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11.
Tsering Karma Shrestha Manish Shakya Kiran Bajracharya Birendra Matin Mir Lozano Jorge Luis Sanchez Nelson Jim Wangchuk Tandin Parajuli Binod Bhuyan Md Arifuzzaman 《Natural Hazards》2022,110(3):1821-1845
Natural Hazards - The Hindu Kush Himalayan region is extremely susceptible to periodic monsoon floods. Early warning systems with the ability to predict floods in advance can benefit tens of... 相似文献
12.
13.
Omkar M. Shrestha Achyuta Koirala Jörg Hanisch Klaus Busch Martin Kerntke Stefan Jäger 《GeoJournal》1999,49(2):165-172
An engineering and environmental geological map of the Kathmandu Valley in Nepal has been elaborated within a project of German-Nepalese
cooperation. In the Kathmandu Valley, the major geo-environmental problems arise from haphazard exploitation of geologic resources,
local landslide zones, severe problems of garbage disposal, river flooding and a dramatic river pollution. The map was prepared
by the use of GIS techniques. It contains all basic geological and environmental data, as geotechnical risk zones (landslide-prone
areas or those of poor foundation conditions), areas for preferable extraction of construction material and those not to be
allowed to be exploited, areas of immediate need of reforestation in order to prevent landslide or badland development, groundwater
protection zones, and suitable garbage disposal sites.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
14.
Finu Shrestha Xiao Gao Narendra Raj Khanal Sudan Bikash Maharjan Rajendra Bahadur Shrestha Li-zong Wu Pradeep Kumar Mool Samjwal Ratna Bajracharya 《山地科学学报》2017,14(10):1969-1984
Changes in glacial lakes and the consequences of these changes, particularly on the development of water resources and management of glacial lake outburst flood(GLOF) risk, has become one of the challenges in the sustainable development of high mountain areas in the context of global warming. This paper presents the findings of a study on the distribution of, and area changes in, glacial lakes in the Koshi basin in the central Himalayas.Data on the number of glacial lakes and their area was generated for the years 1977, 1990, 2000, and 2010 using Landsat satellite images. According to the glacial lake inventory in 2010, there were a total of 2168 glacial lakes with a total area of 127.61 km~2 and average size of 0.06 km~2 in the Koshi basin. Of these,47% were moraine dammed lakes, 34.8% bedrock dammed lakes and 17.7% ice dammed lakes. The number of glacial lakes increased consistently over the study period from 1160 in 1977 to 2168 in 2010, an overall growth rate of 86.9%. The area of glacial lakes also increased from 94.44 km~2 in 1977 to 127.61 km~2 in 2010, a growth rate of 35.1%. A large number of glacial lakes in the inventory are small in size(≤ 0.1km~2). End moraine dammed lakes with area greater than 0.1 km~2 were selected to analyze the change characteristics of glacial lakes in the basin. The results show that, in 2010, there were 129 lakes greater than 0.1 km~2 in area; these lakes had a total area of 42.92km~2 in 1997, increasing to 63.28 km~2 in 2010. The distribution of lakes on the north side of the Himalayas(in China) was three times higher than on the south side of the Himalayas(in Nepal).Comparing the mean growth rate in area for the 33 year study period(1977-2010), the growth rate on the north side was found to be a little slower than that on the south side. A total of 42 glacial lakes with an area greater than 0.2 km~2 are rapidly growing between 1977 and 2010 in the Koshi basin, which need to be paid more attention to monitoring in the future and to identify how critical they are in terms of GLOF. 相似文献
15.
Badri Bhakta Shrestha Hajime Nakagawa Kenji Kawaike Yasuyuki Baba Hao Zhang 《Natural Hazards》2012,61(2):577-602
Experience shows that debris flows containing large woody debris (driftwood) can be more damaging than debris flows without
driftwood. In this study, the deposition process of debris flows carrying driftwood was investigated using numerical simulations
and flume experiments. Debris-flow trapping due to driftwood jamming in a slit-check dam was also investigated. A numerical
model was developed with an interacting combination of Eulerian expression of the debris flow and Lagrangian expression of
the driftwood, in which the fluctuating coordinates and rotation of the driftwood were treated stochastically. The calculated
shapes and thicknesses of a debris-flow fan and the positions and orientations of the deposited driftwood on a debris-flow
fan were consistent with experimental flume results. The jamming of driftwood in a slit-check dam was evaluated based on geometry
and probability. The simulated results of outflow discharge and the proportion of driftwood passed through the slit-check
dam also agreed with the experimental results. 相似文献
16.
Guoquan Wang James Joyce David Phillips Ramesh Shrestha William Carter 《Landslides》2013,10(4):503-513
Light detection and ranging (LIDAR) is a remote sensing technique that uses light, often using pulses from a laser to measure the distance to a target. Both terrestrial- and airborne-based LIDAR techniques have been frequently used to map landslides. Airborne LIDAR has the advantage of identifying large scarps of landslides covered by tree canopies and is widely applied in identifying historical and current active landslides hidden in forested areas. However, because landslides naturally have relatively small vertical surface deformation in the foot area, it is practically difficult to identify the margins of landslide foot area with the limited spatial resolution (few decimeters) of airborne LIDAR. Alternatively, ground-based LIDAR can achieve resolution of several centimeters and also has the advantages of being portable, repeatable, and less costly. Thus, ground-based LIDAR can be used to identify small deformations in landslide foot areas by differencing repeated terrestrial laser scanning surveys. This study demonstrates a method of identifying the superficial boundaries as well as the bottom boundary (sliding plane) of an active landslide in National Rainforest Park, Puerto Rico, USA, using the combination of ground-based and airborne LIDAR data. The method of combining terrestrial and airborne LIDAR data can be used to study landslides in other regions. This study also indicates that intensity and density of laser point clouds are remarkably useful in identifying superficial boundaries of landslides. 相似文献
17.
M. L. Shrestha 《Meteorology and Atmospheric Physics》2000,75(1-2):21-28
Summary ?Nepal, lying in the southern periphery of the Tibetan Plateau receives about 80% of the total annual rainfall during summer
monsoon (June–September). Rainfall analysis shows that summer monsoon is more active in the southern part of Nepal but in
the high Himalayas and Trans-Himalayan region other weather systems like western disturbances are also as effective as monsoon
in giving rainfall.
The influence of Southern Oscillation (SO) in Nepal monsoon rainfall is found to be very significant. The years with significant
negative (positive) Southern Oscillation Index (SOI) have less (more) rainfall in most of the cases during the 32-year period.
This relationship is also found to vary with time. The years with deficient rainfall are associated most of the times with
negative departure of SOI and the composite chart during these occasions shows about 95% area of Nepal experiencing below
normal rainfall. Likewise at the time of positive departure of SOI, most of the region (94%) experienced above normal rainfall.
There is a good relation between SOI and rainfall over Nepal during monsoon. The correlation coefficient between Nepal monsoon
rainfall and monthly SOI shows a statistically significant in-phase relationship during and after monsoon but poor relation
during the months prior to monsoon season. These results suggest that monsoon plays an active and effective role on the interannual
variability including SOI.
Received December 28, 1999/Revised May 22, 2000 相似文献
18.
The P–T–t evolution of the exhumed Himalayan metamorphic core in the Likhu Khola region,East Central Nepal
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The recent identification of multiple strike‐parallel discontinuities within the exhumed Himalayan metamorphic core has helped revise the understanding of convergence accommodation processes within the former mid‐crust exposed in the Himalaya. Whilst the significance of these discontinuities to the overall development of the mountain belt is still being investigated, their identification and characterization has become important for potential correlations across regions, and for constraining the kinematic framework of the mid‐crust. The result of new phase equilibria modelling, trace element analysis and high‐precision Lu–Hf garnet dating of the metapelites from the Likhu Khola region in east central Nepal, combined with the previously published monazite petrochronology data confirms the presence of one of such cryptic thrust‐sense tectonometamorphic discontinuities within the lower portion of the exhumed metamorphic core and provides new constraints on the P–T estimates for that region. The location of the discontinuity is marked by an abrupt change in the nature of P–T–t paths of the rocks across it. The rocks in the footwall are characterized by a prograde burial P–T path with peak metamorphic conditions of ~660°C and ~9.5 kbar likely in the mid‐to‐late Miocene, which are overlain by the hanging wall rocks, that preserve retrograde P–T paths with P–T conditions of >700°C and ~7 kbar in the early Miocene. The occurrence of this thrust‐sense structure that separates rock units with unique metamorphic histories is compatible with orogenic models that identify a spatial and temporal transition from early midcrustal deformation and metamorphism in the deeper hinterland to later deformation and metamorphism towards the shallower foreland of the orogen. Moreover, these observations are comparable with those made across other discontinuities at similar structural levels along the Himalaya, confirming their importance as important orogen‐scale structures. 相似文献
19.
Yoshikazu Araki Kshitij C. Shrestha Nao Maekawa Yuji Koetaka Toshihiro Omori Ryosuke Kainuma 《地震工程与结构动力学》2016,45(2):297-314
Shaking table tests are performed on a one‐bay one‐story steel frame with superelastic Cu–Al–Mn shape memory alloy (SMA) tension braces. The frame is subjected to a series of scaled ground motions recorded during the 1995 Kobe earthquake, Japan. The test results demonstrate that the SMA braces are effective to prevent residual deformations and pinching. It is also shown that the time history responses observed from the shaking table tests agree well with the numerical predictions using a rate‐independent piecewise‐linear constitutive model calibrated to the quasi‐static component tests of the SMA braces. This suggests that the loading rate dependence of Cu–Al–Mn SMAs as well as the modeling error due to the piecewise linear approximation can be neglected in capturing the global response of the steel frame. Numerical simulations under a suite of near‐fault ground motion records are further performed using the calibrated analytical models to demonstrate the effectiveness of the SMA braces when the variability of near‐fault ground motions is taken into account. A stopper, or a deformation restraining device, is also proposed to prevent premature fracture of SMA bars in unexpectedly large ground motions while keeping the self‐centering capability in moderate to large ground motions. The effectiveness of the stopper is also demonstrated in the quasi‐static component and shaking table tests. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
20.
CHU Duo PUBU Tundrop NORBU Ghancan SAGAR Bajrachary MANDIRA Shresth GUO Jianping 《Acta Meteorologica Sinica》2011,25(6):734-741
Measuring rainfall from space appears to be the only cost effective and viable means in estimating regional precipitation
over the Tibet, and the satellite rainfall products are essential to hydrological and agricultural modeling. A long-standing
problem in the meteorological and hydrological studies is that there is only a sparse raingauge network representing the spatial
distribution of precipitation and its quantity on small scales over the Tibet. Therefore, satellite derived quantitative precipitation
estimates are extremely useful for obtaining rainfall patterns that can be used by hydrological models to produce forecasts
of river discharge and to delineate the flood hazard area. In this paper, validation of the US National Oceanic and Atmospheric
Administration (NOAA) Climate Prediction Center (CPC) RFE (rainfall estimate) 2.0 data was made by using daily rainfall observations
at 11 weather stations over different climate zones from southeast to northwest of the Tibet during the rainy season from
1 June to 30 September 2005 and 2006. Analysis on the time series of daily rainfall of RFE-CPC and observed data in different
climate zones reveals that the mean correlation coefficients between satellite estimated and observed rainfall is 0.74. Only
at Pali and Nielamu stations located in the southern brink of the Tibet along the Himalayan Mountains, are the correlation
coefficients less than 0.62. In addition, continuous validations show that the RFE performed well in different climate zones,
with considerably low mean error (ME) and root mean square error (RMSE) scores except at Nielamu station along the Himalayan
range. Likewise, for the dichotomous validation, at most stations over the Tibet, the probability of detection (POD) values
is above 73% while the false alarm rate (FAR) is between 1% and 12%. Overall, NOAA CPC RFE 2.0 products performed well in
the estimation and monitoring of rainfall over the Tibet and can be used to analyze the precipitation pattern, produce discharge
forecast, and delineate the flood hazard area. 相似文献