Predicting Potential Climate Change Impacts on Groundwater Nitrate Pollution and Risk in an Intensely Cultivated Area of South Asia

Abstract

One of the potential impacts of climate change is enhanced groundwater contamination by geogenic and anthropogenic contaminants. Such impacts should be most evident in areas with high land-use change footprint. Here, we provide a novel documentation of the impact on groundwater nitrate (GW NOd 3 ) pollution with and without climate change in one of the most intensely groundwater-irrigated areas of South Asia (northwest India) as a consequence of changes in land use and agricultural practices at present and predicted future times. We assessed the probabilistic risk of GW NOd 3 pollution considering climate changes under two representative concentration pathways (RCPs), i.e., RCP 4.5 and 8.5 for 2030 and 2040, using a machine learning (Random Forest) framework. We also evaluated variations in GW NOd 3 distribution against a no climate change (NCC) scenario considering 2020 status quo climate conditions. The climate change projections showed that the annual temperatures would rise under both RCPs. The precipitation is predicted to rise by 5% under RCP 8.5 by 2040, while it would decline under RCP 4.5. The predicted scenarios indicate that the areas at high risk of GW NOd 3 pollution will increase to 49 and 50% in 2030 and 66 and 65% in 2040 under RCP 4.5 and 8.5, respectively. These predictions are higher compared to the NCC condition (43% in 2030 and 60% in 2040). However, the areas at high risk can decrease significantly by 2040 with restricted fertilizer usage, especially under the RCP 8.5 scenario. The risk maps identified the central, south, and southeastern parts of the study area to be at persistent high risk of GW NOd 3 pollution. The outcomes show that the climate factors may impose a significant influence on the GW NOd 3 pollution, and if fertilizer inputs and land uses are not managed properly, future climate change scenarios can critically impact the groundwater quality in highly agrarian areas.

Exploring Groundwater Quality Trends in Valliyar Sub-Basin, Kanniyakumari District, India through Advanced Machine Learning Techniques

“…In the case of Kattathurai, the strong correlation between TH and Ca [28] indicates that agricultural activities, which often involve the use of calcium-containing compounds, significantly impact water hardness. The strong correlation between TDS and EC, along with Cl, suggests that agricultural runoff, which is rich in soluble salts, influences the water quality [29,30]. Weak to moderate correlations between independent variables like temperature, relative humidity, and wind speed with water quality parameters imply that while climatic factors do influence water quality, their impact is overshadowed by agricultural practices [31].…”

Crop Rotation and Nitrogen Fertilizer on Nitrate Leaching: Insights from a Low Rainfall Study

“…− leaching with periods of greater precipitation [76,77]. Nevertheless, during drought phases, nitrification inhibition occurs, leading to N accumulation in the soil.…”

Climate Change Impacts on Nitrate Leaching and Groundwater Nitrate Dynamics Using a Holistic Approach and Med-CORDEX Climatic Models

“…Rising nitrate levels in aquifers are a long-term concern worldwide, particularly in aquifers underneath predominantly agricultural areas [1]. The prolonged and intensive fertilizing treatments employed to attain crop-yield amplification tend to serve as the primary cause of groundwater nitrate pollution [2,3].…”

“…Villa et al (2022) [18] emphasize the importance of high-resolution climate input data for estimating nitrogen leaching under climate change scenarios, while Davamani et al (2024) suggest that improved simulation models can capture local changes [19]. The impact of climate change on water resources, including nitrogen leaching and nitrate concentrations in groundwater, is still uncertain and requires further research [1,16,20,21].…”