Estimation of Non-Point Source Pollution in a Typical River of India

Estimation of non-point source (NPS) pollution from cropland runoff is an important feature of regional water quality planning. In the present work, influx of non-point source pollutant loads in terms of the nitrate (NO₃) and ortho-phosphate (o-PO₄) loads from agricultural areas at different locations of Kali River in western Uttar Pradesh, India, were monitored. Different mathematical techniques, based on mass balance and reaction kinetics, were used to estimate the influx of these loads between different reaches of Kali River. A total of 576 field data sets were obtained from sixteen sampling stations during the period from March 1999 to February 2000 for analysis. Remote sensing IRS-LISS III and PAN digital data were utilized to obtain land use and land cover. A Geographical Information System (GIS) was used to develop a digital elevation model in order to delineate flow paths and agricultural areas contributing non-point pollution to different sampling points. The NPS loads estimated from different existing equations were compared with the corresponding observed values and the suitability of these equations was assessed for Kali River. Certain basin characteristics were critical for assessing the impact of non-point source pollutant loads in the river. The length of the river reach showed the highest correlation with the corresponding non-point source loads.