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1.
Estimating potential landslide sites of an upland sub-watershed in Western Ghat’s of Kerala (India) through frequency ratio and GIS 总被引：10，自引：0，他引：10
The purpose of this study is to assess the susceptibility of landslides in parts of Western Ghats, Kerala, India, using a
geographical information system (GIS). Landslide inventory of the area was made by detailed field surveys and the analysis
of the topographical maps. The landslide triggering factors are considered to be slope angle, slope aspect, slope curvature,
slope length, distance from drainage, distance from lineaments, lithology, land use and geomorphology. ArcGIS version 8.3
was used to manipulate and analyse all the collected data. Probabilistic-likelihood ratio was used to create a landslide susceptibility
map for the study area. The result was validated using the Area under Curve (AUC) method and temporal data of landslide occurrences.
The validation results showed satisfactory agreement between the susceptibility map and the existing data on landslide locations.
As the result, the success rate of the model was (84.46%) and the prediction rate of the model was (82.38%) shows high prediction
accuracy. In the reclassified final landslide susceptibility zone map, 5.68% of the total area is classified as critical in
nature. The landslide susceptibility map thus produced can be used to reduce hazards associated with landslides and to land
cover planning. 相似文献
2.
Nitin D. Rai Tor A. Benjaminsen Siddhartha Krishnan C. Madegowda 《Singapore journal of tropical geography》2019,40(1):124-139
Protected areas have had significant impacts on local communities primarily through the physical removal of people. In some instances, people continue to live within protected areas due to the inability of the state to evict them. The restrictions on livelihoods placed on people living inside protected areas lead to in situ displacement. We show how conservation enclosures in the Biligiri Rangaswamy Temple Tiger Reserve have produced a class of people that the state ‘lets die’ by banning customary practices such as fire use, hunting and harvesting of forest produce. Using longitudinal ethnographic, socio‐economic and ecological data, we demonstrate that conservation policy has alienated indigenous forest dwellers from their agricultural and forest‐land. The outcomes of conservation policy include dispossession through increased crop losses, reduced income from agriculture and forest produce, as well as a forest that is dominated by weeds due to fire suppression. The ban on hunting in particular has increased wildlife densities, which has enabled the state to accumulate revenues through the establishment of wildlife tourism facilities. All in all, centralized protected area governance has changed the relationships among people, forest and the state in a way that has produced adverse effects for both livelihoods and the ecosystem. 相似文献
3.
Lalmani Babu Madhu Kaul Kumar Rajou Singh Rajesh Singh Krishna Kumar 《Earth, Moon, and Planets》1999,84(3):151-162
The propagationmechanism of low latitude daytime whistlers is investigated on the basis of ground measurements made continuously
during daytime in North India at Jammu (geomag. lat. 22°26°N;L = 1.17). On February 14, 1998 extremely small dispersion (ESD)
whistlers with dispersion varying from 5–10 sec1/2 in surprisingly large numbers were recorded at Jammu during daytime in the late afternoon. The results of a study of the
characteristics of ESD whistlers are presented and the discussion indicates that ESD whistlers recorded are the VLF waves
radiated from the return stroke of the lightning discharge launched at the ionosphere with different initial wave normal angles,
propagated upwards under eitherquasi-longitudinal conditions or pro-longitudinal whistler mode, turned around at different
heights due to quasi-transverse propagation and received at Jammu with the dispersion of the order of 5–10 sec1/2. The validity of this suggestion has been tested by performing actualray-tracing computations in thepresence of equatorial
anomaly model.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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A three-dimensional numerical model is developed and used to study the coastal upwelling processes and corresponding seasonal changes in the sea level along the west coast of India. The upwelling and associated sea level variations are seen as a response of coastal ocean to pure wind stress forcing. The model is designed to represent coastal ocean physics by resolving surface and bottom Ekman layers as realistically as possible. The prognostic variables are the three components of the velocity field, temperature, salinity and turbulent energy. The governing equations together with their boundary conditions are solved by finite-difference techniques. Experiments are performed to investigate sea level fluctuations associated with the thermal response and alongshore currents of the coastal waters. The model is forced with mean monthly wind stress forcing of January, May, July and September representing northeast monsoon and different phases of the southwest monsoon. It is known from the observational study that the upwelling process reaches to the surface waters by May along the coastal waters of the extreme southwest peninsular region. The process is more intense in July compared to May and September and its strength decreases from south to north. However, during the northeast monsoon season, which is represented by January wind stress forcing in the model, downwelling is simulated along the coast. The model simulations of the coastal response are compared with the observations and are found to be in good agreement. The maximum computed vertical velocity of about 2.0 2 10 -3 cm s -1 is predicted in July in the southern region off the coast. 相似文献
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7.
R. Jyothibabu N.V. Madhu P.A. Maheswaran K.V. Jayalakshmy K.K.C. Nair C.T. Achuthankutty 《Continental Shelf Research》2008
Stratification (throughout the year) and low solar radiation (during monsoon periods) have caused low chlorophyll a and primary production (seasonal average 13–18 mg m−2 and 242–265 mg C m−2 d−1, respectively) in the western Bay of Bengal (BoB). The microzooplankton (MZP) community of BoB was numerically dominated by heterotrophic dinoflagellates (HDS) followed by ciliates (CTS). The highest MZP abundance (average 665±226×104 m−2), biomass (average 260±145 mg C m−2) and species diversity (Shannon weaver index 2.8±0.42 for CTS and 2.6±0.35 for HDS) have occurred during the spring intermonsoon (SIM). This might be due to high abundance of smaller phytoplankton in the western BoB during SIM as a consequence of intense stratification and nitrate limitation (nitracline at 60 m depth). The strong stratification during SIM was biologically evidenced by intense blooms of Trichodesmium erythraeum and frequent Synechococcus–HDS associations. The high abundance of smaller phytoplankton favors microbial food webs where photosynthetic carbon is channeled to higher trophic levels through MZP. This causes less efficient transfer of primary organic carbon to higher trophic levels than through the traditional food web. The microbial food web dominant in the western BoB during SIM might be responsible for the lowest mesozooplankton biomass observed (average 223 mg C m−2). The long residence time of the organic carbon in the surface waters due to the active herbivorous pathways of the microbial food web could be a causative factor for the low vertical flux of biogenic carbon during SIM. 相似文献
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Clifford E. Singer T. S. Gopi Rethinaraj Samuel Addy David Durham Murat Isik Madhu Khanna Brandon Kuehl Jianding Luo Wilma Quimio Kothavari Rajendran Donna Ramirez Ji Qiang Jürgen Scheffran T. Nedjla Tiouririne Junli Zhang 《Climatic change》2008,88(3-4):309-342
Probability distributions for carbon burning, atmospheric CO2, and global average temperature are produced by time series calibration of models of utility optimization and carbon and heat balance using log-linear production functions. Population growth is used to calibrate a logistically evolving index of development that influences production efficiency. Energy production efficiency also includes a coefficient that decreases linearly with decreasing carbon intensity of energy production. This carbon intensity is a piecewise linear function of fossil carbon depletion. That function is calibrated against historical data and extrapolated by sampling a set of hypotheses about the impact on the carbon intensity of energy production of depleting fluid fossil fuel resources and increasing cumulative carbon emissions. Atmospheric carbon balance is determined by a first order differential equation with carbon use rates and cumulative carbon use as drivers. Atmospheric CO2 is a driver in a similar heat balance. Periodic corrections are included where required to make residuals between data and model results indistinguishable from independently and identically distributed normal distributions according to statistical tests on finite Fourier power spectrum amplitudes and nearest neighbor correlations. Asymptotic approach to a sustainable non-fossil energy production is followed for a global disaggregation into a tropical/developing and temperate/more-developed region. The increase in the uncertainty of global average temperature increases nearly quadratically with the increase in the temperature from the present through the next two centuries. 相似文献
10.
A GIS-based statistical methodology for landslide susceptibility zonation is described and its application to a study area
in the Western Ghats of Kerala (India) is presented. The study area was approximately 218.44 km2 and 129 landslides were identified in this area. The environmental attributes used for the landslide susceptibility analysis
include geomorphology, slope, aspect, slope length, plan curvature, profile curvature, elevation, drainage density, distance
from drainages, lineament density, distance from lineaments and land use. The quantitative relationship between landslides
and factors affecting landslides are established by the data driven-Information Value (InfoVal) — method. By applying and
integrating the InfoVal weights using ArcGIS software, a continuous scale of numerical indices (susceptibility index) is obtained
with which the study area is divided into five classes of landslide susceptibility. In order to validate the results of the
susceptibility analysis, a success rate curve was prepared. The map obtained shows that a great majority of the landslides
(74.42%) identified in the field were located in susceptible and highly susceptible zones (27.29%). The area ratio calculated
by the area under curve (AUC) method shows a prediction accuracy of 80.45%. The area having a high scale of susceptibility
lies on side slope plateaus and denudational hills with high slopes where drainage density is relatively low and terrain modification
is relatively intense. 相似文献