Assessing the influence of morpho-structural setting on landslide abundance

Knowing the factors that influence landslide abundance and distribution is important to evaluate landslide susceptibility and hazard. Visual interpretation of aerial photographs (API) can be used to collect spatially distributed information on bedding attitude (BA), in an area. Where a map of the location of bedding traces (BTs), i.e. lines showing the intersection of bedding planes with the local topography, is available, the map can be used to obtain BA point data and to prepare maps showing morpho-structural domains. The possibility of using BA maps to investigate the influence of morpho-structural settings on landslide abundance is hampered by the lack of understanding of the influence of the length of the BTs, and of the parameters used to interpolate the BA data on the structural zonation. To investigate the problem, we used information on 207 BTs obtained through API in the Collazzone area, Central Italy, and we prepared 150 maps showing BA information. This was accomplished using 15 different values for the segmentation length of the BTs (S), and 10 different values for the tension parameter (T) used for the interpolation. We compare the results against previous results obtained for the same area adopting a heuristic approach to the segmentation of the same set of BTs. Next, we compare the geographical distribution of old deep-seated, deep-seated and shallow landslides in five morpho-structural domains in the study area, and we analyse the influence of the structural settings on the abundance of the different types of landslides.     

新编华南花岗岩分布图及其说明

展示了新编的<华南花岗岩分布图(1:250万)>,并作了简要说明.该图在前人相关图件的基础上,收集了近15年来华南花岗岩研究的新的主量元素和年代学资料修编而成.此外,该图反映了华南不同时代花岗岩的富铝程度.     

Discrete element analysis for active and passive pressure distribution on retaining wall

Analysis based on Discrete Element Method (DEM) is presented for active and passive earth pressure distribution behind a retaining wall under different modes of wall movement. Soil mass in the present model is treated as comprising of blocks which are connected by elasto-plastic Winkler-springs. The solution of this method satisfies all equilibrium and compatibility conditions. Formulation of the method is briefly reviewed. Examples are shown to demonstrate the applicability of the method for analyses of earth pressure behind a gravity retaining wall. The DEM can be used to study the sliding patterns of backfill blocks which effect the earth pressure distribution behind the wall. Advantages of this method over the conventional limit equilibrium method are also discussed.     

条子泥围垦区水盐特征与植被分布的关系

为了探究江苏东台条子泥围垦区的水盐分布规律,揭示圆环状植被分布与土壤水盐条件的关系,于2019年9月对围垦区内用作湿地恢复的区域进行测量和采样。在植被环附近测量了二维、三维大地电阻率,采集降水、地表水、土壤、地下水等样品,测试样品的水盐指标和D、18O同位素组成。结果表明:植被圆环下方3 m深度内均存在对应的高电阻率/低盐度区域,且随着植被类型由中心向外环变化,对应的土壤水盐度也逐渐增大;土壤水盐度是不同植被呈现圆环状分布的重要影响因素,其变化受降水入渗和土壤蒸发引起的盐分集结共同作用;土壤盐度直接影响了不同植被种群的分布格局,而植被对入渗和蒸发过程的影响也反作用于土壤盐度分布。     

Source distribution of ocean microseisms and implications for time-dependent noise tomography

A qualitative analysis of ocean microseism source distribution observed in North America during fall and winter months was carried out. I review the theory of the origin of ocean microseisms and show that it can be used in conjunction with wave-wave interaction maps to quantify the source distribution anisotropy. It is demonstrated that microseisms generation in the North Atlantic and in the North Pacific Oceans are inherently different. North Atlantic microseisms are generated predominantly in the deep ocean, while North Pacific microseisms are dominated by coastal reflections. In spite of these differences both result from repeated ocean wave patterns that give rise to an anisotropic noise pattern, which cannot be randomized by time averaging. Considering time-varying ambient noise imaging, which aims to resolve a fraction of a percent changes in the crust over short distances, the source anisotropy would introduce a relatively significant error that needs to be accounted for.     

SOME LAWS GOVERNING THE REGIONAL GEOLOGIC OCCURRENCE OF FERROUS AND NONFERROUS METAL ORES

This article surveys the geographical distribution of metal ores, grouped into six categories: iron, manganese, chromium, silver-lead-zinc, copper and tin. The author reviews the occurrence of these ores throughout the world, and their association primarily with broad geotectonic zones. The essential information is encompassed in six maps. Legends explain the classification of the deposits by age (metallogenic eras), type and paragenetic associations of minerals. The symbols for these various classifications of ores are superimposed on maps showing the zones of Precambrian (cratonal), Paleozoic, Mesozoic and Cenozoic folding. The particular interest of this paper is that the author has made this survey as a preliminary to dividing the earth's surface into metallogenic provinces (of which he distinguishes 21), giving a brief discussion of each and showing its connection to areas of different ages and geotectonic structures. The ultimate aim is to construct “prognostic maps”, or maps drawn on such a basis that they may be used to predict the occurrence of a given ore or ores in a given region. — Paul T. Broneer     

Rapid evaluation of the hydrochemistry of a sedimentary basin using only ‘standard’ formation water analyses: example from the Canadian portion of the Williston Basin

The Canadian portion of the Williston Basin is used as an example of how > 15,000 ‘standard’ formation water analyses in about 15 aquifers can be evaluated rapidly using easily available culling and data distribution display software. Techniques and software used include a program for culling erroneous and missing data in ‘standard’ formation water analyses, electronic grids of stratigraphic surfaces and unit boundaries from the new Geological Atlas of the Western Canada Sedimentary Basin, grid manipulation software, and a geochemical modelling program (SOLMINEQ.88).Intra- and inter-basinal hydrochemical continuity at the regional scale was matched visually by comparing salinity maps on the Canadian side of the basin with salinity maps from the American side, and with the adjacent Alberta Basin. Inter-aquifer continuity to identify aquifer systems and the relative strength of aquitards was determined using a combination of. (1) salinity distribution maps; (2) maps showing salinity differences between aquifers and across intervening aquitards; and (3) the relation among SO₄ in formation waters, the distribution of anhydrite, and the saturation of the formation waters with respect to anhydrite. Evaporites strongly influence the composition of adjacent formation waters, even to the extent that in one aquifer the normal increase of salinity with depth is reversed. The process of freshwater influx into the western part of the basin is demonstrated by a series of salinity maps; they suggest that the process is current and has included removal of halite from the major basinal aquitard. This regional-scale evaluation required an elapsed time of only about 10 working days, hence a fairly rapid study.     

Sediment yield assessment and identification of check dam sites for Rawal Dam catchment

Sediment yield is the amount of erosional debris from drainage basin deposited in reservoirs. The economic life of storage reservoir depends upon the estimation of the time it takes for the reservoir to be filled with the deposition of sediments. This research is based on assessing the sediment yield in Rawal Dam catchment by using Soil and Water Assessment Tool (SWAT) model. Digital Elevation Model (DEM), land use maps, soil maps, and weather data of the study watershed were used as input to SWAT model. Monthly sedimentation data of year 2010 and discharge data from 1998 to 2005 is being used for model calibration and validation, respectively. Whereas simulations are being generated from 1998 to 2011 for both sedimentation and discharge. Modified Universal Soil Loss Equation (MUSLE) was used for the estimation of sediment yield. The Nash and Sutcliffe coefficient of the model was found to be 0.79 which depicts its effectiveness. After the estimation of the sediment yield and discharge by using SWAT model, double mass curve was used to evaluate the sedimentation rate. The rate of sediment transport can be reduced by the construction of check dams. Various sites have also been proposed for check dams construction to prevent the sediments transported into the Rawal Catchment.     

Spatial analysis of land use and shallow groundwater vulnerability in the watershed adjacent to Assateague Island National Seashore,Maryland and Virginia,USA

Spatial relations between land use and groundwater quality in the watershed adjacent to Assateague Island National Seashore, Maryland and Virginia, USA were analyzed by the use of two spatial models. One model used a logit analysis and the other was based on geostatistics. The models were developed and compared on the basis of existing concentrations of nitrate as nitrogen in samples from 529 domestic wells. The models were applied to produce spatial probability maps that show areas in the watershed where concentrations of nitrate in groundwater are likely to exceed a predetermined management threshold value. Maps of the watershed generated by logistic regression and probability kriging analysis showing where the probability of nitrate concentrations would exceed 3 mg/L (>0.50) compared favorably. Logistic regression was less dependent on the spatial distribution of sampled wells, and identified an additional high probability area within the watershed that was missed by probability kriging. The spatial probability maps could be used to determine the natural or anthropogenic factors that best explain the occurrence and distribution of elevated concentrations of nitrate (or other constituents) in shallow groundwater. This information can be used by local land-use planners, ecologists, and managers to protect water supplies and identify land-use planning solutions and monitoring programs in vulnerable areas.     

An improved Monte Carlo simulation method for discontinuity orientations based on Fisher distribution and its program implementation

Fisher distribution is the most commonly used probability density function for discontinuity orientations. Based on Fisher distribution, Monte Carlo simulation method for discontinuity orientations was reviewed and improved. Those orientations extending beyond the edge of an upper hemisphere projection (OEBEUHP) often have an important influence on both the mean orientation and Fisher constant K, thus affecting simulation results. The detailed algorithms for identifying and adjusting those OEBEUHP were developed in this paper. Based on the improved method, a program for generating discontinuity orientations and plotting their stereographic projection maps, named as MCSDO, was developed. Due to the aforementioned adjustment, the generated orientations by MCSDO are close to the original discontinuity orientations, which were mapped in field, and satisfactory. Only the original orientations and target number of generated orientations need to be input. By running the program we can directly obtain the follows: orientations of generated discontinuities, mean orientations of both original and generated discontinuities, Fisher constant K of both original and generated discontinuities, and stereographic projection maps of both original and generated discontinuities. MCSDO is a freeware designed for researchers and practicing engineers, and can be easily mastered with a little computer knowledge.     

Assessment of the spatio-temporal distribution of soil properties in East Kolkata wetland ecosystem (A Ramsar site: 1208)

The present investigation was made to characterize spatial and temporal variations in soil properties and to evaluate possible differences that could be dependent on the tannery effluent discharges, municipal sewage discharges, vegetation cover, soil settlement rate, crop rotation, etc. Soil total organic matter (TOM), cations like, Sodium (Na), Ammonium (NH₄), Potassium (K), Calcium (Ca) and Magnesium (Mg) contents in the bank soils and bottom sediments were recorded from seven different characteristic sites in East Kolkata wetland ecosystem, a Ramsar site (Ramsar site No. 1208). The profile maps were constructed by geostatistical methods to describe the spatial distribution as well as temporal variations of all the factors to identify the influences of composite wastewaters. The work was initiated to identify causes and consequences of the waste dumping in the concerned region for the past hundred years and thereby to suggest necessary precautionary measures to prevent further loss of soil quality.     

Spatial distribution of uranium and vanadium in the upper phosphorite member in Eshidiyya basin, southern Jordan

Geostatistical analysis of geochemical exploration data can provide useful information for evaluating the mineralization potential of geologic bodies. The main objective of this study was to evaluate the spatial distribution of U and V over an area in the upper phosphorite member, the A0 unit, in Eshidiyya basin in southern Jordan. Drill-hole samples were analyzed. The geochemistry of the analyzed elements was assessed. The spatial variability of U and V was also assessed using semivariance analysis. Both U and V were found to exhibit a normal distribution as indicated by the constructed histograms and the calculated skewness and kurtosis coefficients. Exponential models with nugget effects were fitted to the experimental semivariograms. Ordinary kriging was performed to generate geochemical maps. The applied interpolation technique proved to be the best in producing geochemical exploration maps for both U and V in Eshidiyya phosphorites. The constructed geochemical maps helped visualize a WNW–ESE U mineralization trend in the studied phosphorites. This trend should be taken into consideration in any future exploration programs for U in south Jordan.     

The Distrbution of Various Mercury Species in Soil

According to the mercury species with different solubilities,the analytical procedure involving sequential chemical extraction has been applied to partitioning the mercury species in soils into seven fractions.Soil samples collected from five localities in different areas (the high-mercury ares.the man-made mercury-polluted area and the reference area)were an alyzed for the seven mercury species.It is found that high mercury contents of soils can be attributed to both man-made pollution and geological processes,but the two kinds of solis show obvious differences in the distribution of their mercury species.     

Sinkhole distribution in a rapidly developing urban environment: Hillsborough County, Tampa Bay area, Florida

Sinkhole formation in Florida is a common event. The Florida karst plain is significantly altered by human development and sinkholes cause considerable property damage throughout much of the state. We present in this paper a morphometric analysis of karst depressions in the Tampa Bay area, and the relation with the known distribution of sinkholes. We selected the Tampa Bay area because it is particularly susceptible to the evolution of karst depressions in relation with development of the built-up environment. Karst depressions were mapped from the 1:24,000 USGS topographic maps and a morphometric analysis was performed by using parameters such as shape, circularity index, perimeter, area, length, width, and orientation. Maps showing the distribution of depression density, and the sectors with greatest areas of karst depression were produced using a GIS. These results were compared with data compiled from the database of sinkhole occurrences in Florida maintained by the Florida Geological Survey. Our analysis demonstrates that the distribution of new sinkhole occurrences differs from the distribution of existing sinkholes, indicating that there are processes acting today that are influencing karst landscape formation that are different from those acting in the past.     

Resource suitability analysis in regional planning—with special reference to Wisconsin,USA

The demands and needs of our presently increasing population require that the social decisions for land use must be based on the best and most reliable information that the decision-makers can obtain. Growing mass of natural resource information should be presented in a concise and practical form which the planners and public administrators can readily use without a need to learn about natural resources in detail. One of the means to present this information is a resource evaluation system which consists of four levels of maps: basic resource maps, single-factor maps, limiting-factor maps and final land suitability maps. The basic process used in the system is developing a series of individual maps showing specific kinds of information and superimposing them to identify a degree of suitability for a specific land use. The authors provide an overview of the use of land suitability maps in land use planning in the United States; show what natural resource data planners can require and put to use; outline the way in which earth scientists can evaluate and present the data needed; and finally demonstrate the land suitability analysis by case studies. Also briefly discussed is the need for information other than earth-science data. Land use planning and decision-making process is an intricate mixture of scientific, engineering, ecological, sociological, economic, cultural and political factors and forces. Obvious as it may seem this fact is nevertheless often ignored in practice resulting in misunderstandings and mutual disbelief of parties involved.     

Mineral potential mapping for rare earth elements mineralization with AHP method in the Kerman-Kashmar Tectonic Zone,Central Iran

One of the major strengths of a GIS is the ability to integrate and combine multiple layers of geoscience data for producing mineral potential maps showing favorable areas for mineral exploration. Once the data is prepared properly, the GIS, jointly with other statistical and geostatistical software packages, can be used to manipulate and visualize the data in order to produce a mineral prospectivity map. Many spatial modeling techniques can be employed to produce mineral potential maps. This paper demonstrates a technique to define favorable areas for REE mineralization with AHP technique using geological, geochemical, geophysical, alteration and faults density spatial data in the Kerman-Kashmar Tectonic Zone of central Iran. The AHP is a powerful and flexible multi-criteria decision-making tool for dealing with complex problems where both qualitative and quantitative aspects need to be considered. This approach is knowledgedriven method and can be applied in other areas for conventional use in mineral exploration.     

属性数据与空间数据连接对土壤有机碳储量估算的影响

土壤有机碳(Soil Organic Carbon, SOC) 库在陆地生态系统中具有重要作用。在基于GIS利用土壤类型法估算SOC储量时,由于土壤图比例尺的限制,属性数据与空间数据的连接会导致对SOC储量的估算结果产生很大不确定性。利用中国滇黔桂地区（云南省、贵州省和广西壮族自治区）798个土壤剖面及1∶[KG-*2]50万土壤图在不同的制图单元水平上,分别采用算术平均值法、中值法和面积加权平均值法（以土种志中的面积为权重）估算了该地区1 m深度SOC储量,并与基于土壤学专业知识连接方法（Pedological Knowledge Based Method, PKB）的估算结果进行了比较。结果表明：面积加权平均值法比中值法和算术平均值法的估算结果更为准确,而且在土类、亚类和土属水平上应用面积加权平均值法对SOC储量的估算结果差异不大。在采用较大比例尺、较为详细的土壤图时,PKB法较理想;反之,则面积加权平均值法较好。     

GIS-based prospectivity-mapping based on geochemical multivariate analysis technology: A case study of MVT Pb–Zn deposits in the Huanyuan-Fenghuang district,northwestern Hunan Province,China

This paper demonstrates a partial least-squares regression (PLS) method for geochemical modelling, and then uses the models and geological favourable features to obtain mineral potential maps. The PLS is one of multivariate analysis technologies, which can identify variations in associations and correlations among geochemical elements and mineralisation. The method is here used to calculate principal components as well as to identify correlations between Pb–Zn (mineralization) and 25 stream sediment elements for constructing geochemical models in the Huayuan-Fenghuang district of northwestern Hunan Province, China. The models showing the distribution of geochemical anomaly are useful in interpreting the distribution of faults and the Cambrian Qingxudong Formation (ore-bearing formation), and to better define the architecture on mineralisation in the study area. In addition, the models and other favourable features (proxies) are easily integrated into single possibility map by Boost Weights-of-Evidence (Boost WofE) approach for targets.     

Frequency distribution of river bed materials

The size distribution of river bed material plays an important role in the study of fluvial hydraulic processes. It is not always easy to sample the river bed material for the determination of its size distribution, but knowledge of the frequency distribution and of bed material sizes can be used to predict its size distribution. Therefore, data on bed material size distributions of 63 streams from 10 different countries have been analysed to determine the frequency distribution which can be best fitted to them. The log normal distribution cannot be fitted to the bed material mixtures when the entire range of sizes is considered. The method of power transformation is found to normalize these mixtures. Relationships have been proposed between the parameters of the normalization and the stream slope. These relations can be used to predict the size distribution of the river bed material.     

Prediction of spatial soil organic carbon distribution using Sentinel-2A and field inventory data in Sariska Tiger Reserve

Dynamic and vigorous top soil is the source for healthy flora, fauna, and humans, and soil organic matters are the underpinning for healthy and productive soils. Organic components in the soil play significant role in stimulating soil productivity processes and vegetation development. This article deals with the scientific demand for estimating soil organic carbon (SOC) in forest using geospatial techniques. We assessed distribution of SOC using field and satellite data in Sariska Tiger Reserve located in the Aravalli Hill Range, India. This study utilized the visible and near-infrared reflectance data of Sentinel-2A satellite. Three predictor variables namely Normalized Difference Vegetation Index, Soil Adjusted Vegetation Index, and Renormalized Difference Vegetation Index were derived to examine the relationship between soil and SOC and to identify the biophysical characteristic of soil. Relationship between SOC (ground and predicted) and leaf area index (LAI) measured through satellite data was examined through regression analysis. Coefficient of correlation (R ²) was found to be 0.95 (p value < 0.05) for predicted SOC and satellite measured LAI. Thus, LAI can effectively be used for extracting SOC using remote sensing data. Soil organic carbon stock map generated through Kriging model for Landsat 8 OLI data demonstrated variation in spatial SOC stocks distribution. The model with 89% accuracy has proved to be an effective tool for predicting spatial distribution of SOC stocks in the study area. Thus, optical remote sensing data have immense potential for predicting SOC at larger scale.