Changes in the spatial distribution of subtidal macrobenthos due to predation by white shrimp (<Emphasis Type="Italic">Litopenaeus setiferus</Emphasis>)

Manipulative caging experiments were conducted in North Inlet, South Carolina, to measure the predatory effect of juvenile penaeid white shrimp,Litopenaeus setiferus, on their subtidal macrobenthic prey. We used the natural neighbor interpolation procedure within a Geographic Information System (GIS) to map macrobenthos distributions at both the start and end of the cage deployments. Moran’s I, a commonly used index of spatial autocorrelation, provided a quantitative metric for evaluating the statistical significance of the observed changes. We tested the hypothesis that juvenile white shrimp are optimal foragers by assessing whether their predatory behavior was targeted at higher density macrobenthos patches inside the enclosures, resulting in a more homogeneous distribution of prey after seven days. Since large changes in patchiness could occur over seven days without incurring a significant change in index value, we treated each index as a continuous measure of patchiness, and examined whether the value increased or decreased consistently among treatment replicates. Using Moran’s I, the abundance and spatial distribution of macrobenthos inside control, partial, open, and shrimp inclusion treatments varied in their response. After seven days, decreased patchiness was consistently observed in the high density shrimp treatment replicates, and increased patchiness in the open plots. The GIS natural neighbor interpolation created a succinct visual representation of dramatic changes in prey spatial distribution and prey densities throughout each cage. The GIS interpolation conveyed the dynamic nature of the spatial variability that would not have been evident by calculation of Moran’s I alone. Although we could only weakly support our hypothesis, the combination of visual interpolation methods with index calculations has great potential for gaining further insights into the role of different factors as they affect changes in spatial distribution of benthic infauna.     

Factors of poultry farming adoption in Oyo State,Nigeria: A study in agency- and infrastructure-based diffusion

In this paper, use is made of the multiple regression technique in an attempt to provide explanation for the pattern of adoption of intensive poultry farming technique — an agency and infrastructure based innovation. This paper deals with two aspects of the diffusion. The first examines the factors of spatial pattern of adoption and the second, the adoption intensity. The paper then turns to consider the planning implications of these factors. In Oyo State, market factor expressed as the population size of towns, distance to agency location and from previous adopters largely account for the spatial variation in the time of adoption of ‘modern’ poultry farming technique. The intensity of adoption (poultry population) on the other hand is influenced by the number of adopters, distance to infrastructure, profitability considerations, literacy factor and the time of adoption.     

Use of satellite remote sensing data in the mapping of global landslide susceptibility

Satellite remote sensing data has significant potential use in analysis of natural hazards such as landslides. Relying on the recent advances in satellite remote sensing and geographic information system (GIS) techniques, this paper aims to map landslide susceptibility over most of the globe using a GIS-based weighted linear combination method. First, six relevant landslide-controlling factors are derived from geospatial remote sensing data and coded into a GIS system. Next, continuous susceptibility values from low to high are assigned to each of the six factors. Second, a continuous scale of a global landslide susceptibility index is derived using GIS weighted linear combination based on each factor’s relative significance to the process of landslide occurrence (e.g., slope is the most important factor, soil types and soil texture are also primary-level parameters, while elevation, land cover types, and drainage density are secondary in importance). Finally, the continuous index map is further classified into six susceptibility categories. Results show the hot spots of landslide-prone regions include the Pacific Rim, the Himalayas and South Asia, Rocky Mountains, Appalachian Mountains, Alps, and parts of the Middle East and Africa. India, China, Nepal, Japan, the USA, and Peru are shown to have landslide-prone areas. This first-cut global landslide susceptibility map forms a starting point to provide a global view of landslide risks and may be used in conjunction with satellite-based precipitation information to potentially detect areas with significant landslide potential due to heavy rainfall.     

Rock Joint Surfaces Measurement and Analysis of Aperture Distribution under Different Normal and Shear Loading using GIS

Summary The geometry of the rock joint is a governing factor for joint mechanical and hydraulic behaviour. A new method for evaluating the aperture distribution, based on measurement of joint surfaces and three dimensional characteristics of each surface, is developed. This method allows one to determine and visualize the aperture distribution under different normal stresses and shear displacements, which is difficult to observe experimentally. A new laser scanner system is designed and developed for joint surface measurements. Special attention is paid to both surfaces’ data gained by measurements and processing, such as x-y coordinate table modification, data referencing, and matching between upper and lower surfaces. The surfaces of an artificial joint in granite are measured, processed, analyzed and three dimensional approaches are carried out for surface characterization. Parameters such as “asperity’s heights”, “slope angles”, and “aspects” distribution at micro scale, local concentration of elements and their spatial localization at local scale are determined by Geographic Information System (GIS). These parameters are used for joint surfaces matching and its real behavior quantitative analysis. The upper surface is brought down to make contact with the lower surface and the distance between the two surfaces is evaluated from the joint mean experimental aperture, which is obtained from normal and shear tests. Changes of aperture distribution at different normal stresses and various shear displacements are visualized and interpreted. Increasing normal load causes negative changes in aperture frequency distribution which indicates high joint matching. However, increasing shear displacement causes a rapid increase in the aperture and positive changes in the aperture frequency distribution, which could be due to un-matching, surface anisotropy and spatial localization of contact points with proceeding shear. Author’s address: Mostafa Sharifzadeh, Department of Mining, Metallurgy and Petroleum Engineering, Amirkabir University of Technology, Hafez 424, Tehran 15875-4413, Iran     

Late Miocene fluvial sediment transport from the southern Appalachian Mountains to southern Florida: An example of an old mountain belt sediment production surge

Past geomorphological models assume that erosion of sediments from old mountain belts occurred at a relatively constant rate, based on comparatively uniform isostatic adjustment caused by unloading. Late Miocene strata of the south‐eastern United States provide an example of pulsed tectonism resulting in a surge in siliciclastic sediment production and transport. Regional tectonism (uplift of the southern Appalachian Mountains) and climatic conditions during the Late Miocene resulted in the long‐distance (up to 1000 km) fluvial transport of coarse siliciclastic sediments onto a stable carbonate platform in southern Florida. The sediments are unusual in that they are significantly coarser than marine‐transported sands in southern Florida, with discoidal quartz and quartzite clasts up to 40 mm in diameter locally present, and have relatively high potassium feldspar contents (up to 16% in some sample fractions), whereas feldspar is rare in modern Florida beach sands. It is suggested that previously documented rejuvenation of the southern Appalachian Mountains during the Middle to Late Miocene time, coupled with the Messenian sea‐level low, generated the increased rate of sediment production and necessary hydraulic gradient to allow rapid transport of coarse sediments. Tectonic influence on the river pathway in Florida, as well as in the southern Appalachian Mountains, may have maintained the river on the narrow carbonate platform. The Florida Platform during the Late Miocene must also have had a sufficiently wet climate to cause episodic transport of the coarse sediments. Siliciclastic sediment transport on the Florida Platform during the Late Miocene greatly differed from Pleistocene to modern conditions, which are dominated by the transport of fine‐grained sands by longshore marine processes.     

Studies on the chromium concentrations in topsoils and subsoils of two rapidly industrialized cities in the Yangtze River Delta in east China

A total of 782 topsoil samples (0–20 cm) and 371 subsoil samples (20–40 cm) were collected from agricultural land in two rapidly industrialized areas with a large number of small rural industries in southeast China, Zhangjiagang City (ZJG) and Changshu City (CS), to measure soil chromium (Cr) concentrations. Kriging and cokriging were used to predict the spatial distribution of Cr in the topsoils and subsoils. Paired-samples t test and spatial distribution maps were used to compare the Cr concentrations in topsoils and subsoils. The mean Cr concentration in ZJG topsoils was significantly higher than that in ZJG subsoils and the mean Cr concentration in CS topsoils showed no significant difference from that in CS subsoils. The Cr concentrations in topsoils were higher than those in subsoils over most of the area of ZJG and part of CS, suggesting that Cr accumulation had occurred in these areas and extrinsic factors have an important role controlling the distribution of Cr in topsoils. Semivariogram/cross-semivariogram was used to evaluate soil Cr spatial variability. The Cr in ZJG topsoils, ZJG subsoils, and CS topsoils had moderate spatial dependence and the Cr in CS subsoils had strong spatial dependence. Cr in ZJG subsoils had longer effective range than Cr in ZJG topsoils, suggesting that the anthropogenic factors affecting Cr distribution in ZJG topsoils; and Cr in CS topsoils had longer effective range than Cr in CS subsoils, indicating that soil formation may be the major explanation for the decrease in the variation of Cr in topsoils. A significant correlation was found between the Cr in topsoils and Cr in subsoils, indicating that natural factors also play an important role as extrinsic factors that control the distribution of Cr in topsoils.     

Evidence of women’s empowerment in India: a study of socio-spatial disparities

Various national and international communities have addressed women’s issues and taken various efforts to empower them so as to enhance their social and health status and involve them in developmental activities. The Indian DHS survey (National Family Health Survey, 1998–1999) provides an opportunity to study women’s empowerment in India. The survey collected information on several dimensions of women’s empowerment from 90,303 ever-married women (ages 15–49), from all the states of India. Utilizing these data sets, four indices – household autonomy index, mobility index, attitude towards gender index and attitude towards domestic violence index – are constructed to measure the different dimensions of empowerment. Using these indices, the spatial and socio-economic and cultural disparities that exist within India are analyzed. Finally, an attempt is made to identify some important determinants for women’s empowerment using multiple logistic regression analysis. The results show that at the national level, 43% of the women have high household autonomy; 23% of the women have high freedom to move outside their home; 40% of the women have no gender preference attitude; and only 43% of the women defy domestic violence. But there are significant divergences in these indices of women’s empowerment across the different states and socio-economic and cultural settings within India. Women’s educational levels emerged as an important predictor for all the four dimensions of women’s empowerment. Additionally, media exposure and age have emerged as the important predictors for some dimensions of woman’s empowerment. This paper was presented by Prof. Kamla Gupta at the International Geographical Union Conference (IGU), held in Canada, 2002.     

Research on Temporal and Spatial Variation Characteristics of Vegetation Cover in Qilian Mountains from 1982 to 2006

Based on GIMMS NDVI data of Qilian Mountains region during 1982-2006, using the maximum synthesis, mean method, slope analysis and correlation analysis, the spatial and temporal changes of vegetation cover and its correlations with climatic factors were studied in Qilian Mountains. The results showed that: ①Vegetation NDVI of Qilian Mountains increases from west to east in general, showing the distribution pattern of much more vegetation in east regions than in west regions; ②Vegetation NDVI of Qilian Mountains has generally increased in the past twenty five years, but there are obvious spatial differences, especially vegetation NDVI of middle and east regions increase obviously; ③There have been obvious differences on spatial variation of seasonal NDVI in the past twenty five years in Qilian Mountains, and the increased area of vegetation NDVI is the largest in summer, followed by autumn, spring, but the most reduced area of vegetation NDVI is in winter. The regions of increased vegetation NDVI concentrate on southern mountain of Qinghai Province and in Buha River Basin, while the regions of reduced vegetation NDVI concentrate on Wushaoling, Lenglongling and Daban mountain in each season; ④The correlations between monthly average vegetation NDVI and temperature and precipitation are very significant, which indicates that temperature and precipitation are the main factors affecting the change of vegetation NDVI in Qilian Mountains, but intensive human activities are also important factors affecting the change of vegetation NDVI in some areas.     

寒冻风化控制的祁连山风化碎屑的空间分布

寒冻风化是冰缘地貌区及高寒山区的主要物理风化过程,其提供的风化碎屑物质是该区域崩塌等灾害性地貌过程的主要物质来源。由于寒冻风化对基岩的破碎是由温度控制的累积过程,过去温度变化对地貌演化具有重要意义,但其时间尺度的选取尚需进一步探究。因此本文选取祁连山北部为研究区,通过对比分析风化碎屑的空间分布特征与不同时间尺度温度变化控制的平均寒冻风化强度的空间分布特征,探讨干旱半干旱高寒山区风化碎屑空间分布的主要控制因素。结果显示,万年尺度及十万年尺度平均寒冻风化强度的高值与风化碎屑边界存在较好的空间一致性,祁连山西段万年尺度平均寒冻风化强度的高值与风化碎屑边界的空间相关性优于十万年尺度。本研究同时指出,温度升高导致寒冻风化的作用区向高海拔区域移动,进而产生新的高风险灾害区域。本研究强调寒冻风化对灾害性地貌过程的调控作用,为全球变暖背景下灾害性地貌过程的预测提供了新的思路,可以成为防灾减灾决策的重要参考。     

Present day relief-shaping systems acting on the southern slope of the Făgăraş Mountains (Romania)

The present topography of the Făgăraş Mountains is a snapshot of the long-term evolution that brought about significant alterations of the landscape, and especially of the relief, which has acquired different features depending on the intensity of the relationship between the exogenous and endogenous agents. At present, relief shaping in the study area is controlled by the orographic and climatic features. However, the climate of the high and middle-height mountains is the main cause that determines the mechanism, the intensity and the spatial distribution of the shaping processes. The considerable height of the Făgăraş Mountains, which exceeds 2500 m altitude is responsible for the vertical zonation of climate and vegetation which implicitly induce the setting of the systems of relief modelling, too.     

Some Results on the Spatial Breakdown Point of Robust Point Estimates of the Variogram

The effect of outliers on estimates of the variogram depends on how they are distributed in space. The ‘spatial breakdown point’ is the largest proportion of observations which can be drawn from some arbitrary contaminating process without destroying a robust variogram estimator, when they are arranged in the most damaging spatial pattern. A numerical method is presented to find the spatial breakdown point for any sample array in two dimensions or more. It is shown by means of some examples that such a numerical approach is needed to determine the spatial breakdown point for two or more dimensions, even on a regular square sample grid, since previous conjectures about the spatial breakdown point in two dimensions do not hold. The ‘average spatial breakdown point’ has been used as a basis for practical guidelines on the intensity of contaminating processes that can be tolerated by robust variogram estimators. It is the largest proportion of contaminating observations in a data set such that the breakdown point of the variance estimator used to obtain point estimates of the variogram is not exceeded by the expected proportion of contaminated pairs of observations over any lag. In this paper the behaviour of the average spatial breakdown point is investigated for cases where the contaminating process is spatially dependent. It is shown that in two dimensions the average spatial breakdown point is 0.25. Finally, the ‘empirical spatial breakdown point’, a tool for the exploratory analysis of spatial data thought to contain outliers, is introduced and demonstrated using data on metal content in the soils of Sheffield, England. The empirical spatial breakdown point of a particular data set can be used to indicate whether the distribution of possible contaminants is likely to undermine a robust variogram estimator.     

Disentangling Shallow and Deep Processes Causing Surface Movement

Understanding and predicting surface movement is important both technically and for social reasons. The shallow processes contributing to subsidence include construction works, peat oxidation, clay compaction, and groundwater withdrawal; deep causes are hydrocarbon and salt production. We describe an inversion procedure we have devised to disentangle the deep and shallow causes of surface movement. It employs a Bayesian inversion scheme, using forward models and other ‘a priori’ information about shallow and deep compaction. Parameter estimation thus takes place at two different depths, thereby disentangling the deep and shallow compaction processes responsible for surface movement. The uncertainty in the surface measurements and ‘a priori’ estimates is naturally incorporated. Furthermore, spatial and temporal correlations can be taken into account through inclusion of the covariance matrix. The inversion scheme is demonstrated for two synthetic cases. The first combines a compacting gas field and a compacting shallow peat layer. We demonstrate that assumptions on the shape of the subsidence bowl are not necessary. We also show how neglecting either deep or shallow causes of subsidence can produce spurious results. The advantage of using the ‘a priori’ estimates of the compaction and the covariance matrix obtained by Monte Carlo simulations is demonstrated with a second synthetic example involving two polders and different depths of their water table. A robust solution is obtained for each polder unit, while a simpler (and faster) ‘a priori’ estimate based on the expected average clay thickness fails to reproduce the actual compaction. Monte Carlo simulations can also be applied to compaction in depleting gas reservoirs. Information on spatial correlations is often available, even when the absolute values of the ‘a priori’ compaction data are quite uncertain. Explicitly incorporating such ‘a priori’ known spatial correlations improves the result significantly.     

Quaternary zoogeography of the Nearctic Dicrostonyx lemmings

Twenty-four fossil localities of Dicrostonyx lemmings are reported in North America. The fossil localities are all extralimital except two, one in Alaska and one in the Northwest Territories. The Pleistocene fossil distribution parallels the modern ranges: Dicrostonyx hudsonius east of Hudson Bay and the Appalachian Mountains and D. torquatus to the west. Dicrostonyx remains of the late Quaternary are generally found in disharmonious faunas and may therefore not be an accurate indicator of a strict tundra environment.     

A method for flood hazard mapping based on basin morphometry: application in two catchments in Greece

Basin morphometric parameters play an important role in hydrological processes, as they largely control a catchment’s hydrologic response. Their analysis becomes even more significant when studying runoff reaction to intense rainfall, especially in the case of ungauged, flash flood prone basins. Unit hydrographs are one of the useful tools for estimating runoff when instrumental data are inadequate. In this work, instantaneous unit hydrographs based on the time-area method have been compiled along the drainage networks of two small rural catchments in Greece, situated approximately 25 km northeast of its capital, Athens. The two catchments drained by ephemeral torrents, namely Rapentosa and Charadros, have been subject to flash flooding during the last decades, which caused extensive damages at the local small towns of Marathon and Vranas. Hydrograph compilation in numerous locations along the catchments’ drainage networks directly reflected the runoff conditions across each basin against a given rainfall. This gave a holistic assessment of their hydrologic response, allowing the detection of areas where peak flow rates were elevated and therefore, there was higher flood potential. The resulting flood hazard zonation showed good correlation with locations of damages induced by past flood events, indicating that the method can successfully predict flood hazard spatial distribution. The whole methodology was based on geographic information software due to its excellent capabilities on storing and processing spatial data.     

宇宙成因核素~(10)Be揭示的北祁连山侵蚀速率特征

山脉侵蚀速率的大小和时空分布信息是研究山脉构造—气候相互作用和地貌演化的关键切入点,其大小是受气候还是构造控制争论已久。宇宙成因核素10Be方法为从千年至万年尺度上定量研究流域平均侵蚀速率提供了一种先进和快捷的技术手段,为揭示侵蚀速率与现代气候和构造地貌因子的关系并进行相关分析提供了基础。利用该方法对北祁连山近现代侵蚀速率进行了研究。所采集的9个流域现代河沙样品,结合前人数据进行共同分析,结果显示该区侵蚀速率的变化范围为18.7~833 mm/ka,北祁连山中段的侵蚀速率约为323 mm/ka,该区侵蚀速率与降雨量没有明显的对应关系,但与流域平均坡度呈现很好的非线性关系,揭示坡度是该区侵蚀速率的最主要控制因素。通过对比北祁连山地表平均侵蚀速率和该区域的断层垂直滑动速率发现整体上该区域地表侵蚀速率要低于祁连山北缘断层的垂直滑动速率,反映了北祁连山正处于地形抬升和生长的过程之中。     

The perceived landfall location of evacuees from Hurricane Gustav

Hurricane evacuations in the United States are costly, chaotic, and sometimes unnecessary. Many coastal residents consider evacuation after viewing a forecasted graphic of where the storm is anticipated to make landfall. During the evacuation process, hurricane tracks commonly deviate from the forecasted landfall track and many evacuees may not pay attention to these track deviations after evacuating. Frequently, a disconnect may occur between the actual landfall track, the official forecasted track, and the perceived track of each individual as they made their evacuation decision. Specifically for evacuees, a shift in track may decrease the hazards associated with a landfalling hurricane since evacuees perceive their threat level to be high at the time of evacuation. Using survey data gathered during the evacuation from Hurricane Gustav (2008) in coastal Louisiana (USA), we calculated a type of Z-score to measure the distance error between each evacuee’s perceived landfall location and the actual landfall location from each evacuee’s home zip code. Results indicate a personal landfall bias in the direction of home zip code for evacuees of three metropolitan regions. Evacuees from the greater New Orleans area displayed the highest error, followed by evacuees from greater Lafayette. Furthermore, we validate the authenticity of the previous results by employing two additional methods of error assessment. A large regional error score might possibly be a predictor of evacuation complacency for a future hurricane of similar magnitude, although there are many other variables that must be considered.     

A quantitative appraisal of earthquake hazard parameters computed from Gumbel I method for different regions in and around Turkey

Useful information concerning the earthquake hazard parameters distributed in Turkey and the adjacent areas are estimated in the present work. Based on Gumbel’s I distribution parameters we are able to estimate the hazard values of the investigated area which are the mean return periods, the most probable maximum magnitude in the time period of t-years and the probability for an earthquake occurrence of magnitude ≥M during a time span of t-years. Figures concerning the spatial distribution of probabilities and the return periods are plotted and we considered them of particular interest for mapping the earthquake hazard in Turkey and the surrounding areas. These figures effectively produce a brief earthquake hazard atlas. The quantitative appraisal of the hazard parameters is useful for engineers, planners, etc., because it provides a tool for earthquake resistant design.     

The US Geological Survey's national coal resource assessment: the results

The US Geological Survey and the State geological surveys of many coal-bearing States recently completed a new assessment of the top producing coal beds and coal zones in five major producing coal regions—the Appalachian Basin, Gulf Coast, Illinois Basin, Colorado Plateau, and Northern Rocky Mountains and Great Plains. The assessments, which focused on both coal quality and quantity, utilized geographic information system technology and large databases. Over 1,600,000 million short tons of coal remain in over 60 coal beds and coal zones that were assessed. Given current economic, environmental, and technological restrictions, the majority of US coal production will occur in that portion of the assessed coal resource that is lowest in sulfur content. These resources are concentrated in parts of the central Appalachian Basin, Colorado Plateau, and the Northern Rocky Mountains.     

Changing poverty distribution in Bolivia: the role of rural–urban migration and urban services

Bolivia is a country with high levels of poverty and inequality among its peoples and regions. For the nation and its urban and rural areas, trends in the social and spatial distribution of poverty (and extreme poverty) are identified from 1976 to 2003 using UBN data with minor support where appropriate from poverty lines. The main survey between 1992 and 2001 uses composite and selected UBN to track detailed poverty change for the country’s nine departments, its ten largest cities and a selection of other smaller urban and rural municipalities. Because of rising background increases in population in the various surveyed administrative units, many instances of relative reductions in poverty are accompanied by rising absolute increases. Marked spatial variations in poverty and development in the country over the last several decades are identified as the main driver for the country’s quickening pace of rural–urban migration. As a result, the paper concludes by assessing two different but closely related views. One investigation tests the notion that because more poor people have been living in Bolivia’s cities than in its rural areas since the mid to late 1990s, rapid rural–urban migration has simply shifted the locus of poverty from the countryside to the cities in a process called, the ‘urbanisation of poverty.’ A second, more challenging, investigation assesses the view that the flow of poor rural people to the better serviced urban areas of Bolivia has actually acted to alleviate national poverty levels.     

Deformation of an elastic layer coupling in different ways to a base due to a very long vertical strike-slip dislocation

The closed-form analytic expressions for the displacement and stresses at any point of an elastic layer lying over a base due to a very long vertical strike-slip dislocation are obtained. The interface between the layer and the base is assumed to be either ‘smooth-rigid’ or ‘rough-rigid’ or ‘welded’. The variations of displacement and stresses with the horizontal distance from the fault for different types of coupling of the layer with the base have been studied. It is found that the displacement for ‘welded interface’ lies between the displacements due to ‘smooth rigid’ and ‘rough-rigid’ interfaces for different positions of the observer and different values of the ratio of rigidities of the layer and half-space.