Assessment of Key Ground Water Quality Parameters and Their Mapping Using GIS in Central Brahmaputra Valley Zone of Assam, India

Groundwater is considered as one of major part of the purest forms of water available in nature.
Hence, to understand the use of the ground water resources and to get sustainable ground water
quality the fundamental characteristics of the groundwater need to be analyzed. In the present study,
GIS-based mapping of the groundwater in the central Brahmaputra Valley Zone is done with a view to
observe the various quality characters. The results of this investigation could be used by decisionmakers
for the sustainable management of groundwater resources. The groundwater pH of the district
was found to be within the desirable limit as recommended by WHO but 67.30% sample covering
79% of the total geographical area of the district was slightly alkaline in nature. Groundwater quality
parameters that surpassed the desirable limit recommended by WHO, were electrical conductivity and
nitrate which accounted for 41.22% and 0.79% of the total samples. Total Dissolved Solids, calcium,
magnesium, carbonate, bicarbonate and nitrate in groundwater were recorded within the desirable
limit of WHO and thus could be considered as safe. Spatial autocorrelation run for all the quality
parameters with respect to their positions and values over the entire district envisaged the possibilities
of forming different pattern namely CLUSTER for pH, EC, As, F, Fe, Al, Mn,HCO3, RANDOM for Mg,
Ca, CO3, NO3, SO4 and DISPERSED for TDS. GIS-aided mapping of groundwater quality parameters
embracing their category wise spatial distribution, area, maximum and minimum values, surface
autocorrelation of observed values could give a better idea to opt for suitable need-based
management strategy for the entire district.