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1.
Recent developments of 30 m global land characterization datasets(e.g., land cover, vegetation continues field) represent the finest spatial resolution inputs for global scale studies. Here, we present results from further improvement to land cover mapping and impact analysis of spatial resolution on area estimation for different land cover types. We proposed a set of methods to aggregate two existing 30 m resolution circa 2010 global land cover maps, namely FROM-GLC(Finer Resolution Observation and Monitoring-Global Land Cover) and FROM-GLC-seg(Segmentation), with two coarser resolution global maps on development, i.e., Nighttime Light Impervious Surface Area(NL-ISA) and MODIS urban extent(MODIS-urban), to produce an improved 30 m global land cover map—FROM-GLC-agg(Aggregation). It was post-processed using additional coarse resolution datasets(i.e., MCD12Q1, GlobCover2009, MOD44 W etc.) to reduce land cover type confusion. Around 98.9% pixels remain 30 m resolution after some post-processing to this dataset. Based on this map, majority aggregation and proportion aggregation approaches were employed to create a multi-resolution hierarchy(i.e., 250 m, 500 m, 1 km, 5 km, 10 km, 25 km, 50 km, 100 km) of land cover maps to meet requirements for different resolutions from different applications. Through accuracy assessment, we found that the best overall accuracies for the post-processed base map(at 30 m) and the three maps subsequently aggregated at 250 m, 500 m, 1 km resolutions are 69.50%, 76.65%, 74.65%, and 73.47%, respectively. Our analysis of area-estimation biases for different land cover types at different resolutions suggests that maps at coarser than 5 km resolution contain at least 5% area estimation error for most land cover types. Proportion layers, which contain precise information on land cover percentage, are suggested for use when coarser resolution land cover data are required. 相似文献
2.
The potential for flooding and sediment transport is greatly affected by river channel form and changes in land use. Therefore the modelling of channel morphology prior to canalization and of land‐use change is important with respect to the prediction of floods and sediment yield and their consequences. A combination of land‐use transformation maps and soil properties shows certain decision rules for the conversion of forest into arable or vice versa. The model proposed, from this study, was used to simulate possible past and/or future channel and land‐use patterns. Subsequently, the outcome of this simulation was used to assess the risk of flooding, sediment transport and soil‐erosion under different conditions. In this study, channel morphology prior to canalization and land‐use change in the Ishikari basin, Hokkaido, Japan, were analysed by comparing three scenarios using a physical based channel and slope model. The results indicate that pre‐canalization channel morphology has a significant impact on flood peak, but no significant effect on sediment yield. In contrast, land‐use change has a significant effect on soil eroded from hillslopes, but no significant effect on flooding for Ishikari basin. This study also illustrates the challenges that a simple model, such as a physical based channel and slope model, can simulate large‐scale river basin processes using fewer hydrological data resources. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
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地势是地面高低起伏的形势,是地球内营力和外营力共同作用的结果,是地壳内部结构、构造及其发展在地表的反映.空间重力异常与地形、地貌密切相关,反映地壳内部结构和构造的变化.均衡原理认为高山下面地壳厚,平原下面地壳薄,即地势的起伏同莫霍面的起伏呈镜像关系.中国海陆地质地球物理系列图编制了大地构造格架图和大地构造格架演化图等专题图件,对中国海陆各主要块体的时空演化进行研究,研究了中国海陆地势的"跷跷板"演化过程.本文根据中国海陆1:500万空间重力异常图和莫霍面深度图分析了海陆地貌特征,按照构造地貌的分类原则,将中国海域和陆域作为一个整体进行地貌分类,在中国大陆地势呈三个地貌阶梯的基础上,总结出中国海陆地貌总体特征为西高东低,呈五级阶梯分布. 相似文献
4.
Habip Eroğlu Günay Çakır Fatih Sivrikaya Abdullah E. Akay 《Stochastic Environmental Research and Risk Assessment (SERRA)》2010,24(5):699-704
Soil erosion is one of the most important environmental problems. In the case of small scale areas where soil properties and
climate have relatively uniform characteristics, vegetation cover and topography (i.e. ground slope) are the main factors
that affect the amount of soil erosion. Lack of vegetation cover on bare soil areas, including forest road side slopes, especially
in mountainous regions with steep slopes, may significantly increase the erosion rate. Determining and classifying erosion
risks in such areas can help preventing environmental impacts. In this study, remotely sensed data and elevation data were
used to extract and classify bare soil erosion risk areas for a study area selected from Hatila Valley Natural Protected Area
in northeastern Turkey. High resolution IKONOS imagery was used to apply land use classification in ERDAS Imagine 9.0. To
generate erosion risk map of the bare soil areas, classified image was superimposed on top of slope map, generated based on
a Digital Elevation Model (DEM) in ArcGIS 9.2. The results indicated that 1.43, 5.85, 34.62, 53.16, and 4.94% of the bare
soil areas in the study area were under very low, low, medium, high, and very high erosion risks, respectively. The overall
classification accuracy of 82.5% indicated the potential of the proposed methodology. 相似文献
5.
Landslides constitute one of the major natural hazards that could cause significant losses of life and property. Mapping or delineating areas prone to landsliding is therefore essential for land‐use activities and management decision making in hilly or mountainous regions. A landslide hazard map can be constructed by a qualitative combination of maps of site conditions, including geology, topography and geomorphology, by statistical methods through correlating landslide occurrence with geologic and geomorphic factors, or by using safety factors from stability analysis. A landslide hazard map should provide information on both the spatial and temporal probabilities of landsliding in a certain area. However, most previous studies have focused on susceptibility mapping, rather than on hazard mapping in a spatiotemporal context. This study aims at developing a predictive model, based on both quasi‐static and dynamic variables, to determine the probability of landsliding in terms of space and time. The study area selected is about 13 km2 in North Lantau, Hong Kong. The source areas of the landslides caused by the rainstorms of 18 July 1992 and 4–5 November 1993 were interpreted from multi‐temporal aerial photographs. Landslide data, lithology, digital elevation model data, land cover, and rainfall data were digitized into a geographic information system database. A logistic regression model was developed using lithology, slope gradient, slope aspect, elevation, slope shape, land cover, and rolling 24 h rainfall as independent variables, since the dependent variable could be expressed in a dichotomous way. This model achieved an overall accuracy of 87·2%, with 89·5% of landslide grid cells correctly classified and found to be performing satisfactorily. The model was then applied to rainfalls of a variety of periods of return, to predict the probability of landsliding on natural slopes in space and time. It is observed that the modelling techniques described here are useful for predicting the spatiotemporal probability of landsliding and can be used by land‐use planners to develop effective management strategies. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
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To establish an experimental, practical and open scientific experimental platform for earthquake monitoring and prediction, with reference to that of the southern California earthquake center(SCEC), China Earthquake Administration initiated a project for an experimental field in Sichuan and Yunnan Province in 2014. The chosen area is a seismically active region in the southeastern margin of the Tibetan plateau. A series of work compiling basic maps have been launched to collect fundamental data of this area including geologic structure, earthquake geology, geophysics, geodesy, and geochemistry. The map of earthquake surface ruptures in this region is one of these basic maps. This paper presents the compilation of this map. It includes earthquake epicenters, earthquake surface ruptures, faults, strata, magmatic rocks, and geographical data. This work summarized 87 destructive earthquakes, and 22 earthquake surface rupture zones, and analyzed the distribution characterization of earthquake epicenters, strata and magmatic rocks. The content in the map is reliable and integrated. This work will provide reliable earthquake-geology data for establishing geodynamics models and other future research of the national experimental field of earthquake monitoring and prediction in Sichuan and Yunnan Province. 相似文献
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Abstract Flood hazard maps were developed using remote sensing (RS) data for the historical event of the 1988 flood with data of elevation height, and geological and physiographic divisions. Flood damage depends on the hydraulic factors which include characteristics of the flood such as the depth of flooding, rate of the rise in water level, propagation of a flood wave, duration and frequency of flooding, sediment load, and timing. In this study flood depth and “flood-affected frequency” within one flood event were considered for the evaluation of flood hazard assessment, where the depth and frequency of the flooding were assumed to be the major determinant in estimating the total damage function. Different combinations of thematic maps among physiography, geology, land cover and elevation were evaluated for flood hazard maps and a best combination for the event of the 1988 flood was proposed. Finally, the flood hazard map for Bangladesh and a flood risk map for the administrative districts of Bangladesh were proposed. 相似文献
9.
玉树地震诱发了2 036处滑坡。应用地理信息系统与遥感技术,选取与地表破裂距离、峰值加速度(PGA)、高程、坡度、坡向、曲率、坡位、与水系距离、岩性、与断裂距离、与公路距离、归一化植被指数(NDVI)等12个因素作为玉树地震滑坡危险性评价因子,采用加法与减法2种证据权方法,开展玉树地震滑坡危险性评价研究工作。结果表明:基于加法证据权方法得到评价结果的正确率为80.32%,基于减法证据权方法得到结果的正确率为80.19%。将滑坡危险性评价结果图分为极高危险区、高危险区、中危险区、低危险区与极低危险区5类。这一成果可划分出滑坡危险区,为灾后滑坡防治、基础设施重建与自然环境保护提供参考。 相似文献
10.
Masoud Masoudi A. M. Patwardhan S. D. Gore 《Stochastic Environmental Research and Risk Assessment (SERRA)》2006,21(1):15-24
South of the Zagros belt, the entire land of Southern Iran faces problems arising out of various types of land degradation of which water erosion forms a major type. A new model has been developed for assessing the risk of water erosion. Taking into consideration nine indicators of water erosion the model identifies areas with ‘Potential Risk’ (risky zones) and areas of ‘Actual Risk’ as well as projects the probability of the worse degradation in future. The Qareh Aghaj subbasin (1,265,000 ha), which covers the upper reaches of Mond River, has been chosen for a test risk assessment of this kind. The preparation of risk maps based on the GIS analysis of these indicators will be helpful for prioritizing the areas to initiate remedial measures. The different kinds of data for indicators of water erosion were gathered from the records and published reports of the governmental offices of Iran. By fixing the thresholds of severity classes of the nine indicators a hazard map for each indicator was first prepared in GIS. The risk classes were defined on the basis of risk scores arrived at by assigning the appropriate attributes to the indicators and the risk map was prepared by overlaying nine hazard maps in the GIS. Areas under potential risk have been found to be widespread (63%) in the basin and when classified into subclasses with different probability levels the model projects a statistical picture of the risk of land degradation. 相似文献
11.
Geospatial and geostatistical approach for groundwater potential zone delineation 总被引：1，自引：0，他引：1 
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下载免费PDF全文 Javed Mallick Chander Kumar Singh Hussein Al‐Wadi Mohd Ahmed Atiqur Rahman Satyanarayan Shashtri Saumitra Mukherjee 《水文研究》2015,29(3):395-418
Over the past few decades, groundwater has become an essential commodity owing to increased demand as a result of growing population, industrialization, urbanization and so on. The water supply situation is expected to become more severe in the future because of continued unsustainable water use and projected change in hydrometeorological parameters due to climate change. This study is based on the integrated approach of remote sensing, geographical information system and multicriteria decision‐making techniques to determine the most important contributing factors that affect the groundwater resources and to delineate the groundwater potential zones. Ten thematic layers, namely, geomorphology, geology, soil, topographic elevation (digital elevation model), land use/land cover, drainage density, lineament density, proximity of surface water bodies, surface temperature and post‐monsoon groundwater depth, were considered for the present study. These thematic layers were selected for groundwater prospecting based on the literature; discussion with the experts of the Central Ground Water Board, Government of India; field observations; geophysical investigation; and multivariate techniques. The thematic layers and their features were assigned suitable weights on Saaty's scale according to their relative significance for groundwater occurrence. The assigned weights of the layers and their features were normalized by using the analytic hierarchy process and eigenvector method. Finally, the selected thematic maps were integrated using a weighted linear combination method to create the final groundwater potential zone map. The final output map shows different zones of groundwater potential, namely, very good (16%), good (35%), moderate (28%) low (17%) and very low (2.1%). The groundwater potential zone map was finally validated using the discharge and groundwater depth data from 28 and 98 pumping wells, respectively, which showed good correlation. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
12.
The availability of airborne LiDAR data provides a new opportunity to overcome some of the problems associated with traditional, field‐based, geomorphological mapping such as restrictions on access and constraints of time or cost. The combination of airborne LiDAR data and GIS technology facilitates the rapid production of geomorphological maps of floodplain environments; however, unfiltered LiDAR data, which include vegetation and buildings, are currently more suitable for geomorphological mapping than data that have been filtered to remove these features. Classification of LiDAR data according to elevation in a GIS enables the user to identify and delineate geomorphological features in a manner similar to field mapping, but it is necessary to use a range of classification intervals in order to map the various types of feature that occur within a single reach. Comparison of a LiDAR‐derived geomorphological map with an independently produced field geomorphological map showed a high degree of similarity between the results of the two methods, although ground‐truthing is essential in cases where a high degree of accuracy is required. Ground‐truthing of a LiDAR‐derived geomorphological map showed that around 80% of features mapped using both methods were identified from the LiDAR data, suggesting that the method is suitable for applications such as production of base maps for use in field mapping and selection of sites for detailed investigation. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
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Rock falls induced by earthquakes: a statistical approach 总被引：2，自引：0，他引：2
During September and October 1997 a seismic sequence of moderate magnitude struck the Umbria and Marche regions, central Italy. As a consequence of the main shocks several rock falls were triggered along the flanks of the Valnerina valley, an important canyon formed by the erosion of the Nera river on limestone formations. This landslide data set was used to explore the correlation existing among rock falls and several causal factors, like slope angle, geology and strong ground motion parameters. All the data have been digitised and georeferenced with the aid of a Geographic Information System in the form of digital thematic layers. The landslide inventory has been overlaid to the maps of causal factors, and the result arranged in order to create a data structure suitable to perform a multivariate statistics. A multiple regression allowed to formulate a predictive rule that can be used to produce a rock fall susceptibility map in case of an earthquake, in regions with similar geologic and geomorphologic characteristics. 相似文献
14.
Le Yu XueCao Li CongCong Li YuanYuan Zhao ZhenGuo Niu HuaBing Huang Jie Wang YuQi Cheng Hui Lu YaLi Si ChaoQing Yu HaoHuan Fu Peng Gong 《中国科学:地球科学(英文版)》2017,60(2):277-285
A technically transparent and freely available reference sample set for validation of global land cover mapping was recently established to assess the accuracies of land cover maps with multiple resolutions. This sample set can be used to estimate areas because of its equal-area hexagon-based sampling design. The capabilities of these sample set-based area estimates for cropland were investigated in this paper. A 30-m cropland map for China was consolidated using three thematic maps (cropland, forest and wetland maps) to reduce confusion between cropland and forest/wetland. We compared three area estimation methods using the sample set and the 30 m cropland map. The methods investigated were: (1) pixel counting from a complete coverage map, (2) direct estimation from reference samples, and (3) model-assisted estimation combining the map with samples. Our results indicated that all three methods produced generally consistent estimates which agreed with cropland area measured from an independent national land use dataset. Areas estimated from the reference sample set were less biased by comparing with a National Land Use Dataset of China (NLUD-C). This study indicates that the reference sample set can be used as an alternative source to estimate areas over large regions. 相似文献
15.
我国海洋地质地球物理工作起步晚,整体调查程度较低,进一步加强我国海洋地学编图显得十分必要.我国实施的"海洋地质保障工程",将分"中国海陆"、"中国海及邻域"和"中国各海区"三个层次来进行地学编图.第一层次编制了空间重力异常图、布格重力异常图、磁力异常图、地震层析成像图、莫霍面深度图、地质图、大地构造格架图和大地构造格架演化图等8种图件.编图反映出中国海陆重力异常是"线性异常带纵横交错,块状异常区坐落其间"、重力梯级带主要为块体结合带;陆地磁力异常大致正负磁异常相间分布,海域北部为沟-弧-盆相关异常、南部磁条带异常;莫霍面总体特征为"东西分带,南北分块";地震层析成像反映出中国东部和西部岩石层厚度的差异以及上地幔软流层的分布特点;大地构造格架和演化图再现了块体体制向板块体制的转换过程.本次编图强调地球深部结构的变化对表层构造的关联,重视地球物理资料与地质构造的结合,以深-浅层结合来划分中国大地构造格架.已有成果表明,中国海陆大地构造格局可以用"块体构造学说"来描述. 相似文献
16.
Results taken from 270 publications on rates are summarized, and collated with those from 149 publications reviewed previously (Young, 1969, 1974). The data are classified by major climatic zone, normal or steep relief, and consolidated or unconsolidated rocks. Representative rates and their ranges are given for soil creep, solifluction, surface wash, solution (chemical denudation), rock weathering, slope retreat, cliff (free face) retreat, marine cliff retreat, and denudation, the last being compared with representative rates of uplift. Solifluction is of the order of 10 times faster than soil creep, but both cause only very slow ground loss. Solution is an important cause of ground loss for siliceous rocks, on which it may be half as rapid as on limestones. Total denudation, brought about mainly by surface wash, reaches a maximum in the semi-arid and probably also the tropical savanna zones. Acceleration of natural erosion rates by human activities ranges from 2–3 times with moderately intense land use to about 10 times with intensive land use (and considerably higher still where there is recognized accelerated soil erosion). Where there is active uplift, typical rates are of the order of 10 times faster than denudation, although in some high, steep mountain ranges these may approach equality. 相似文献
17.
Processes of soil erosion and sediment transport are strongly influenced by land use changes so the modelling of land use changes is important with respect to the simulation of soil degradation and its on‐site and off‐site consequences. The reliability of simulation results from erosion models is circumscribed by considerable spatial variation in many parameters. However, most of the currently widely used erosion models at the mesoscale are semidistributed, which leads to difficulties in incorporating a high degree of spatial information, especially land use information, so that the effects of land use changes on soil erosion have hitherto not been investigated in detail using these models. In this article, a grid‐based distributed erosion and sediment transport model is introduced, which simulates the spatial pattern of erosion and deposition rates and sediment transport processes in river channels. In this model, land use affects soil erosion through altering soil loss and influencing sediment delivery. Simulated soil erosion for events recorded in 1989 and 1996 in the Lushi basin in China was analyzed by comparing it with historical land use maps. The results indicated that even relatively minor land use changes had a significant effect on regional soil erosion rates and sediment transport to rivers. The average erosion rate increased from 1989 to 1996, after the transformation of forest to farmland. The results of the study suggest that the proposed soil erosion model can be applied in similar river basins. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
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可控源音频大地电磁法（CSAMT）的应用是百里店矿山多种地球物理研究的一部分．由于激发极化法（IP）的穿透率和分辨率是与几何因素密切相关,对于较深部的地质特征,靠IP法不容易分辨出来．CSAMT较好地解决了这个问题,首先,根据区域地质背景、成矿条件和矿区岩石物性特征,开展了面积性的激电测量,进而开展了CSAMT方法的探测研究．通过对CSAMT原始数据的分析解释,发现测区深部存在两条低电阻率梯级带,其中一条为陡倾斜;另一条为缓倾斜,两者在地下800m左右深度处相互斜交．经地质推断解释认为：这是测区内金矿的主要控矿、导矿及容矿构造． 相似文献
20.
In the northeastern part of Hungary near the township of Tokaj a landscape research project has been performed in a 9 km2 area. The aim of this study is to examine the possibilities of expressing the climatic sensitivity of the given small landscape unit by analysing the capabilities of such a small sample area and synthésizing the data obtained. The landscape analysis consisted of field and laboratory measurements, theoretical calculations, analyses of maps, as well as the construction of thematic maps (on the scale of 1:10000) and cartograms. In view of climatic sensitivity four of the landscape factors were regarded as crucial: (1) the water budget of the soils, (2) the thickness of the soils and loose sediments, (3) insolation, and (4) land use. By synthesis of these factors a five-grade climatic sensitivity map was produced. On the basis of the areal proportion of the different classes of sensitivity it was established that the study area is moderately sensitive to climate. Examination of the moisture content of soil clearly indicated different responses of the areas from the different sensitivity classes to changes in temperature and precipitation. The four main landscape factors selected proved to be useful in the rough delineation of the classes on the climatic sensitivity map. However, the use of the other landscape factors improved its accuracy. 相似文献