排序方式： 共有25条查询结果，搜索用时 15 毫秒
1.
R. K. Prasad N. C. Mondal Pallavi Banerjee M. V. Nandakumar V. S. Singh 《Environmental Geology》2008,55(3):467-475
Remote Sensing and Geographic Information System has become one of the leading tools in the field of hydrogeological science,
which helps in assessing, monitoring and conserving groundwater resources. It allows manipulation and analysis of individual
layer of spatial data. It is used for analysing and modelling the interrelationship between the layers. This paper mainly
deals with the integrated approach of Remote Sensing and geographical information system (GIS) to delineate groundwater potential
zones in hard rock terrain. The remotely sensed data at the scale of 1:50,000 and topographical information from available
maps, have been used for the preparation of ground water prospective map by integrating geology, geomorphology, slope, drainage-density
and lineaments map of the study area. Further, the data on yield of aquifer, as observed from existing bore wells in the area,
has been used to validate the groundwater potential map. The final result depicts the favourable prospective zones in the
study area and can be helpful in better planning and management of groundwater resources especially in hard rock terrains. 相似文献
2.
Robert S. Pomeroy Blake D. Ratner Stephen J. Hall Jate Pimoljinda V. Vivekanandan 《Marine Policy》2006,30(6):786-793
This paper examines lessons from past approaches to natural disasters, as well as early lessons from the post-2004 Asian tsunami rehabilitation, to draw out general principles for rehabilitating livelihoods in poor coastal communities. We contend that avoiding the mistakes of the past requires: (1) a framework for understanding the diversity of coastal people's livelihood strategies and the sources of their vulnerability, (2) a process for designing interventions that build on this understanding in order to strengthen and revitalize coastal communities, including a means of assessing and selecting the most promising livelihood options, and (3) a focus on the longer-term challenge of building future resilience and sustainability in the communities by addressing the root causes of vulnerability. 相似文献
3.
4.
5.
Anagnostou M.N. Anagnostou E.N. Vivekanandan J. Ogden F.L. 《Geoscience and Remote Sensing Letters, IEEE》2007,4(4):601-605
This letter evaluates the consistency of rainfall drop size distribution (DSD) parameters that were estimated from attenuation-corrected X-band dual-polarization (XPOL) radar measurements with estimates from a colocated S-band dual-polarization radar (S-Pol). The DSD retrieval technique uses reflectivity and differential reflectivity, and a constrained relationship to estimate the three parameters of a ldquonormalizedrdquo gamma distribution model. The more definitive S-Pol DSD parameter estimates are used as a reference to assess the performance of the corresponding XPOL estimates for different rain-path attenuation values. Results show that XPOL attenuation-corrected profiles can provide rainfall DSD estimations that are consistent to an S-band dual-polarization radar, even in cases of moderate to high rain-path attenuation. 相似文献
6.
D. S. Suresh Babu V. Nandakumar B. John B. K. Jayaprasad S. V. Pramod 《Environmental Geology》2000,39(3-4):390-397
Impact of catchment erosion and the resultant reservoir siltation from a tropical environment is reported here to discuss
the effect of a reservoir in the natural degradation of an evergreen-forested segment. While an area of 8.01 km2 has been affected by direct inundation at the full reservoir level, another 2.6 km2 area once under thick forest cover, had also lost its identity over the last 38 years by indirect degradation. This zone
mainly falls in the confluence of tributaries, namely Neyyar and Mullayar, with the reservoir. The capacity of the reservoir
was found to be reduced by 28.8 Mm3 during this period and the annual average loss is calculated as 0.75 Mm3 (0.71%), indicating the intensity of erosion from the catchment zone. In case the proposed upper dam in the reservoir comes
into existence, an additional area of 2.4 km2 from the virgin forest would be submerged and more area would face degradation around the inundated zone.
Received: 29 July 1998 · Accepted: 16 November 1998 相似文献
7.
Suhas S. Shetye Hema Naik Siby Kurian Damodar Shenoy Nandakumar Kuniyil Michelle Fernandes Afreen Hussain 《Marine Ecology》2020,41(5):e12614
The increasing atmospheric CO2 concentration in the last few decades has resulted in a decrease in oceanic pH. In this study, we assessed the natural variability of pH in coastal waters off Goa, eastern Arabian Sea. pHT showed large variability (7.6–8.1) with low pH conditions during south-west monsoon (SWM), and the variability is found to be associated with upwelling rather than freshwater runoff. Considering that marine biota inhabiting dynamic coastal waters off Goa are exposed to such wide range of natural fluctuations of pH, an acidification experiment was carried out. We studied the impact of low pH on the local population of sea urchin Stomopneustes variolaris (Lamarck, 1816). Sea urchins were exposed for 210 days to three treatments of pHT: 7.96, 7.76 and 7.46. Our results showed that S. variolaris at pHT 7.96 and 7.76 were not affected, whereas the ones at pHT 7.46 showed adverse effects after 120 days and 50% mortality by 210 days. However, even after exposure to low pH for 210 days, 50% organisms survived. Under low pH conditions (pHT 7.46), the elemental composition of sea urchin spines exhibited deposition of excess Sr2+ as compared to Mg2+ ions. We conclude that although the sea urchins would be affected in future high CO2 waters, at present they are not at risk even during the south-west monsoon when low pH waters reside on the shelf. 相似文献
8.
Radio interferometers are used to construct high resolution images of the sky at radio frequencies and are the key instruments for accessing the statistical properties of the evolution of neutral hydrogen over cosmic time. Here we use simulated observations of the model sky to assess the efficacy of different estimators of the large-scale structure and power spectrum of the sky brightness distribution. We find that while the large-scale distribution can be reasonably estimated using the reconstructed image from interferometric data, estimates of the power spectrum of the intensity fluctuations calculated from the image are generally biased. This bias is found to be more pronounced for diffuse emission. The visibility based power spectrum estimator, however, gives an unbiased estimate of the true power spectrum. This work demonstrates that for an observation with diffuse emission the reconstructed image can be used to estimate the large-scale distribution of the intensity, while to estimate the power spectrum, visibility based methods should be preferred.With the upcoming experiments aimed at measuring the evolution of the power spectrum of the neutral hydrogen distribution, this is a very important result. 相似文献
9.
F. S. Marzano A. Mugnai E. A. Smith X. Xiang J. Turk J. Vivekanandan 《Meteorology and Atmospheric Physics》1994,54(1-4):29-51
Summary One of the recent campaigns devoted to precipitation studies using both active and passive microwave remote sensing systems was the Convection and Precipitation/Electrification Experiment (CaPE), which took place in central Florida during the summer of 1991. During CaPE, the airborne Advanced Microwave Precipitation Radiometer (AMPR), having four channels at 10.7, 19.35, 37.1 and 85.5 GHz and the National Center for Atmospheric Research CP-2 multiparameter radar at S-band (3 GHz) and X-band (10 GHz) were operated simultaneously. In this paper, we compare estimated hydrometeor liquid/ice water contents and surface rainrates, both retrieved from the AMPR radiometer and CP-2 radar measurements, for a case study consisting of a heavy precipitating storm over land near Cape Canaveral on August 12, 1991. The multi-frequency radiometer-based retrieval scheme uses a cloud-precipitation dataset generated from a cloud model and extended by a physically-constrained Monte Carlo procedure, along with a discrete-ordinate radiative transfer model and a principal component statistical technique to help formulate non-linear regression equations for the sought-after hydrometeor quantities. By applying linear discriminant analysis, the algorithm is used to estimate column integrated liquid/ice water contents, as well as the vertical profiles of these quantities to within a specified accuracy. Rainfall rates are estimated either by non-linear regression or by a suitable fallout model. The analysis has confined itself to along-track nadir-looking AMPR measuremets to avoid complications with variable polarization mixing and geometric distortion for off-nadir observations. Considering the different model assumptions used in the two types of retrieval algorithms and the diverse geophysical information content within the two types of measurements, substantial agreement between the radar- and radiometer-derived retrievals has been achieved for the columnar liquid/ice water contents and rainrates.With 19 FiguresThe National Center for Atmospheric Research (NCAR) is sponsored by the National Science Foundation. 相似文献
10.
N. Sundararajan Y. Srinivas M. Narasimha Chary G. Nandakumar A. Hanmantha Chary 《Journal of Earth System Science》2004,113(3):259-267
The contacts associated with an outlier in biotite gneiss and sandstones near Tiruvuru, Krishna district, Andhra Pradesh which
are generally favourable for groundwater occurrence were investigated employing refraction seismic method. Results were examined
by correlating the signals with local geology, bore well data and other available information in order to improve the reliability
of interpretation 相似文献