Effect of Faults and Fractures on Springwater Quality and Discharge of West Phaileng, Mizoram

Abstract

The North Eastern part of India compromises of hilly slopes and ridges. The main source of water is of river, streams, rainfall and springs. Due to change in environmental variables, many springs and streams are drying up as discharge decreases. A lithological study shows the area to consist of clay, silt, shale, siltstone and sandstone where porosity is low leading to low yielding capacity. Hydrogeological and geochemical composition studied represents the water within this region as immature and major ions composition shows Na+>Mg2+>Ca2+>Mn2+>Fe2+>K+ in cations and anoins HCO3->Cl->SO42->NO3->PO43-. The mineral saturation indices constructed using PHREEQC showed supersaturation with dolomite, siderite and vivianite. The hydrogeochemical formation mechanism using Gibbs Diagram and Piper diagram suggested rock weathering type. Principal Component Analysis (PCA) was performed as a multivariate analysis to determine the correlation between different components of hydrogeochemistry. The assessment of springwater quality using water quality index (WQI) shows good quality for most of the samples. A conceptual recharge model was the constructed anticipating mountain front recharge as major recharge of spring water. The springwater hydrograph was modelled using Maillets. It was observed that two types of flow, firstly the initial larget slope corresponding to conduit flow and secondly smaller slope to the diffuse flow was system. Thus the main mechanism of recharge in the hilly regions of West Phaileng was attributed to the mountain front recharge which is influenced by faults and fractures.