Geology and geomorphology of Cumbum valley and Varushanadu hills,Madural district,Tamil Nadu through remote sensing

The Varushanad hills forms the eastern offshoot of the Western Ghats and the Cumbum valley divides the Varushnad hills from the Western Ghats. Investigations were carried out in about 1700 sq Km comprising the Cumbum valley and the Varushanad hills of the Western Ghats situated in Periakulam Srivalliputhur and Usilampatti taluks of Tamil Nadu on the geological and geomorphological aspects. Remote sensing techniques were used and limited field checks were made. Visual interpretation of aerial photographs on 1:60,000 scale was carried out for identifying the geomorphological features, drainage pattern and lithology. Digital analysis of the Landsat computer compatible tape (CCT) path-row 154–053 was also carried out to delineate major lithological variations. Major lineaments were also mapped from the Landsat imagery and false colour composite. The rock types of the Cumbum valley and the Varushanad hills are mainly charnockites, granite gneiss and pink granites which have been deformed by folds and faults. The various geomorphological units of the area are ridges, valleys, bazada zone and pediment zone of mountain complex. Resources evalution studies on the potential zone of ground water and possible construction materials were also discussed.     

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.     

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.     

Study of drainage profiles in Jharia Coalfield,eastern India from aerial photographs: Implication for land use planning

Drainage analysis of an area through aerial photographs helps a lot in knowing its soil textrue, mainly its porosity, permeability, grainsize and compactness. These observations may be used as a guide for land use planning over the area. Studies have been conducted in Jharia Coalfield through scanning of acrial photographs to know the textural characters of soil/rock cover over the area. Nature of valley profiles have been studied in detail. The overall drainage pattern and drainage texture have also been studied. The observation have been used to infer about the textue of the materials (rock/soil) traversed by the drainage lines in the region. The observations suggest that the major part of the field is covered by materials of moderate cohesiveness with good porosity, permeability and recharge capacity. These informations have been used as critical inputs for future land use planning in the area.     

Use of aerial photo-interpretation techniques for land evaluation of a part of Bolangir district,Orissa

The land evaluation has been of paramount importance for the planned development and resource utilization of an area, specially for locating better potential zones for increasing agricultural production. Large areas in the country are yet to be evaluated based on their productivity and potentiality. A case study was undertaken in a part of Bolangir district of Orissa, by using small scale aerial photographs.     

Origin of Rumjatar table-land,Nepal Himalayas

The Rumjatar Table-land with an area of 2.5 sq km and general southerly slope of 4′ is a unique feature amidst 2500 sq km of rugged Himalayan terrain of the Midland region of Napal, which has been studied through aerial photographs aud toposheets, with field checks. Though it exhibits some characteristics of a peneplain, it is in fact a “fock-fan” developed through denudation processes acting on weak rocks in a valley. The rock fan has now assumed the form of an upland through downcutting by the bounding streams on the sides, and concurrent uplift of the Himalayas. It is topped by soil cover.     

Utilisation of integrated remote sensing technique for coastal geomorphic and geologic data extraction—A case study for Coondapur,south Kanara district (Karnataka)

Coastal zone is associated with several geomorphic features of erosional and depositional nature, be sides the broad geologic information. The area around Coondapur of south Kanara district, Karnataka, possesses all the major characteristics of coastal zone and these are extractable through intergated remotely sensed data namely Landsat-1 MSS imagery, Salyut-7 KATE space photograph and aerial photographs. The visual interpretation is carried out with developing remote sensing keys to decipher major geomorphic-geologic information like: spit, double spit, beach deposit, alluvium, levee deposit, la|terite and other rock types. It is concluded that the major geomorphic-geologic characteristics as well as subdeltaic drainage, soil erosoin are obtained through space borne data. The aerial photographs provide the detailed geomorphic and geologic information.     

Studying town morphology through Remote Sensing

Remotely-sensed data products have got unique advantage over conventional data-gathering techniques in the study of urban morphology. The physical parameters like built-up area density, street pattern, population density, urban structure as well as functional characteristics which can be derived from land use/land cover map, are clearly visible on aerial data products. This technique provides synoptic view of the area which makes the study comprehensive and uniform. Sequential aerial photographs and satellite imagery help in studying the growth of urban area and temporal changes in urban structure. These informations are very useful in the planning of city extension. Here an attempt has been made to study the urban morphology of Saharanpur city by using panchromatic aerial photographs on scale 1∶10,000, IRS-1B LISS II geocoded imagery on 1∶50,000 scale and photo-maps on 1∶4000 scale, and the results are very encouraging.     

陕西神府煤田新民烧变区煤层自燃边界范围的遥感调查

本课题以可见光黑白航空像片为主要信息源,对陕西神府煤田新民烧变区进行了1:5万航空遥感地质调查,圈定了该区烧变岩分布范围及煤层自燃边界线。文中着重介绍了遥感调查煤层烧变区的技术方法与工作成果。调查区为煤层自燃死火区。调查首先从烧变岩的基本地质特征入手,划分了烧变岩的宏观类型,确定了烧变岩的主要形成时代,探讨了烧变岩的形成机理;第二,根据掌握资料选取已知区,研究烧变岩及煤层自燃边界线的影像特征,建立初步解译标志;第三,在全区范围内进行煤层自燃边界线的遥感调查,并对解译标志进行补充、修改与完善。在调查中,解译与调绘相结合,遥感与地面调查方法相结合,最终圈定了区内各煤层的自燃边界线,并经钻孔验证,精度达到要求。     

Automated lithological mapping by integrating spectral enhancement techniques and machine learning algorithms using AVIRIS-NG hyperspectral data in Gold-bearing granite-greenstone rocks in Hutti,India

In this study, we proposed an automated lithological mapping approach by using spectral enhancement techniques and Machine Learning Algorithms (MLAs) using Airborne Visible Infrared Imaging Spectroradiometer-Next Generation (AVIRIS-NG) hyperspectral data in the greenstone belt of the Hutti area, India. We integrated spectral enhancement techniques such as Principal Component Analysis (PCA) and Independent Component Analysis (ICA) transformation and different MLAs for an accurate mapping of rock types. A conjugate utilization of conventional geological map and spectral enhancement products derived from ASTER data were used for the preparation of a high-resolution reference lithology map. Feature selection and extraction methods were applied on the AVIRIS-NG data to derive different input dataset such as (a) all spectral bands, (b) shortwave infrared bands, (c) Joint Mutual Information Maximization (JMIM) based optimum bands, and (d) optimum bands using PCA, to choose optimum input dataset for automated lithological mapping. The comparative analysis of different MLAs shows that the Support Vector Machine (SVM) outperforms other Machine Learning (ML) models. The SVM achieved an Overall Accuracy (OA) and Kappa Coefficient (k) of 85.48% and 0.83, respectively, using JMIM based optimum bands. The JMIM based optimum bands were more suitable than other input datasets to classify most of the lithological units (i.e. metabasalt, amphibolite, granite, acidic intrusive and migmatite) within the study area . The sensitivity analysis performed in this study illustrates that the SVM is less sensitive to the number of samples and mislabeling in the model training than other MLAs. The obtained high-resolution classified map with accurate litho-contacts of amphibolite, metabasalt, and granite can be coupled with an alteration map of the area for targeting the potential zone of gold mineralization.     

Geology in parts of Sainj Valley,Kulu district,Himachal Pradesh

The paper highlights the findings of photogeological studies, with selective field checks, carried out in Sainj Valley. For the first time, a photogeological map of the area has been prepared using large scale aerial photographs Structurally the area forms‘Window in a Window’ structure as the oldest rocks of Kulu formation are thrusted over the younger rocks of Larji Group (Larji and Banjar formations) and further Banjars are thrusted over Larjis. Thus, Larjis being stratigraphically youngest, occupy the lowest tectonic position. The Kulu formation mainly consists of Central Crystalline, schists and gneisses. Banjar is composed of quartzite, metabasics, slate and phyllite. Larji predominantly consists of dolomite and quartzite with slate and phyllite. The photogeological studies have helped to bring out the lineament pattern, landslide zones, major structural trends and main geological formations. The lineaments mainly trend in NNE-SSW, NW-SE, NE-SW and NNW-SSE directions. A key for photo-characters of different litho units and terrain elements of the area is established.     

Monitoring of salt affected soils — A case study using aerial photographs,salyut‐7 space photographs,and landsat TM data

Soils of part of Ukai‐kakarapar Command area, Gujarat (India) have been mapped at 1:25, 000 scale using aerial photographs of December 1977. It was observed that about 36.3% of the area was affected by soil salinity/alkalinity. The test area has been remapped using Salyut‐7 space photographs taken during Indo‐Soviet joint flight in April, 1984. The area affected by soil salinity/alkalinity was found to be substantially higher (80.3%). The earlier mapping using aerial photographs was done when the soil surface was compartively moist (December 1977) as compared to date of Salyut‐7 photography (April 1984), when the soil surface was likely to be devoid of moisture and the salts moved to the surface. To have easy comparision with the map prepared by using aerial photographs, Landsat TM data of December, 1985 was used in which 45.7% of the total area was mapped as salt affected. The extent of area delineated using Landsat TM was higher than that of 1977 but much lesser than the area delineated using Salyut‐7 (MKF‐6M) photographs. This indicated that the increase in the extent of salt affected area in the map prepared using the MKF‐6M photographs might be partly due to actual increase in the salinity/alkalinity and partly due to the seasonal affects. Among the various bands of MKF‐6M, band ‐4 was found to be the best for delineating the salt affected soils. The boundaries were sharper in the FCC and band No.4 of MKF‐6M than in the aerial photographs.     

Use of aerial photo-interpretation techniques for watershed management studies in drought prone areas

In the semiarid regions of the country a large part is subjected to drought in the years of scanty rainfall. In order to improve agricultural conditions of these regions soil and water management programmes are taken up Use of aerial photo-interpretation techniques can be successfully employed for data collection purposes for these areas. The important diciplines are Geology, Geomorphology, Soils, Hydrology and Land Use where aerial Photographs can be most commonly used. A brief decription of drought prone area in Gokak Taluq of Belgaum district is given which demonstrates the basic interrelationship of physiographic unit with geological conditions, soils and hydrology. A scientific planning of drought prone area requires control measures on watershed basis. Accurate delineation of watersheds and subwatershed is feasible through the use of aerial photographs, which also serve as base maps for compilation of other kinds of data as well.     

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.     

GNSS辅助摄影测量中几个问题的探讨

GNSS辅助摄影测量是在数字摄影测量基础上发展起来的一种技术手段。它使航空摄影、像片控制点布设、外方位元素的获取和空中三角测量进入了一个新时代。本文对航摄分区和补摄、区域划分以及像控点布设应注意的问题进行了探讨,同时,对应用前景进行了概述。     

Delineation of shallow Deccan basaltic aquifers from Maharashtra using aerial photointerpretation

The Deccan basaltic lava flows form shallow unconfined aquifers tapped for irrigation by large diameter dugwells. Aerial photographs form an important utility in the hydrogeological mapping of these shallow basaltic aquifers. Aerial photographs provide extensive information regarding the agricultural landuse in the agricultural sector from the Deccan basaltic terrain of Maharashtra. A zonation based on the cultivation, patterns brings out, quite clearly, the relationship between the agriculture in the area and the irrigation potential of the aquifer(s). This, relationship itself points to the inherent heterogeneity of the Deccan basaltic aquifers. Cultivation patterns/signatures that emerge through aerial photointerpretation can form the basis for a systematic hydrogeological mapping leading to aquifer characterisation of Deccan basalts, especially in regions where rock surfaces are not, directly exposed (such as is evident in many agricultural belts of Maharashtra state).     

Photogeologic mapping north of Khairwara,Udaipur district,Rajasthan

Photogeologic mapping of a sample area defined by latitudes 24° O to 6′N and longitudes 73° 30′ to 45′ E from a part of the Aravalli orogen, illustrates the advantages, as well as limitations, of photo-interpretation (PI) in terrains comprsing, highly deformed ancient rock formations. Discrimination between psammitic and pelitic metasediments is easy, using micro-relief and drainage parameters as PI elements; but that between pelites, ultra-basic schists and impure marbles is difficult and less reliable. Trends of foliations, several sets of joints and faults are distinct on the aerial photographs, but complete reconstruction of the superposed fold geometry is not possible. Within the area studied, dominantly pelitic, psammitic and a little clacareous metasediments, intruded by ultra-basics, exhibit a prominent and persistent NNE trend defined by lithologic contacts, bedding and foliations, with steep northwesterly dips. In its central part, bands of psammites within the pelites exhibit a hook shaped fold interference pattern (type 3 of Ramsay, 1967) with the later upright (Fleuty, 1964) fold axial trace trending northwesterly.     

Analysis of urban landuse change using sequential aerial photographs and spot data: An example of north Bhubaneswar,Orissa

As urban area undergoes a rapid change it will be necessary to review development and the urban plans once in five years in relation to important public and other decisions taken from time to time. In order to know the trend of development and landuse patterns, analysis of sequential aerial photographs and satellite imagery of different years can be a useful tool for interpretation of various landuses and their comparison, In the present study an attempt has been made to understand the change detection using sequential aerial photographs of 1974 and 1989, and comparison with SPOT data of I988 with the help of ‘USEMAP’ GIS software package.     

Morphometric analysis of sub-watersheds in Gurdaspur district, Punjab using remote sensing and GIS techniques

Morphometric analysis of two sub-watersheds was carried using remote sensing and GIS techniques. Detailed drainage map prepared from aerial photographs and SOI toposheets was updated using latest IRS-ID PAN sharpened LISS-III analog data. Updated drainage maps were used for the morphometric analysis of the two sub-watersheds. Both the sub-watersheds show dendritic to sub-dendritic drainage pattern with moderate drainage texture. High bifurcation ratio indicates a strong structural control on the drainage. Logarithm of number of stream vs. stream order show deviation from straight line indicating regional upliftment. In spite of mountainous relief, low drainage density values indicate that the area is underlain by impermeable sub-surface material. Circulatory and elongation ratios show that both the sub-watersheds have elongated shape.