Numerical modeling on benthic macroinvertebrate dynamics in rivers considering functional feeding groups and bed-residence groups

摘要

This study developed an integrated numerical simulation model to describe benthic macroinvertebrate dynamics in gravel-bed rivers, especially in response to benthic habitat changes due to altered sediment regimes upstream and downstream of dams. In particular, the macroinvertebrate dynamics model takes into consideration benthic groups classified as Functional Feeding Groups (FFGs) and Bed-Residence Groups (BRGs), whilst the associated sediment transport model evaluates habitats in gravel-bed rivers based on bed load and suspended load dynamics. For the purpose of validation, the model was applied at three observation sites (Upstream of the Dam (UD), Downstream of the Dam (DD) and downstream of a tributary confluence (DC)) around the Agi-gawa Dam on the Agi River in Japan. Simulated results indicate that the composition rates of FFGs and BRGs were slightly overestimated by the model for the UD and DD reaches. However, with respect to BRGs, the results of the simulation reflect appropriate composition rate trends from DD to UD, taking into account the supply of fine sediment via the tributary.