Hydrochemical Characteristics of Groundwater in the Nainital Lake Basin: Implication on the Landslide Hazards

Hydrochemical characteristics of the groundwater occuring in and around the Nainital lake basin indicate that Ca²⁺/Mg²⁺ ratios are less than one. Statistical analyses reveal that the variation in Ca²⁺/Mg²⁺ ratios is mainly due to variation in Ca²⁺. The groundwater is geochemically undersaturated with respect to calcite and dolomite and has a tendency to dissolve the calcareous rocks more readily than it is expected in ideal dolomite terrain. The higher infiltration rates and lower surface runoff indicate that the groundwater will play a major role in the hillside stability. Further, the groundwater movement will enhance dissolution of carbonate rocks and lead to enlargement of fractures. Hence, the quantum of groundwater seepage and their hydrochemical character seem to play a crucial role in the landslide hazards as experienced by the lake basin frequently.