Volume No. 6 Issue No.: 2 Page No.: 222-231 Oct-Dec 2011




V. Sudha* and N. K. Ambujam

Centre for Water Resources, Anna University Chennai, Chennai, Tamil Nadu (INDIA)


Received on : September 07, 2011




Agricultural runoff is the primary cause of water pollution in developing countries like India and it is an emerging global problem. Agricultural activities that cause non point source pollution include application of excess fertilizers and pesticides, plowing, planting, irrigation, grazing and livestock activities. The major Agricultural Non Point Source (AGNPS) pollutants that result from these activities are sediment, nutrients, pathogens, pesticides, and salts. Major consequence of agricultural runoff is algal blooms. Explosions of algal blooms occur when high levels of plant nutrients such as phosphorus and nitrogen enter an aquatic body and that quickly overwhelms the resource. The study area was selected as the freshwater reservoir, located at Krishnagiri which is one of the drought prone districts of Tamil Nadu, South India. The catchment area of the reservoir is an agricultural watershed with high rate of soil erosion. The reservoir is being used for various purposes such as irrigation, drinking, fish rearing, livestock rearing and recreation. Because of the catastrophe of high erosion and sedimentation the storage capacity of the reservoir was reduced from 66.10 Mm3 to 39.70 Mm3. So the present study focuses on the impacts of overloading of nutrients on the quality of sediment and water in the reservoir. The sediment and water samples were collected from the fifteen locations at various zones of the reservoir like riverine, transition and lacustrine by traveled in a boat. The physio-chemical characteristics and nutrients were analysed in both the water and sediment samples. Any change in water quality or quantity of the reservoir will certainly hamper the development of that particular area. The statistical analyses were revealed that there is a threat of high spatial gradient of biologically labile and refractory phosphorus fractions in the sediments, which may involve in the internal cycle of nutrients and produce deleterious effects on water quality. The present study also recommends an emergency need for the environmental restoration of the freshwater reservoir at Krishnagiri, India.


Keywords : Agricultural Non Point Source, Agricultural runoff, Sediment nutrients, Algal bloom, Phosphorus fractions