基于GF-1卫星遥感的冰川边界识别

高分一号（GF-1）卫星的成功发射开启了国产高分辨率对地观测的新时代, 为探讨国产高分卫星在冰川边界识别中的有效性, 在缺少短波红外和热红外波段的情况下, 将GF-1影像、 建立的波段比值Band1/Band4, 数字高程模型和坡度相结合, 采用面向对象的分析方法, 经过反复试验, 确定影像分割和合并尺度, 进而确定冰川边界的知识规则, 最终实现冰川边界的识别。以研究区第二次冰川编目数据集作为参考数据, 采用混淆矩阵的方法对识别结果进行验证, 总体精度和Kappa系数为90.05%和0.79。同时将识别结果与人工修订冰川边界进行对比, 可以发现除少量冰舌末端冰川外, 该方法可以有效地对冰川进行识别。建立的知识规则显示仅仅利用蓝色波段和DEM就可以有效地提取裸冰区, 波段比值、 坡度和纹理特征更有助于冰舌的提取。该研究表明GF-1卫星数据可以有效识别冰川范围, 为冰川研究提供可靠的数据和研究基础。     

Application of probabilistic-based frequency ratio model in groundwater potential mapping using remote sensing data and GIS

The main goal of this study is to investigate the application of the probabilistic-based frequency ratio (FR) model in groundwater potential mapping at Langat basin in Malaysia using geographical information system. So far, the approach of probabilistic frequency ratio model has not yet been used to delineate groundwater potential in Malaysia. Moreover, this study includes the analysis of the spatial relationships between groundwater yield and various hydrological conditioning factors such as elevation, slope, curvature, river, lineament, geology, soil, and land use for this region. Eight groundwater-related factors were collected and extracted from topographic data, geological data, satellite imagery, and published maps. About 68 groundwater data with high potential yield values of ≥11 m³/h were randomly selected using statistical software of SPSS. Then, the groundwater data were randomly split into a training dataset 70 % (48 borehole data) for training the model and the remaining 30 % (20 borehole data) was used for validation purpose. Finally, the frequency ratio coefficients of the hydrological factors were used to generate the groundwater potential map. The validation dataset which was not used during the FR modeling process was used to validate the groundwater potential map using the prediction rate method. The validation results showed that the area under the curve for frequency model is 84.78 %. As far as the performance of the FR approach is concerned, the results appeared to be quite satisfactory, i.e., the zones determined on the map being zones of relative groundwater potential. This information could be used by government agencies as well as private sectors as a guide for groundwater exploration and assessment in Malaysia.     

Seismic vulnerability assessment of earthquake-prone mega-city Shillong,India using geophysical mapping and remote sensing

ABSTRACT

The concept of seismic vulnerability is a yard-stick of damage estimation from a probable earthquake considering physical cum social dimension and enables a basis for decision-makers to develop preparedness and mitigation strategies. We aim at vulnerability assessment of the typical urban system of capital city Shillong situated on hilly terrain. High-resolution satellite imagery of Shillong facilitates analysis of building footprints, communication network, and open ground. Different building typologies are identified taking into account the building’s structural configuration assessed through a rapid visual survey of more than 15% of total residential households. Slope map demarcates the landslide-prone area through discrete elevation modelling. A methodology incorporating several parameters e.g. building typology, slope angle, shear wave velocity characteristics, geomorphology, and the number of occupants in correlation with a physical measurement of vulnerability is presented and is applied to estimate the dimension of vulnerability. Additionally, MASW survey indicates lithology up to 30?m deep along with the existence of stiff soil and rocks at different depths whereas resonant frequency is identified to be in the range of 6–8?Hz through H/V ratio. Integrating all, it is observed that more than 60% of Shillong city falls under moderate to higher vulnerability and the rest is less vulnerable.     

Understanding the tectonic behaviour of the Shillong Plateau,India using remote sensing data

Shillong Plateau in India is tectonically and geologically interesting entity in the subducted front of Indian Plate below Burmese Plate to the southeast and Tibetan Plate to the north and associated with thrusts and shears along the plate boundaries. Horse-tail geometry in the foothills of the Arunachal Himalaya, east of Jia Bhareli river, associated with south-convex foothill ranges in the eastern Himalaya and exactly similar structural geometry in the eastern part of Shillong Plateau in Meghalaya seems to develop due to resistance received by the plateau in its eastward journey. Wide separation of Karbi Anglong Plateau and Shillong Plateau to the southeast as compared to northwestern part defines the shape of Kopili graben. Low seismic activity in southeastern part of Shillong Plateau might be related to stress released field generated by its clockwise rotation. Satellite derived images and digital elevation data from Landsat ETM+ and SRTM data shows that the central part of Shillong Plateau possesses young topography with strong structural fabrics along with relatively high topography aligning NE-SW following Kolkota-Pabna-Mymansingh High and if extended passes through western part of Arunachal Pradesh in eastern Himalayas. This alignment has been observed in Precambrian gneissic complex west of the Proterozoic intracratonic Shillong Basin. The epicentral plot for the period 1918 to 2009 shows their high concentration within the Shillong Plateau aligning along this trend. The active geodynamics of Shillong Plateau is reflected in its seismic activity pattern in relation with the structural fabrics, northward migration of the Brahmaputra in the north front of the Plateau and by shrinking pattern of Chandubi Lake in the Kulsi river catchment, a north-flowing tributary of the Brahmaputra in the north-central part of the plateau.     

Deglacial Control on Sedimentation and Basin Evolution of Permo-Carboniferous Talchir Formation, Talchir Gondwana Basin, Orissa, India

The Permo-Carboniferous Talchir Formation in the southeastern part of the Talchir basin is represented by about 260 m thick clastic succession resting on the Precambrian basement rocks of the Eastern Ghats Group. The succession is tentatively subdivided into four lithostratigraphic units, namely A-I, A-II, B and C from base to top. Unit A-I comprises mud-matrixed, very poorly sorted diamictites and interbedded thin sandstone and mudstone yielding dropstones. They reveal deposition in a proglacial lake environment in which ice rafting and suspension sedimentation, as well as meltwater-underflow processes, produced variety of facies. The succession of unit A-II is dominated by pebble to boulder conglomerates and sandstones. They were deposited mostly from various kinds of high-energy sediment gravity flows, both subaerial and subaqueous, and formed steep-faced fan-delta on the margin of the basin. Unit B demonstrates turbidite sedimentation in lake-margin slope and base-of-slope environments, in which a sublacustrine channel-fan system developed. The lake-margin slope was dissected by channels which were accompanied by overbank and levee deposits. Sediments delivered from the mouth of a channel were deposited at the base-of-slope, forming a fan lobe which prograded onto the lake basin floor. Unit C dominantly consists of mudstone with intercalations of siltstone and sandstone and forms a large-scale coarsening-upward deltaic sequence eventually covered by the fluvial deposits of the Karharbari Formation.Following the glacially influenced sedimentation, the Talchir succession shows a vertical facies progression suggesting gradual deepening of the lake basin and eventual filling up of it due to rapid delta progradation. Such a succession represents deglacial control on basin evolution during the Talchir time. In the initial stage of glacial recession, collapse of a glacier and failure of montane glacial lakes frequently occurred and gave rise to generation of a highly sediment-laden debris flow and a catastrophic flood, which brought abundant coarse clastics into the lake and built a fan-delta on the basin margin. The continued recession and disappearance of glacier resulted in abundant supply of ice-melt water into the graben as well as eustatic sea-level rise, being the cause of the rise in lake-level. Subsequent rapid delta progradation and eventual filling-up of the lake basin suggest rapid lake-level fall after deepening of lake basin. It was possibly caused by the regional uplift due to post-glacial isostatic rebound. Rapid draining of lake water through the graben gave rise to the establishment of an axial drainage system which rapidly filled the lake basin in form of an axially fed delta.     

Morphometric analysis of Morar River Basin, Madhya Pradesh, India, using remote sensing and GIS techniques

Hydrogeological mapping and drainage analysis can form an important tool for groundwater development. Assessment of drainage and their relative parameters have been quantitatively carried out for the Morar River Basin, which has made positive scientific contribution for the local people of area for the sustainable water resource development and management. Geographical Information System has been used for the calculation and delineation of the morphometric characteristics of the basin. The dendritic type drainage network of the basin exhibits the homogeneity in texture and lack of structural control. The stream order ranges from first to sixth order. The drainage density in the area has been found to be low which indicates that the area possesses highly permeable soils and low relief. The bifurcation ratio varies from 2.00 to 5.50 and the elongation ratio (0.327) reveals that the basin belongs to the elongated shaped basin category. The results of this analysis would be useful in determining the effect of catchment characteristics such as size, shape, slope of the catchment and distribution of stream net work within the catchment.     

Drainage morphometry of upper Vaigai river sub-basin, Western Ghats, South India using remote sensing and GIS

The study area is a one of the sub-basin of Vaigai River basin in the Theni and Madurai districts, Western Ghats of Tamil Nadu. The Vaigai sub-basin extends approximately over 849 km² and it has been sub-divided into 48 watersheds. It lies between 09°30′00″ and 10°00′00″N latitudes and 77°15′10″ and 77°45′00″ E longitudes in the western part of Tamil Nadu, India. It originates at an altitude of 1661m in the Western Ghats of Tamil Nadu in Theni district. The drainage pattern of these watersheds are delineated using geo-coded Indian remote sensing satellite (IRS) ID, linear image self-scanning (LISS) III of geo-coded false colour composites (FCC), generated from the bands 2, 3 and 4 on 1:50,000 scale in the present study. The Survey of India (SOI) toposheets 58G/5, 58 G/6, 58G/9 and 58G/10 on a scale of 1:50,000 scale was used as a base for the delineation of watershed. In the present study, the satellite remote sensing data has been used for updation of drainages and the updated drainages have been used for morphometric analysis. The morphometric parameters were divided in three categories: basic parameters, derived parameters and shape parameters. The data in the first category includes area, perimeter, basin length, stream order, stream length, maximum and minimum heights and slope. Those of the second category are bifurcation ratio, stream length ratio, RHO coefficient, stream frequency, drainage density, and drainage texture, constant of channel maintenance, basin relief and relief ratio. The shape parameters are elongation ratio, circularity index and form factor. The morphometric parameters are computed using ESRI’s ArcGIS package. Drainage density ranges from 1.10 to 4.88 km/km² suggesting very coarse to fine drainage texture. Drainage frequency varies from 1.45 to 14.70 which is low to very high. The bifurcation ratio ranges from 0.55 to 4.37. The low values of bifurcation ratios and very low values of drainage densities indicate that the drainage has not been affected by structural disturbances and also that the area is covered under dense vegetation cover. Elongation ratio ranges from 0.11 to 0.57. Drainage texture has the minimum of 1.63 and maximum of 11.44 suggesting that the drainage texture is coarse to fine. It is concluded that remote sensing and GIS have been proved to be efficient tools in drainage delineation and updation. In the present study these updated drainages have been used for the morphometric analysis.     

基于多源遥感与航空物探数据的岩性分类方法

遥感影像可以获取地表岩性的光谱、色调、纹理等信息,但其所提取的信息局限于地表,对深层地质问题解释并无明显优势;航空物探数据则对地下深部异常体信息的提取更具优势。单一某类数据难以满足基础地质、资源勘查等方面复杂应用的需求。因此,提出一种遥感与航空物探信息联合分析方法,以新疆某地为研究区,结合遥感与航空物探多源数据特征,基于随机森林方法对研究区岩性进行分类。结果表明,与使用单一某类数据相比,遥感与航空物探信息联合分析方法能提高岩性分类精度。该方法对于推动遥感与航空物探技术在地质填图中的精细化应用,具有一定实用价值与指导意义。     

A GIS and remote sensing based evaluation of groundwater potential zones in a hard rock terrain of Vaigai sub-basin, India

In this paper, remote sensing, geographic information systems (GIS) and fieldwork techniques were combined to study the groundwater conditions in Vaigai basin, Tamilnadu. Several digital image processing techniques, including standard color composites, intensity–hue–saturation transformation and decorrelation stretch were applied to map rock types. Remote sensing data were interpreted to produce lithological and lineament maps such as geology, geomorphology, soil hydrological group, land use/land cover and drainage map were prepared and analyzed using GIS Arc Map GIS Raster Calculator module as geomorphology?×?12?+?drainage?×?9?+?lineament?×?5?+?geology?×?8?+?land use?×?2?+?relief?×?4. The final cumulative map generated by applying the above equation had weight values ranging from 0.315 to 4.515. The overall results demonstrate that the use of remote sensing and GIS provide potentially powerful tools to study groundwater resources and design a suitable exploration plan, the thematic maps for the study area.     

结合场梯度的位场数据图像非均匀映射技术

利用图像表达位场数据时,位场数据根据色标被映射成颜色,生成的图像能否客观真实地表达出位场数据的内涵特征,关键取决于采用的色标是否合理。为了提高图像表达位场数据细节信息的能力,借鉴图像灰度非均匀整量的思想,给出了一种基于场值梯度的色标文件生成方法。对比于传统的采用根据位场场值大小平均分配色阶的方法,理论模型试验和实际资料的应用结果,都显示了本方法在提高图像表达位场数据细节信息能力上的有效性和优越性。     

Flood monitoring, mapping and assessing capabilities using RADARSAT remote sensing, GIS and ground data for Bangladesh

Remote sensing is the most practical method available to managers of flood-prone areas for quantifying and mapping flood impacts. This study explored large inundation areas in the Maghna River Basin, around the northeastern Bangladesh, as determined from passive sensor LANDSAT data and the cloud-penetrating capabilities of the active sensors of the remote imaging microwave RADARSAT. This study also used passive sensor LANDSAT wet and dry images for the year 2000. Spatial resolution was 30 m by 30 m for comparisons of the inundation area with RADARSAT images. RADARSAT images with spatial resolution of 50 m by 50 m were used for frequency analysis of floods from 2000 to 2004. Time series images for 2004 were also used. RADARSAT remote sensing data, GIS data, and ground data were used for the purpose of flood monitoring, mapping and assessing. A supervised classification technique was used for this processing. They were processed for creating a maximum water extent map and for estimating inundation areas. The results of this study indicated that the maximum extent of the inundation area as estimated using RADARSAT satellite imaging was about 29, 900.72 km² in 2004, which corresponded well with the heavy rainfall around northeast region, as seen at the Bhairab Bazar station and with the highest water level of the Ganges–Brahmaputra–Meghna (GBM) Rivers. A composite of 5 years of RADARSAT inundation maps from 2000 to 2004, GIS data, and damage data, was used to create unique flood hazard maps. Using the damage data for 2004 and the GIS data, a set of damage maps was also created. These maps are expected to be useful for future planning and flood disaster management. Thus, it has been demonstrated that RADARSAT imaging data acquired over the Bangladesh have the ability to precisely assess and clarify inundation areas allowing for successful flood monitoring, mapping and disaster management.     

Groundwater potential index in a crystalline terrain using remote sensing data

Demand for groundwater for drinking, agricultural and industrial purposes has increased due to uncertainty in the surface water supply. Agriculture is the main occupation of the rural people in Guntur district, Andhra Pradesh, India. Development of groundwater in the district is very less, indicating a lot of scope for further development of groundwater resources. However, assessment of groundwater conditions, particularly in a crystalline terrain, is a complex task because of variations in weathering and fracturing zones from place to place. Systematic studies for evaluation of groundwater potential zones have been carried out in a crystalline terrain of the district. Information on soils, geological formations and groundwater conditions is collected during the hydrogeological survey. Topographical and drainage conditions are derived from the Survey of India topographical maps. Geomorphological units and associated landform features inferred and delineated from the Indian remote sensing satellite imagery (IRS ID LISS III FCC) are moderately buried pediplain (BPM), shallow buried pediplain (BPS), valley fills (VF), structural hill (SH), residual hills (RH), lineaments and land use/land cover. A groundwater potential index (GPI) is computed for relative evaluation of groundwater potential zones in the study area by integrating all the related factors of occurrence and movement of groundwater resources. Accordingly, the landforms, BPM, BPS, VF, SH and RH, of the area are categorized as very good groundwater potential zone, good to moderate groundwater potential zone, moderate to poor groundwater potential zone, poor to very poor groundwater potential zone and very poor groundwater potential zone, respectively, for development and utilization of both groundwater and surface water resources for eliminating water scarcity. This study could help to improve the agrarian economy for better living conditions of the rural people. Taking the total weight-score of the GPI into account, a generalized classification of groundwater potential zones is evaluated for a quick assessment of the occurrence of groundwater resources on regional scale.     

基于多源遥感数据的云南西双版纳地区地质构造解译

西双版纳地区地处云南横断山系纵谷南段西双版纳热带雨林区,常年高温多雨、植被茂密、地形复杂,出露地质信息少,给区域地质调查工作造成了很大的困难。为有效获取该地区更多的地质信息,配合使用Landsat 8 OLI、SPOT 6、Sentinel-1A雷达遥感数据和高程数据等多源数据,基于建立的解译标志,提取区内地质构造信息,大至宏观上的大地构造背景信息、小至露头尺度构造信息,并详细分析区内各类型线性断裂构造的遥感影像特征与地质意义。提取的构造结果表明,原地质构造与解译构造吻合度较高,同时新解译出大量的线性构造。研究成果为完善该地区的地质构造轮廓与特征认识提供了丰富的遥感基础资料。     

基于遥感信息的土地资源可持续利用研究

遥感信息是对自然界的反映，它具有宏观、动态、准确、快速的优点，可以及时提供动态数据。基于遥感信息，对吉林西部土地资源利用状况进行调查，运用主成分分析法，可以不损失或很少损失原有的信息，将原来个数较多而且彼此相关的变量转换为新的个数较少而且彼此独立或不相关的新变量。对土地资源可持续利用进行定量分析研究，指出土地利用中存在的问题，并提出吉林西部土地资源可持续利用发展模式。     

Stratigraphy of the upper Gondwana formations around Sohagpur,western part of the Satpura Gondwana Basin,Central India

The present work provides a detailed lithological map of the western part of the Satpura basin around Sohagpur and reports the presence of new archosauromorph fossil bones from that region. The study area is dominated by the Bagra Formation along with a narrow patch of the underlying upper part of the Denwa Formation. The lower Denwa and the underlying Pachmarhi formations are absent here. The presence of the Pachmarhi Formation, as a tongue shaped area, as mapped by Crookshank (1936) is discarded in this study on the basis of lithology and petrographic analyses, instead the presence of the Bagra Formation is suggested in this area. A comparison of the lithologies and the vertebrate faunas of the upper Gondwana formations between eastern and western part of the basin has been carried out for the first time. The comparison indicates that the Denwa Formation present in the western sector represents only the topmost part of the formation while the complete succession of Denwa is preserved in the eastern sector. The Bagra Formation in the western sector documents the presence of sheet-like sandstone bodies unlike the eastern part. The vertebrate fauna of the eastern part is dominated by temnospondyl amphibians while that of the western part is dominated by archosauromorph. The vertebrate fossils of upper part of Denwa Formation, found from similar lithologies in west and east though, have differences in the amount of transportation before their burial.     

Integration of remote sensing data with the field and laboratory investigation for lithological mapping of granitic phases: Kadabora pluton, Eastern Desert, Egypt

In the current study, an integration of Enhanced Thematic Mapper Plus (ETM+), field, and laboratory data have been used for lithological mapping of different granitic phases in the Kadabora area, Eastern Desert, Egypt. Application of enhancement techniques, including a new proposed band ratio combination (ratio 5/3, 3/1, 7/5 in RGB, respectively) and supervised classification images are used in discriminating different granitic phases in the Kadabora pluton from each other and from their environs. The data have been proved with the help of field and geochemical investigations. The results revealed that: (1) the Kadabora granitic pluton could be distinguished into three phases that recognized by field and laboratory investigation including granodiorite (phase I), monzogranite (phase II), and syeno-alkali feldspar granite (phase III). These phases are arranged according to their relative ages while the country rocks include ophiolitic mélange and metagabbro–diorite complex. It is also confirmed that the granitic pluton is invaded by dyke swarms which is trending in N–S direction. Geochemically, results show that the granodiorite is calc-alkaline, I-type and formed under subduction tectonic regime. Monzogranite falls within the alkaline and highly fractionated calc-alkaline granites, whereas syeno-alkali feldspar granite extends into proper alkaline granitoids field. Monzogranite and syeno-alkali feldspar granite belong to the A₂-subtype granite. This A₂-subtype granite was probably formed in an extensional regime, subsequent to subduction which can lead to tensional break-up of the crust (i.e., post-collisional, post-orogenic granites). The monzogranite and the syeno-alkali feldspar granite were probably formed by partial melting of relatively anhydrous lower crust source and/or tonalite to granodiorite is viable alternative to the granulite source.     

Application of Bayesian networks for fire risk mapping using GIS and remote sensing data

This study estimates fire risk in Swaziland using geographic information system (GIS) and remote sensing data. Fire locations were identified in the study area from remotely sensed Moderate Resolution Imaging Spectroradiometer (MODIS) active fire and burned area data for the period between April 2000 to December 2008 and January 2001 and December 2008, respectively. A total of thirteen biophysical and socio-economic explanatory variables were analyzed and processed using a Bayesian network (BN) and GIS to generate the fire risk maps. The interdependence of each of the factors was probabilistically determined using the expectation-maximization (EM) learning algorithm. The final probabilistic outputs were then used to classify the country into five fire risk zones for mitigation and management. Accuracy assessments and comparison of the fire risk maps indicate that the risk maps derived from the active fire and burned area data were 93.14 and 96.64% accurate, respectively, demonstrating sufficient agreement between the risk maps and the existing data. High fire risk areas are observed in the Highveld particularly plantation forests and grasslands and within the Lowveld sugarcane plantations. Land tenure and land cover are the dominant determinants of fire risk, the implications of which are discussed for fire management in Swaziland. Limitations of the data used and the modeling approach are also discussed including suggestions for improvements and future research.     

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

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

新疆乌什塔拉地区遥感、化探、地质综合找矿研究

新疆乌什塔拉地区位于中亚天山成矿带的东南部,该成矿带上已发现众多矿床。在乌什塔拉地区开展地质矿产调查时,为快速确定找矿靶区,以遥感技术为先导,利用ETM+自然彩色合成、最小噪声分离等方法解译岩体、断层;之后对ETM+数据采用掩膜技术剔除干扰后,利用主成分分析法提取矿化蚀变信息;并将地质、化探、遥感等多元信息叠合进行综合分析。结果表明,利用主成分分析法提取的蚀变信息与化探异常、岩体、断层吻合较好,蚀变信息在工作区西北部、北部(喀拉塔格附近)及南部(阿拉塔格附近)具有面状、带状分布特征,而在工作区西南部、中部(阿勒格乌拉西)及东南部(扎合布拉格北沟附近)等地具有线状特征。经综合分析、筛选,共圈定了19处找矿靶区,对其中5处重点部位进行野外检查,发现利用主成分分析法提取的蚀变异常多由岩脉、断层、夕卡岩化、黏土化、褐铁矿化等引起。对蚀变带取样化学分析,确定了金、铜、铁矿化点3处。