The focus of the paper is to identify instrumentation that could significantly advance this vision for geophysics and hydrology during the next 3–5 years. We acknowledge that this is one of a number of possible ways forward and seek only to offer a relatively narrow and achievable vision. The vision focuses on the measurement of geological structure and identification of flow paths using electrical and magnetic methods. The paper identifies instruments, provides examples of their use, and describes how synergy between measurement and modelling could be achieved. Of specific interest are the airborne systems that can cover large areas and are appropriate for watershed studies. Although airborne geophysics has been around for some time, only in the last few years have systems designed exclusively for hydrological applications begun to emerge. These systems, such as airborne electromagnetic (EM) and transient electromagnetic (TEM), could revolutionize hydrogeological interpretations. Our vision centers on developing nested and cross scale electrical and magnetic measurements that can be used to construct a three‐dimensional (3D) electrical or magnetic model of the subsurface in watersheds. The methodological framework assumes a ‘top down’ approach using airborne methods to identify the large scale, dominant architecture of the subsurface. We recognize that the integration of geophysical measurement methods, and data, into watershed process characterization and modelling can only be achieved through dialogue. Especially, through the development of partnerships between geophysicists and hydrologists, partnerships that explore how the application of geophysics can answer critical hydrological science questions, and conversely provide an understanding of the limitations of geophysical measurements and interpretation. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
3.
H.F. Malenda N.A. Sutfin G. Guryan S. Stauffer J.C. Rowland K.H. Williams K. Singha 《地球表面变化过程与地形》2019,44(9):1799-1815
Stratigraphy is a fundamental component of floodplain heterogeneity and hydraulic conductivity and connectivity of alluvial aquifers, which affect hydrologic processes such as groundwater flow and hyporheic exchange. Watershed-scale hydrological models commonly simplify the sedimentology and stratigraphy of floodplains, neglecting natural floodplain heterogeneity and anisotropy. This study, conducted in the upper reach of the East River in the East River Basin, Colorado, USA, combines point-, meander-, and floodplain-scale data to determine key features of alluvial aquifers important for estimating hydrologic processes. We compare stratigraphy of two meanders with disparate geometries to explore floodplain heterogeneity and connectivity controls on flow and transport. Meander shape, orientation, and internal stratigraphy affected residence time estimates of laterally exchanged hyporheic water. Although the two meanders share a sediment source, vegetation, and climate, their divergent river migration histories resulted in contrasting meander hydrofacies. In turn, the extent and orientation of these elements controlled the effective hydraulic conductivity and, ultimately, estimates of groundwater transport and hyporheic residence times. Additionally, the meanders’ orientation relative to the valley gradient impacted the hydraulic gradient across the meanders—a key control of groundwater velocity. Lastly, we combine our field data with remotely sensed data and introduce a potential approach to estimate key hydrostratigraphic packages across floodplains. Prospective applications include contaminant transport studies, hyporheic models, and watershed models. © 2019 John Wiley & Sons, Ltd. 相似文献
4.
5.
Electrical geophysical methods, including electrical resistivity, time‐domain induced polarization, and complex resistivity, have become commonly used to image the near subsurface. Here, we outline their utility for time‐lapse imaging of hydrological, geochemical, and biogeochemical processes, focusing on new instrumentation, processing, and analysis techniques specific to monitoring. We review data collection procedures, parameters measured, and petrophysical relationships and then outline the state of the science with respect to inversion methodologies, including coupled inversion. We conclude by highlighting recent research focused on innovative applications of time‐lapse imaging in hydrology, biology, ecology, and geochemistry, among other areas of interest. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
6.
The flow about a circular cylinder placed centrally inside a channel is studied numerically with an unstructured collocated grid finite volume method based on the primitive variable formulation. The distance between the channel walls is allowed to vary to change the blockage ratio. Simulations are carried out over a range of Reynolds numbers that are consistent with the two-dimensional assumption. The study confirms that transition to vortex shedding regime is delayed when the channel walls are close to the cylinder because of the interaction between the vortices from the channel wall and cylinder wake. In the unsteady vortex shedding regime, the wake pattern is opposite to the classic Karman street in respect of the positions of the shed vortices. The cylinder drag coefficient and Strouhal number are considerably increased at smaller gaps while the root-mean-squared lift coefficient is significantly decreased. Several important flow parameters are correlated with the input parameters, namely Reynolds number and blockage ratio. 相似文献
7.
Grana Dario Parsekian Andrew D. Flinchum Brady A. Callahan Russell P. Smeltz Natalie Y. Li Ang Hayes Jorden L. Carr Brad J. Singha Kamini Riebe Clifford S. Holbrook W. Steven 《Mathematical Geosciences》2022,54(8):1315-1345
Mathematical Geosciences - Understanding the subsurface structure and function in the near-surface groundwater system, including fluid flow, geomechanical, and weathering processes, requires... 相似文献
8.
This article provides a counter-narrative to the dominant discourse of marginalization and criminalization of Ghana’s illegal gold miners (galamsey) by focusing on the contested mercury debate. We first examine the complex and multifaceted policy problem that underlies the current conflictual aspects in the small-scale mining sector, arguing that mercury use and contamination are key elements in the antigalamsey rhetoric. Second, we describe an interdisciplinary pilot study on human and environmental health that involved health personnel and illegal miners from two sites. Through participatory ranking and mapping activities, we explored participants’ understanding of mercury and other life hazards as well as causes and consequences of mercury contamination. We used chemical indicator strips to sample contaminated areas in collaboration with the miners. By drawing upon novel concepts from the environmental justice and ecohealth literature, we propose a political ecology of human and environmental health that advocates recognition of galamsey operators and their participation in learning opportunities as a first step out of the current impasse in the Ghanaian small-scale mining sector. 相似文献
9.
This study integrated spatially distributed field observations and soil thermal models to constrain the impact of frozen ground on snowmelt partitioning and streamflow generation in an alpine catchment within the Niwot Ridge Long-Term Ecological Research site, Colorado, USA. The study area was comprised of two contrasting hillslopes with notable differences in topography, snow depth and plant community composition. Time-lapse electrical resistivity surveys and soil thermal models enabled extension of discrete soil moisture and temperature measurements to incorporate landscape variability at scales and depths not possible with point measurements alone. Specifically, heterogenous snowpack thickness (~0–4 m) and soil volumetric water content between hillslopes (~0.1–0.45) strongly influenced the depths of seasonal frost, and the antecedent soil moisture available to form pore ice prior to freezing. Variable frost depths and antecedent soil moisture conditions were expected to create a patchwork of differing snowmelt infiltration rates and flowpaths. However, spikes in soil temperature and volumetric water content, as well as decreases in subsurface electrical resistivity revealed snowmelt infiltration across both hillslopes that coincided with initial decreases in snow water equivalent and early increases in streamflow. Soil temperature, soil moisture and electrical resistivity data from both wet and dry hillslopes showed that initial increases in streamflow occurred prior to deep soil water flux. Temporal lags between snowmelt infiltration and deeper percolation suggested that the lateral movement of water through the unsaturated zone was an important driver of early streamflow generation. These findings provide the type of process-based information needed to bridge gaps in scale and populate physically based cryohydrologic models to investigate subsurface hydrology and biogeochemical transport in soils that freeze seasonally. 相似文献
10.
Pallabee Choudhury J. K. Catherine V. K. Gahalaut Sumer Chopra Rakesh Dumka Ketan Singha Roy 《Natural Hazards》2013,65(2):1109-1118
We report the results of GPS measurements of post-seismic deformation due to the 2001 Bhuj earthquake in the Kachchh region, western India. The estimated horizontal velocity vectors in ITRF05 are in the range of 48?C49?mm/year in N46?C50°E. The observed velocity at the Gandhinagar permanent site, a far off site from the earthquake source region and probably unaffected by the post-seismic deformation, is 49?±?1?mm/year in N47°E, which is consistent with the predicted motion of Indian plate at Gandhinagar. At other sites in the source region, transient post-seismic deformation is found to be low; it attenuated rapidly within 3?C4?years of the earthquake and is much low now. Our results support the idea that mantle rheology is weak in the region. 相似文献