Seasonal Groundwater Quality Status and Nitrogen Contamination in the Shallow Aquifer System of the Kathmandu Valley, Nepal

Groundwater nitrogen contamination in the Kathmandu Valley exhibits significant seasonal and sediment-type variability. Research reveals that ammonium (NH4-N) concentrations decrease during the wet season in gravel-dominated areas, while nitrate (NO3-N) levels rise in both clay and gravel regions, with greater fluctuation observed in gravel-bearing zones over two years of monitoring. Iron (Fe2+) concentrations also drop during the wet season across sediment types. The study analyzed spatially distributed shallow dug well samples from 2016's dry and wet seasons, alongside long-term monitoring of two shallow dug wells and one deep tube well, providing critical insights into subsurface nitrogen dynamics affecting groundwater quality in this UNESCO World Heritage Site.

Shakya, B. M., Nakamura, T., Kamei, T., Shrestha, S. D., & Nishida, K. (2019). Seasonal Groundwater Quality Status and Nitrogen Contamination in the Shallow Aquifer System of the Kathmandu Valley, Nepal. Water, 11(10), 2184. https://doi.org/10.3390/w11102184