Impact of climate change and land management on nitrate pollution in the high plains aquifer

High concentrations of nitrate in groundwater pose risks to human and environmental health. This study evaluates the potential impact of climate change, land use, and fertilizer application rates on groundwater nitrate levels in the High Plains Aquifer under four Shared Socioeconomic Pathway (SSP) scenarios. A random forest model, with predictors such as fertilizer application rates, cropland coverage, and climate variables from six Coupled Model Intercomparison Project models, is used to project future nitrate concentrations. Results show increases across all scenarios, with nitrate levels rising by 4% under SSP5-8.5 and up to 13% under SSP2-4.5 when accounting for climate change effects. Fertilizer application rates are identified as the primary driver of projected changes. The northern and central regions of the aquifer exhibited the most pronounced increases. The projected changes in nitrate levels, observed across both low- and high-greenhouse gas emission pathways, highlight the need to develop integrated management strategies that consider shared socioeconomic scenarios and water resource protection constraints.