[O-08] Poster presentations by senior high school students

[O08-P23] Research on the relationship between the water retention of surface soil on riverbanks and river flooding

*Atsuki Konishi¹, *Tsukasa Sakurai¹, *Nanami Ishida¹, *Junsei Oyake¹ (1.Ibaraki Prefectural Hitachi Daiichi High School)

Keywords:river flooding, surface soil, water retention

Large-scale heavy rain disasters have occurred frequently in recent years. In Hitachi City, including the Miyata River near our school, Since there are many rivers, there is a need for flood prevention measures. One measure against flooding is to prevent water from stagnating in rivers. The river near our school is short and has a steep slope, so the water that flows into it is quickly drained into the sea. Therefore, it is important to prevent water from flowing into the river as a countermeasure against flooding, and we believe that the water retention capacity of the surface soil on the riverbank is related. Water retention was evaluated by porosity and water retention capacity. Based on a literature review, we hypothesized that humus soil has the best water retention properties, and conducted experiments using weathered granite soil, humus soil, and Kanuma soil. However, the result was that the water retention capacity of humus soil was the lowest, which contradicted the hypothesis. We are currently testing our hypothesis by conducting experiments with different conditions, such as stacking samples on top of each other. Therefore, we conducted an experiment using a mixture of weathered granite soil and humus soil, and found that Kanuma soil was still superior. Based on the above, it was thought that Kanuma soil had the best water retention properties, and that the mixture had lost its excellent water retention properties due to partial replacement with Kanuma soil.