The present study was conducted to measure globally alarming of ten heavy metals (Pb, Cd, Cr, Cu, Hg, Al, Ni, Co, Zn and Mn) in surface water and sediment of the Old Brahmaputra River in Bangladesh. The observed order of heavy metal mean concentration in water and sediments is Al > Mn > Ni > Co > Cu > Pb > Zn > Cr > Cd > Hg in mg/l and Al > Mn > Zn > Ni > Pb > Cr > Cu > Co > Cd > Hg in mg/kg, respectively. The significant variations of Cr, Cu, Al and Ni were found in the water of all seasons (p < 0.05), while sediment showed Pb and Hg exhibited substantial changes in terms of seasons (p < 0.05). Principal component analysis and correlation matrix revealed that significant anthropogenic input of Pb, Cd, Cr, Cu, Hg, Al, Ni, Co, Zn and Mn in water and sediment. In case of water, very strong linear relationships exhibited in Ni versus Cu (0.911), Ni versus Al (0.910), Mn versus Co (0.882), Cr versus Al (0.877), Cu versus Cd (0.853), Ni versus Pb (0.850), Zn versus Cr (0.833), Ni versus Cd (0.828), Cu versus Cr (0.827), Al versus Cd (0.827) and Zn versus Co (0.804) at the significance level 0.05. In sediments, very strong linear relationships were noted in Zn versus Cr (0.889), Al versus Pb (0.848), Co versus Al (0.819) and Mn versus Co (0.806) at the significance level 0.05. The result discovered that water and sediment quality of the Old Brahmaputra River became contaminated due to the anthropogenic sources of industrial, domestic and irrigation discharges. This environmental monitoring and assessment research will be useful for the management and planning for the protection of this river.

The groundwater is the most precious resources around the world and is shrinking day by day. In connection, there is a need for demarcation of potential ground-water zone. The geographical information system (GIS) and remote sensing techniques have become important tools to locate ground-water potential zones. This research has been carried out to identify groundwater potential zone in Ariyalur of south India with help of GIS and remote sensing techniques. To identify the groundwater potential zone used by different thematic layers of geology, geomorphology, drainage, drainage density, lineaments, lineaments density, soil, rainfall, and slope with inverse distance weightage (IDW) methods. From the overall result the potential zone of groundwater in the study area classified into five classes named as very good (13.34 %), good (51.52 %), moderate (31.48 %), poor (2.82 %) and very poor (0.82 %). This study suggested that, very good potential zone of groundwater occur in patches in northern and central parts of Jayamkondam and Palur regions in Ariyalur district. The result exhibited that inverse distance weightage method offers an effective tool for interpreting groundwater potential zones for suitable development and management of groundwater resources in different hydro-geological environments.