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61.
Drought analysis in Jordan under current and future climates 总被引:2,自引:0,他引:2
Mohammed I. Al-Qinna Nezar A. Hammouri Mutewekil M. Obeidat Fayez Y. Ahmad 《Climatic change》2011,106(3):421-440
Droughts have adverse socioeconomic, agricultural, and environmental impacts that can be reduced by assessing and forecasting
drought behavior. The paper presents detailed analyses of both meteorological and vegetative droughts over the period from
1970 to 2005. Standardized Precipitation Index (SPI) and Normalized Difference Vegetation Index (NDVI) have been used to quantify
drought according to severity, magnitude and spatial distribution at the Hashemite Kingdom of Jordan. Results suggest that
the country faced during the past 35 years frequent non-uniform drought periods in an irregular repetitive manner. Drought
severity, magnitudes and life span increased with time from normal to extreme levels especially at last decade reaching magnitudes
of more than 4. Generated NDVI maps spatial analyses estimate crop-area percentage damage due to severe and extremely severe
drought events occurred during October, December, and February of 2000 to be about 10%, 45%, and 30%, respectively. In response
to drought spatial extent, the paper suggest the presence of two drought types, local drought acting on one or more geographical
climatic parts and national drought, of less common but more severe, that extend over the whole country. Droughts in Jordan
act intensively during January, February and March and tend to shift position with time by alternative migrations from southern
desert parts to northern desert parts and from the eastern desert parts to highlands and Jordan Rift Valley (JRV) at the west.
The paper also investigates the potential use of Global Climate Model’s (GCM) to forecast future drought events from 2010
till 2040. Tukey HSD test indicates that ECHAM5OM GCM is capable to predicted rainfall variation at the country and suggests
future droughts to become more intensive at the northern and southern desserts with 15% rainfall reduction factor, followed
by 10% reduction at the JRV, and 5% at the highlands. 相似文献
62.
On November 4th 2007, along the Grijalva River in the state of Chiapas, Mexico, has occurred one of the largest landslides
ever known. This landslide, known as Juan del Grijalva, destroyed the town of the same name, killing 20 people, and moved 55 million cubic meters of rock and debris down slope
to completely block the Grijalva River. In order to understand the characteristics and factors that triggered the Juan del
Grijalva landslide, geologic studies were conducted at the site. The results indicate that the landslide was composed of a
lithologic sequence of thin-bedded shales and thin to medium-thick-bedded sandstones. This was faulted into several blocks
dipping in the same sense as the mass movement. The main triggering factor was the increment of the pore pressure into the
lithologic unit due to water saturation after 5 days of heavy rain before the incident. According to records from the last
century, the Juan del Grijalva mass movement represents one of the largest mass movements recorded all over the world. The
risk conditions of the area after the landslide lead to the rapid construction of an artificial channel to drain the accumulating
mass of water upstream and therefore prevent a future catastrophic inundation down stream. 相似文献
63.
The location of the seismic event hypocenter is the very first task undertaken when studying any seismological problem. The
accuracy of the solution can significantly influence consecutive stages of analysis, so there is a continuous demand for new,
more efficient and accurate location algorithms. It is important to recognize that there is no single universal location algorithm
which will perform equally well in any situation. The type of seismicity, the geometry of the recording seismic network, the
size of the controlled area, tectonic complexity, are the most important factors influencing the performance of location algorithms.
In this paper we propose a new location algorithm called the extended double difference (EDD) which combines the insensitivity
of the double-difference (DD) algorithm to the velocity structure with the special demands imposed by mining: continuous change
of network geometry and a very local recording capability of the network for dominating small induced events. The proposed
method provides significantly better estimation of hypocenter depths and origin times compared to the classical and double-difference
approaches, the price being greater sensitivity to the velocity structure than the DD approach. The efficiency of both algorithms
for the epicentral coordinates is similar. 相似文献
64.
Shillong basin, one of the Purana basins of the Indian peninsula is situated in the central and eastern parts of the Shillong
plateau of NE India. Metasedimentary and metavolcanic rocks of the basin are of Mesoproterozoic age and lithostratigraphically
belong to Shillong Group (erstwhile Shillong series) comprising Lower Metapelitic Formation (LMF) and Upper Quartzitic Formation
(UQF). A long, persistent, faulted and tectonically attenuated conglomerate known as Nongkhya-Sumer-Mawmaram-conglomerate
separates these two formations. In the present work, quantitative strain analyses of the pebbles of Sumer, Nongkhya and Mawmaram
conglomerates of Ri-Bhoi and West Khasi Hills districts of Meghalaya are carried out using manual and computerized programmes.
Eight different techniques for intrapebble, interpebble and bulk rock strain estimation are applied and results are compared
systematically. Sumer and Mawmaram conglomerates bear the testimony of broadly flattening type of deformation (0 < k < 1) while Nongkhya conglomerate shows constriction type (1 < k < α). The change in strain ellipsoid shape from Nongkhya to Mawmaram area is accompanied by a change of fabric from S < L to L < S tectonites. Affinity of rotational strain is more in Nongkhya conglomerate as compared to Sumer and Mawmaram conglomerates.
The compactness of pebbles is high in case of Nongkhya conglomerate and low to moderate in Sumer and Mawmaram conglomerates
indicating high strain in Nongkhya conglomerate (northeastern part of Shillong basin) relative to Sumer and Mawmaram conglomerates
(southwestern part of Shillong basin). Thus strain magnitude increases from SW to NE direction of the Shillong basin. 相似文献
65.
The results of Zayü-Qingshuihe MT sounding profile carried out in eastern Tibetan Plateau are presented in this paper. Using 2-D RRI method, the resistivity distribution with depth is obtained along the profile. It is featured by the resistivity zones in the horizontal direction and layers in the vertical direction. The Bangong-Nujiang suture zone and Jinshajiang suture zone are both important electrical conductivity-separating zones in the plateau, and the former is a zone with relatively low resistivity while the latter is an electrical conductivity gradient zone. The highly electrical conductive bodies in the mid and lower crust of northern Qiangtang and Bayan Har Terrain might be caused by regional melting due to shear heating during the process of subduction in tectonic evolution. 相似文献
66.
This paper examines the potential role of forest set-asides in global carbon sequestration policy. While set asides that protect
forests from timber harvests and land-use conversion may alleviate concerns with permanence, and they may provide large ancillary
environmental benefits, they may also lead to large leakage. This paper uses a global land use and forestry model to examine
the efficiency of three crediting schemes for set-asides. The results show that if set-asides are integrated into a global
forestry carbon sequestration program that includes a wide range of other management options, then 300 million hectares of
land would be set-aside, and up to 128 Pg C could be sequestered in global forests by 2105. Under alternative policies that
focus exclusively on set-asides, more forestland can be set-asides, up to 3.2 billion hectare, but these policies invite large
leakage in the near-term, and in the long-run, they less net carbon is removed from the atmosphere. Specifically, leakage
is estimated to be 47–52%, depending on the policy, and by the end of the century, up to 17% less carbon will be sequestered
in all forests. 相似文献
67.
Kapil Bisht Yogesh Joshi Shashi Upadhyay Poonam Metha 《Journal of the Geological Society of India》2018,92(2):173-176
Glaciers being very sensitive to climate change have been identified as one of the best indicators of climate change and evidences have proved that most of the Himalayan glaciers have receded with an increased rate during the recent past under the influence of global warming. Lichenometric study was carried out on the moraines of Milam glacier (located in Pithoragarh district of Uttarakhand) with the help of lichen species Dimelaena oreina having an average annual growth rate of 1.31 mm. The study revealed that Milam glacier has receded 1450 m in last 69.37 years with an average recession rate of 20.90 m/year. Since lichenometric studies are cost effective and ecofriendly in comparison to carbon dating, satellite and remote sensing based studies and also reliable, hence, it should be promoted in Himalaya which is an abode of glaciers. 相似文献
68.
Carbon emissions—and hence fossil fuel combustion—must decline rapidly if warming is to be held below 1.5 or 2 °C. Yet fossil fuels are so deeply entrenched in the broader economy that a rapid transition poses the challenge of significant transitional disruption. Fossil fuels must be phased out even as access to energy services for basic needs and for economic development expands, particularly in developing countries. Nations, communities, and workers that are economically dependent on fossil fuel extraction will need to find a new foundation for livelihoods and revenue. These challenges are surmountable. In principle, societies could undertake a decarbonization transition in which they anticipate the transitional disruption, and cooperate and contribute fairly to minimize and alleviate it. Indeed, if societies do not work to avoid that disruption, a decarbonization transition may not be possible at all. Too many people may conclude they will suffer undue hardship, and thus undermine the political consensus required to undertake an ambitious transition. The principles and framework laid out here are offered as a contribution to understanding the nature of the potential impacts of a transition, principles for equitably sharing the costs of avoiding them, and guidance for prioritizing which fossil resources can still be extracted. 相似文献
69.
Fabien Gibert Juan Cuesta Jun-Ichi Yano Nicolas Arnault Pierre H. Flamant 《Boundary-Layer Meteorology》2007,125(3):553-573
We question the correlation between vertical velocity (w) on the one hand and the occurrence of convective plumes in lidar reflectivity (i.e. range corrected backscatter signal Pz
2) and depolarization ratio (Δ) on the other hand in the convective boundary layer (CBL). Thermal vertical motion is directly
investigated using vertical velocities measured by a ground-based Doppler lidar operating at 2 μm. This lidar provides also
simultaneous measurements of lidar reflectivity. In addition, a second lidar 200 m away provides reflectivities at 0.53 and
1 μm and depolarization ratio at 0.53 μm. The time series from the two lidars are analyzed in terms of linear correlation
coefficient (ρ). The main result is that the plume-like structures provided by lidar reflectivity within the CBL as well as the CBL height
are not a clear signature of updrafts. It is shown that the lidar reflectivity within the CBL is frequently anti-correlated
(ρ (w, Pz
2 )) with the vertical velocity. On the contrary, the correlation coefficient between the depolarization ratio and the vertical
velocity ρ (w, Δ ) is always positive, showing that the depolarization ratio is a fair tracer of updrafts. The importance of relative humidity
on the correlation coefficient is discussed.
An erratum to this article can be found at 相似文献
70.
Prabhin Sukumaran Dhananjay A. Sant K. Krishnan Govindan Rangarajan 《Journal of the Geological Society of India》2012,79(1):41-52
A high resolution quantitative granulometric record for site Uchediya [21°43′2.22″ N, 73° 6′26.22″ E; 10 m a. s. l.] gives
understanding towards accretion history of the late Holocene flood plain in the lower reaches of Narmada River. Two sediment
facies (sandy and muddy) and seven subfacies (sandy subfacies: StMS+FS+CS, SmFS+MS, SlFS+VFS, and StMS + CS; muddy subfacies: FmSILT+VFS+FS, FmSILT+VFS (O) and FmSILT+VFS (T)) are identified based on cluster analysis supplemented with sedimentary structures observed in field and other laboratory
data. Changes in hydrodynamics are further deduced based on various sedimentological parameters and their ratios leading to
arrive at a depositional model. 相似文献