[A-HW27] Biodiversity, nutrients and other materials in ecosystems from headwaters to coasts

[AHW27-P06] Post-landslide nutrient concentration change in a small suburban catchment

*Sai Tun Aung Si¹, Shin-ichi Onodera¹, Sharon Kimbi¹, Mitsuyo Saito¹ (1.Graduate School of Advanced Science and Engineering, Hiroshima University)

Keywords:nutrient concentration, dissolved nutrient, dissolved inorganic nitrogen

This study investigates the post-landslide nutrient concentration variations in a small suburban catchment, the Hanno River catchment. It is located near Saijo Town, Higashihiroshima City, Japan, following a large landslide in July 2018. The study area with a watershed area of 2.62 km², which is dominated by evergreen forests, deciduous forests and urban land use. Water samples were collected from the Hanno River and long-term nutrient species were analyzed from 2020 to 2023. The dissolved nutrients were measured in the laboratory. The results showed that nitrate nitrogen (NO3-N) is the main dissolved nutrient in this catchment. The higher concentrations of NO3-N were often detected between November and April, while the lowest concentrations of NO3-N were mainly observed in July, August and September. Moreover, the dissolved inorganic nitrogen (DIN) is higher in winter and lower in summer. It might be due to the algae since they consume the nutrients in the summer. The findings of this study can contribute to future considerations in urban planning and water resource management.