Introducing an irrigation water quality index (IWQI) based on the case study of the Dwarka River basin, Birbhum, West Bengal, India

Abstract

The assessment of groundwater for irrigation was a crucial step towards sustainable water resource management. Traditionally, irrigation water suitability was carried out by assessing several irrigation parameters individually. In this research, an attempt was made to develop a new irrigation water quality (IWQI) index by integrating various irrigation water suitability parameters i.e., sodium adsorption ratio (SAR), Magnesium Adsorption Ratio (MAR), residual sodium carbonate (RSC), Exchangeable sodium ratio or Kelly ratio (KR), Soluble Sodium Percentage (SSP), total hardness (TH), Electrical Conductivity (EC), Permeability index (PI) and fluoride (F−). A stretch of the Dwarka River basin was selected as a type area for this research. Water sample collection, analysis followed by classification of water parameters into five different classes, and assigning weights and ranks were the principal methodologies adopted for the building up of the Irrigation water quality index (IWQI). The order of abundance of anions in the study area was HCO3− > Cl− > CO3−2 > SO42− > F− and cation are Ca+2 > Na+ > Mg+2 > K+. A total of 607 water samples were collected and the computed IWQI with respect to the present study reveals that 95.38% (579 samples) of the total water sample were suitable for irrigation whereas the remaining 4.61% (28 samples) of the total sample show unsuitability for irrigation. Nawapara, Junidpur, Chakpara, Bhelian were among the most polluted village. Outcomes of the present study can be a first-hand tool to the policymakers, planners, and government officials for sustainable water resource management in the study area.