STUDY OF INFLUENCE OF EFFLUENT ON GROUND WATER USING REMOTE SENSING, GIS AND MODELING TECHNIQUES

Abstract. The area lies in arid zone of western Rajasthan having very scanty rains and very low ground water reserves. Some of the other problems that are faced by the area are disposal of industrial effluent posing threat to its sustainability of water resource. Textiles, dyeing and printing industries, various mechanical process and chemical/synthetic dyes are used and considerable wastewater discharged from these textile units contains about high amount of the dyes into the adjoining drainages. This has caused degradation of water quality in this water scarce semi-arid region of the country. Pali city is located South-West, 70 Kms from Jodhpur in western Rajasthan (India). There are four Common Effluent Treatment Plant (CETP) treating wastewater to meet the pollutant level permissible to river discharge, a huge amount of effluent water of these factories directly meets the into the river Bandi – a tributary of river Luni. In order to monitor the impact of industrial effluents on the environment, identifying the extent of the degradation and evolving possible means of minimizing the impacts studies on quality of effluents, polluted river water and water of adjoining wells, the contamination migration of the pollutants from the river to ground water were studied.

Remote sensing analysis has been carried out using Resourcesat −1 multispectral satellite data along with DEM derived from IRS P5 stereo pair. GIS database generated of various thematic layers viz. base layer – inventorying all waterbodies in the vicinity, transport network and village layer, drainage, geomorphology, structure, land use. Analysis of spatial distribution of the features and change detection in land use/cover carried out. GIS maps have been used to help factor in spatial location of source and hydro-geomorphological settings. DEM & elevation contour helped in delineation of watershed and identifying flow modelling boundaries. Litholog data analysis carried out for aquifer boundaries using specialized software. Establishment of other boundary conditions was based on well data. Calibration and validation of was done using ground water modelling software. Change detection analysis indicated areas of impact on land use/ cover particularly, agriculture activity. Normalised difference vegetation index found to have negative correlation with pollution level. Population dynamics have been studied and it is found to be poorly correlated with land degradation. Water levels do not show significant variations in past twenty years baring normal seasonal fluctuation. Chemical analysis of ground water samples studies in time series. The water quality studied through various parameters shows concentration in mid-reach of the Bandi river. Analysis of litholog data shows three unconfined aquifers. Pump test and resistivity survey was carried out for initial aquifer properties in local water levels. Modelling contaminant migration helped in prediction of the extent of the adversity. Surface flow is checked allowing more water but it is proving to be accumulation point in absence of good rainfall & flow in the river. Hotspots of dumping /active contamination were identified with certain remediation efforts and supply of solid waste to cement industry in addition to bio-filter for heavy metals.