講演情報
[PS-02-21]Seasonal variations in nutrient at the downstream of a river with groundwater interaction
*Chanthang Chin1, Shin-ichi Onodera1, Mitsuyo Saito1, Nang Yu War1, Yusuke Tomozawa1, Miho Awamura1, Kelly Tiku Tarh1, Sharon Bih Kimbi1 (1. Graduate School of Advanced Science and Engineering, Hiroshima University)
キーワード：
River water-groundwater interaction、nutrient、monitoring
Accurate quantification of river catchment nutrient load is essential for water quality in catchment areas, particularly in systems constrained by limited monitoring frequency. This study investigates the temporal variation of dissolved nutrient loads in the Takahashi River catchment; Japan bases on high frequency monitoring data. Weekly of key nutrient species silica oxide (SiO 2 -Si) measurements obtained from two sampling sites (river and groundwater) were analyzed alongside river discharge data from 2020 to 2022. Time series analyzes were conducted to assess seasonal patterns and discharge-driven variability within the catchment. Results showed that, average SiO 2 -Si concentrations remained relatively stable throughout the monitoring period, with average values of 4.72 mg/L in river water and 7.35 mg/L in groundwater, respectively, reflecting dominant geogenic sources with limited anthropogenic influence. Nutrient loads estimated from concentration and discharge data revealed clear seasonal trends and flow driven variability, with higher fluxes during high-flow periods. The results highlight the importance of hydrological periods conditions in controlling nutrient transport and emphasize the need for intensified monitoring during storm events.