Hydrogeochemical constraints on groundwater resource sustainable development in the arid Golmud alluvial fan plain on Tibetan plateau

Groundwater resource in alluvial aquifers is significantly essential for the sustainable development of arid regions worldwide. Forty-eight phreatic groundwaters were sampled and analyzed to elucidate the hydrochemical features, genesis and constraints on domestic and irrigational water supply in a hyper-arid alluvial fan on Tibetan plateau. The human health risk assessment and entropy-weighted water quality index (EWQI) along with drinking water guidelines were introduced to assess groundwater quality for domestic purpose, and the irrigation suitability was discussed in terms of the potential soil permeability damage and salinity hazard. The results indicated groundwater in the Golmud alluvial fan plain is slightly alkaline water and dominated in the hydrochemical faces of mixed Cl–Mg–Ca type, and followed Cl–Na type and mixed HCO₃–Na–Ca type. Groundwater nitrite (~ 6.25%) and ammonia (~ 2.08%) exceed the drinking water standards in the farmlands and human settlements at the alluvial fan front, but would not threaten human health. The geogenic toxic elements of fluoride and boron would potentially pose health risks to the populations of infants, children and adult males at some sporadic locations. The risks are mainly attributed to the aqueous fluoride. Groundwaters in the alluvial fan plain are almost suitable for domestic purpose according to the EWQI appraisal results (35–151), and have suitable quality for irrigation regardless of sodium adsorption ratio, percentage sodium and permeability index. But, salinity hazard is widespread and should be concerned. Groundwater chemistry is basically governed by the natural rock–water interactions and influenced by agricultural practices and urban domestic effluents at the alluvial fan front. These anthropogenic contamination inputs resulted in the excessive nitrogen and elevated salinity of groundwater. Measures should be taken to protect groundwater resources in alluvial aquifers out of anthropogenic contamination. Geogenic fluoride is also needed to pay attention in the drinking water supply.