水理模型実験による水害防備林の洪水氾濫流木捕捉機能強化の検討

抄録

Measures for enhanced inundation driftwood trapping by inland flood-restraining forest belts were examined in a hydraulic model experiment. The forest model (scale: 1/100) consisted of rods with a diameter of 3.05 mm set in a 3-cm square lattice form. The model driftwood pieces (length: 1 cm) all passed through the initial model forest. Subsequently, parts representing ropes, nets, boards and piles were installed between the trees in the rearmost row at a height of 2.4 cm to represent the situation of actual flood-fighting measures implemented by residents near rivers. The ropes were 0.33 mm in diameter and were set 3 mm apart, the nets were 0.35 mm in diameter and were set 3 mm apart, the boards were 9 mm in width and were set 3 mm apart, and the piles had a rectangular cross section of 1 × 1.2 mm and were set 4 mm apart. Each of the capture ratios was improved to approximately 56, 50, 7 and 49%. These results show the effectiveness of using simple and practical installations in inland flood-restraining forest belts for enhanced trapping.