CASE STUDY Variation of Water Quality Parameters with Siltation Depth for River Ichamati Along International Border with Bangladesh Using Multivariate Statistical Techniques P. K. Roy • S. Pal • G. Banerjee • M. Biswas Roy • D. Ray • A. Majumder Received: 17 April 2014 / Accepted: 21 July 2014 / Published online: 20 August 2014 Ó The Institution of Engineers (India) 2014 Abstract River is considered as one of the main sources of freshwater all over the world. Hence analysis and maintenance of this water resource is globally considered a matter of major concern. This paper deals with the assessment of surface water quality of the Ichamati river using multivariate statistical techniques. Eight distinct surface water quality observation stations were located and samples were collected. For the samples collected statisti- cal techniques were applied to the physico-chemical parameters and depth of siltation. In this paper cluster analysis is done to determine the relations between surface water quality and siltation depth of river Ichamati. Multiple regressions and mathematical equation modeling have been done to characterize surface water quality of Ichamati river on the basis of physico-chemical parameters. It was found that surface water quality of the downstream river was different from the water quality of the upstream. The analysis of the water quality parameters of the Ichamati river clearly indicate high pollution load on the river water which can be accounted to agricultural discharge, tidal effect and soil erosion. The results further reveal that with the increase in depth of siltation, water quality degraded. Keywords Water quality parameter  Depth of siltation  Dendrogram  Cluster analysis  Multiple Linear Regressions Introduction River Ichamati traverses a course of about 216 km and finally discharges into the river Kalindi at Hasnabad in the district of North 24 Parganas and ultimately finds its way into Bay of Bengal near New Moore Island as a part of Kalindi- Raimangal estuary in the deltaic southern part of West Bengal. The river Ichamati brings silt and soil from upstream and gradually fills up the riverbeds, and so, as time pro- gresses, the river is unable to cope with larger volumes of water, which spills over and floods the surroundings. The rate of accumulation of soil and silt on the riverbeds increases as more and more trees are cut (deforestation) in the Himalayan Mountain range thereby loosening the soil which is then carried downstream by the rapidly flowing water stream. This is then aggravated by the seasonal heavy downpours report of SWRE [1]. River also plays an important role in the assimilation and transport of domestic water, which form constant pollution sources, and also agricultural runoff, which is temporal and commonly affected by climate [2]. A river is a system comprising both the main course and the tributaries, carrying the one-way flow of a significant load of matter in dissolved and particulate phases from both natural and anthropogenic sources [3]. The quality of a river at any point reflects several major influences, including the lithology of the basin, atmospheric inputs, climatic conditions and anthropogenic inputs [4, 5]. The multivariate statistical methods have been employed to extract significant information from Physico- chemical parameters and depth of siltation datasets in compound systems. The present study attempts to establish a mathematical model between water quality parameter and depth of siltation. Since the data obtained in this study had multivariate nature and several of the variables were cor- related, cluster analysis and multiple regression analysis P. K. Roy (&)  S. Pal  G. Banerjee  D. Ray  A. Majumder School of Water Resources Engineering (SWRE), Jadavpur University, Kolkata 700032, WestBengal, India e-mail: pk1roy@yahoo.co.in M. Biswas Roy GCBT College, Habra, West Bengal, India 123 J. Inst. Eng. India Ser. E (July–December 2014) 95(2):97–103 DOI 10.1007/s40034-014-0038-9