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Integrated Remote Sensing and factor analytic GIS model for evaluating groundwater pollution potential
O. P. Dubey, D. C. Sharma
Irrigation Research Institute, Roorkee,
Roorkee 247667, Uttaranchal
Background
In order to fulfill growing needs, pollutants are being increasingly added to the groundwater system through various human activities and natural processes. Applications of fertilizers and pesticides to enhance crop production have become a common practice. In case fertilizer application exceeds the plant uptake, the residual joins the water table. This increases nitrate concentration in groundwater. Similarly, excess applications of pesticides that are complex organic chemicals may have adverse health effects. Long-term use of saline irrigation water combined with poor management and adverse climatic conditions for example, low rainfall and high evaporation, leads to accumulation of salts in the root zone. Poor agricultural practice results in a loss of crop yield and deterioration of soil structure. Poorly designed and improperly managed waste disposal sites contribute significant amount of leachate. This leachate may affect the water quality. Improperly designed and maintained septic tank becomes a threat to groundwater quality. Disposal of waste through wells adds pollutant to the groundwater and also accelerate their movement towards a production well. In and around major pollutant is industrial waste that includes heavy metals, toxic compounds and radioactive material. Another significant source of metal contaminants are tailing produced at mining sites. An indiscriminate groundwater development in coastal aquifers leads to an excessive saltwater intrusion. The impact of the intrusion is further aggravated by an excessive upcoming of the freshwater-saltwater interface below a pumping well, caused by faulty well design or operation (too long a pumping spell and/or too little a rest period between the two successive pumping spells). In India, even during ancient time, well-defined legislation was in existent to control the water pollution. The Athervaveda provides panel action for polluting water.
"}k u vkiLrUos {jUrq ;ks u% nqjfiz;s ra fun~/ke: A ifo=s.k I`fFkfo eksr iqukfe AA " AvFkZosn dk.M 12 & 'yksd 30 A
Which means, let us have the life-sustaining water through good conduct and proper means (adequate resources), " O goddess Earth give punishment to those who are responsible for polluting water".
In recent years, land and water sectors were put to stresses in order to meet the demand of the growing population. Groundwater is more dependable source of water as compared to surface water (Viverkar 1999). Gradually, quality of water in addition to quantity is gaining importance in the selection of suitable sites for the groundwater development. Groundwater Pollution Potential (GWPP) of any given geographical location depends upon a wide range of above surface, surface and subsurface environmental parameters Brown 1972, Jackson1986). Evaluation of GPP involves decision-making keeping in view multiple interwoven criteria (ESCAP 1996). Generally, data required for GWPP is either not available or not sufficient. Collection, storage, and processing of required data is difficult, costly, and time consuming. As a result GWPP studies are generally based on questionable data. Remotely sensed data has proven capability in providing many above surface, surface and sub surface characteristics of a land unit. Synergistic use of remote sensing and ancillary data can be made for the development of the database required for GWPP (Daniel.et.al.1994, ESCAP 1996) GIS can be used to store, process and retrieve the developed database. GPP. Groundwater and its pollution system is a complex system (Biawas 1971, Hamil et. al. 1996). In this study an attempt has been made to represent the GWP system by Factor Analytic Model (FAM).
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