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The regional climate model (RegCM4) is customized for 10-year climate simulation over Indian region through sensitivity studies on cumulus convection and land surface parameterization schemes. The model is configured over 30° E–120° E and 15° S–45° N at 30-km horizontal resolution with 23 vertical levels. Six 10-year (1991–2000) simulations are conducted with the combinations of two land surface schemes (BATS, CLM3.5) and three cumulus convection schemes (Kuo, Grell, MIT). The simulated annual and seasonal climatology of surface temperature and precipitation are compared with CRU observations. The interannual variability of these two parameters is also analyzed. The results indicate that the model simulated climatology is sensitive to the convection as well as land surface parameterization. The analysis of surface temperature (precipitation) climatology indicates that the model with CLM produces warmer (dryer) climatology, particularly over India. The warmer (dryer) climatology is due to the higher sensible heat flux (lower evapotranspiration) in CLM. The model with MIT convection scheme simulated wetter and warmer climatology (higher precipitation and temperature) with smaller Bowen ratio over southern India compared to that with the Grell and Kuo schemes. This indicates that a land surface scheme produces warmer but drier climatology with sensible heating contributing to warming where as a convection scheme warmer but wetter climatology with latent heat contributing to warming. The climatology of surface temperature over India is better simulated by the model with BATS land surface model in combination with MIT convection scheme while the precipitation climatology is better simulated with BATS land surface model in combination with Grell convection scheme. Overall, the modeling system with the combination of Grell convection and BATS land surface scheme provides better climate simulation over the Indian region. 相似文献
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In this study, the nature of basin‐scale hydroclimatic association for Indian subcontinent is investigated. It is found that, the large‐scale circulation information from Indian Ocean is also equally important in addition to the El Niño‐Southern Oscillation (ENSO), owing to the geographical location of Indian subcontinent. The hydroclimatic association of the variation of monsoon inflow into the Hirakud reservoir in India is investigated using ENSO and EQUatorial INdian Ocean Oscillation (EQUINOO, the atmospheric part of Indian Ocean Dipole mode) as the large‐scale circulation information from tropical Pacific Ocean and Indian Ocean regions respectively. Individual associations of ENSO & EQUINOO indices with inflow into Hirakud reservoir are also assessed and found to be weak. However, the association of inflows into Hirakud reservoir with the composite index (CI) of ENSO and EQUINOO is quite strong. Thus, the large‐scale circulation information from Indian Ocean is also important apart form the ENSO. The potential of the combined information of ENSO and EQUINOO for predicting the inflows during monsoon is also investigated with promising results. The results of this study will be helpful to water resources managers due to fact that the nature of monsoon inflow is becoming available as an early prediction. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
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Glacial lakes of the Hinku and Hongu valleys, Makalu Barun National Park and Buffer Zone, Nepal 总被引：1，自引：0，他引：1
Alton C. Byers Daene C. McKinney Marcelo Somos-Valenzuela Teiji Watanabe Damodar Lamsal 《Natural Hazards》2013,69(1):115-139
In recent decades, many of the larger glaciers in the Himalaya and Andes that have experienced increased melting have become glacial lakes. Some of these lakes present a risk of glacial lake outburst floods that can unleash stored lake water and eroded debris, often causing enormous devastation downstream. Many of these new glacial lakes have formed in the Mt. Everest and Makalu Barun National Parks of Nepal, nine of which in the remote Hinku and Hongu valleys have been designated as “potentially dangerous” based on remote sensing analyses. Until recently, however, relatively little ground-based information was available for these lakes, including their physical characteristics, danger level, prospective downstream impacts in the event of an outburst, and mitigation methods appropriate and applicable to remote regions within the Nepal Himalaya. This paper describes three separate, interdisciplinary expeditions to the Hinku and Hongu valleys between 2009 and 2012 that were designed to close these information gaps. Each expedition combined remote sensing with field-based analyses, repeat photography, interviews with local people, bathymetric surveys, ground penetrating radar, and flood modeling. Eight of the “potentially dangerous” lakes surveyed were found to be stable, and one that had escaped mention in previous studies (L464) was found to contain a high risk of an outburst flood. In the data-deficient high mountain world, we suggest that the combined use of sophisticated remote sensing and modeling technologies with traditional, field-based methods can provide the most thorough understanding of glacial lakes possible at this time, including the actual risks that they pose as well as the most appropriate and community-based risk reduction strategies. 相似文献
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An assessment of conditions before and after the 1998 Tam Pokhari outburst in the Nepal Himalaya and an evaluation of the future outburst hazard 
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下载免费PDF全文 Damodar Lamsal Takanobu Sawagaki Teiji Watanabe Alton C. Byers Daene C. McKinney 《水文研究》2016,30(5):676-691
On 3 September 1998, a glacial lake outburst flood (GLOF) that originated from Tam Pokhari occurred in the Hinku valley of the eastern Nepal Himalaya. This study analyses the lake's geomorphic and hydrologic conditions prior to the outburst, and evaluates the conditions that could contribute to a future flood through photogrammetric techniques. We processed high‐resolution Corona KH‐4A (2.7 m) and ALOS PRISM (2.5 m) stereo‐images taken before and after the GLOF event, and produced detailed topographic maps (2‐m contour interval) and DEMs (5 m × 5 m). We (re‐) constructed lake water surfaces before (4410 ± 5 m) and after (4356 ± 5 m) the outburst, and reliably estimated the lake water surface lowering (54 ± 5 m) and the water volume released (19.5 ± 2.2 × 106 m3) from the lake, showing good agreement with the results obtained from ground‐based measurements. The most relevant conditions that may have influenced the catastrophic drainage of Tam Pokhari in 1998 include the presence of: (i) a narrow (75 ± 6 m), steep (up to 50°) and high (120 ± 5 m) moraine dam; (ii) high lake level (8 ± 5 m of freeboard) and (iii) a steep overhanging glacier (>40°). The lake outburst substantially altered the immediate area, creating a low and wide (>500 m) outwash plain below the lake, a wide lake outlet channel (~50 m) and a gentle channel slope (~3–5°). Our new data suggest that the likelihood of a future lake outburst is low. Our results demonstrate that the datasets produced by photogrammetric techniques provide an excellent representation of micro‐landform features on moraine dams, lake water surfaces and the changes in both over time, thereby allowing highly accurate pre‐ and post‐GLOF (volumetric) change analysis of glacial lakes. Furthermore, it enables precise measurement of several predictive variables of GLOFs that can be useful for identifying potentially dangerous glacial lakes or prioritizing them for detailed field investigations. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
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B. K. Ranganath N. Pradeep V. B. Manjula Balakrishna Gowda M. D. Rajanna Damodar Shettigar P. P. Nageswara RAo 《Journal of the Indian Society of Remote Sensing》2004,32(1):49-58
The study evaluates the potential of satellite remote sensing technology for detection, mapping and monitoring of diseased
rubber plantation affected by Corynespora and Gloeosporium fungi, which causes leaf spot and leaf fall. Multi-date satellite
data of IRS-1C have been analyzed adopting enhancement and classification techniques to identify and extract information on
the spatial extent and distribution of healthy and diseased rubber plants with an accuracy of 90%. The diseased rubber plantations
have shown considerable reduction in the near-infrared reflectance followed by a rise in the reflectance in red and short
wave infrared. Vegetation index images generated for different periods have shown the progress of disease incidence, severity
and recovery of rubber plantations after fungicidal spraying. The study has demonstrated the use of remote sensing technology
in identifying and delineating diseased rubber plantations. Early detection of the disease would be of immense value for taking
up necessary control measures and minimize the loss. 相似文献
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Natural Hazards - This study presents a numerical investigation on the seismic behaviour of aged concrete gravity dams under near source and far source ground motions. Two-dimensional formulation... 相似文献
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Rajib Maity 《水文研究》2012,26(21):3182-3194
In this paper, Split Markov Process (SMP) is developed to assess one‐step‐ahead variation of daily rainfall at a rain gauge station. SMP is an advancement of general Markov Process and specially developed for probabilistic assessment of change in daily rainfall magnitude. The approach is based on a first‐order Markov chain to simulate daily rainfall variation at a point through state/sub‐state transitional probability matrix (TPM). The state/sub‐state TPM is based on the historical transitions from a particular state to a particular sub‐state, which is the basic difference between SMP and general Markov Process. The cumulative state/sub‐state TPM is represented in a contour plot at different probability levels. The developed cumulative state/sub‐state TPM is used to assess the possible range of rainfall in next time step, in a probabilistic sense. Application of SMP is investigated for daily rainfall at four rain gauge stations – Khandwa, Jabalpur, Sambalpur, and Puri, located at various parts in India. There are 99 years of record available out of which approximately 80% of data are used for calibration, and 20% of data are used to assess the performance. Thus, 80 years of daily monsoon rainfall is used to develop the state/sub‐state TPM, and 19 years data are used to investigate its performance. Model performance is assessed in terms of hit rate (HR), false alarm rate (FAR), and percentage captured. It is found that percentage captured is maximum for Khandwa (70%) and minimum for Sambalpur (44%) whereas hit rate is maximum for Sambalpur and minimum for Khandwa (73%). FAR is around 30% or below for Jabalpur, Sambalpur, and Puri. FAR is maximum for Khandwa (37%). Overall, the assessed range, particularly the upper limit, provides a quantification possible extreme value in the next time step, which is a very useful information to tackle the extreme events, such as flooding, water logging and so on. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
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Bibhash Nath Jyoti Prakash Maity Jiin-Shuh Jean Gavin Birch Sandeep Kar Huai-Jen Yang Ming-Kuo Lee Rasmani Hazra Debashis Chatterjee 《Applied Geochemistry》2011,26(5):705-713
Major ion and trace element analyses were performed on groundwater samples collected from the Bengal Delta (Chakdaha municipality, West Bengal and Manikgonj town, Bangladesh) and Chianan Plains (SW Taiwan) to compare geochemical characteristics. Results showed that concentrations of Na, K, Mg, Cl and SO4 were generally higher in Chianan Plain (CNP) groundwaters, while high Ca was observed in Bengal Delta Plain (BDP) groundwater. Measured As concentrations in groundwaters of BDP and CNP showed large variations, with mean As concentrations of 221 μg/L (range: 1.1-476 μg/L) in Chakdaha, 60 μg/L (range: 0.30-202 μg/L) in Manikgonj, and 208 μg/L (range: 1.3-575 μg/L) in CNP groundwater. The Fe-reduction mechanism was found to be the dominant geochemical process in releasing As from sediment to groundwater in Chakdaha, West Bengal, however the Mn-reduction process was dominant in groundwaters of Manikgonj, Bangladesh. In Chianan Plain groundwater, a combination of geochemical processes (e.g., bacterial Fe-reduction, mineral precipitation and dissolution reactions) controlled release of As. Fluorescence spectral patterns of the groundwater showed low relative fluorescence intensity (RFI) of dissolved humic substances in BDP groundwater (mean: 63 and 72 QSU, Chakdaha and Manikgonj, respectively), while high RFI was observed in CNP groundwater (mean: 393 QSU). The FT-IR spectra of the extracted humic acid fractions from sediments of Chianan Plain showed a stronger aliphatic band at 2850-3000 cm−1 and a higher resolved fingerprint area (from 1700 to 900 cm−1) compared with BDP sediments. The geochemical differences between the study areas may play a crucial role in the clinical manifestation of Blackfoot disease observed only in Chianan Plain, SW Taiwan. 相似文献