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Groundwater vulnerability assessment in shallow aquifer of Kathmandu Valley using GIS-based DRASTIC model 总被引:1,自引:0,他引:1
Dhundi Raj Pathak Akira Hiratsuka Isao Awata Luonan Chen 《Environmental Geology》2009,57(7):1569-1578
In this paper, groundwater aquifer vulnerability map has been developed by incorporating the major geological and hydro-geological
factors that affect and control the groundwater contamination using GIS based DRASTIC model. This work demonstrates the potential
of GIS to derive a map by overlying various spatially referenced digital data layers that portrays cumulative aquifer sensitivity
ratings across the Kathmandu Valley, Nepal, providing a relative indication of groundwater vulnerability to contamination.
In fact, the groundwater is the major natural resources in Kathmandu for drinking purpose. The decline in groundwater levels
due to the over exploitation and thus extracted water from shallow aquifer has been contaminated by the infiltration of pollutants
from polluted river and land surface is continuous and serious. As the demand for water for human and industrial use has escalated
and at the same time, the engineering and environmental costs are much higher for new water supplies than maintaining the
existing sources already in use. Management of groundwater source and protecting its quality is therefore essential to increase
efficient use of existing water supplies. Aquifer vulnerability maps developed in this study are valuable tools for environmental
planning and predictive groundwater management. Further, a sensitivity analysis has been performed to evaluate the influence
of single parameters on aquifer vulnerability assessment such that some subjectivity can be reduced to some extent and then
new weights have been computed for each DRASTIC parameters. 相似文献
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The authors describe the characteristics, problems and treatment of a seawater pumped-storage power plant which is the first high headtype power plant in the world. The authors propose a general geologic investigation program using boreholes for underground projects. The effectiveness of the investigations conducted by EPDC are evaluated before construction of the vertical shaft of the seawater pumped-storage power plant in Okinawa island, Japan. In the investigation stage of the project, no adit was excavated and all geological and geotechnical information about the underground facilities were obtained efficiently from exploration by drill holes including logging and geotechnical tests such as observation by borehole scanner, prospecting by VSP, initial stress measurement by sleeve fracturing method and JFT test. 相似文献
3.
D. R. Pathak H. N. Gharti A. B. Singh A. Hiratsuka 《Geotechnical and Geological Engineering》2008,26(2):113-120
Accurate and efficient simulation of the slope stability, certainly gives the reliable approach for the hazard preparedness.
However, inherent difficulties associated with the slope failure make the situation very difficult. First, the computation
of fracture path based on the strict mathematical formalism is cumbersome especially for the progressive failure phenomenon.
Second, due to the lack of reliable knowledge on material properties, stochastic simulation is necessary. Stochastic modeling
together with the progressive failure phenomenon is apparently difficult task. In this paper, heterogeneous slope is simulated
considering the progressive failure phenomenon using the modified finite element method introducing the fracture along the
edge of the meshes thus incorporating the time evolution of the fracture surface. This is achieved by restructuring the tessellation
in every fracture stage. Unlike remeshing this technique only increases the number of total nodes while number of meshes remaining
same, which is simple and natural. Further, in this research, effect of uncertainty in the material properties upon the uncertainty
in the response of soil slope has been evaluated, hence giving the reliable probabilistic estimation of the factor of safety,
failure surface and deformation of the slope. Thus the simulation based on the more reliable understanding of the material
properties and the efficient numerical procedure for the progressive failure phenomenon can give the reliable result of the
simulation for the heterogeneous soil slope thus enabling the more accurate way for hazard preparedness. 相似文献
4.
Masumi Yamamuro Jun-Ichi Hiratsuka Yu Ishitobi Shinya Hosokawa Yoshiyuki Nakamura 《Journal of Oceanography》2006,62(4):551-558
Zostera marina L. was intensively harvested until the early 1950s in Lake Nakaumi, a eutrophic estuarine lagoon. We have estimated the amount
of nitrogen (N) and phosphorus (P) removed from the lagoon through Z. marina harvesting. Lake Nakaumi lies in Tottori and Shimane prefectures, and the annual harvest of Z. marina in the late 1940s in Tottori was recorded as at least 56,250 t wet weight. The nutrient content of 56,250 t of Z. marina was calculated to be 61.9 t of N and 12.9 t of P, which is equivalent to 5.3% and 11%, respectively, of present annual nutrient
loads to the lake. The nutrients formerly used by Z. marina were likely used by phytoplankton after the Z. marina started to decline in the mid-1950s at Lake Nakaumi. This shift in the chief primary producer, from benthic macrophytes to
phytoplankton, caused a subsequent shift in secondary producers. Benthic fish and crustacean populations decreased and the
non-commercial filter-feeding bivalve, Musculus senhausia, increased in Lake Nakaumi after the decline of seagrass beds. This affected the local economy, inducing not only eutrophication
but also the collapse of local fisheries. On the other hand, at adjacent Lake Shinji, loss of submerged aquatic vegetation
induced an increase of the commercial filter-feeding bivalve, Corbicula japonica, which doubled the fishery yield in the lake. 相似文献
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