Seasonal Assessment of Irrigation Water Quality of Karanja Reservoir, Bidar, Karnataka (India): A Multivariate Analysis

Abstract

This study assesses the seasonal variation and irrigation suitability of Karanja Reservoir water, Bidar, Karnataka (India) from January 2023 to December 2024. The surface and bottom water samples were collected seasonally and were evaluated for irrigation water indices such as Electrical Conductivity (EC), Total Hardness (TH), Sodium Adsorption Ratio (SAR), Soluble Sodium Percentage (SSP), Percentage Sodium (%Na), Residual Sodium Carbonate (RSC), Kelly's Ratio (KR), Magnesium Hazard (MH), Permeability Index (PI), Potential Salinity (PS), Irrigation Water Quality Index (IWQI), US Salinity Laboratory (USSL), Corrosivity Ratio (CR) and Chloro-Alkaline Indices (CAI1 and CAI2). The results revealed TH, CR, PS, %Na exceeded the permissible limit. A high CR indicated that water should not be transported using metal pipes. Based on the USSL classification, the reservoir water falls within the C2–S1 category, indicating medium salinity and low sodium hazards, while the IWQI classifies it as low-restriction water. Overall, the Karanja reservoir water is moderately suitable for irrigation, provided appropriate soil and water management practices are adopted. Measures such as periodic soil amendments and cultivating salt-tolerant or moderately salt-tolerant crops can help mitigate long-term sodicity and salinity impacts. This study emphasizes the need for ongoing monitoring and sustainable irrigation planning to maintain soil health and support long-term agricultural productivity.