Hydrogeochemical characteristics of Kodku River of Lalitpur District, Nepal

Abstract

Hydro-geochemical characteristics of Kodku River of Lalitpur, Nepal were determined through analysis of physicochemical parameters including major anions and cations. This study also characterizes and evaluates the suitability for drinking and irrigation. The results showed that river water is slightly alkaline toward the downstream. The concentration of BOD, COD, and total coliform was much higher than its prescribed limits for drinking purposes in downstream, whereas a few samples in upstream are fit for drinking with reference to WQI value. The estimated sodium percentage (Na%), sodium adsorption ratio (SAR), permeability index (PI), magnesium adsorption ratio (MAR), and Kelly's ratio (KR) depict the excellent and safe categories for irrigation purposes. The obtained Wilcox diagram also revealed that river water falls under the C1S1 category which is safe for crops. Hydrogeochemical facies in Piper diagrams signifies the dominance of Ca–HCO3 type. Similarly, Gibbs maps indicate mineral (rock) weathering, whereas mixing diagram reveals carbonate weathering as the main controlling factor of major ion species. This study provides information on the hydrogeochemical properties of the river and its suitability for drinking and irrigation. Despite the comprehensiveness, the study can be an effective approach for countries with similar levels of water resources management. HIGHLIGHTS Hydro-geochemical analysis revealed the carbonate weathering dominates in Kodku River.; Concentration of BOD, COD, total coliform and WQI value reflect few samples suitable for drinking.; Na%, SAR, PI, MAR, KR and EC value were shown to be good for irrigation purposes and good for crops.;

Keywords

• controlling factor
• drinking
• hydrogeochemical
• irrigation
• physicochemical