[A-HW27] 流域圏生態系における生物多様性・栄養循環・物質輸送

[AHW27-20] 豪雨イベントにおける非点源汚染の要因特定に向けた時間別統合モデリング手法の適用

*王 崑陽¹、小野寺 真一¹、齋藤 光代¹ (1.広島大学大学院先進理工系科学研究科)

キーワード：非点源汚染、気候変動、硝酸塩流出、豪雨イベント

Non-point source (NPS) pollution is the primary threat to global water quality, with agricultural runoff being a major contributor due to nutrient losses from surface runoff and leaching, especially during rainfall. Climate change exacerbates this issue by increasing heavy rainfall events, which heighten nutrient loss and amplify NPS pollution, leading to significant increases in phosphorus and nitrogen loads in various regions. These higher concentrations stimulate rapid phytoplankton growth, causing algal blooms and eutrophication. Despite the severity of these impacts, existing hydrological models primarily operate on daily time steps, failing to capture the swift nutrient transport dynamics during heavy rainfall, thus underestimating peak pollution levels. Additionally, future precipitation data from General Circulation Models (GCMs) are limited to daily resolutions, hindering accurate modeling of extreme events and potentially leading to underestimated risks of NPS pollution during such episodes. Addressing these challenges is crucial for effective water resource protection and pollution management.
This study adopt two modeling-based approaches in conjunction with statistical methods, evaluated driver factors of nitrate losses in heavy rainfall events and predicting the future peak scenarios under climate change impact. The results showed that under certain conditions, the impact of precipitation duration on nitrate loss is greater than that of precipitation amount. This research indicates that nitrate runoff during future extreme precipitation events could be three times higher than the current peak scenario.