The influence of global climate change on endangered species is of growing concern, especially for rosewood species that are in urgent need of protection and restoration. Ecological niche models are commonly used to e...The influence of global climate change on endangered species is of growing concern, especially for rosewood species that are in urgent need of protection and restoration. Ecological niche models are commonly used to evaluate probable species’ distribution under climate change and contribute to decision-making to define efficient management strategies. A model was developed to forecast which habitat was most likely appropriate for the Dalbergia odorifera. We screened the main climatic variables that describe the current geographic distribution of the species based on maximum entropy modelling (Maxent). We subsequently assessed its potential future distribution under moderate (RCP2.6) and severe (RCP8.5) climate change scenarios for the years 2050 and 2070. The precipitation ranges of the wettest month and the warmest quarter are the primary limiting factors for the current distribution of D. odorifera among the climatic predictors. Climate change will be expected to have beneficial effects on the distribution range of D. odorifera. In conclusion, the main limits for the distribution of D. odorifera are determined by the level of precipitation and human activities. The results of this study indicate that the coasts of southern China and Chongqing will play a key role in the protection and restoration of D. odorifera in the future.展开更多
Himalayan glaciers are shrinking rapidly,especially after 2000.Glacier shrinkage,however,shows a differential pattern in space and time,emphasizing the need to monitor and assess glacier changes at a larger scale.In t...Himalayan glaciers are shrinking rapidly,especially after 2000.Glacier shrinkage,however,shows a differential pattern in space and time,emphasizing the need to monitor and assess glacier changes at a larger scale.In this study,changes of 48 glaciers situated around the twin peaks of the Nun and Kun mountains in the northwestern Himalaya,hereafter referred to as Nun-Kun Group of Glaciers(NKGG),were investigated using Landsat satellite data during 2000-2020.Changes in glacier area,snout position,Equilibrium Line Altitude(ELA),surface thickness and glacier velocity were assessed using remote sensing data supplemented by field observations.The study revealed that the NKGG glaciers have experienced a recession of 4.5%±3.4%and their snouts have retreated at the rate of 6.4±1.6 m·a^(-1).Additionally,there was a 41%increase observed in the debris cover area during the observation period.Using the geodetic approach,an average glacier elevation change of-1.4±0.4 m·a^(-1)was observed between 2000 and 2012.The observed mass loss of the NKGG has resulted in the deceleration of glacier velocity from 27.0±3.7 m·a^(-1)in 2000 to 21.2±2.2 m·a^(-1)in 2020.The ELA has shifted upwards by 83.0±22 m during the period.Glacier morphological and topographic factors showed a strong influence on glacier recession.Furthermore,a higher recession of 12.9%±3.2%was observed in small glaciers,compared to 2.7%±3.1%in larger glaciers.The debris-covered glaciers showed lower shrinkage(2.8%±1.1%)compared to the clean glaciers(9.3%±5%).The glacier depletion recorded in the NKGG during the last two decades,if continued,would severely diminish glacial volume and capacity to store water,thus jeopardizing the sustainability of water resources in the basin.展开更多
The Alborz Mountains are some of the highest in Iran,and they play an important role in controlling the climate of the country’s northern regions.The land surface temperature(LST)is an important variable that affects...The Alborz Mountains are some of the highest in Iran,and they play an important role in controlling the climate of the country’s northern regions.The land surface temperature(LST)is an important variable that affects the ecosystem of this area.This study investigated the spatiotemporal changes and trends of the nighttime LST in the western region of the Central Alborz Mountains at elevations of 1500-4000 m above sea level.MODIS data were extracted for the period of 2000-2021,and the Mann-Kendall nonparametric test was applied to evaluating the changes in the LST.The results indicated a significant increasing trend for the monthly average LST in May-August along the southern aspect.Both the northern and southern aspects showed decreasing trends for the monthly average LST in October,November,and March and an increasing trend in other months.At all elevations,the average decadal change in the monthly average LST was more severe along the southern aspect(0.60°C)than along the northern aspect(0.37°C).The LST difference between the northern and southern aspects decreased in the cold months but increased in the hot months.At the same elevation,the difference in the lapse rate between the northern and southern aspects was greater in the hot months than in the cold months.With increasing elevation,the lapse rate between the northern and southern aspects disappeared.Climate change was concluded to greatly decrease the difference in LST at different elevations for April-July.展开更多
Over the past decade,the presence of mistletoe(Viscum album ssp.austriacum)in Scots pine stands has increased in many European countries.Understanding the factors that influence the occurrence of mistletoe in stands i...Over the past decade,the presence of mistletoe(Viscum album ssp.austriacum)in Scots pine stands has increased in many European countries.Understanding the factors that influence the occurrence of mistletoe in stands is key to making appropriate forest management decisions to limit damage and prevent the spread of mistletoe in the future.Therefore,the main objective of this study was to determine the probability of mistletoe occurrence in Scots pine stands in relation to stand-related endogenous factors such as age,top height,and stand density,as well as topographic and edaphic factors.We used unmanned aerial vehicle(UAV)imagery from 2,247 stands to detect mistletoe in Scots pine stands,while majority stand and site characteristics were calculated from airborne laser scanning(ALS)data.Information on stand age and site type from the State Forest database were also used.We found that mistletoe infestation in Scots pine stands is influenced by stand and site characteristics.We documented that the densest,tallest,and oldest stands were more susceptible to mistletoe infestation.Site type and specific microsite conditions associated with topography were also important factors driving mistletoe occurrence.In addition,climatic water balance was a significant factor in increasing the probability of mistletoe occurrence,which is important in the context of predicted temperature increases associated with climate change.Our results are important for better understanding patterns of mistletoe infestation and ecosystem functioning under climate change.In an era of climate change and technological development,the use of remote sensing methods to determine the risk of mistletoe infestation can be a very useful tool for managing forest ecosystems to maintain forest sustainability and prevent forest disturbance.展开更多
Understanding trends of land use land cover (LULC) changes is important for biodiversity monitoring and conservation planning, and identifying the areas affected by change and designing sustainable solutions to reduce...Understanding trends of land use land cover (LULC) changes is important for biodiversity monitoring and conservation planning, and identifying the areas affected by change and designing sustainable solutions to reduce the changes. The study aims to evaluate and quantify the historical changes in land use and land cover in Mukumbura (Ward 2), Mt Darwin, Zimbabwe, from 2002 to 2022. The objective of the study was to analyse the LULC changes in Ward 2 (Mukumbura), Mt Darwin, Northern Zimbabwe, for a period of 20 years using geospatial techniques. Landsat satellite images were processed using Google Earth Engine (GEE) and the supervised classification with maximum likelihood algorithm was employed to generate LULC maps between 2002 and 2022 with a five (5) year interval, investigating the following variables, forest cover, barren land, water cover and the fields. Findings revealed a substantial reduction in forest cover by 38.8%, water bodies (wetlands, ponds, and rivers) declined by 55.6%, whilst fields (crop/agricultural fields) increased by 93.3% and the barren land cover increased by 26.3% from 2002 to 2022. These findings point to substantial changes in LULC over the observed years. LULC changes have resulted in habitat fragmentation, reduced biodiversity, and the disruption of ecosystem functions. The study concludes that if these deforestation trends, cultivation, and settlement land expansion continue, the ward will have limited indigenous fruit trees. Therefore, the causes for LULC changes must be controlled, sustainable forest resources use practiced, hence the need to domesticate the indigenous fruit trees in arborloo toilets.展开更多
The identification of landslide-prone areas is an essential step in landslide hazard assessment and mitigation of landslide-related losses.In this study,we applied two novel deep learning algorithms,the recurrent neur...The identification of landslide-prone areas is an essential step in landslide hazard assessment and mitigation of landslide-related losses.In this study,we applied two novel deep learning algorithms,the recurrent neural network(RNN)and convolutional neural network(CNN),for national-scale landslide susceptibility mapping of Iran.We prepared a dataset comprising 4069 historical landslide locations and 11 conditioning factors(altitude,slope degree,profile curvature,distance to river,aspect,plan curvature,distance to road,distance to fault,rainfall,geology and land-sue)to construct a geospatial database and divided the data into the training and the testing dataset.We then developed RNN and CNN algorithms to generate landslide susceptibility maps of Iran using the training dataset.We calculated the receiver operating characteristic(ROC)curve and used the area under the curve(AUC)for the quantitative evaluation of the landslide susceptibility maps using the testing dataset.Better performance in both the training and testing phases was provided by the RNN algorithm(AUC=0.88)than by the CNN algorithm(AUC=0.85).Finally,we calculated areas of susceptibility for each province and found that 6%and 14%of the land area of Iran is very highly and highly susceptible to future landslide events,respectively,with the highest susceptibility in Chaharmahal and Bakhtiari Province(33.8%).About 31%of cities of Iran are located in areas with high and very high landslide susceptibility.The results of the present study will be useful for the development of landslide hazard mitigation strategies.展开更多
Current global urbanisation processes are leading to new forms of massive urban constellations. The conceptualisations and classifications of these, however, are often ambiguous, overlap or lag behind in scientific li...Current global urbanisation processes are leading to new forms of massive urban constellations. The conceptualisations and classifications of these, however, are often ambiguous, overlap or lag behind in scientific literature. This article examines whether there is a common denominator to define and delimitate–and ultimately map–these new dimensions of cityscapes. In an extensive literature review we analysed and juxtaposed some of the most common concepts such as megacity, megaregion or megalopolis. We observed that many concepts are abstract or unspecific, and for those concepts for which physical parameters exist, the parameters are neither properly defined nor used in standardised ways. While understandably concepts originate from various disciplines, the authors identify a need for more precise definition and use of parameters. We conclude that often, spatial patterns of large urban areas resemble each other considerably but the definitions vary so widely that these differences may surpass any inconsistencies in the spatial delimitation process. In other words, today we have tools such as earth observation data and Geographic Information Systems to parameterise if clear definitions are provided. This appears not to be the case. The limiting factor when delineating large urban areas seems to be a commonly agreed ontology.展开更多
Conventional synthetic aperture radar(SAR)interferometry(InSAR)has been successfully used to precisely measure surface deformation in the line-of-sight(LOS)direction,while multiple-aperture SAR interferometry(MAI)has ...Conventional synthetic aperture radar(SAR)interferometry(InSAR)has been successfully used to precisely measure surface deformation in the line-of-sight(LOS)direction,while multiple-aperture SAR interferometry(MAI)has provided precise surface deformation in the along-track(AT)direction.Integration of the InSAR and MAI methods enables precise measurement of the two-dimensional(2D)deformation from an interferometric pair;recently,the integration of ascending and descending pairs has allowed the observation of precise three-dimensional(3D)deformation.Precise 3D deformation measurement has been applied to better understand geological events such as earthquakes and volcanic eruptions.The surface deformation related to the 2016 Kumamoto earthquake was large and complex near the fault line;hence,precise 3D deformation retrieval had not yet been attempted.The objectives of this study were to①perform a feasibility test of precise 3D deformation retrieval in large and complex deformation areas through the integration of offset-based unwrapped and improved multiple-aperture SAR interferograms and②observe the 3D deformation field related to the 2016 Kumamoto earthquake,even near the fault lines.Two ascending pairs and one descending the Advanced Land Observing Satellite-2(ALOS-2)Phased Array-type L-band Synthetic Aperture Radar-2(PALSAR-2)pair were used for the 3D deformation retrieval.Eleven in situ Global Positioning System(GPS)measurements were used to validate the 3D deformation measurement accuracy.The achieved accuracy was approximately 2.96,3.75,and 2.86 cm in the east,north,and up directions,respectively.The results show the feasibility of precise 3D deformation measured through the integration of the improved methods,even in a case of large and complex deformation.展开更多
Digital Elevation Models (DEMs) depict the configuration of the earth surface and are being applied in many areas in earth and environmental sciences. In this study, the accuracy of the Advanced Land Observing Satelli...Digital Elevation Models (DEMs) depict the configuration of the earth surface and are being applied in many areas in earth and environmental sciences. In this study, the accuracy of the Advanced Land Observing Satellite World 3D Digital Surface Model version 2.1 (ALOS W3D30), the Shuttle Radar Topography Mission Digital Elevation Model version 3.0 (SRTM30) and the Advanced Space borne Thermal Emission and Reflection Radiometer Global DEM version 2.0 (ASTER GDEM2) was statistically assessed using high accuracy GPS survey data. Root-Mean-Square errors of ~5.40 m, ~7.47 m and ~20.03 m were obtained for ALOS W3D30, SRTM30 and ASTER GDEM2 respectively. In further analyses, we discovered that ALOS W3D30 and SRTM30 were much more accurate in regions where the height intervals were within 201 m - 400 m and >801 m. ALOS W3D30 proved to be the most accurate DEM that best represents the topography of the earth’s surface and could be used for some earth and environmental applications in Nigeria. We recommend that this study should serve as a guide in the use of any of these DEMs for earth and environmental applications in Nigeria.展开更多
It is practically impossible and unnecessary to obtain spatial-temporal information of any given continuous phenomenon at every point within a given geographic area. The most practical approach has always been to obta...It is practically impossible and unnecessary to obtain spatial-temporal information of any given continuous phenomenon at every point within a given geographic area. The most practical approach has always been to obtain information about the phenomenon as in many sample points as possible within the given geographic area and estimate the values of the unobserved points from the values of the observed points through spatial interpolation. However, it is important that users understand that different interpolation methods have their strength and weaknesses on different datasets. It is not correct to generalize that a given interpolation method (e.g. Kriging, Inverse Distance Weighting (IDW), Spline etc.) does better than the other without taking into cognizance, the type and nature of the dataset and phenomenon involved. In this paper, we theoretically, mathematically and experimentally evaluate the performance of Kriging, IDW and Spline interpolation methods respectively in estimating unobserved elevation values and modeling landform. This paper undertakes a comparative analysis based on the prediction mean error, prediction root mean square error and cross validation outputs of these interpolation methods. Experimental results for each of the method on both biased and normalized data show that Spline provided a better and more accurate interpolation within the sample space than the IDW and Kriging methods. The choice of an interpolation method should be phenomenon and data set structure dependent.展开更多
For a better visual impression,3D information systems and architecture need detailed,photo-realistic visualization of 3D data-sets.However,easy accessibility with efficient rendering becomes difficult due to the detai...For a better visual impression,3D information systems and architecture need detailed,photo-realistic visualization of 3D data-sets.However,easy accessibility with efficient rendering becomes difficult due to the detailed data associated with 3D objects.Therefore,different applications demand different levels of detail(LoD).Currently,City Geography Markup Language(CityGML),as the Open Geospatial Consortium standard,is being used to model and represent buildings in different LoDs(LoD0–LoD4),but it does not provide methods to generate different LoDs automatically.Thus,generalized(abstracted)3D scenes of buildings need to be generated to fulfill the demands of task-specific applications by reducing data volume.This paper discusses various ways to generalize building models,within the framework of CityGML,reducing the level of detail from higher LoD to lower.The LoD4 data is parsed and analyzed.Various heuristics are applied to simplify the ground plan and the results are then aggregated.The minimum length of an edge for simplification is restricted to the CityGML generalization specifications provided and is characterized by differing accuracies and minimal dimensions of objects for LoD1 and LoD2.This could maintain the accuracy of generalized objects and avoid the elimination or merging of important features.Second,the heights of the walls of the simplified ground plans are raised with the aim to construct simplified 3D building models.Algorithms for simplification and aggregation aiming to derive LoD2 and LoD1 are implemented and tested on a number of buildings of Putrajaya,Malaysia.The experiment results show that the minimum length of edges to be simplified is inversely proportional to the size of generalized models.展开更多
Data fusion has shown potential to improve the accuracy of land cover mapping,and selection of the optimal fusion technique remains a challenge.This study investigated the performance of fusing Sentinel-1(S-1)and Sent...Data fusion has shown potential to improve the accuracy of land cover mapping,and selection of the optimal fusion technique remains a challenge.This study investigated the performance of fusing Sentinel-1(S-1)and Sentinel-2(S-2)data,using layer-stacking method at the pixel level and Dempster-Shafer(D-S)theory-based approach at the decision level,for mapping six land cover classes in Thu Dau Mot City,Vietnam.At the pixel level,S-1 and S-2 bands and their extracted textures and indices were stacked into the different single-sensor and multi-sensor datasets(i.e.fused datasets).The datasets were categorized into two groups.One group included the datasets containing only spectral and backscattering bands,and the other group included the datasets consisting of these bands and their extracted features.The random forest(RF)classifier was then applied to the datasets within each group.At the decision level,the RF classification outputs of the single-sensor datasets within each group were fused together based on D-S theory.Finally,the accuracy of the mapping results at both levels within each group was compared.The results showed that fusion at the decision level provided the best mapping accuracy compared to the results from other products within each group.The highest overall accuracy(OA)and Kappa coefficient of the map using D-S theory were 92.67%and 0.91,respectively.The decision-level fusion helped increase the OA of the map by 0.75%to 2.07%compared to that of corresponding S-2 products in the groups.Meanwhile,the data fusion at the pixel level delivered the mapping results,which yielded an OA of 4.88%to 6.58%lower than that of corresponding S-2 products in the groups.展开更多
3D navigation within a 3D-GIS environment is increasingly getting more popular and spreading to various fields.In thelast decade,especially after the 9/11 disaster,evacuating the complex and tall buildings of today in...3D navigation within a 3D-GIS environment is increasingly getting more popular and spreading to various fields.In thelast decade,especially after the 9/11 disaster,evacuating the complex and tall buildings of today in case of emergencyhas been an important research area for scientists.Most of the current navigation systems are still in the 2D environmentand that is insufficient to visualize 3D objects and to obtain satisfactory solutions for the 3D environment.Therefore,there is currently still a lack of implementation of 3D network analysis and navigation for indoor spaces in respect toevacuation.The objective of this paper is to investigate and implement 3D visualization and navigation techniques andsolutions for indoor spaces within 3D-GIS.For realizing this,we have proposed a GIS implementation that is capable ofcarrying out 3D visualization of a building model stored in the CityGML format and perform analysis on a networkmodel stored in Oracle Spatial.The proposed GUI also provides routing simulation on the calculated shortest paths withvoice commands and visual instructions.展开更多
The vertical distribution of single scattering albedos （SSAs） of Asian dust mixed with pollutants was derived using the multi-wavelength Raman lidar observation system at Gwangju （35.10°N,126.53°E）.Verti...The vertical distribution of single scattering albedos （SSAs） of Asian dust mixed with pollutants was derived using the multi-wavelength Raman lidar observation system at Gwangju （35.10°N,126.53°E）.Vertical profiles of both backscatter and extinction coefficients for dust and non-dust aerosols were extracted from a mixed Asian dust plume using the depolarization ratio from lidar observations.Vertical profiles of backscatter and extinction coefficients of non-dust particles were input into an inversion algorithm to retrieve the SSAs of non-dust aerosols.Atmospheric aerosol layers at different heights had different light-absorbing characteristics.The SSAs of non-dust particles at each height varied with aerosol type,which was either urban/industrial pollutants from China transported over long distances at high altitude,or regional/local pollutants from the Korean peninsula.Taking advantage of independent profiles of SSAs of non-dust particles,vertical profiles of SSAs of Asian dust mixed with pollutants were estimated for the first time,with a new approach suggested in this study using an empirical determination of the SSA of pure dust.The SSAs of the Asian dust-pollutants mixture within the planetary boundary layer （PBL） were in the range 0.88-0.91,while the values above the PBL were in the range 0.76-0.87,with a very low mean value of 0.76 ± 0.05.The total mixed dust plume SSAs in each aerosol layer were integrated over height for comparison with results from the Aerosol Robotics Network （AERONET） measurements.Values of SSA retrieved from lidar observations of 0.92 ± 0.01 were in good agreement with the results from AERONET measurements.展开更多
In order to promote the application of Beijing-1 small satellite(BJ-1) remote sensing data,the multispectral and panchromatic images captured by BJ-1 were used for land cover classification in Pangzhuang Coal Mining.A...In order to promote the application of Beijing-1 small satellite(BJ-1) remote sensing data,the multispectral and panchromatic images captured by BJ-1 were used for land cover classification in Pangzhuang Coal Mining.An improved Intensity-Hue-Saturation(IHS) fusion algorithm is proposed to fuse panchromatic and multispectral images,in which intensity component and panchromatic image are combined using the weights determined by edge pixels in the panchromatic image identified by grey absolute correlation degree.This improved IHS fusion algorithm outper-forms traditional IHS fusion method to a certain extent,evidenced by its ability in preserving spectral information and enhancing spatial details.Dempster-Shafer(D-S) evidence theory was adopted to combine the outputs of three member classifiers to generate the final classification map with higher accuracy than that by any individual classifier.Based on this study,we conclude that Beijing-1 small satellite remote sensing images are useful to monitor and analyze land cover change and ecological environment degradation in mining areas,and the proposed fusion algorithms at data and decision levels can integrate the advantages of multi-resolution images and multiple classifiers,improve the overall accuracy and produce a more reliable land cover map.展开更多
One of the most powerful functions of Geographic Information System for Transportation (GIS-T) is Dynamic Segmentation (DS), which is used to increase the efficiency and precision of road management by generating segm...One of the most powerful functions of Geographic Information System for Transportation (GIS-T) is Dynamic Segmentation (DS), which is used to increase the efficiency and precision of road management by generating segments based on attributes. The road segments describing transportation data are both spatially and temporally referenced. For a variety of transportation applications, historical road segments must be preserved. This study presents an appropriate approach to preserve and retrieve the historical road segments efficiently. In the proposed method, only the portions of segments of a time stamp that have been changed into new segments rather than storing the entire segments for every old time stamp are recorded .The storage of these portions is based on the type of changes. A recursive algorithm is developed to retrieve all segments for every old time stamp. Experimental results using real data of Tehran City, Iran justify the strength of the proposed approach in many aspects. An important achievement of the results is that database volume for 2006, 2007 and 2008 within the Historical Line Event Table (HLET) is reduced by 70%, 80% and 78%, respectively. The proposed method has the potential to prevent from vast data redundancy and the unnecessary storage of entire segments for each time stamp. Since the present technique is performed on ordinary plain tables that are readable by all GIS software, special software platforms to manage the storage and retrieval of historical segments are not needed. In addition, this method simplifies spatio-temporal queries.展开更多
Quantitative glacial chronologies of past glaciations are sparse in the Himalaya, and mostly absent in the Kashmir Himalaya. We used cosmogenicBe exposure dating, and geomorphological mapping to reconstruct glacial ad...Quantitative glacial chronologies of past glaciations are sparse in the Himalaya, and mostly absent in the Kashmir Himalaya. We used cosmogenicBe exposure dating, and geomorphological mapping to reconstruct glacial advances of the Thajwas Glacier(TG) in the Great Himalayan Range of the Kashmir Himalaya. FromBe exposure dating of ten moraine boulders, four glacial stages with ages ~20.77 ±2.28 ka, ~11.46 ± 1.69 ka, ~9.12 ± 1.39 ka and ~4.19 ± 0.78 ka, were identified. The reconstructed cosmogenic radionuclide ages confirmed the global Last Glacial Maximum(g LGM), Younger Dryas, Early Holocene, and Neoglaciation episodes. As per area and volume change analyses, the TG has lost 51.1 km~2 of its area and a volume of 2.64 km~3 during the last 20.77 ± 2.28 ka. Overall, the results suggested that the TG has lost 64% of area and 73% of volume from the Last glacial maximum to Neoglaciation and about 85.74% and 87.67% of area and volume, respectively, from Neoglaciation to the present day. The equilibrium line altitude of the TG fluctuated from 4238 m a.s.l present to3365 m a.s.l during the g LGM(20.77 ± 2.28 ka). The significant cooling induced by a drop in mean ambient temperature resulted in a positive mass balance of the TG during the g LGM. Subsequently the melting accelerated due to the continuing rise of the global ambient temperature. Paleo-glacial history reconstruction of the Kashmir Himalaya, with its specific geomorphic and climatic setting, would help close the information gap about the chronology of past regional glacial episodes.展开更多
Mountain forests are more prone to environmental predispositions(EPs)than submountain ones.While remote sensing of mountain forests enables instantaneous damage mapping,the investigation of the causes requires field d...Mountain forests are more prone to environmental predispositions(EPs)than submountain ones.While remote sensing of mountain forests enables instantaneous damage mapping,the investigation of the causes requires field data.However,a local field or regionally modeled environmental characteristics influence remote data evaluation differently.This study focused on the evaluation of EPs effects damaging mountain forests between various spatial resolutions during environmental change.The evaluation was divided into managed and natural forests in the Hruby Jeseník Mts.(Czech Republic;240-1491 m a.s.l.;50.082°N,17.231°E).Damage was assessed through the discrimination analysis of the normalised difference vegetation index(NDVI)by MODIS VI during alternating drought and flood periods 2003-2014.The local environmental influence was assessed using the discrimination function(DF)separability of forest damage in the training sets.The regional influence was assessed through map algebra estimated via the DF and a forest decline spatial model based on EPs from differences between risk growth conditions and biomass fuzzy sets.Management,EPs and soil influenced forest NDVI at different levels.The management afflicted the NDVI more than the EPs.The EPs afflicted the NDVI more than the soil groups.Strong winters and droughts had a greater influence on the NDVI than the flood events,with the winter of 2005/2006 inverting the DF direction,and the 2003 drought increasing differences in managed forest biomass and decreasing differences in natural forest biomasses.More than 50% of declining managed forests in the training sets occurred on Leptosols,Podzols and Histosols.On a regional scale,the soil influence was eliminated by multiple predispositions.The EPs influenced 96% of natural forest and 65% of managed forest,though managed forest damage was more evident.The mountain forest NDVI decline was dependent on both management and risk predispositions.展开更多
This research compares the potential of SRTM-V4.1 and ASTER-V2.1 with 30-m pixel size to derive topographic attributes （elevation, slopes, aspects, and flow accumulation） and hydrologic indices such as STI （sedimen...This research compares the potential of SRTM-V4.1 and ASTER-V2.1 with 30-m pixel size to derive topographic attributes （elevation, slopes, aspects, and flow accumulation） and hydrologic indices such as STI （sediment transport index）, CTI （compound topographic index） and SPI （stream power index） to detect areas associated with flash floods cansed by rainfall storms and sediment accumulation. The study area is Guelmim city in Morocco, which has been flooded several times over the past 50 years, and which was declared a ＂disaster area＂ in December 2014 after violent rainfall storms killed 46 people and caused significant damage to the infrastructure. The obtained results indicate that the SRTM DEM performs better than ASTER in terms of micro-topography, hydrologic-network and structural information characterization. In addition, with reference to a topographic contours map （1：50000）, the derived global height surfaces accuracies are ＋3.15 m and 4-9.17 m for SRTM and ASTER, respectively. These accuracies are significantly influenced by topography; errors are larger （SRTM = 11.34 m, ASTER = 19.20 m） for high altitude terrain with strong slopes, while they are smaller （SRTM = 1.92 m, ASTER = 3.76 m） in the low to medium-relief areas with indulgent slopes. Moreover, all the considered hydrological indices are significantly characterized with SRTM compared to ASTER. They demonstrated that the rainfall and the topographic morphology are the major contributing factors in flash flooding and catastrophic inundation in this area. The runoff waterpower delivers vulnerable topsoil and contributes strongly to the erosion and transport of soil material and sediment to the plain areas through waterpower and gravity. Likewise, the role of the lithology associated with the terrain morphology is decisive in the erosion risk and land degradation in this region.展开更多
The pervasive herdsmen-farmers conflicts in the north-central region of Nigeria have changed the narrative of Nigeria’s enduring ethnic crises to ideologies, which are in-controvertibly sinister. The consequences of ...The pervasive herdsmen-farmers conflicts in the north-central region of Nigeria have changed the narrative of Nigeria’s enduring ethnic crises to ideologies, which are in-controvertibly sinister. The consequences of this tension, which has defied possible military responses, political, religious and cultural strategies are potentially devastating, not just for Nigeria, but the whole of West African region. Since the particular nature of these conflicts increasingly highlights the significance and inevitability of land resources for crops farming and cattle rearing, it is imperative to create awareness of the elemental nature of soils, especially their diversities in these conflict-prone areas. This study’s objective was to produce a Geographic Information System (GIS) based digital soil map (DSM) of the north-central region of Nigeria, and to delineate soil distribution and unique properties. Based on this study, the DSM offers a quick access to quantitative soil data covering the study area. It indicates that soil mapping units 15d, 18d and 24b are dominant, and constitute about 40% of the local arable lands. The broad pattern of distribution of these soils reflects both the climatic conditions and the geological structure of the region. The soils are highly weathered with limited capacities to supply essential nutrients needed by crop plants. These issues raise a number of questions, most of which focuses on the best possible way to maximize these soils to accommodate both crop farming and cattle rearing. It is our hope that taking the advantage of GIS to stimulate the knowledge and consciousness of soil distribution in the region will place the weight where it is appropriate in terms of food security through crops production and cattle rearing, and hence forge a more realistic pathway to reconciliation and conflict resolution.展开更多
基金the National Natural Science Foundation of China(NSFC 31761143002,NSFC 3207178)China Postdoctoral Science Foundation(2022M710405)the National Forest and Grassland Genetic Recourse(No.2005DKA21003).
文摘The influence of global climate change on endangered species is of growing concern, especially for rosewood species that are in urgent need of protection and restoration. Ecological niche models are commonly used to evaluate probable species’ distribution under climate change and contribute to decision-making to define efficient management strategies. A model was developed to forecast which habitat was most likely appropriate for the Dalbergia odorifera. We screened the main climatic variables that describe the current geographic distribution of the species based on maximum entropy modelling (Maxent). We subsequently assessed its potential future distribution under moderate (RCP2.6) and severe (RCP8.5) climate change scenarios for the years 2050 and 2070. The precipitation ranges of the wettest month and the warmest quarter are the primary limiting factors for the current distribution of D. odorifera among the climatic predictors. Climate change will be expected to have beneficial effects on the distribution range of D. odorifera. In conclusion, the main limits for the distribution of D. odorifera are determined by the level of precipitation and human activities. The results of this study indicate that the coasts of southern China and Chongqing will play a key role in the protection and restoration of D. odorifera in the future.
基金as part of the Department of Science and Technology (DST), Government of India sponsored research projects titled “Centre of Excellence for Glaciological Research in Western Himalaya”the financial assistance received from the Department under the projects to conduct the research。
文摘Himalayan glaciers are shrinking rapidly,especially after 2000.Glacier shrinkage,however,shows a differential pattern in space and time,emphasizing the need to monitor and assess glacier changes at a larger scale.In this study,changes of 48 glaciers situated around the twin peaks of the Nun and Kun mountains in the northwestern Himalaya,hereafter referred to as Nun-Kun Group of Glaciers(NKGG),were investigated using Landsat satellite data during 2000-2020.Changes in glacier area,snout position,Equilibrium Line Altitude(ELA),surface thickness and glacier velocity were assessed using remote sensing data supplemented by field observations.The study revealed that the NKGG glaciers have experienced a recession of 4.5%±3.4%and their snouts have retreated at the rate of 6.4±1.6 m·a^(-1).Additionally,there was a 41%increase observed in the debris cover area during the observation period.Using the geodetic approach,an average glacier elevation change of-1.4±0.4 m·a^(-1)was observed between 2000 and 2012.The observed mass loss of the NKGG has resulted in the deceleration of glacier velocity from 27.0±3.7 m·a^(-1)in 2000 to 21.2±2.2 m·a^(-1)in 2020.The ELA has shifted upwards by 83.0±22 m during the period.Glacier morphological and topographic factors showed a strong influence on glacier recession.Furthermore,a higher recession of 12.9%±3.2%was observed in small glaciers,compared to 2.7%±3.1%in larger glaciers.The debris-covered glaciers showed lower shrinkage(2.8%±1.1%)compared to the clean glaciers(9.3%±5%).The glacier depletion recorded in the NKGG during the last two decades,if continued,would severely diminish glacial volume and capacity to store water,thus jeopardizing the sustainability of water resources in the basin.
文摘The Alborz Mountains are some of the highest in Iran,and they play an important role in controlling the climate of the country’s northern regions.The land surface temperature(LST)is an important variable that affects the ecosystem of this area.This study investigated the spatiotemporal changes and trends of the nighttime LST in the western region of the Central Alborz Mountains at elevations of 1500-4000 m above sea level.MODIS data were extracted for the period of 2000-2021,and the Mann-Kendall nonparametric test was applied to evaluating the changes in the LST.The results indicated a significant increasing trend for the monthly average LST in May-August along the southern aspect.Both the northern and southern aspects showed decreasing trends for the monthly average LST in October,November,and March and an increasing trend in other months.At all elevations,the average decadal change in the monthly average LST was more severe along the southern aspect(0.60°C)than along the northern aspect(0.37°C).The LST difference between the northern and southern aspects decreased in the cold months but increased in the hot months.At the same elevation,the difference in the lapse rate between the northern and southern aspects was greater in the hot months than in the cold months.With increasing elevation,the lapse rate between the northern and southern aspects disappeared.Climate change was concluded to greatly decrease the difference in LST at different elevations for April-July.
基金funded by National Science Centre,Poland under the project"Assessment of the impact of weather conditions on forest health status and forest disturbances at regional and national scale based on the integration of ground and space-based remote sensing datasets"(project no.2021/41/B/ST10/)Data collection and research was also supported by the project no.EZ.271.3.19.2021"Modele ryzyka zamierania drzewostanow glownych gatunkow lasotworczych Polski"funded by the General Directorate of State Forests in Poland。
文摘Over the past decade,the presence of mistletoe(Viscum album ssp.austriacum)in Scots pine stands has increased in many European countries.Understanding the factors that influence the occurrence of mistletoe in stands is key to making appropriate forest management decisions to limit damage and prevent the spread of mistletoe in the future.Therefore,the main objective of this study was to determine the probability of mistletoe occurrence in Scots pine stands in relation to stand-related endogenous factors such as age,top height,and stand density,as well as topographic and edaphic factors.We used unmanned aerial vehicle(UAV)imagery from 2,247 stands to detect mistletoe in Scots pine stands,while majority stand and site characteristics were calculated from airborne laser scanning(ALS)data.Information on stand age and site type from the State Forest database were also used.We found that mistletoe infestation in Scots pine stands is influenced by stand and site characteristics.We documented that the densest,tallest,and oldest stands were more susceptible to mistletoe infestation.Site type and specific microsite conditions associated with topography were also important factors driving mistletoe occurrence.In addition,climatic water balance was a significant factor in increasing the probability of mistletoe occurrence,which is important in the context of predicted temperature increases associated with climate change.Our results are important for better understanding patterns of mistletoe infestation and ecosystem functioning under climate change.In an era of climate change and technological development,the use of remote sensing methods to determine the risk of mistletoe infestation can be a very useful tool for managing forest ecosystems to maintain forest sustainability and prevent forest disturbance.
文摘Understanding trends of land use land cover (LULC) changes is important for biodiversity monitoring and conservation planning, and identifying the areas affected by change and designing sustainable solutions to reduce the changes. The study aims to evaluate and quantify the historical changes in land use and land cover in Mukumbura (Ward 2), Mt Darwin, Zimbabwe, from 2002 to 2022. The objective of the study was to analyse the LULC changes in Ward 2 (Mukumbura), Mt Darwin, Northern Zimbabwe, for a period of 20 years using geospatial techniques. Landsat satellite images were processed using Google Earth Engine (GEE) and the supervised classification with maximum likelihood algorithm was employed to generate LULC maps between 2002 and 2022 with a five (5) year interval, investigating the following variables, forest cover, barren land, water cover and the fields. Findings revealed a substantial reduction in forest cover by 38.8%, water bodies (wetlands, ponds, and rivers) declined by 55.6%, whilst fields (crop/agricultural fields) increased by 93.3% and the barren land cover increased by 26.3% from 2002 to 2022. These findings point to substantial changes in LULC over the observed years. LULC changes have resulted in habitat fragmentation, reduced biodiversity, and the disruption of ecosystem functions. The study concludes that if these deforestation trends, cultivation, and settlement land expansion continue, the ward will have limited indigenous fruit trees. Therefore, the causes for LULC changes must be controlled, sustainable forest resources use practiced, hence the need to domesticate the indigenous fruit trees in arborloo toilets.
基金the Basic Research Project of the Korea Institute of Geoscience and Mineral Resources(KIGAM)Project of Environmental Business Big Data Platform and Center Construction funded by the Ministry of Science and ICT.
文摘The identification of landslide-prone areas is an essential step in landslide hazard assessment and mitigation of landslide-related losses.In this study,we applied two novel deep learning algorithms,the recurrent neural network(RNN)and convolutional neural network(CNN),for national-scale landslide susceptibility mapping of Iran.We prepared a dataset comprising 4069 historical landslide locations and 11 conditioning factors(altitude,slope degree,profile curvature,distance to river,aspect,plan curvature,distance to road,distance to fault,rainfall,geology and land-sue)to construct a geospatial database and divided the data into the training and the testing dataset.We then developed RNN and CNN algorithms to generate landslide susceptibility maps of Iran using the training dataset.We calculated the receiver operating characteristic(ROC)curve and used the area under the curve(AUC)for the quantitative evaluation of the landslide susceptibility maps using the testing dataset.Better performance in both the training and testing phases was provided by the RNN algorithm(AUC=0.88)than by the CNN algorithm(AUC=0.85).Finally,we calculated areas of susceptibility for each province and found that 6%and 14%of the land area of Iran is very highly and highly susceptible to future landslide events,respectively,with the highest susceptibility in Chaharmahal and Bakhtiari Province(33.8%).About 31%of cities of Iran are located in areas with high and very high landslide susceptibility.The results of the present study will be useful for the development of landslide hazard mitigation strategies.
文摘Current global urbanisation processes are leading to new forms of massive urban constellations. The conceptualisations and classifications of these, however, are often ambiguous, overlap or lag behind in scientific literature. This article examines whether there is a common denominator to define and delimitate–and ultimately map–these new dimensions of cityscapes. In an extensive literature review we analysed and juxtaposed some of the most common concepts such as megacity, megaregion or megalopolis. We observed that many concepts are abstract or unspecific, and for those concepts for which physical parameters exist, the parameters are neither properly defined nor used in standardised ways. While understandably concepts originate from various disciplines, the authors identify a need for more precise definition and use of parameters. We conclude that often, spatial patterns of large urban areas resemble each other considerably but the definitions vary so widely that these differences may surpass any inconsistencies in the spatial delimitation process. In other words, today we have tools such as earth observation data and Geographic Information Systems to parameterise if clear definitions are provided. This appears not to be the case. The limiting factor when delineating large urban areas seems to be a commonly agreed ontology.
基金This study was funded by the Korea Meteorological Administration Research and Development Program(KMI2017-9060)the National Research Foundation of Korea funded by the Korea government(NRF-2018M1A3A3A02066008)+1 种基金In addition,the ALOS-2 PALSAR-2 data used in this study are owned by the Japan Aerospace Exploration Agency(JAXA)and were provided through the JAXA’s ALOS-2 research program(RA4,PI No.1412)The GPS data were provided by the Geospatial Information Authority of Japan.
文摘Conventional synthetic aperture radar(SAR)interferometry(InSAR)has been successfully used to precisely measure surface deformation in the line-of-sight(LOS)direction,while multiple-aperture SAR interferometry(MAI)has provided precise surface deformation in the along-track(AT)direction.Integration of the InSAR and MAI methods enables precise measurement of the two-dimensional(2D)deformation from an interferometric pair;recently,the integration of ascending and descending pairs has allowed the observation of precise three-dimensional(3D)deformation.Precise 3D deformation measurement has been applied to better understand geological events such as earthquakes and volcanic eruptions.The surface deformation related to the 2016 Kumamoto earthquake was large and complex near the fault line;hence,precise 3D deformation retrieval had not yet been attempted.The objectives of this study were to①perform a feasibility test of precise 3D deformation retrieval in large and complex deformation areas through the integration of offset-based unwrapped and improved multiple-aperture SAR interferograms and②observe the 3D deformation field related to the 2016 Kumamoto earthquake,even near the fault lines.Two ascending pairs and one descending the Advanced Land Observing Satellite-2(ALOS-2)Phased Array-type L-band Synthetic Aperture Radar-2(PALSAR-2)pair were used for the 3D deformation retrieval.Eleven in situ Global Positioning System(GPS)measurements were used to validate the 3D deformation measurement accuracy.The achieved accuracy was approximately 2.96,3.75,and 2.86 cm in the east,north,and up directions,respectively.The results show the feasibility of precise 3D deformation measured through the integration of the improved methods,even in a case of large and complex deformation.
文摘Digital Elevation Models (DEMs) depict the configuration of the earth surface and are being applied in many areas in earth and environmental sciences. In this study, the accuracy of the Advanced Land Observing Satellite World 3D Digital Surface Model version 2.1 (ALOS W3D30), the Shuttle Radar Topography Mission Digital Elevation Model version 3.0 (SRTM30) and the Advanced Space borne Thermal Emission and Reflection Radiometer Global DEM version 2.0 (ASTER GDEM2) was statistically assessed using high accuracy GPS survey data. Root-Mean-Square errors of ~5.40 m, ~7.47 m and ~20.03 m were obtained for ALOS W3D30, SRTM30 and ASTER GDEM2 respectively. In further analyses, we discovered that ALOS W3D30 and SRTM30 were much more accurate in regions where the height intervals were within 201 m - 400 m and >801 m. ALOS W3D30 proved to be the most accurate DEM that best represents the topography of the earth’s surface and could be used for some earth and environmental applications in Nigeria. We recommend that this study should serve as a guide in the use of any of these DEMs for earth and environmental applications in Nigeria.
文摘It is practically impossible and unnecessary to obtain spatial-temporal information of any given continuous phenomenon at every point within a given geographic area. The most practical approach has always been to obtain information about the phenomenon as in many sample points as possible within the given geographic area and estimate the values of the unobserved points from the values of the observed points through spatial interpolation. However, it is important that users understand that different interpolation methods have their strength and weaknesses on different datasets. It is not correct to generalize that a given interpolation method (e.g. Kriging, Inverse Distance Weighting (IDW), Spline etc.) does better than the other without taking into cognizance, the type and nature of the dataset and phenomenon involved. In this paper, we theoretically, mathematically and experimentally evaluate the performance of Kriging, IDW and Spline interpolation methods respectively in estimating unobserved elevation values and modeling landform. This paper undertakes a comparative analysis based on the prediction mean error, prediction root mean square error and cross validation outputs of these interpolation methods. Experimental results for each of the method on both biased and normalized data show that Spline provided a better and more accurate interpolation within the sample space than the IDW and Kriging methods. The choice of an interpolation method should be phenomenon and data set structure dependent.
基金We would like to convey our deepest acknowledgement firstly to Universiti Teknologi Malaysia(UTM)for providing research grant Vote No.Q.J130000.7127.04J81Last but not least our sincere appreciation to The Research Management Centre(RMC)of UTM and The Ministry of Higher Education(MOHE),Malaysia for enabling us to carry out this research project.
文摘For a better visual impression,3D information systems and architecture need detailed,photo-realistic visualization of 3D data-sets.However,easy accessibility with efficient rendering becomes difficult due to the detailed data associated with 3D objects.Therefore,different applications demand different levels of detail(LoD).Currently,City Geography Markup Language(CityGML),as the Open Geospatial Consortium standard,is being used to model and represent buildings in different LoDs(LoD0–LoD4),but it does not provide methods to generate different LoDs automatically.Thus,generalized(abstracted)3D scenes of buildings need to be generated to fulfill the demands of task-specific applications by reducing data volume.This paper discusses various ways to generalize building models,within the framework of CityGML,reducing the level of detail from higher LoD to lower.The LoD4 data is parsed and analyzed.Various heuristics are applied to simplify the ground plan and the results are then aggregated.The minimum length of an edge for simplification is restricted to the CityGML generalization specifications provided and is characterized by differing accuracies and minimal dimensions of objects for LoD1 and LoD2.This could maintain the accuracy of generalized objects and avoid the elimination or merging of important features.Second,the heights of the walls of the simplified ground plans are raised with the aim to construct simplified 3D building models.Algorithms for simplification and aggregation aiming to derive LoD2 and LoD1 are implemented and tested on a number of buildings of Putrajaya,Malaysia.The experiment results show that the minimum length of edges to be simplified is inversely proportional to the size of generalized models.
基金the Hungarian Scientific Research Fund in support of the ongoing research,“Time series analysis of land cover dynamics using medium-and high-resolution satellite images”[grant number NKFIH 124648K],at the Department of Physical Geography and Geoinformatics(the former name of the Department of Geoinformatics,Physical and Environmental Geography),University of Szeged,Szeged,Hungary.
文摘Data fusion has shown potential to improve the accuracy of land cover mapping,and selection of the optimal fusion technique remains a challenge.This study investigated the performance of fusing Sentinel-1(S-1)and Sentinel-2(S-2)data,using layer-stacking method at the pixel level and Dempster-Shafer(D-S)theory-based approach at the decision level,for mapping six land cover classes in Thu Dau Mot City,Vietnam.At the pixel level,S-1 and S-2 bands and their extracted textures and indices were stacked into the different single-sensor and multi-sensor datasets(i.e.fused datasets).The datasets were categorized into two groups.One group included the datasets containing only spectral and backscattering bands,and the other group included the datasets consisting of these bands and their extracted features.The random forest(RF)classifier was then applied to the datasets within each group.At the decision level,the RF classification outputs of the single-sensor datasets within each group were fused together based on D-S theory.Finally,the accuracy of the mapping results at both levels within each group was compared.The results showed that fusion at the decision level provided the best mapping accuracy compared to the results from other products within each group.The highest overall accuracy(OA)and Kappa coefficient of the map using D-S theory were 92.67%and 0.91,respectively.The decision-level fusion helped increase the OA of the map by 0.75%to 2.07%compared to that of corresponding S-2 products in the groups.Meanwhile,the data fusion at the pixel level delivered the mapping results,which yielded an OA of 4.88%to 6.58%lower than that of corresponding S-2 products in the groups.
基金This study was supported by TUBITAK–The Scientific and Technological Research Council of Turkey(Project No.112Y050)research grant.We are indebted for its financial support.
文摘3D navigation within a 3D-GIS environment is increasingly getting more popular and spreading to various fields.In thelast decade,especially after the 9/11 disaster,evacuating the complex and tall buildings of today in case of emergencyhas been an important research area for scientists.Most of the current navigation systems are still in the 2D environmentand that is insufficient to visualize 3D objects and to obtain satisfactory solutions for the 3D environment.Therefore,there is currently still a lack of implementation of 3D network analysis and navigation for indoor spaces in respect toevacuation.The objective of this paper is to investigate and implement 3D visualization and navigation techniques andsolutions for indoor spaces within 3D-GIS.For realizing this,we have proposed a GIS implementation that is capable ofcarrying out 3D visualization of a building model stored in the CityGML format and perform analysis on a networkmodel stored in Oracle Spatial.The proposed GUI also provides routing simulation on the calculated shortest paths withvoice commands and visual instructions.
基金funded by the Korea Meteorological Administration Research and Development Program (Grant No.CATER 2012-7080)a National Research Foundation of Korea (NRF) grant funded by the Korean government (MEST) (Grant No.2012R1A1A2002983)the Global Ph.D. Fellowship program sponsored by the National Research Foundation of Korea
文摘The vertical distribution of single scattering albedos （SSAs） of Asian dust mixed with pollutants was derived using the multi-wavelength Raman lidar observation system at Gwangju （35.10°N,126.53°E）.Vertical profiles of both backscatter and extinction coefficients for dust and non-dust aerosols were extracted from a mixed Asian dust plume using the depolarization ratio from lidar observations.Vertical profiles of backscatter and extinction coefficients of non-dust particles were input into an inversion algorithm to retrieve the SSAs of non-dust aerosols.Atmospheric aerosol layers at different heights had different light-absorbing characteristics.The SSAs of non-dust particles at each height varied with aerosol type,which was either urban/industrial pollutants from China transported over long distances at high altitude,or regional/local pollutants from the Korean peninsula.Taking advantage of independent profiles of SSAs of non-dust particles,vertical profiles of SSAs of Asian dust mixed with pollutants were estimated for the first time,with a new approach suggested in this study using an empirical determination of the SSA of pure dust.The SSAs of the Asian dust-pollutants mixture within the planetary boundary layer （PBL） were in the range 0.88-0.91,while the values above the PBL were in the range 0.76-0.87,with a very low mean value of 0.76 ± 0.05.The total mixed dust plume SSAs in each aerosol layer were integrated over height for comparison with results from the Aerosol Robotics Network （AERONET） measurements.Values of SSA retrieved from lidar observations of 0.92 ± 0.01 were in good agreement with the results from AERONET measurements.
基金Under the auspices of National Natural Science Foundation of China (No. 40871195)Opening Fund of Beijing-1Small Satellite Data Applications from State Key Laboratory for Remote Sensing Science (No. 200709)National High Technology Research and Development Program of China (No. 2007AA12Z162)
文摘In order to promote the application of Beijing-1 small satellite(BJ-1) remote sensing data,the multispectral and panchromatic images captured by BJ-1 were used for land cover classification in Pangzhuang Coal Mining.An improved Intensity-Hue-Saturation(IHS) fusion algorithm is proposed to fuse panchromatic and multispectral images,in which intensity component and panchromatic image are combined using the weights determined by edge pixels in the panchromatic image identified by grey absolute correlation degree.This improved IHS fusion algorithm outper-forms traditional IHS fusion method to a certain extent,evidenced by its ability in preserving spectral information and enhancing spatial details.Dempster-Shafer(D-S) evidence theory was adopted to combine the outputs of three member classifiers to generate the final classification map with higher accuracy than that by any individual classifier.Based on this study,we conclude that Beijing-1 small satellite remote sensing images are useful to monitor and analyze land cover change and ecological environment degradation in mining areas,and the proposed fusion algorithms at data and decision levels can integrate the advantages of multi-resolution images and multiple classifiers,improve the overall accuracy and produce a more reliable land cover map.
文摘One of the most powerful functions of Geographic Information System for Transportation (GIS-T) is Dynamic Segmentation (DS), which is used to increase the efficiency and precision of road management by generating segments based on attributes. The road segments describing transportation data are both spatially and temporally referenced. For a variety of transportation applications, historical road segments must be preserved. This study presents an appropriate approach to preserve and retrieve the historical road segments efficiently. In the proposed method, only the portions of segments of a time stamp that have been changed into new segments rather than storing the entire segments for every old time stamp are recorded .The storage of these portions is based on the type of changes. A recursive algorithm is developed to retrieve all segments for every old time stamp. Experimental results using real data of Tehran City, Iran justify the strength of the proposed approach in many aspects. An important achievement of the results is that database volume for 2006, 2007 and 2008 within the Historical Line Event Table (HLET) is reduced by 70%, 80% and 78%, respectively. The proposed method has the potential to prevent from vast data redundancy and the unnecessary storage of entire segments for each time stamp. Since the present technique is performed on ordinary plain tables that are readable by all GIS software, special software platforms to manage the storage and retrieval of historical segments are not needed. In addition, this method simplifies spatio-temporal queries.
基金conducted with the help of grants from the Department of Science and Technology (DST), Government of India under the sponsored research project titled “Centre of Excellence for Glacial Studies in Western Himalaya”granting fellowship to Omar Jaan Paul under the project No. UFR-59313。
文摘Quantitative glacial chronologies of past glaciations are sparse in the Himalaya, and mostly absent in the Kashmir Himalaya. We used cosmogenicBe exposure dating, and geomorphological mapping to reconstruct glacial advances of the Thajwas Glacier(TG) in the Great Himalayan Range of the Kashmir Himalaya. FromBe exposure dating of ten moraine boulders, four glacial stages with ages ~20.77 ±2.28 ka, ~11.46 ± 1.69 ka, ~9.12 ± 1.39 ka and ~4.19 ± 0.78 ka, were identified. The reconstructed cosmogenic radionuclide ages confirmed the global Last Glacial Maximum(g LGM), Younger Dryas, Early Holocene, and Neoglaciation episodes. As per area and volume change analyses, the TG has lost 51.1 km~2 of its area and a volume of 2.64 km~3 during the last 20.77 ± 2.28 ka. Overall, the results suggested that the TG has lost 64% of area and 73% of volume from the Last glacial maximum to Neoglaciation and about 85.74% and 87.67% of area and volume, respectively, from Neoglaciation to the present day. The equilibrium line altitude of the TG fluctuated from 4238 m a.s.l present to3365 m a.s.l during the g LGM(20.77 ± 2.28 ka). The significant cooling induced by a drop in mean ambient temperature resulted in a positive mass balance of the TG during the g LGM. Subsequently the melting accelerated due to the continuing rise of the global ambient temperature. Paleo-glacial history reconstruction of the Kashmir Himalaya, with its specific geomorphic and climatic setting, would help close the information gap about the chronology of past regional glacial episodes.
基金the support by the Project LM2018123 Cze COS of the Ministry of Education,Youth and Sports of the Czech Republic。
文摘Mountain forests are more prone to environmental predispositions(EPs)than submountain ones.While remote sensing of mountain forests enables instantaneous damage mapping,the investigation of the causes requires field data.However,a local field or regionally modeled environmental characteristics influence remote data evaluation differently.This study focused on the evaluation of EPs effects damaging mountain forests between various spatial resolutions during environmental change.The evaluation was divided into managed and natural forests in the Hruby Jeseník Mts.(Czech Republic;240-1491 m a.s.l.;50.082°N,17.231°E).Damage was assessed through the discrimination analysis of the normalised difference vegetation index(NDVI)by MODIS VI during alternating drought and flood periods 2003-2014.The local environmental influence was assessed using the discrimination function(DF)separability of forest damage in the training sets.The regional influence was assessed through map algebra estimated via the DF and a forest decline spatial model based on EPs from differences between risk growth conditions and biomass fuzzy sets.Management,EPs and soil influenced forest NDVI at different levels.The management afflicted the NDVI more than the EPs.The EPs afflicted the NDVI more than the soil groups.Strong winters and droughts had a greater influence on the NDVI than the flood events,with the winter of 2005/2006 inverting the DF direction,and the 2003 drought increasing differences in managed forest biomass and decreasing differences in natural forest biomasses.More than 50% of declining managed forests in the training sets occurred on Leptosols,Podzols and Histosols.On a regional scale,the soil influence was eliminated by multiple predispositions.The EPs influenced 96% of natural forest and 65% of managed forest,though managed forest damage was more evident.The mountain forest NDVI decline was dependent on both management and risk predispositions.
文摘This research compares the potential of SRTM-V4.1 and ASTER-V2.1 with 30-m pixel size to derive topographic attributes （elevation, slopes, aspects, and flow accumulation） and hydrologic indices such as STI （sediment transport index）, CTI （compound topographic index） and SPI （stream power index） to detect areas associated with flash floods cansed by rainfall storms and sediment accumulation. The study area is Guelmim city in Morocco, which has been flooded several times over the past 50 years, and which was declared a ＂disaster area＂ in December 2014 after violent rainfall storms killed 46 people and caused significant damage to the infrastructure. The obtained results indicate that the SRTM DEM performs better than ASTER in terms of micro-topography, hydrologic-network and structural information characterization. In addition, with reference to a topographic contours map （1：50000）, the derived global height surfaces accuracies are ＋3.15 m and 4-9.17 m for SRTM and ASTER, respectively. These accuracies are significantly influenced by topography; errors are larger （SRTM = 11.34 m, ASTER = 19.20 m） for high altitude terrain with strong slopes, while they are smaller （SRTM = 1.92 m, ASTER = 3.76 m） in the low to medium-relief areas with indulgent slopes. Moreover, all the considered hydrological indices are significantly characterized with SRTM compared to ASTER. They demonstrated that the rainfall and the topographic morphology are the major contributing factors in flash flooding and catastrophic inundation in this area. The runoff waterpower delivers vulnerable topsoil and contributes strongly to the erosion and transport of soil material and sediment to the plain areas through waterpower and gravity. Likewise, the role of the lithology associated with the terrain morphology is decisive in the erosion risk and land degradation in this region.
文摘The pervasive herdsmen-farmers conflicts in the north-central region of Nigeria have changed the narrative of Nigeria’s enduring ethnic crises to ideologies, which are in-controvertibly sinister. The consequences of this tension, which has defied possible military responses, political, religious and cultural strategies are potentially devastating, not just for Nigeria, but the whole of West African region. Since the particular nature of these conflicts increasingly highlights the significance and inevitability of land resources for crops farming and cattle rearing, it is imperative to create awareness of the elemental nature of soils, especially their diversities in these conflict-prone areas. This study’s objective was to produce a Geographic Information System (GIS) based digital soil map (DSM) of the north-central region of Nigeria, and to delineate soil distribution and unique properties. Based on this study, the DSM offers a quick access to quantitative soil data covering the study area. It indicates that soil mapping units 15d, 18d and 24b are dominant, and constitute about 40% of the local arable lands. The broad pattern of distribution of these soils reflects both the climatic conditions and the geological structure of the region. The soils are highly weathered with limited capacities to supply essential nutrients needed by crop plants. These issues raise a number of questions, most of which focuses on the best possible way to maximize these soils to accommodate both crop farming and cattle rearing. It is our hope that taking the advantage of GIS to stimulate the knowledge and consciousness of soil distribution in the region will place the weight where it is appropriate in terms of food security through crops production and cattle rearing, and hence forge a more realistic pathway to reconciliation and conflict resolution.
