Evaluation of groundwater quality for irrigation water supply using multi-criteria decision-making techniques and GIS in an agroeconomic tract of Lower Ganga basin, India

Abstract

Groundwater irrigation has evolved the monocropping cultivation pattern to multi-cropping, especially in many arid/semi-arid tracts globally. Irrigation practices with the groundwater of poor quality can limit the selection of the crop, reduce crop yields and degrade the soil quality. The present study has been undertaken to identify the hydrogeochemical phenomena of groundwater systems in the south-western Birbhum district, India and to analyze groundwater suitability for irrigation during the pre-and post-monsoon cycles by adopting the Irrigation Water Quality Index (IWQI) using Multivariate Factor Analysis along with some traditional methods viz. sodium adsorption ratio, sodium percentage, magnesium hazards, residual sodium bicarbonate (RSBC) and carbonate (RSC), Wilcox's and USSL diagrams, permeability index and Kelly's index. The hydrogeochemical analysis revealed that chemical weathering and evaporation are predominant in the aquifer systems. Groundwater quality reflected soil salinity, sodicity and magnesium hazards risks and water toxicity to the sensitive plants at 0–46.4% of the post-monsoon samples and 0–38.4% of the pre-monsoon samples based on the individual traditional methods whereas about 97.73–98.88% of the total area was classified as moderate to severely unsuitable for irrigation during both seasons when integrated multiple parameters using the IWQI method. Prolonged use of such groundwater for irrigation is susceptible to causing moderate to severe infiltration problems at a greater extent of the study area. The study recommends adaptation of salinity, sodicity and RSC/RSBC reduction procedures (e.g., the use of acid and gypsum amendments in the irrigation lands and through water blending) and advanced irrigation practices (viz. drips, sprinklers and micro irrigations) to prevent soil degradation and increase crops productivity. Adopting Managed Aquifer Recharge procedures as well as rainwater harvesting in the areas bearing unsuitable water quality can dilute the ionic concentrations of the groundwater facies which in turn will improve the groundwater quality for irrigation.