"THREE DIMENSIONAL MATHEMATICAL MODEL OF SEDIMENT TRANSPORT IN ESTUARINE REGIONS-- A CASE STUDY OF THE HAIHE RIVER MOUTH" Yuchuan Bai,Huanting SHEN and Shixiong HU     

C.B.SINGH  Narayan PRASAD 《国际泥沙研究》2002,17(4)

The paper presents the 3D finite element simulation of tidal flow and Sediment transport in the estuarine region of the Haihe river. The proposed model adopts sigma-transformation of the hydrodynamic and sediment transport equations. The hydrodynamic and sediment transport models are verified in case of a simple test problem for which analytical solutions are available. Finally the models are applied to muddy Haihe river estuary of North China and it is claimed that hydrodynamic and sediment transport models give a reliable comparison with the observed field data. However, there are certain discrepancies, and some reasonable questions regarding the present state-of-art, in the modeling of three-dimensional multilevel hydrodynamics and sediment transport, which are provided below for answer.  相似文献   

Impact of warmer climate on melt and evaporation for the rainfed, snowfed and glacierfed basins in the Himalayan region   总被引：9，自引：0，他引：9  

Pratap Singh  Lars Bengtsson 《Journal of Hydrology》2005,300(1-4):140-154

The impact of warmer climate on melt and evaporation was studied for rainfed, snowfed and glacierfed basins located in the western Himalayan region. Hydrological processes were simulated under current climatic conditions using a conceptual hydrological model, which accounts for the rainfall–runoff, evaporation losses, snow and glacier melt. After simulations of daily observed streamflow (R²=0.90) for 6 years, the model was used to study the impact of warmer climate on melt and evaporation. Based on the future projected climatic scenarios in the study region, three temperature scenarios (T+1, T+2 and T+3 °C) were adopted for quantifying the effect of warmer climate. The comparison of the effect of warmer climate on different types of basins indicated that the increase in evaporation was the maximum for snowfed basins. For a T+2 °C scenario, the annual evaporation for the rainfed basins increased by about 12%, whereas for the snowfed basins it increased by about 24%. The high increase of the evaporation losses would reduce the runoff. It was found that under a warmer climate, melt was reduced from snowfed basins, but increased from glacierfed basins. For a T+2 °C scenario, annual melt was reduced by about 18% for the studied snowfed basin, while it increased by about 33% for the glacierfed basin. Thus, impact of warmer climate on the melt from the snowfed and glacierfed basins was opposite to each other. The study suggests that out of three types of basins, snowfed basins are more sensitive in terms of reduction in water availability due to a compound effect of increase in evaporation and decrease in melt. For a complex type of basin, the decrease in melt from seasonal snow may be counterbalanced by increase in melt from glaciers. However, on long-term basis, when the areal extent of glaciers will decrease due to higher melt rate, the water availability from the complex basins will be reduced.  相似文献   

Analysis of temperature variability over north-west part of India for the period 1970–2000     

Monika Punia  Suman Nain  Amit Kumar  Bhupendra Pratap Singh  Amit Prakash  Krishan Kumar  V. K. Jain 《Natural Hazards》2015,75(1):935-952

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A study on precursors leading to geomagnetic storms using artificial neural network     

GAURAV SINGH  A K SINGH 《Journal of Earth System Science》2016,125(5):899-908

Space weather prediction involves advance forecasting of the magnitude and onset time of major geomagnetic storms on Earth. In this paper, we discuss the development of an artificial neural network-based model to study the precursor leading to intense and moderate geomagnetic storms, following halo coronal mass ejection (CME) and related interplanetary (IP) events. IP inputs were considered within a 5-day time window after the commencement of storm. The artificial neural network (ANN) model training, testing and validation datasets were constructed based on 110 halo CMEs (both full and partial halo and their properties) observed during the ascending phase of the 24th solar cycle between 2009 and 2014. The geomagnetic storm occurrence rate from halo CMEs is estimated at a probability of 79%, by this model.  相似文献   

TEMPORAL AND SPATIAL CHARACTERISTICS OF RAINFALL IN THE NAM RIVER DAM BASIN OF KOREA     

J. I. PARK  V. P. SINGH 《水文研究》1996,10(9):1155-1171

An investigation into rainfall variability in time and space in the Nam River dam basin of Korea is made with the use of the coefficient of variation and the correlation coefficient. The Nam River dam basin is a small mountainous watershed where wind direction and orography are the dominant influences on the pattern and distribution of rainfall. Rainfall distribution was found to vary with elevation, position, wind direction and distance from a reference station. The results of this study can be used in the design of rain gauge network, hydrological forecasting and for other applications in the Nam River dam basin.  相似文献   

REFLECTION-WINDOW MAPPING OF SHALLOW BEDROCK*     

S. SINGH 《Geophysical Prospecting》1986,34(4):492-507

A field study was undertaken to evaluate the effectiveness of the high frequency seismic reflection technique for mapping of shallow and irregular bedrock. Bedrock reflections were obtained using a hammer source with both in-line and common offset field layouts. The recording equipment included 12-channel enhancement seismographs, 28 Hz vertical geo-phones and a microcomputer. The latter increased the overall versatility of the seismic system. Field sites for this study are typical of the geological settings of the tin mining areas of Malaysia. The topographical ‘lows’ of the irregular bedrock control the localization of tin ore. The subsurface geology consists of a thin low velocity layer (± 300 m/s) overlying the compact overburden (± 1700 m/s) which in turn lies on bedrock. This paper discusses various criteria for designing an optimum window for obtaining usable reflections between the first arrival and the leading edge of the ground roll cone. Detailed mapping of the overburden and the bedrock interface by the reflection method can be useful in delineating areas for exploratory drilling and for optimum planning of mining operations.  相似文献   

Some theoretical aspects of electric field and precipitation growth in a finite thundercloud     

Pratap Singh  T S Verma  N C Varshneya 《Journal of Earth System Science》1986,95(2):293-298

A time-dependent numerical model allowing a simulation of the electric field and precipitation growth in a thundercloud of finite dimensions is described. It is found that slower growth rate (compared to an infinite thundercloud) of the electric field in a finite thundercloud permits larger size growth and higher terminal velocities of hydrometeors owing to an enhancement in precipitation intensity. Calculations also show that a higher maximum of the electric field is needed to slow down the larger particles produced in a thundercloud of finite dimensions. In particular, these solutions also include contribution of screening charge transport in thundercloud electrification.  相似文献   

AN ITERATIVE METHOD FOR DETAILED DEPTH DETERMINATION FROM REFRACTION DATA FOR AN UNEVEN INTERFACE *     

SURENDRA SINGH 《Geophysical Prospecting》1978,26(2):303-311

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THE APPLICATION OF VHF MEASUREMENTS TO EARTHQUAKE PREDICTION*     

R. P. SINGH  D. RANKIN 《Geophysical Prospecting》1985,33(8):1232-1239

The use of Very High Frequency measurements applied to the detection of the variation in dielectric constant as a precursor to earthquakes is examined. It is concluded that such a technique is feasible and that the installation of source and sensor in separate deep boreholes provides a suitable environment for this type of study. The boreholes could also be used for a considerable range of other types of instrumentation.  相似文献   

Analysis of anthropogenic CO₂ signal in ICARTT using a regional chemical transport model and observed tracers     

J. E. CAMPBELL  G. R. CARMICHAEL  Y. TANG  T. CHAI  S. A. VAY  Y.-H. CHOI  G. W. SACHSE  H. B. SINGH  J. L. SCHNOOR  J. WOO  J. M. VUKOVICH  D. G. STREETS  L. G. HUEY  C. O. STANIER 《Tellus. Series B, Chemical and physical meteorology》2007,59(2):199-210

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