Entropy-weighted Irrigation Water Quality Index (EIWQI) for the Analysis of Irrigation Water Quality of Kerala, India

Raicy M C^a , Mohammed Maharoof P^a, Olivia Maria ^b, C D Aju ^c , A. L Achu ^d

^a,Hydrology and Climatology Research Group, Centre for Water Resources Development and Management (CWRDM), Kunnamangalam, Kozhikode-673 570, Kerala, India ^b, School of Earth Sciences, Central University of Karnataka, Kalaburagi, Karnataka, India ^c, Centre for Climate Change Research, Indian Institute of Tropical Meteorology, Pune, India ^d, Department of Climate Variability and Aquatic Ecosystems, Kerala University of Fisheries and Ocean Studies (KUFOS), Kochi, Kerala, India

Abstract

Irrigation water quality assessment is critical in ensuring optimal crop productivity, maintaining soil health, protecting the ecosystems, and promoting sustainable agricultural practices. This study assesses the irrigation water quality of groundwater in Kerala State, South India using various irrigational water quality indices such as Sodium Absorption Ratio (SAR), Residual Sodium Carbonate (RSC), Percentage of Sodium (Na%), Permeability Index (PI), Magnesium Adsorption Ratio (MAR), and Entropy Weighted Irrigation Water Quality Index (EIWQI). For this purpose, the hydrochemical data of 620 observation wells for a period of 5 years from 2018 to 2022 were procured from the Central Groundwater Board, Government of India and the spatiotemporal variations in various irrigation water quality indices were analysed in GIS platform. SAR of groundwater samples varied from 0.2 to 11 indicating varying levels of sodium hazard, while RSC ranged from -7 to 2.2 and Na% ranged from 14 to 84. The PI values ranged from 20 to 200, and MAR values ranged from 5.3 to 98. The EIWQI zonation indicates that the irrigation water quality varies not only based on the physiography of the state, but also on the northern and southern parts of the state. The study concluded that most of the parameters indicate that the highland areas particularly towards the central Kerala is more affected for irrigational groundwater quality when compared to the midland and lowland areas. Most water samples fall into a category that requires careful management to avoid further deterioration. This study implies the importance of regular monitoring and comprehensive analysis of irrigation water quality to ensure sustainable agricultural practices and long-term soil fertility in the state.

Keywords

Irrigational Water Quality; Hydrochemistry; Kerala; Entropy weighted Irrigation Water Quality Index

How to Cite

Raicy Mani, C., Mohammed Maharoof P, Olivia Maria, C D Aju, & A. L Achu. (2026). Entropy-weighted Irrigation Water Quality Index (EIWQI) for the Analysis of Irrigation Water Quality of Kerala, India. Journal of Integrated Earth Sciences, 1(1), 72–82. https://doi.org/10.5281/zenodo.18594158