Interpretation of Synthetic Aperture Radar (SAR) imagery for geological appraisal: A comparative study in Anantapur district of Andhra Pradesh

The paper describes the details of a comparative study of geological interpretations carried out from Synthetic Aperture Radar (SAR) imagery, Landsat MSS (B & W) imagery and Aerial Photographs, covering 2100 sq km of area in Anantapur district of Andhra Pradesh. The area comprises Peninsular—Gneissic Complex and rocks of Dharwar and Cuddapah Super Groups beside the Quaternary alluvial deposits along the Penneru river and its tributaries. Geomorphologically the areas is represented by denudational, fluvial and structural landforms. The study indicates that the details of the geological and geomorphological maps prepared from SAR imagery and aerial photographs are comparable despite the smaller scale of SAR imagery while the same are not exhibited in Landsat imagery mainly due to its low resolution. Although broad lithological units are possible to be discriminated on SAR as well as aerial photographs, some of the finer rock types viz. gabbroic dykes could be discriminated from the delerite dykes in the SAR imagery due to their different surface roughness. Stereoscopic coverage and enhanced micro-relief of SAR imagery gives better geomorphological details in comparison to aerial photographs. A detailed study of lineaments has also been carried out which shows that in SAR imagery there is over-representation of short lineaments due to enhanced micro-relief and radarshadow effects across the look direction and under-representation of lineaments along the look direction. Landsat imagery is perhaps the best for demarcating lineaments of regional magnitude while aerial photographs are good for depicting shorter lineaments. However, certain lineaments seen in SAR imagery are often not continuously seen on aerial photographs.     

Multi level land use surveys using remote sensing techniques

The use of Landsat imagery at 1:1 M and 1:250,000 and aerial photos on 1:65,000 and 1:20,000 scale have been used to study landuse. It has been possible to achieve identification using Landsat imagery up to utility level ( level 1 and II ) and with the aerial photographs further subdivisions of utility into management and identification (level III and IV) .     

Use of remote sensing techniques for detailed hydrogeological investigations in parts of Narmada Sagar command area,MP

Of late, airphoto interpretation and Landsat imagery analysis play a vital role in geological mapping for detailed hydrogeological investigations for ground water prospecting. Certain obscure features like lineaments/fracture zones which are masked by surface soil and cultivated lands are easily visible. In hard rocks like granites and basalts the occurrence and movement of ground water are controlled by the fracture pattern. Delineation of potential zones of ground water for successful exploration is possible by the study and analysis of aerial photographs, visual interpretation of Landsat imagery and interactive data analysis system through computer techniques and applications. These techniques constitute for data integration with conventional methods of hydrogeological investigations and exploratory drilling. As a case study an area of 1500 sq km in part of the Narmada river basin of Madhya Pradesh and also forming a portion of Narmada Sagar area covered under topo sheets 46 N/12 and 46 N/16 was taken up. Aerial photographs pertaining to the area of study and Landsat imagery of band 5 and 7 in scale blown upto 1∶250,00 were scanned and analysed. It was observed that the successful artesian wells are located in pominent lineament/fractured zones in the study area. It is also recommended after through analysis different hyddromorphic zonations for future exploration of ground water.     

Role of aerial photographs and landsat imagery in forest resources surveys

Many of the data needs for efficient management of forest resources can be met by aerial photographs. Commercially important tree species can be distinguished from other less important miscellaneous species with the help of aerial photographs. Forests can be classified according to their height and density classes. Aerial photographs have become indispensable for mapping of forests and preparation of forest inventories. A comparison of interpretation results obtained from landsat imagery and aerial photographs (1 ∶ 10,000 Black and White panchromatic photography) with respect to forestry interpretation is given. It is pointed out that the imagery obtained from satellities can be used for reconnaissance of a region and for deciding the priorities for carrying out more detailed surveys of forest resources with the help of air photointerpretation techniques     

Mapping of wastelands through remote sensing techniques and their reclamation—A case study

Wasteland map (1∶100,000) of Rewasa catchment (Sikar district) has been prepared using aerial photographs and Landsat TM imagery. Thematic Mapper data were helpful in identifying the types of wastelands and details could be derived from the aerial photographs. The types of wastelands identified are sands, gullied land, salt affected areas, and barren rocky area. Depending upon the nature of wasteland, suitable rehabilitation measures like plantations, afforestation have been proposed.     

The geology and structure of the area south of Gani,Kurnool District,Andhra Pradesh — a study based on remotely sensed data

Geological investigations in the area south of Gani, Kurnool District, Andhra Pradesh, were carried out with the help of aerial Photographs and multiband satellite imageries. The rocks of the Cuddapah Group and the Kurnool Group are exposed in the area under study. The Gani-Kalava anticline and the ENE-WSW trending Kalava fault are the important structural features of the area. The anticlinal structure could be better studied using the aerial photographs, while the fault is clearer on the imagery. Small scale folds involving the Cuddapahs and the Kurnools along the northern limb of the fold could be mapped using the aerial photographs. The Gani-Kalava anticline is a post-Kurnool structure, formed by movement along the Kalava fault and in the first instance the minor folds appear to be drags on the northern limb. However, certain structural and stratigraphic relations suggest that the folding in the Cuddapahs may be a pre-Kurnool phenomenon.     

Geology of the area around Badami,Bijapur District,Karnataka state—A study based on interpretation of remotely sensed data

Geological studies in the area around Badami, Bijapur District, Karnataka, were carried out with the help of Landsat imagery and aerial photographs. The study are forms a part Kaladgi Basin which is located on the northernmost fringes of the exposed Dharwar Craton. Archaen Peninsular Gneiss and intrusive Granodiorite/Granites (≈Clospet Granite) form the basement for the Middle to Late Proterozoic Kaladgi Super Group sediments which are, in turn, overlain in the north by the Upper Cretaceous to Lower Eocene Deccan flood basalt lavas. Geological mapping of the study area and inferences about the structural setup were primarily based on interpretation of the remotely sensed data. The combined interpretative study of Landsat imagery and aerial photographs was instrumental in mapping of the lithostratigraphic units exposed in the study area along with the structures associated with them.     

Reclamative grouping of ravines using Cartosat-1 PAN stereo data

Information on the depth and bed width of ravines (network of gullies) at large scales is critical for their reclamation and management. Hitherto such information has been generated from aerial photographs and space borne stereo images with medium to coarse ‘z’ – axis resolution. The present study, aims at demonstrating the potential of Cartosat ?1 (an Indian Earth observations satellite) stereo images with 2.5 m spatial resolution in deriving morphometric information on ravines for their reclamative grouping. The study area is a part of Jhansi and Hamirpur districts of Uttar Pradesh, northern India. The approach involves acquiring precise ground control points using Differential GPS (DGPS), triangulation, DEM extraction and generation of ortho image as well as anaglyphs for stereo viewing. The depth and bed width of ravines were measured in the field for validation. A comparison with field observations reveal that the bed width of ravines and depth can be measured successfully with Carto-1 stereo data. The anaglyph data was used to delineate various categories of ravines based on their depth and bed width. Results indicate that the Cartosat-1 stereo images are quite suitable for delineation of three categories of ravines, namely shallow (<3 m deep and <18 m bed width), medium deep (3–9 m deep and >18 m bed width) and deep (>9 m deep) which are important for their reclamation.     

Morphology and land systems of a part of visakhapatnam district,Andhra Pradesh from air photo studies

Landforms in an area of 1667 sq.km in Visakhapatnam district of Andhra Pradesh along the east coast of India has been mapped with the aid of aerial photographs. Simultaneously the current land use has been noted and the data collected in the field of the nature of surficial deposits, drainage and erosion. An attempt is made to classify the area into land systems designated as (1) hill and hillocks, (2) rolling plains, (3) fluvial plain and (4) coastal zone and give details of their characteristic features. Recommendations are made for better landuse of some of the areas taking into consideration the knowledge of their total potential.     

Remote sensing application in urban fringe study a case studý — Delhi

This paper is based on a case study of Delhi. The attempt has been made to find out the usefulness of aerial remote sensing in the study of urban fringe where all sorts of haphazard developments take place. Unauthorised construction, illegal sub-division of land, urban sprawl, environmental degradation are all parts of urban fringe Attempt has been made to find out the efficacy of aerial photos at pre-planning stage and their role in assigning various landuses for planned development of urban fringe zone. For the first time, the concept of “Urban Index” has been used to determine the scale of urbanity by aerial remote sensing technique. Growth of settlements, land speculation, impact of anticipated development proposal have been studied. Aerial photographs have been used to detect depressions, drainage pattern, flooding problems, location of high ground water table areas which are very important for a comprehensive planning and for environmental protection. Limitations of topomaps compared to aerial photographs have been worked out. The study is based on air photo-interpretation technique supported by field checking. *** DIRECT SUPPORT *** A04KF011 00003     

Photo-interpretation and site assessment survey — A case study

A study was undertaken to find out the possibility of using the available aerial photos on scale 1 : 50 000 for selection of areas suitable for industrial plantation. Micro relief or terrain & vegetation density classes were interpreted on air photos and a PI map was prepared. The PI map was then overlaid on land facet & soil facet maps and the result shows that PI map is a useful tool for planning of raw material supply to the forest based industry. The growth data is to be obtained from field sample plots laid out in each stratum.     

Study of geology and structure of perungulathur area in thiruvannamalai sambuvarayar district,tamil nadu,using remote sensing techniques

Remote sensing technique can play a vital role in geological, geomorphological and structural studies. Geology and structure of Perungulathur area in Thiruvannamalai Sambuvarayar district was studied by using Landsat imagery and aerial photographs with limited field checks. Charnockite, which forms the country rock of the area, and the interbedded pink granite and amphibolite exhibit typical tonal and textural characters on aerial photographs. The study has brought out a partly exposed structural basin which is represented by the folded structure of amphibolite and pink granite within the charnockitic country rock.     

Use of aerial photographs for soil erosion studies

Using air photos soil loss from agricultural fields has been estimated in respect of the Rana and granitic areas of south-west of Merida, Spain, applying the universal soil-loss equation. The results of soil-loss have been shown as soil erosion susceptibility and soil erosion hazard classes. This study has shown that large scale aerial photographs (1:12500) are quite useful in evaluating many of the parameters of the universal soil loss equation with limited field checks.     

热带森林植被的动态变化遥感监测

本文讨论了以热带森林植被为主体的再生资源的面积动态变化监测。研究中包括两个部分。首先,我们利用多时相遥感图像对大面积的西双版纳州进行地类判读,系统地分析了森林植被的动态变化。其次,利用Landsat MSS和TM数据对自然保护区的动态变化进行了包含无监督分类和归一化差值植被指数分析的数字图像处理,变化分类也相当符合实际。总的实验结果表明,这种监测方法是很有效的,可在再生资源监测中特别是在森林植被监测中加以推广应用。     

Geology of the area around Katta,sindhudurg district,Maharashtra. Based on aerospace data

Geological studies of the area around Katta, in the southern part of the Ratnagiri District of Maharashtra, were carried out with the help of visual remote sensing techniques using LANDSAT imageries on 1:250,000 scale and aerial photographs on 1:60,000 scale. The major stratigraphic units represented in the area under study are the Archean Complex, Kaladgi Supergroup, Deccan Trap, Laterite and Alluvium. The Kaladgis unconformably overlie the Archean metasediments and also at places exhibit faulted contacts with the latter. The major part of the area is covered by a thick evergreen vegetation. The interpretation followed by field work and laboratory work revealed the following:

1. The different lithologic units could be delineated on the aerial photographs.
2. Different lineaments marked on the imagery were found to be due either to faults or fracture zones. Some of the older faults appear to have been rejuvenated after the formation of the laterites.
3. Some of the lithologic horizons can be identified on the Landsat imagery by virtue of their spatial signatures.

These studies indicate that even in the area covered with thick vegetation, aerospace imagery in appropriate band and data scale can provide significant geological information.     

Aerial remote sensing application in hydrogeological and geomorphic mapping of a rocky terrain: A case study from Uttar Pradesh

Ground water prospecting in hard rock areas of Uttar Pradesh is quite difficult, owing to the geological and geomorphic controls of sub-surface strata on the occurrence and movement of ground water resources, and, therefore, it requires systematic investigations, mainly with the aid of remotely sensed and data, which undoubtedly provide realistic information on the hydrogeological conditions, geomorphologic features, drainage patterns etc. of any rocky area. In this paper, an endeavour has been made to locate ground water possibilities in the drought-affected, rocky terrain of the southern Mirzapur district of Uttar Pradesh, covering part of block Muirpur which is mainly characterised by the varied geological formations, including Archean complex, pre-Vindhyan matasediments and Gondwana formation, through the application of air photointerpretation technique, primarily based on the geologic/geomorphologic approach. The hydro-investigation in the area was carried out using panchromatic aerial photos of 1∶60,000 scale, chiefly to identify the drainage patterns, major geomorphic geo structural and lithological units; as these may control the ground water regime of the area, Further. the present study was also ably supported with limited field survey and hydrogeological data, for achieving reliable results.     

Capability of photointerpretation methods for mapping of Vindhyan and Deccan Trap terrain — A case study from Jhalawar area,Rajasthan

Geological mapping of the Vindhyan and Deccan Trap terrain around Jhalawar was accomplished by aerial photointerpretation with limited field checks in parts, by conventional field mapping for part of the area and also by interpretation of LANDSAT imagery. A comparative assessment of the data producing capability and accuracy of these methods is made from the case study. Major geological formations comprising Semri, Kaimur, Rewa and Bhander groups of Vindhyan supergroup, Deccan Trap and recent fluvial sediments are equally interpretable from all three level (i.e. ground, air and space) surveillance data. All the members and units are mappable on air photos and on ground but not on the LANSAT imagery. It is difficult to plot all the flows and flow units of Deccan Trap on a topographic base map during conventional field mapping but these are more or less separable on aerial photos. Structural trends are decipherable by photointerpretation but lineaments are well depicted on LANDSAT imagery. Physical and petrological characters of rocks can, however, only be studied in situ and by laboratory analysis of samples. Aerial photointerpretation techniques can be applied for geological mapping of Vindhyan and Deccan Trap terrain with high degree of confidence and reasonable accurate maps can be generated. LANDSAT imagery are useful for generation of small scale reconnalssance and lineament pattern maps. The best system of mapping such terrain would be photointerpretation with limited field check and collection of essential groundtruth and specimens for laboratory analysis along selected traverses thus minimising the time and cost of survey.     

Quantitative monitoring of land use changes in relation to hydrology of Bhavani basin using remote sensing techniques — a case study

The paper summarises a part of the results of an on-going project for quantifying the land use changes in Bhavani basin (Geographic co-ordinates N lat 10°55′ - 11°45′,E Long. 76°30′ - 77°45′). Landsat and aerial data have been used in monitoring the dynamic changes in land use patterns. Visually interpreted Landsat MSS data of two different dates in conjunction with the historic data acquired from the Survey of India topographic maps and field data were used in this investigation. Also land use changes over two test-sites in the basin were studied using aerial photographs. During the study, it has been observed that a direct correlation exists between the rainfall and the area irrigated. The repetitive coverage of the satellite data are found to be quite remarkable, especially the 1:250,000 False Colour Composites (FCC) in assessing rapidly the temporal land use changes of a region at a cheaper cost.     

Preliminary study of Landsat digital data related to parts of Chandrapur project area,Maharashtra

This paper mainly projects the attempts made in analysing the computer line printer outputs of bands 4,5 and 7 obtained from Landsat digital data, with reference to a selected area of Chandrapur project in Chandrapur district, Maharashtra. The distinction into various landuse patterns has been carried out on the printed outputs and they have been compared with the available toposheets ane aerial photos.