The study area is located in the southwestern part of Bangladesh. Twenty-six groundwater samples were collected from both shallow and deep tube wells ranging in depth from 20 to 60 m. Multivariate statistical analyses including factor analysis, cluster analysis and multidimensional scaling were applied to the hydrogeochemical data. The results show that a few factors adequately represent the traits that define water chemistry.

Hydrochemistry in parts of the Lower Tista Floodplain in northwest Bangladesh is dominated by alkalies and weakly acid, having highest concentration of sodium cations and bicarbonate anions respectively. Groundwater is characterized by sodium-calcium and sodium-potassium cation and bicarbonate-chloride-sulphate anion facies, and genetically ‘normal chloride’, ‘normal sulphate’, and ‘normal carbonated’ type, and soft to saline.

The lower Varuna River basin in Varanasi district situated in the central Ganga plain is a highly productive agricultural area, and is also one of the fast growing urban areas in India. The agricultural and urbanization activities have a lot of impact on the groundwater quality of the study area. The river basin is underlain by Quaternary alluvial sediments consisting of clay, silt, sand and gravel of various grades.

The recent Kosi megaflood, caused by a breach in the Kosi embankment in Nepal on August 18, 2008 and a sudden change in the course of the Kosi River, was one of the most significant and damaging flood events ever to hit Bihar. The Kosi disaster also ranks as one of the greatest disasters in India.

In the present study, the temporal patterns of monsoon floods on five large rivers of the Deccan Peninsula have been investigated. Analyses of the long-term annual maximum discharge/state data, available for the last 100 years or so, show non-random behaviour in terms of distinct periods of high and low floods.