Study of Panchet reservoir
using Remote Sensing images V. K. Srivastava, T. B. V.
M. Rao, D. Devbhuti, S. Sahai Indian School of Mines, Dhanbad-826004 India Abstract Panchet Dam lies on Damodar river 5 kms upstream at the confluence of Barakar and damodar river and at the western fringe of Raniganj Coalfield in west Bengal. The reservoir has been constructed with multipurpose objectives for the benefits of the mankind & hence they need to be monitored regularly. Satellite remote sensing data is an effective tool in such overview monitoring study. It provides and synoptic view of the whole area in multispctral mode in different times of the year. Various aspects of the Panchet reservoir, such as temporal variation in reservoir water levels images in various bands and its colour composite. This technique has been found successful in the present study. Introduction Panchet Dam and Reservoir, an important member of Damodar Valley corporation group of reservoirs built on Barakar liea at the western fringe of Raniganj Coalfield of east India. This Damodar river rises in the eastern part of Palamau district of Bihar at an elevation of approximately 600 mt and has a course of 538 kms before it merges with Hooghly in West Bengal. The basin of this river deposited and is surrounded by the qranite gneiss of chhrta nagpur marked dreaks in the river cores and its tributaries) are affected by the boundary fault scarps. The Catchments of this river receives an average rainfall of 120-150 cm of which 90% rainfall occurs during the four months only i.e. June to Sept. of a year. In addition to this, valley receives rainfall from tropical cyclones in the upper catchments plateau part of the area. As mentioned above the concentrated rainfall during the monsoon over cneissic rocks, sandstones and shale under hot and humid climate causes severe erosion of rock materials and thereby loading the water streams with great amount of sediments. This causes choking of riverbed, which in turn results in flooding of surrounding region n. Prior to construction of various dams on this river, the region had bad experience of severe floods. However, presently minor floods are also not uncommon. Panchet reservoir contracted with the multipurpose objectives such as flood control irrigation, power generation and finally management of water resources as a whole. Therefore, the Dam and reservoir workers such as sharma (1964), Ray (1982), Datta et al (1988) and scientist OF DVC (personal discussions) have studied one aspect or the Other using conventional survey data. But here Geotechnical aspect of dam have been studied using Satellite Remote Sensing technique. Such techniques has been already used by srivastava et al (1988) fro Maithon Dam Reservoir study. Remote Sensing Image from satellite Remote Sensing technique. Such technique has been already used by Srivastava et al (1988) for maithon dam reservoir study. of reserovir water leveis this helps static and dynamic aspect of landcape and landuse pattern. In view of these significant characteristics of satellite remote sensing Images, Landsat TM imagery of May, 87 both in B/W and colour composites have been studied on following points.
A generalized geological map of the area in and around Panchat Dam is shown in Fig. 1. Along with location (after Datta et al (1992). The Achaean metamorphic rocks comprising bank and part of the right bank is composed of Barakar stage, of the Gondwanas. The contact of Gondwana and Archaean is free from crushing or mylonitisation and is water tight. The regionalfoliation trend of the Archean being NW-SEwith moderate dip towards left bank. A NE-SW trending fault located on the right bank oriented oblique to the dam alignment has brought the non-garnetiferous rocks in juxtaposition with the garnetiferous ones. As no crushing indication in fault zone has been observed, it is considered to be harmless to dam site even though its considerable magnitude. A number of crises cross faults aligned NNW-SSE and NEW-SW which have traversed both the rock groups are mapped. Dolerite dykes trending NW-SE are discontinuously exposed in the area. Methodology and data used Here the Landsat Thematic mapper imagery of May'87 in bands 2(0.52 -60oum) 3 ( 0.63-.69 um,) and 4 (0.76-0. 90 um ) both is B & W and their colour combinations have been interpreted using the standard photo-interpretation technique. The sedimentation map has been prepared from the digitally processed black and white imagery in visible bands. Here the spectral reflectance values group for reservoir water has been sliced into various subclasses using he digital processing facility of RRSSC. IIT, Kharagpur (West Bengal) Finally following overlay maps have been prepared and are described here.
Conclusions The synoptic view of reservoir area by the satellite remote sensing images in multispectral mode in different time of the year have been of much value in the study of regional geotechtonic and characteristics of reservoir. Though the above observations and results are of preliminary nature but the availability of this little information in real time adds much significance to this technique. thus the remote sensing technique provides and effective way in monitoring preliminary aspects of the man mode dam reservoir. Acknowledgement The authors are grateful to Prof. D.K. Sinha, Director, Indian, School of Mines, Dhanbad for providing all the facilities, and encouragement to carry out the present work. References
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