HIGH-FREQUENCY SHALLOW SEISMIC REFLECTION MAPPING IN TIN MINING*

Field results of shallow seismic reflections obtained with a propane-oxygen detonator (POD) are presented. The survey site was in a tin-mining area of the Kinta Valley in Malaysia. The shallow and irregular limestone bedrock is overlain by alluvial “tailing” and virgin sediments. Sizes of such mining areas can range from about 320 ± 320 m² to 900 ± 900 m². The survey was intended to delineate the topography of the bedrock, which is of vital importance in tin ore exploration and exploitation. The equipment included single- and 12-channel signal enhancement seismographs, the POD, a hammer and thumper. The inexpensive and portable POD generates directional waves of reproducible form, variable energy of high frequency, and only a few surface waves at short offsets. Reflections at around 200 Hz were obtained from the shallow bedrock at about 25 m as well as from very shallow lithological interfaces. The interpretation of seismograms is supported by drill-hole lithological sections and synthetic seismograms. The data illustrate the successful use of shallow reflections for mapping irregular bedrock. Reflection seismics can provide better horizontal and vertical details than the refraction method. Further improvements based on the data-processing flexibility of new signal enhancement seismographs and synthetic seismograms are suggested.     

EVALUATION AND GENERALIZATION OF 13 MASS-TRANSFER EQUATIONS FOR DETERMINING FREE WATER EVAPORATION

Thirteen equations based on the mass-transfer method for determining free water evaporation were expressed in seven generalized equations. These seven equations were then compared with pan evaporation at four climatological stations in north-western Ontario, Canada. The comparisons were based on monthly evaporation. Equations were compared by calibrating them on the entire data sets as well as by calibrating on part of the data and then verifying them on the remainder of the data. The results of comparison showed that all equations were in reasonable agreement with observed evaporation, and that the effect of wind velocity on monthly evaporation was marginal. However, when an equation with parameters obtained at one site was applied to compute evaporation at another site, the computed evaporation was not in good agreement with observed values. © 1997 by John Wiley & Sons, Ltd.     

KINEMATIC WAVE MODELLING OF VERTICAL MOVEMENT OF SNOWMELT WATER THROUGH A SNOWPACK

Vertical movement of snowmelt water through snowpacks is modelled by applying the kinematic wave theory. Analytical solutions are obtained for moisture flux, particle velocity, time history and velocity of meltwater front and total moisture content for a single melt event assuming that the melt rate is constant. These solutions are extended to the case involving more than one event. © 1997 by John Wiley & Sons Ltd.     

THE USE OF ENTROPY IN HYDROLOGY AND WATER RESOURCES

Since the development of the entropy theory by Shannon in the late 1940s and of the principle of maximum entropy (POME) by Jaynes in the late 1950s there has been a proliferation of applications of entropy in a wide spectrum of areas, including hydrological and environmental sciences. The real impetus to entropy-based hydrological modelling was provided by Amorocho and Espildora in 1972. A great variety of entropy applications in hydrology and water resources have since been reported, and new applications continue to unfold. This paper reviews the recent contributions on entropy applications in hydrology and water resources, discusses the usefulness and versatility of the entropy concept, and reflects on the strengths and limitations of this concept. The paper concludes with comments on its implications in developing countries. © 1997 by John Wiley & Sons, Ltd.     

ERRORS OF KINEMATIC-WAVE AND DIFFUSION-WAVE APPROXIMATIONS FOR SPACE-INDEPENDENT FLOWS ON INFILTRATING SURFACES

Error equations for the kinematic-wave and diffusion-wave approximations were derived under simplified conditions for space-independent flows occurring on infiltrating planes or channels. These equations specify error as a function of time in the flow hydrograph. The kinematic-wave, diffusion wave and dynamic-wave solutions were parameterized through a dimensionless parameter γ which is dependent on the initial conditions. This parameter reflects the effect of initial flow depth, channel-bed slope, lateral inflow and channel roughness when the initial condition is non-vanishing; and it reflects the effect of bed slope, channel roughness, lateral inflow and infiltration when the initial condition is vanishing. The error equations were found to be the Riccati equation.     

Assessment of glacier stored water in Karakoram Himalaya using satellite remote sensing and field investigation

Karakoram Himalaya(KH) has continental climatic conditions and possesses largest concentration of glaciers outside the polar regions. The melt water from these glaciers is a major contributor to the Indus river. In this study, various methods have been used to estimate the ice volume in the Karakoram Range of glaciers such as Coregistration of Optically Sensed Images and Correlation(COSI-Corr) method and Area-Volume relations. Landsat 8 satellite data has been used to generate the ice displacement, velocity and thickness map. Our study for 558 Karakoram glaciers revealed that the average ice thickness in Karakoram is 90 m. Ground Penetrating Radar(GPR) survey has been conducted in one of the KH glacier i.e. Saser La glacier and the collected GPR data is used for the validation of satellite derived thickness map. GPR measured glacier thickness values are found comparable with satellite estimated values with RMSE of 4.3 m. The total ice volume of the Karakoram glaciers is estimated to be 1607±19 km3(1473±17 Gt), which is equivalent to 1473±17 km3 of water equivalent. Present study also covers the analysis of glacier surface displacement, velocity and ice thickness values with reference to glacier mean slope.     

Strange attractors in the Saturn ring system

The three rings A, B and C of Saturn and the two gaps French and Cassini divisions in between them have been subjected to a study of deterministic chaos and we have shown the existence of spatially distributed strange attractors, implying thereby that the system is open, dissipative, nonequilibrium and non-Markovian in character.     

Groundwater Prospect Zoning Using Remote Sensing and Geographical Information System: A Case Study in Dala-Renukoot Area, Sonbhadra District, Uttar Pradesh

In the present study, ground water prospect zones in Dala-Renukoot area, in Sonebhadra district. Uttar Pradesh, India have been delineated, through integration of various thematic maps using ARC/INFO GIS. Thematic maps in respect of geology, geomorphology. slope, drainage, land-use/land cover, lineament and lineament intersection frequency were prepared on 1:50,000 scale using remote sensing and conventional methods. These maps were scanned and registered with reference to a basemap and are input as separate layers using ARC/INFO GIS. Each theme was assigned a weightage depending on its influence on the movement and storage of groundwater and each unit in every theme map is assigned a knowledge based ranking from 1 to 5 depending on its significance to groundwater occurrence. All the themes are overlaid, two at a time and the resultant composite coverage is classified into five groundwater prospect categories. This output map is correlated with the groundwater data collected in the field.