eated geological units have been overlaid on IRS-ID LISS III satellite imagery ... The present study demonstrates that IRS-ID LISS-III data in conjunction with.
Photonirvachak Journal of the Indian Society of Remote Sensing, Vol. 31, No. 4, 2003
Delineation and Characterization of Geomorphological Features in a Part of Lower Maharahstra Metamorphic Plateau Using IRS-ID LISS-III Data G.P. OBI REDDY A N D A.K. MAJI National Bureau o f Soil Survey & Land Use Planning, Amravati Road, Nagpur-440 010, India.
ABSTRACT In the present study, an attempt has been made to delineate and characterize the different geomorphic units of Tundiya fiver catchment in a part of Lower Maharahstra Metamorphic Plateau, north-eastern part of Nagpur district, Maharashtra. The drainage, contour and delineated geological units have been overlaid on IRS-ID LISS III satellite imagery (bands 2,3 and 4) in EASI/PACE analysis system to delineate and characterize different geomorphological units and analysis of their processes based on the field observations. The study area is basically of metamorphic in origin with different geological formations and is influenced by the various fluvio-morphological processes. Based on the satellite data analysis, the distinct geomorphological units viz., table top summits, structural hills, subdued plateau, linear ridges, shallow, moderate and deeply buried foot slopes, shallow valley fills and deep valley fills have been delineated and characterized. The information generated from satellite data in the form of vector layers has been used in GIS to generate geological and geomorphological maps of the study area. The present study demonstrates that IRS-ID LISS-III data in conjunction with geology, drainage and contour parameters to enable detailed evaluation of different geomorphological units and analysis of their processes based on the field observations. The delineated geomorphological units can be utilized for evaluation and management of natural resources and geo-environment on sustainable basis at fiver catchment level.
Introduction G e o m o r p h o l o g i c a l m a p p i n g i n v o l v e s the identification and characterization of the fundamental units o f the landscape. Geomorphic Recd. Jan. 30, 2003; in final form May 5, 2003
unit is defined as an individual and genetically h o m o g e n e o u s l a n d f o r m produced by a definite constructional or destructional geomorphic process (Fairbridge, 1968). Each part of the land surface is the end product o f an evolution governed by parent
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geological material, geomorphological processes, past and present climate and time (Demek, 1972). Detail information on geomorphic units and their processes in an area is very useful in evaluation and management of land resources, environmental planning and developmental activities (Cook and Doornkamp, 1974; Crofts, 1974; Panizza, 1978; Demek, 1982). Geomorphological features are manifestations of underlying parent materials and the nature and duration of geomorphic processes that have produced the associated geomorphic units (Wright, 1993). The geomorphic position on a toposequence plays a vital role in classification o f g e o m o r p h i c units. Delineation and characterization of geomorphological features and analysis of their processes is of immense help in the fields of pedology, h y d r o l o g y and environmental engineering applications. The remote sensing techniques have become the most efficient tools for geological, structural, geomorphological studies and their mapping because of its synoptic view, multi-spectral, multitemporal capabilities (Krishnamurthy and Srinivas, 1996). The geomorphic units have specific set of characteristics that determine its image signature. High resolution satellite data provides reliable source of information to delineate and generate comprehensive and detail inventory of geomorphic units in an area (Mukerjee, 1982). The geomorphological mapping of a terrain and analysis of their processes also help in soil resources mapping, g r o u n d w a t e r potential zones identification, landscape ecological planning, hazard mapping and other e n v i r o n m e n t a l applications (Reddy et al., 2001). In the present study, Tundiya river c a t c h m e n t in L o w e r Maharashtra Metamorphic Plateau in northern part of Nagpur district has been selected for delineation and characterization of geomorphological units using IRS-ID LISS III satellite imagery and analysis of their processes based on the field observations.
Study Area The study area lies between 21 ° 30' 00" to 21 ° 40' 30" N latitudes and 79014 ' 00" to 79°31' 00" E longitudes and is located in north-eastern part of
Nagpur district, Maharashtra, covering an area o f about 362.18 km 2 (Fig. 1). Physiographically, the dissected structural hills of the metamorphic plateau are observed in the northern, western and south-eastern parts of the study area with elevation ranging from 380 to 580 m above msl. The buried foot slopes occupy the lower parts of dissected hills with an elevation ranging from 340 to 380 m above msl. The depositional valley floors extend from south-west to north-east in the lower portion of the catchment with elevation ranging from 320 to 360 m above msl. The climate is mainly hot subhumid type with mean annual temperature of 27°C and mean annual rainfall of 1120 mm. The natural vegetation of the study area mainly comprises of dry deciduous tree species o f Palas (Butea monosperma), Teak (Tectona grandis), Babool (Acacia arabica), Tendu (Diospyrous tomantosa), Bet (Ziziphus jujuba), Imli (Tamarindus indica), and Neem (Azadirachta indica).
Methodology The IRS-ID LISS-III satellite data of March 2000 pertaining to the study area was collected and registered to S u r v e y of India (SOl) topographical sheets at 1"50,000 scale in EASI/ PACE (ver 7.0) image analysis system (PCI, 2000). The surface lithological analysis of the study area has been carried out through visual interpretation of the satellite data considering the geological Quadrangle map on 1: I mile scale (GSI, 1978) as a base. The boundaries of the geological units have been modified based on the image characteristics and field observations. The slope map of the area was generated from the Digital Elevation Model (DEM) using the standard in-built algorithm of SPANS GIS ver 7.0 (PCI, 1997). Visual interpretation techniques have been followed in delineation of geomorphic units based on the tone, texture, shape, drainage pattern, colour and differential erosion characteristics of the satellite imagery in conjunction with collateral information. Adequate field checks were c o n d u c t e d for deriving information on geomorphic units and to establish the relationship between the image elements and geomorphic unit characteristics. The various land
Delineation and Characterization of Geomorphological Features...
Maharashtra
243
Nagpur district
Tundiya Catchmenl 21" 40' 21" 39'
2 ~ 35' 21" 34' 21" 33' 21 ° 32' 21" 31' 79* 15'
79* t8'
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79* 24'
79* 27'
21" 30'
Fig. 1. Location map of the study area use/land cover types recognized from satellite imagery were also considered in delineation of geomorphic units. The boundary delineation of geomorphic units have been carded out based on the changes in topographic slopes, relief patterns, crest type, drainage texture and image characteristics of the area. The linear, equalization and root enhancement techniques have been followed in analyzing the satellite imagery for better interpretation of the geomorphological units. The drainage, contour and delineated geological units have been overlaid on enhanced IRS-ID LISS III satellite imagery to delineate and characterize
different geomorphic units. Subsequently, detailed geomorphological analysis has been carded out based on their genesis and processes in association with image characteristics. The drainage parameters were analysed to assess their influence on genesis of geomorphic units, characteristics and their processes. The delineated units in the form of vector layers have been imported to GIS for generation of geological and g e o m o r p h o l o g i c a l maps. The various geomorphological processes were analysed based on the g e o m o r p h i c unit position, slope and morphometric prope~ies of the unit. Field checks
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G.P. Obi Reddy and A.K. Maji
have been carried out in selected sites to verify the boundaries and properties of the delineated geomorphic units.
Results & Discussion Slope The nearly level to level slopes (0-1%) are mainly associated with deep valley fills with an area of about 49.50 per cent of the Total Geographical Area (TGA). The very gentle slopes (1-3%) are mostly associated with shallow and deep valley fills and are having 14.30% of the TGA. Gentle slopes (3-5%) are observed in shallow and moderate buried foot slopes and deep valley fills with an area of about 7.06%. The moderate slope areas (5-10%) are in association with moderately buried foot slopes and occupy an area of about 10.80%. The majority of the strong slopes (10-15%) are in association with linear ridges and structural hills and are found in the western, north-western and south-eastern parts of the study area covering an area of about 5.62%. Steep slopes (15-30%) are associated with structural hills in the western, n o r t h - w e s t e r n and south-eastern parts and covering an area of 7.56%. The very steep slopes are (>30%) mainly spread in the structural hills and linear ridges and covering an area of about 4.30% of TGA.
Morphometric Characteristics The development of drainage pattern depends on the bedrock lithology and geological structures of the area (Pike, 2000). The order and type of drainage pattern influence the geomorphological processes and the genesis of the type of landform, The drainage pattern of the catchment is trellis and radial at higher elevations and parallel to subparallel in the lower elevations. The basin is characterized by 6 ~ order drainage basin (Strahler, 1964). High drainage density and stream frequency are found on structural hills and subdued plateau due to the presence of impermeable sub-surface, high structural complexity and low permeability of the terrain with high relief. The moderate drainage density and stream frequency exist on moderately
buried foot slopes. The shallow and deeply buried foot slopes are associated with low drainage density and frequency because of high permeable sub-soil material and low relief, which are in turn favourable for high infiltration. The deep valley fills are associated with 5a' and 6 'h order drainage streams with moderate structural disturbances and distorted drainage pattern (Strahler, 1964). The buried foot slopes are influenced by permeable lithology, moderate to nearly level plains and medium to low drainage density. It reveals that the type of drainage morphometry, underlying lithology and slope factors have great influence in the genesis of geomorphic units and their processes. Geology Geologically, study area is complex and represented by different formations belonging to Gneiss, Sausar Group, Sakoli Group, Granite and recent alluvium (GSI, 1978). The geological analysis and delineation of different geological units of the study area have been carried out through visual interpretation of the satellite data based on the distinct characteristics of different formations (Fig.2). The regional succession of the study area is shown in Table 1. Gneiss formations occurring in the study area belong to highly metamorphosed Gneiss of Lower Proterozoic to Archaean age (Krishnan, 1982). The igneous rocks show dark reddish to gray colour on the imagery and occur as intrusives within the metamorphic rocks. They occupy mainly northern, central and southern parts of the study area. Sausar Group consists of Bichuva, Charbaoli, Mansar and Lohangi formations. Bichuva formations are narrow and elongated and identified based on the white to dark green clour on the imagery. Charbaoli formations are linear in nature and they show light grey to green colour on the imagery. Mansar formations are isolated in nature and are noticed with light red to dark red colour on the imagery. They consist of m u s c o v i t e - b i o t i t e schist associated with manganiferrous quartzites. Lohangi formation consists of calc-gneisses and black manganiferrous marble with some manganese ores and occasionally containing small amount of dolomite and
Delineation and Characterization of Geomorphological Features ...
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References
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Fig. 2. Geological map of the study area (Modified after GSI, 1978) Table 1. The regional geological succession of the study area. Recent
I
Middle Proterozoic
Alluvium
Sausar Group
Sakoli Group
F
Archaean Lower [ Proterozoic L.
Lohangi formation
Calc-gneisses and black manganiferousmarble with some manganese ores
Bichua formation
Crystalline limestone and dolomite
Mansar formation
Muscovite-biotite schite with manganese ores
Chorbaoli formation
Quartzite and quartz-muscovite schist
Chlorite-Schist
Chlorite-muscovite schist and phyllite (undifferented) a. Chlorite schist with andalusite porphyroblast, b. Chlorite schist with chloritoid porphyroblast, c. Chlorite schist with magnetite, d. Phyllite, e. Chlorite muscovite schist with kyanite, dumortierite or sillimanite and Biotite gneisses, granulite and biotite aplite
Granite Gneiss
(Source: Geological Quadrangle map of Maharashtra and Madhya Pradesh, Geological Sur:ey of lndia, 1978)
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G.P. Obi Reddy and A.K. Maji
piedmontite. Chlorite schists formation belonging to Sakoli Group are noticed as linear and isolated in central part of the study area with light gray colour. Middle Proterozoic Granite formations occur in small outcrops in southern part of the study area and they show white to blue colour. They are associated with dykes and veins of pegmatite and aplite. Quaternary alluvium depos'.'ts have been identified based on the image characteristics of white to light red colour. They consist of loose, unindurated sequence of interlayred clay/silt and sand beds with occasional kankar layers admixed with cobbles and pebbles. This alluvium is underlain by Gneiss and Lohnagi formations. Geomorphology The underlying lithology, slope and the type of existing drainage pattern influence the genesis and processes of different geornorphic units (Subramanyan, 1981). Due to complexity of
geomorphic evolution, the catchment shows distinct geomorphic units. Both the endogenetic and exogenetic geomorphic processes have played important role in the carving of the present day landscape. The fluvio-denudational geomorph0logical processes are actively involved in landscape reduction processes. The physio-chemical weathering and multiple slope dissections under the influence of steep slopes, high drainage density and precipitation conditions have led to the development of ridge-valley land systems in the western part of the area. The fluvial-depositional geomorphic units are formed by transported material through the actions of corrosive and erosive activities and slope retreat processes at higher elevations. Nine distinct geomorphological units (Table 2, Fig. 3) have been delineated and characterized. The processes of the units were analyzed based on the field observations.
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