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Geosciences, Volume 7, Issue 4 (December 2017)

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Cover Story (view full-size image) Two different pathways have long been used to explain the origin of petrified wood: replacement, [...] Read more.
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Open AccessArticle Efficiency of Geographically Weighted Regression in Modeling Human Leptospirosis Based on Environmental Factors in Gilan Province, Iran
Geosciences 2017, 7(4), 136; https://doi.org/10.3390/geosciences7040136
Received: 22 September 2017 / Revised: 10 December 2017 / Accepted: 13 December 2017 / Published: 19 December 2017
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Abstract
It is of little debate that Leptospirosis is verified as the most important zoonosis disease in tropical and humid regions. In North of Iran, maximum reports have been dedicated to Gilan province and it is considered as an endemic problem there. Therefore, modeling
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It is of little debate that Leptospirosis is verified as the most important zoonosis disease in tropical and humid regions. In North of Iran, maximum reports have been dedicated to Gilan province and it is considered as an endemic problem there. Therefore, modeling or researching about different aspects of it seems indispensable. Hence, this paper investigated various models of Geographically Weighted Regression (GWR) approach and impacts of seven environmental variables on modelling leptospirosis in Gilan. Accordingly, counts of patients were considered as dependent variable during 2009–2011 at village level and environmental variables were utilized as independent variables in the modelling. In addition, performance of two Kernels (Fixed and Adaptive), two Weighting Functions (Bisquare and Gaussian) and three Bandwidth Selection Criteria (AIC (Akaike Information Criterion), CV (Cross Validation) and BIC (Bayesian information criterion)) were compared and assessed in GWR models. Results illustrated: (1) Leptospirosis and effective variables vary locally across the study area (positive and negative); (2) Adaptive kernel in comparison to Fixed kernel, Bisquare weighting function to Gaussian, and also AIC to CV and BIC (due to R2 and Mean Square Error (MSE) validation criteria); (3) Temperature and humidity were founded as impressive factors (include higher values of coefficients); Finally, contain more reliable results consecutively. However, the provided distribution maps asserted that central villages of Gilan not only are more predisposed to leptospirosis prevalence, but also prevention programs should focus on these regions more than others. Full article
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Open AccessReview Analysis of Slope Sensitivity to Landslides by a Transdisciplinary Approach in the Framework of Future Development: The Case of La Trinité in Martinique (French West Indies)
Geosciences 2017, 7(4), 135; https://doi.org/10.3390/geosciences7040135
Received: 19 November 2017 / Revised: 12 December 2017 / Accepted: 14 December 2017 / Published: 19 December 2017
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Abstract
Landslide hazard and risk assessment (LHA & LRA) in the French West Indies is a big challenge, particularly in Martinique, where several factors contribute to high slope sensitivity to landslides. This sensitivity is particularly due to volcanic ground, hurricane seasons, and growing pressure
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Landslide hazard and risk assessment (LHA & LRA) in the French West Indies is a big challenge, particularly in Martinique, where several factors contribute to high slope sensitivity to landslides. This sensitivity is particularly due to volcanic ground, hurricane seasons, and growing pressure from urban development. Thus, to protect future goods and inhabitants and avoid increased slope sensitivity to landslide, it is necessary to analyze by different ways and complementary approaches the future planned areas. This research focuses on a site the City Council of ‘La Trinité’ wishes to develop. The goals consist of locating landslide-prone areas and providing some recommendations/indications for future projects. The site is characterized by a hilly topography alternating steep slopes, gentle slopes, and eroded areas and is located on a complex lithology (i.e., andesite, basalt, and weathered materials). By combining several approaches and techniques (geology, geomorphology, geophysics, and modeling), it is demonstrated that some areas are particularly susceptible to landslide, notably where colluviums are juxtaposed to highly weathered materials. The different documents produced, based on modeling and expert knowledge, combined with indications should allow the definition of new susceptibility classes, taking into account probable anthropic influence and development. Even if the temporal probability of the experimental documents is not taken into account, they help with refining knowledge of landslide-prone areas and different types of instability. The documents should be discussed with end users for future planning. Full article
(This article belongs to the Special Issue Natural Hazards and Risks Assessment)
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Open AccessReview Pyplis–A Python Software Toolbox for the Analysis of SO2 Camera Images for Emission Rate Retrievals from Point Sources
Geosciences 2017, 7(4), 134; https://doi.org/10.3390/geosciences7040134
Received: 11 October 2017 / Revised: 27 November 2017 / Accepted: 11 December 2017 / Published: 15 December 2017
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Abstract
Ultraviolet (UV) SO2 cameras have become a common tool to measure and monitor SO2 emission rates, mostly from volcanoes but also from anthropogenic sources (e.g., power plants or ships). Over the past decade, the analysis of UV SO2 camera data
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Ultraviolet (UV) SO2 cameras have become a common tool to measure and monitor SO2 emission rates, mostly from volcanoes but also from anthropogenic sources (e.g., power plants or ships). Over the past decade, the analysis of UV SO2 camera data has seen many improvements. As a result, for many of the required analysis steps, several alternatives exist today (e.g., cell vs. DOAS based camera calibration; optical flow vs. cross-correlation based gas-velocity retrieval). This inspired the development of Pyplis (Python plume imaging software), an open-source software toolbox written in Python 2.7, which unifies the most prevalent methods from literature within a single, cross-platform analysis framework. Pyplis comprises a vast collection of algorithms relevant for the analysis of UV SO2 camera data. These include several routines to retrieve plume background radiances as well as routines for cell and DOAS based camera calibration. The latter includes two independent methods to identify the DOAS field-of-view (FOV) within the camera images (based on (1) Pearson correlation and (2) IFR inversion method). Plume velocities can be retrieved using an optical flow algorithm as well as signal cross-correlation. Furthermore, Pyplis includes a routine to perform a first order correction of the signal dilution effect (also referred to as light dilution). All required geometrical calculations are performed within a 3D model environment allowing for distance retrievals to plume and local terrain features on a pixel basis. SO2 emission rates can be retrieved simultaneously for an arbitrary number of plume intersections. Hence, Pyplis provides a state-of-the-art framework for more efficient and flexible analyses of UV SO2 camera data and, therefore, marks an important step forward towards more transparency, reliability and inter-comparability of the results. Pyplis has been extensively and successfully tested using data from several field campaigns. Here, the main features are introduced using a dataset obtained at Mt. Etna, Italy on 16 September 2015. Full article
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Open AccessArticle Investigating the Apparent Seismic Diffusivity of Near-Receiver Geology at Mount St. Helens Volcano, USA
Geosciences 2017, 7(4), 130; https://doi.org/10.3390/geosciences7040130
Received: 16 October 2017 / Revised: 27 November 2017 / Accepted: 7 December 2017 / Published: 15 December 2017
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Abstract
We present an expanded approach of the diffusive approximation to map strongly scattering geological structures in volcanic environments using seismic coda intensities and a diffusive approximation. Seismic data from a remarkably consistent hydrothermal source of Long-Period (LP) earthquakes, that was active during the
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We present an expanded approach of the diffusive approximation to map strongly scattering geological structures in volcanic environments using seismic coda intensities and a diffusive approximation. Seismic data from a remarkably consistent hydrothermal source of Long-Period (LP) earthquakes, that was active during the late 2004 portion of the 2004–2008 dome building eruption of Mount St. Helens Volcano, are used to obtain coefficient values for diffusion and attenuation, and describe the rate at which seismic energy radiates into the surrounding medium. The results are then spatially plotted as a function of near-receiver geology to generate maps of near-surface geological and geophysical features. They indicate that the diffusion coefficient is a marker of the near-receiver geology, while the attenuation coefficients are sensitive to deeper volcanic structures. As previously observed by other studies, two main scattering regimes affect the coda envelopes: a diffusive, multiple-scattering regime close to the volcanic edifice and a much weaker, single-to-multiple scattering regime at higher source-receiver offsets. Within the diffusive, multiple-scattering regime, the spatial variations of the diffusion coefficient are sufficiently robust to show the features of laterally-extended, coherent, shallow geological structures. Full article
(This article belongs to the Special Issue Volcano Monitoring – Placing the Finger on the Pulse)
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Open AccessArticle Mercury Contamination of Cattle in Artisanal and Small-Scale Gold Mining in Bombana, Southeast Sulawesi, Indonesia
Geosciences 2017, 7(4), 133; https://doi.org/10.3390/geosciences7040133
Received: 2 August 2017 / Revised: 30 November 2017 / Accepted: 11 December 2017 / Published: 14 December 2017
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Abstract
The industrial mining sector is one of the main contributors to environmental damage and toxic metal pollution, although some contamination originates from natural geological sources. Due to their position at the top of the food chain, cattle tend to bioaccumulate mercury (Hg) in
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The industrial mining sector is one of the main contributors to environmental damage and toxic metal pollution, although some contamination originates from natural geological sources. Due to their position at the top of the food chain, cattle tend to bioaccumulate mercury (Hg) in their bodies. We used analyses of cattle hair samples to investigate Hg contamination in cattle farmed within and outside of an artisanal and small-scale gold-mining area in Bombana, Southeast Sulawesi, Indonesia. We also examined the factors that might have influenced the toxicity, such as the environmental conditions, sex, and age of the cattle. A total of 63 hair samples were analyzed by particle-induced X-ray emission spectrometry. The mean Hg concentration was significantly higher in hair from cattle farmed within the artisanal and small-scale gold mining area (11.44 μg/g hair) than in those farmed outside the area (2.89 μg/g hair, p < 0.05). A possible cause of this is contamination by mercury persistent in terrestrial food chain. The results indicates that the level of toxic metals such as Hg need to be controlled in food sources to protect human health, especially in Bombana, Indonesia. Full article
(This article belongs to the Special Issue Urban Environmental and Medical Geochemistry)
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Open AccessArticle Evaluating Conveyance-Based DEM Correction Technique on NED and SRTM DEMs for Flood Impact Assessment of the 2010 Cumberland River Flood
Geosciences 2017, 7(4), 132; https://doi.org/10.3390/geosciences7040132
Received: 7 October 2017 / Revised: 28 November 2017 / Accepted: 8 December 2017 / Published: 14 December 2017
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Abstract
This study assessed the uncertainty in flood impact assessment (FIA) that may be introduced by errors in moderate resolution regional and moderate resolution global Digital Elevation Models (DEM). One arc-second National Elevation Dataset (NED) and one arc-second Shuttle Radar Topography Mission (SRTM) DEMs
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This study assessed the uncertainty in flood impact assessment (FIA) that may be introduced by errors in moderate resolution regional and moderate resolution global Digital Elevation Models (DEM). One arc-second National Elevation Dataset (NED) and one arc-second Shuttle Radar Topography Mission (SRTM) DEMs were selected to represent moderate resolution regional and global DEMs. The relative performance for scenarios based on each of the DEMs was compared to a “control” terrain (combination of surveyed river bathymetry and a 1/3 arc-second LiDAR for floodplains)-based scenario. Furthermore, a conveyance-based DEM correction technique was applied to the DEMs for investigating the suitability of the technique on selected DEMs, and determining subsequent improvement in the FIA. The May 2010 flood on the Cumberland River near Nashville, TN, was selected as the case study. It was found that the hydraulic properties necessary to implement the selected DEM correction technique could be more readily estimated from NED compared to SRTM. However, this study also prescribed alternate methods to extract necessary hydraulic properties if the DEM quality was compromised. NED-based hydrodynamic modeling resulted in a high overestimation of the simulated flood stage, but the SRTM-based model was unable to produce any reasonable result prior to DEM correction. Nevertheless, after DEM correction, both models became stable and produced less error. Error in simulated flood consequence (i.e., total structures affected and total loss in dollars) also dropped accordingly, following the DEM correction. Therefore, application of this conveyance-based correction technique is reasonably effective on both moderate-resolution regional and global DEMs. The effectiveness of the technique on moderate resolution global DEM underscores the potential for users of remote and data-poor areas. Full article
(This article belongs to the Special Issue Integrated Risk Analysis and Management of Floods)
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Open AccessArticle Assessment by Portable Gamma Spectrometry of External Gamma Radiation Hazard due to Granitic Materials and Indoor Space Typology
Geosciences 2017, 7(4), 131; https://doi.org/10.3390/geosciences7040131
Received: 13 November 2017 / Revised: 5 December 2017 / Accepted: 10 December 2017 / Published: 14 December 2017
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Abstract
Building materials can contribute to ionizing radiation hazards due to their variable content in radioactive isotopes. Uranium, thorium, and potassium radioisotopes are present in various building materials due to their presence in raw materials: minerals and rocks. Among natural building materials, granite is
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Building materials can contribute to ionizing radiation hazards due to their variable content in radioactive isotopes. Uranium, thorium, and potassium radioisotopes are present in various building materials due to their presence in raw materials: minerals and rocks. Among natural building materials, granite is one of those deserving more attention in terms of radioactive hazards. Granites are commonly used in historical buildings of NW Portugal and NW Spain, due to the geological characteristics of these areas. However, radioactive isotopes are present in variable proportions in granites, and thus, in relation to other potential building materials, granites might present a higher radiological hazard. This work discusses multivariate analysis results obtained by spectrometry of a portable range in indoor spaces, presenting different proportions of granite used as a building material in order to evaluate a typology proposed for assessing gamma radiation hazards. Full article
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Open AccessArticle Mainstreaming Multi-Risk Approaches into Policy
Geosciences 2017, 7(4), 129; https://doi.org/10.3390/geosciences7040129
Received: 7 November 2017 / Revised: 3 December 2017 / Accepted: 6 December 2017 / Published: 12 December 2017
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Abstract
Multi-risk environments are characterized by domino effects that often amplify the overall risk. Those include chains of hazardous events and increasing vulnerability, among other types of correlations within the risk process. The recently developed methods for multi-hazard and risk assessment integrate interactions between
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Multi-risk environments are characterized by domino effects that often amplify the overall risk. Those include chains of hazardous events and increasing vulnerability, among other types of correlations within the risk process. The recently developed methods for multi-hazard and risk assessment integrate interactions between different risks by using harmonized procedures based on common metrics. While the products of these assessments, such as multi-hazard and -risk indexes, maps, cascade scenarios, or warning systems provide innovative and effective information, they also pose specific challenges to policy makers and practitioners due to their novel cross-disciplinary aspects. In this paper we discuss the institutional barriers to the adoption of multi-risk approaches, summarizing the results of the fieldwork conducted in Italy and Guadeloupe and of workshops with disaster risk reduction practitioners from eleven European countries. Results show the need for a clear identification of responsibilities for the implementation of multi-risk approaches, as institutional frameworks for risk reduction remain to this day primarily single-risk centered. Authorities are rarely officially responsible for the management of domino effects between e.g., tsunamis and industrial accidents, earthquake and landslides, floods and electricity network failures. Other barriers for the implementation of multi-risk approaches include the limited measures to reduce exposure at the household level, inadequate financial capacities at the local level and limited public-private partnerships, especially in case of interactions between natural and industrial risks. Adapting the scale of institutions to that of multi-risk environments remains a major challenge to better mainstream multi-risk approaches into policy. To address it, we propose a multi-risk governance framework, which includes the phases of observation, social and institutional context analysis, generation of multi-risk knowledge and stakeholder engagement processes. Yet, more research is needed in order to test the framework and to identify the hallmark characteristics of effective multi-risk governance. Full article
(This article belongs to the Special Issue Natural Hazards and Risks Assessment)
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Open AccessArticle Landscape Pattern Detection in Archaeological Remote Sensing
Geosciences 2017, 7(4), 128; https://doi.org/10.3390/geosciences7040128
Received: 13 October 2017 / Revised: 28 November 2017 / Accepted: 29 November 2017 / Published: 11 December 2017
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Abstract
Automated detection of landscape patterns on Remote Sensing imagery has seen virtually little or no development in the archaeological domain, notwithstanding the fact that large portion of cultural landscapes worldwide are characterized by land engineering applications. The current extraordinary availability of remotely sensed
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Automated detection of landscape patterns on Remote Sensing imagery has seen virtually little or no development in the archaeological domain, notwithstanding the fact that large portion of cultural landscapes worldwide are characterized by land engineering applications. The current extraordinary availability of remotely sensed images makes it now urgent to envision and develop automatic methods that can simplify their inspection and the extraction of relevant information from them, as the quantity of information is no longer manageable by traditional “human” visual interpretation. This paper expands on the development of automatic methods for the detection of target landscape features—represented by field system patterns—in very high spatial resolution images, within the framework of an archaeological project focused on the landscape engineering embedded in Roman cadasters. The targets of interest consist of a variety of similarly oriented objects of diverse nature (such as roads, drainage channels, etc.) concurring to demark the current landscape organization, which reflects the one imposed by Romans over two millennia ago. The proposed workflow exploits the textural and shape properties of real-world elements forming the field patterns using multiscale analysis of dominant oriented response filters. Trials showed that this approach provides accurate localization of target linear objects and alignments signaled by a wide range of physical entities with very different characteristics. Full article
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Open AccessFeature PaperArticle Semi-Automatic Detection of Indigenous Settlement Features on Hispaniola through Remote Sensing Data
Geosciences 2017, 7(4), 127; https://doi.org/10.3390/geosciences7040127
Received: 15 October 2017 / Revised: 29 November 2017 / Accepted: 29 November 2017 / Published: 5 December 2017
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Abstract
Satellite imagery has had limited application in the analysis of pre-colonial settlement archaeology in the Caribbean; visible evidence of wooden structures perishes quickly in tropical climates. Only slight topographic modifications remain, typically associated with middens. Nonetheless, surface scatters, as well as the soil
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Satellite imagery has had limited application in the analysis of pre-colonial settlement archaeology in the Caribbean; visible evidence of wooden structures perishes quickly in tropical climates. Only slight topographic modifications remain, typically associated with middens. Nonetheless, surface scatters, as well as the soil characteristics they produce, can serve as quantifiable indicators of an archaeological site, detectable by analyzing remote sensing imagery. A variety of pre-processed, very diverse data sets went through a process of image registration, with the intention to combine multispectral bands to feed two different semi-automatic direct detection algorithms: a posterior probability, and a frequentist approach. Two 5 × 5 km2 areas in the northwestern Dominican Republic with diverse environments, having sufficient imagery coverage, and a representative number of known indigenous site locations, served each for one approach. Buffers around the locations of known sites, as well as areas with no likely archaeological evidence were used as samples. The resulting maps offer quantifiable statistical outcomes of locations with similar pixel value combinations as the identified sites, indicating higher probability of archaeological evidence. These still very experimental and rather unvalidated trials, as they have not been subsequently groundtruthed, show variable potential of this method in diverse environments. Full article
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Open AccessArticle Supercontinent Cycle and Thermochemical Structure in the Mantle: Inference from Two-Dimensional Numerical Simulations of Mantle Convection
Geosciences 2017, 7(4), 126; https://doi.org/10.3390/geosciences7040126
Received: 27 September 2017 / Revised: 13 November 2017 / Accepted: 30 November 2017 / Published: 5 December 2017
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Abstract
In this study, we conduct numerical simulations of thermochemical mantle convection in a 2D spherical annulus with a highly viscous lid drifting along the top surface, in order to investigate the interrelation between the motion of the surface (super)continent and the behavior of
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In this study, we conduct numerical simulations of thermochemical mantle convection in a 2D spherical annulus with a highly viscous lid drifting along the top surface, in order to investigate the interrelation between the motion of the surface (super)continent and the behavior of chemical heterogeneities imposed in the lowermost mantle. Our calculations show that assembly and dispersal of supercontinents occur in a cyclic manner when a sufficient amount of chemically-distinct dense material resides in the base of the mantle against the convective mixing. The motion of surface continents is significantly driven by strong ascending plumes originating around the dense materials in the lowermost mantle. The hot dense materials horizontally move in response to the motion of continents at the top surface, which in turn horizontally move the ascending plumes leading to the breakup of newly-formed supercontinents. We also found that the motion of dense materials in the base of the mantle is driven toward the region beneath a newly-formed supercontinent largely by the horizontal flow induced by cold descending flows from the top surface occurring away from the (super)continent. Our findings imply that the dynamic behavior of cold descending plumes is the key to the understanding of the relationship between the supercontinent cycle on the Earth’s surface and the thermochemical structures in the lowermost mantle, through modulating not only the positions of chemically-dense materials, but also the occurrence of ascending plumes around them. Full article
(This article belongs to the Special Issue Mantle Circulation and Plate Movement)
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Open AccessArticle Geospatial Analysis of Land Use and Land Cover Transitions from 1986–2014 in a Peri-Urban Ghana
Geosciences 2017, 7(4), 125; https://doi.org/10.3390/geosciences7040125
Received: 20 September 2017 / Revised: 21 November 2017 / Accepted: 27 November 2017 / Published: 1 December 2017
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Abstract
Recently, peri-urbanisation has led to the transformation of the rural landscape, changing rural land uses into peri-urban land uses, under varying driving factors. This paper analyzes the dynamic transitions among identified land use and land cover (LULC) types in the Bosomtwe district of
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Recently, peri-urbanisation has led to the transformation of the rural landscape, changing rural land uses into peri-urban land uses, under varying driving factors. This paper analyzes the dynamic transitions among identified land use and land cover (LULC) types in the Bosomtwe district of Ghana, from 1986 to 2014. An integrated approach of geo-information tools of satellite remote sensing in Earth Resource Data Analysis System (ERDAS) Imagine 13 and ArcMap 10.2 Geographic Information System (GIS), with Markov chain analytical techniques were used to examine the combined forest land cover transitions, relative to build-up, recent fallows and grasslands and projected possible factors influencing the transitions under business as usual and unusual situations. Statistical analyses of the classified Landsat TM, ETM+ and Landsat 8 Operational Land Imager and Thermal Infrared Sensor (OLI/TIS) indicated that over the period of 24 years, the Bosomtwe district has undergone a series of land use conversions with remarkable forest losses especially between 2002 and 2010. In 2010 dense forest cover was degraded to low forest by 4040 ha indicating 0.40% transition probability in the future. There was a remarkable increase of built-up/bare and concrete area with a 380% increment in the 1986–2002 transition periods. The application of the Markov futuristic land use dynamics by the years 2018 and 2028, projected from the 2014 LULC indicated a future steady decline in the area coverage of the dense forest to low forest category. This is currently being driven (as at the 2017 LULC trends), by the combined effects of increasing build up bare and concrete surface land uses as well as the expanding recent fallows and grassland. The paper concluded that the health of the ecosystem and biodiversity of the lake Bosomtwe need to be sustainably managed by the Bosomtwe district assembly. Full article
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Open AccessArticle The Morphometry of the Deep-Water Sinuous Mendocino Channel and the Immediate Environs, Northeastern Pacific Ocean
Geosciences 2017, 7(4), 124; https://doi.org/10.3390/geosciences7040124
Received: 7 September 2017 / Revised: 6 November 2017 / Accepted: 6 November 2017 / Published: 29 November 2017
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Abstract
Mendocino Channel, a deep-water sinuous channel located along the base of Gorda Escarpment, was for the first time completely mapped with a multibeam echosounder. This study uses newly acquired multibeam bathymetry and backscatter, together with supporting multichannel seismic and sediment core data to
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Mendocino Channel, a deep-water sinuous channel located along the base of Gorda Escarpment, was for the first time completely mapped with a multibeam echosounder. This study uses newly acquired multibeam bathymetry and backscatter, together with supporting multichannel seismic and sediment core data to quantitatively describe the morphometry of the entire Mendocino Channel and to explore the age and possible causes that may have contributed to the formation and maintenance of the channel. The first 42 km of the channel is a linear reach followed for the next 83.8 km by a sinuous reach. The sinuous reach has a sinuosity index of 1.66 before it changes back to a linear reach for the next 22.2 km. A second sinuous reach is 40.2 km long and the two reaches are separated by a crevasse splay and a large landslide that deflected the channel northwest towards Gorda Basin. Both sinuous reaches have oxbow bends, cut-off meanders, interior and exterior terraces and extensive levee systems. The lower sinuous reach becomes more linear for the next 22.2 km before the channel relief falls below the resolution of the data. Levees suddenly decrease in height above the channel floor mid-way along the lower linear reach close to where the channel makes a 90° turn to the southwest. The entire channel floor is smooth at the resolution of the data and only two large mounds and one large sediment pile were found on the channel floor. The bathymetry and acoustic backscatter, together with previously collected seismic data and box and piston cores provide details to suggest Mendocino Channel may be no older than early Quaternary. A combination of significant and numerous earthquakes and wave-loading resuspension by storms are the most likely processes that generated turbidity currents that have formed and modified Mendocino Channel. Full article
(This article belongs to the Special Issue Marine Geomorphometry)
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Open AccessArticle Flood Risk Assessment in Urban Areas Based on Spatial Analytics and Social Factors
Geosciences 2017, 7(4), 123; https://doi.org/10.3390/geosciences7040123
Received: 1 November 2017 / Revised: 15 November 2017 / Accepted: 22 November 2017 / Published: 27 November 2017
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Abstract
Flood maps alone are not sufficient to determine and assess the risks to people, property, infrastructure, and services due to a flood event. Simply put, the risk is almost zero to minimum if the flooded region is “empty” (i.e., unpopulated, has not properties,
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Flood maps alone are not sufficient to determine and assess the risks to people, property, infrastructure, and services due to a flood event. Simply put, the risk is almost zero to minimum if the flooded region is “empty” (i.e., unpopulated, has not properties, no industry, no infrastructure, and no socio-economic activity). High spatial resolution Earth Observation (EO) data can contribute to the generation and updating of flood risk maps based on several aspects including population, economic development, and critical infrastructure, which can enhance a city’s flood mitigation and preparedness planning. In this case study for the Don River watershed, Toronto, the flood risk is determined and flood risk index maps are generated by implementing a methodology for estimating risk based on the geographic coverage of the flood hazard, vulnerability of people, and the exposure of large building structures to flood water. Specifically, the spatial flood risk index maps have been generated through analytical spatial modeling which takes into account the areas in which a flood hazard is expected to occur, the terrain’s morphological characteristics, socio-economic parameters based on demographic data, and the density of large building complexes. Generated flood risk maps are verified through visual inspection with 3D city flood maps. Findings illustrate that areas of higher flood risk coincide with areas of high flood hazard and social and building exposure vulnerability. Full article
(This article belongs to the Special Issue Integrated Risk Analysis and Management of Floods)
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Open AccessArticle Investigation of Hydrogeological Structures of Paiko Region, North-Central Nigeria Using Integrated Geophysical and Remote Sensing Techniques
Geosciences 2017, 7(4), 122; https://doi.org/10.3390/geosciences7040122
Received: 29 September 2017 / Revised: 8 November 2017 / Accepted: 21 November 2017 / Published: 24 November 2017
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Abstract
Aeromagnetic data coupled with Landsat ETM+ data and SRTM DEM have been processed in order to map regional hydrogeological structures in the basement complex region of Paiko, North Central Nigeria. Lineaments were extracted from derivative maps of aeromagnetic, Landsat ETM+ and SRTM DEM
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Aeromagnetic data coupled with Landsat ETM+ data and SRTM DEM have been processed in order to map regional hydrogeological structures in the basement complex region of Paiko, North Central Nigeria. Lineaments were extracted from derivative maps of aeromagnetic, Landsat ETM+ and SRTM DEM datasets. Ground geophysical investigation utilizing Radial Vertical Electrical Sounding (RVES) was established in nine transects comprised of four sounding stations which are oriented in three azimuths. Source Parameter Imaging (SPI) was employed to map average depths of structures from aeromagnetic dataset. Selected thematic layers which included lineaments density, lithologic structure, slope, drainage density and geomorphologic maps were integrated and modeled using ArcGIS to generate a groundwater potential map of the area. Groundwater zones were classified into four categories: Very good, good, moderate and poor according to their potential to yield sustainable water to drilled wells. The results from RVES survey reveal a close correlation to lineaments delineated from surface structural mapping and remotely sensed datasets. Hydrogeological significance of these orientations suggest that aeromagnetic data can be used to map relatively deep-seated fractures which are likely to be open groundwater conduits while remotely sensed lineaments and orientations delineated from the RVES survey may indicate areas of recharge. Regions with high lineament density attributable to thick regolith and highly fractured basement have better groundwater potential. Drill depths in this area should target a minimum of 80 m to ensure sufficient and sustainable supplies to drilled wells. The outcome of this study would act as information framework that would guide the siting of productive water wells while providing needed information for relevant agencies in need of data for the development of groundwater resources. Full article
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