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421.
Zhang Zhiqiang Wang Gongwen Carranza Emmanuel John M. Yang Shuren Zhao Ke Yang Wangdong Sha Deming 《Natural Resources Research》2022,31(4):2163-2179
Natural Resources Research - Methods for the analysis and integration of multi-source geophysical datasets are fundamental technologies for three-dimensional (3D) geological modeling and subsurface... 相似文献
422.
Natural Resources Research - The special issue entitled “Developments in Quantitative Assessment and Modeling of Mineral Resource Potential” is composed of 17 papers that cover a... 相似文献
423.
Akoanung Ayaba ABENDONG ENDENE Emmanuel Enoh Jeanot FONGOH AKOACHERE Richard Ayuk II NJENG Napoleon Ngenge 《地下水科学与工程》2014,7(2):182-194
The need to understand flow within aquiferous formations for a complete evaluation of groundwater resource and quality control prompts the determination of groundwater velocities through well dilution technique. Well dilution techniques utilize tracer solutions after establishing an initial homogenous condition to monitor the flow rate of ambient groundwater into the wells. Application of dilution techniques in wells makes it feasible to determine the velocities of groundwater in the aquiferous formation surrounding the well. In this study, a simple trigger-tube tracer dilution technique was employed to determine the Darcy and apparent velocities of groundwater in the phreatic aquiferous formation in Bamenda, Cameroon. Eighteen (18) hand dug-wells at different locations within Bamenda were sampled by utilizing sodium chloride (NaCl) as the conservative tracer. Field estimates of groundwater flow velocities in the phreatic aquiferous formation in Bamenda reveal Darcy’s groundwater velocity in the range of 0.39 m/d at Nacho to 130.64 m/d at Foncha Street and apparent velocity in the range of 0.78 m/d at Nacho to 277.86 m/d at Foncha Street. The immense variations in the velocities of groundwater indicate that the groundwater flows at different rates and directions within the aquiferous formation in Bamenda, possibly due to variations in their hydraulic conductivities. Moreover, the spatial variations in the formation types, facies changes, thickness, and layering of the aquiferous formation also contribute to the variation of velocities. Areas with low groundwater velocities are associated with a lower contaminant transport rate when compared to areas with high groundwater velocities. The findings of this study are important for assessing the rates of pollutant movement in the subsurface, as well as the effectiveness and efficacy of the trigger-tube technique in evaluating the hydraulic properties of aquiferous formations. 相似文献
424.
425.
Long-term monitoring of a large deep-seated landslide (La Clapiere,South-East French Alps): initial study 总被引:1,自引:1,他引:0
Edouard Palis Thomas Lebourg Emmanuel Tric Jean-Philippe Malet Maurin Vidal 《Landslides》2017,14(1):155-170
The large-scale deformation of high mountain slopes finds its origin in many phenomena (inherent parameters, external stresses) with very different time constants (instantaneous to geological scale). Gravitational effect, tectonic forces and water infiltration are generally the principal causes of slope instability. However, it can be very difficult to distinguish which cause is dominant and which are their respective effects. To gain a better understanding of the complex processes taking place during the evolution of an unstable slope and separate the causes responsible of the landslide dynamic, an observational study based on geodetic, meteorological, seismological and electrical data has been performed on the La Clapière rockslide (Southern French Alps). This deep-seated landslide (DSL) is known for many years as one of the largest and fastest rock slide in Europe (60 million m3 of highly weathered metamorphic material, moving at 1 to 3 m year?1). The set-up of the “Observatoire Multidisciplinaire des Instabilités de Versants” (OMIV, http://omiv.osug.fr) in 2011 has allowed the production and availability of an important and original data set over several years of accurate monitoring. Thus, for the first time, the long-term study of geodetic data permitted us to highlight acceleration phases in the general movement of the landslide that affect its dynamic. These modifications are associated with variations of the velocity by a factor 3 to 6. The characterization of the origin of these variations was possible due to the comparison with meteorological, electrical and seismological data. Based on these various signals, we were able to establish correlations and contributions of meteorological water infiltration in the dynamic evolution of the La Clapière slope. We determine several response times to the meteorological stress for seismic endogenous events (mainly rockfalls), the resistivity of the ground (quasi-instantaneous) and the kinematics of the slope (from 2 weeks to 2.5 months). Moreover, our results strongly suggest the existence of rainfall threshold of 3.5?±?1 mm day?1 from which the number of seismic endogenous events is highly increased. 相似文献
426.
Kouakou Valentin Koffi Emmanuel Obuobie Andre Banning Stefan Wohnlich 《Environmental Earth Sciences》2017,76(4):185
The Vea catchment, mainly underlain by crystalline basement rocks, is located in Northern Ghana. Hydrogeochemical studies were carried out in this area with the objective of identifying the geochemical processes influencing water quality and suitability of surface and groundwater for agricultural and domestic uses. Sixty-one groundwater and four surface water samples were collected from boreholes, dams and rivers and analysed for Ca2+, Mg2+, Na+, K+, HCO3 ?, Cl?, and SO4 2?, Fetot, PO4 3?, Mntot, NH4 +, NO3 ?, NO2 ?. In addition, pH, total dissolved solids, electrical conductivity, total hardness, turbidity, colour, salinity and dissolved oxygen were analysed. Chloro-alkaline indices 1 and 2, and characterization of weathering processes suggest that the chemistry of groundwater is dominated by the interaction between water and rocks. Cation exchange and silicate weathering are the dominant processes controlling the chemical composition of the groundwater in the area studied. Mineral saturation indices indicate the presence of at least three groups of groundwater in the Vea catchment with respect to residence time. The meteoric genesis index suggests that 86% of the water samples belong to the shallow meteoric water percolation type. The findings further suggest that the groundwater and surface water in the basin studied are mainly Ca–Mg–HCO3 water type, regardless of the geology. Compared to the water quality guidelines of WHO, the study results on sodium absorption ratio, sodium percentage, magnesium hazard, permeability index and residual sodium carbonate indicate that groundwater and surface water in the Vea catchment are generally suitable for drinking and irrigation purposes. 相似文献
427.
Single-element Anomaly Mapping from Stream Sediment Geochemical Landscapes Aided by Digital Terrain Analysis
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The identification of anomalies within stream sediment geochemical data is one of the fastest developing areas in mineral exploration. The various means used to achieve this objective make use of either continuous or discrete field models of stream sediment geochemical data. To map anomalies in a discrete field model of such data, two corrections are required: background correction and downstream dilution correction. Topography and geomorphology are important factors in variations of element con... 相似文献
428.