Geospatial Data Analysis for Study of Suspended Sediments in Govind Ballabh Pant Reservoir, Singrauli Coalfield, India  Dr. A. K. Samantaray Suptdg. Engineer (Environment) Regional Institute – VII Central Mine Planning & Design Institute Ltd. OSHB Building, Sachivalaya Marg, Unit-III Bhubaneswar 751001, Orissa, India Tel.: (+91)-(674) 240-2627, 240-4143 Fax: (+91)-(674) 240-8760 Email: abani@rediffmail.com  N. P. Singh Head, Remote Sensing Cell Central Mine Planning & Design Institute Ltd. Gondwana Place, Kanke Road Ranchi 834008, Jharkhand, India Tel.: (+91)-(651) 242-2196, Fax: (+91)-(651) 223-0447, 223-1851 Email: singhnp@yahoo.com  T. K. Mukherjee General Manager (Geomatics) Central Mine Planning & Design Institute Ltd. Gondwana Place, Kanke Road Ranchi 834008, Jharkhand, India Tel.: (+91)-(651) 223-0041, Fax: (+91)-(651) 223-0447, 223-1851 Email: tuhin_mukherjee@hotmail.com  J. P. Singh Director (Technical/Operation) Central Mine Planning & Design Institute Ltd. Gondwana Place, Kanke Road Ranchi 834008, Jharkhand, India Tel.: (+91)-(651) 223-0020, Fax: (+91)-(651) 223-0447, 223-1851 Abstract The Govind Ballabh Pant (GBP) reservoir covering an area of about 450 sq.km is the resultant reservoir of Rihand dam constructed in the year 1962 on Rihand River near Renukoot town in Sonebhadra district of Uttar Pradesh in India for hydropower generation. The catchment area of the reservoir is 13,385 sq.km. The availability of water in GBP reservoir and abundance of steam coal in nearby Singrauli coalfield have offered an ideal location for various large scale industries like thermal power plants, aluminium plant, chemical plant, cement and coal mining projects around the periphery of this reservoir. As sequel to industrialization in this region, not only the physical environment is being subjected to ever increasing interference, but the effect has also lead to progressive shrinkage in storage capacity and pollution of the GBP reservoir. The reservoir being the ‘Life Line’ of all the industries situated around it, a detail study on suspended sediments and its pollution level in the reservoir is very much warranted for effective reservoir management. Comprehensive geospatial data analysis using satellite data of IRS-IC: LISS-III of the year 1998 & 2001 along with ground collateral data, has been attempted to assess the dispersal pattern of suspended sediments in GBP reservoir and sources thereto. Digital satellite data were processed using Geomatica v.8.2 digital image processing software and the ground collateral data were captured and analysed using GIS. Data of all the four bands of IRS-IC satellite were initially analyzed individually to determine the efficacy of different bands in mapping of suspended sediments. It has been observed that there is a positive functional relationship between the concentration of suspended sediments and the spectral signatures recorded in the visible wavelength bands-1 & 3 and near infrared band-4. Data of band-3, however, has a distinctive edge over other two bands. Based on the histogram distribution of spectral signatures of band-3, four concentration levels of the suspended sediments were identified and nomenclatured as viz. ‘high’, ‘high to moderate’, ‘moderate to low’ and ‘low’. It is evident from the study of satellite data of the year-1998 that suspended sediments are mainly concentrated in western part of the reservoir, where number of thermal power plants, ash ponds as well as coal mining projects is situated. ‘High’ suspended sediment zone is present near Renusagar, Anpara, Singrauli and Vindhyachal Power Plants primarily due to discharge of the ash ponds located on the periphery of the reservoir. The Balia and Matwani streams flowing through Jayant and Dudhichua coal mining projects are also discharging its loads in western part of the reservoir. However, the discharge loads from these two streams are negligible as compared to the overflow load from the ash ponds. Eastern fringe of the reservoir is almost free from suspended sediments except near Rihand Power Plant. IRS data of the year-2001 on the other hand reveals that besides the siltation in western part of the reservoir, the eastern fringe of the reservoir has also started getting silted showing moderate to high siltation. This is mainly because of progressive depletion of vegetation cover in and around the catchments area causing great deal of topsoil erosion resulting in discharge of suspended sediment load in the reservoir. The clay minerals composition is an indicator of identifying the provenance of the sediments/-accumulated silt in the reservoir. Trace elements studies allow assessment of pollution level in the reservoir. An attempt has been made to integrate the available analytical data of the suspended sediments/– accumulated silt using GIS for quantitative assessment, it provenance, as well as status of pollution level. The kaolinite/illite(K/I) ratio study indicate that in western part of the reservoir sediments had high K/I ratio (3.2 to 6.8) which is indicative of Gondwana provenance of the sediments whereas in the eastern part, K/I ratio is low (1.7 to 2.22) indicative of gneissic provenance of the sediments. The chemical analysis of the reservoir sediment indicates that the metal and trace element content of the sediments is slightly higher than the average natural level of Pb. As, Se, Sn, Cd and B. This may be due to chemical composition of rocks exposed around the reservoir. Mercury concentration is also marginally higher than average natural value in almost all parts of the reservoir except in the intermediate part. However, a very high mercury pollution of the sediments was observed close to the dam where Dongia nala meets in the reservoir. The high concentration of mercury is due to discharge of the Kanoria chemical’s chloro-alkali plants in Dongia nala. Periodic geospatial data capture and analysis offers an efficient tool for mapping of suspended sediment dispersal pattern and its provenance, pollution level and follow up remedial measures to prevent further aggravation for efficient reservoir management. |