Advantages of the Open Levee (Kasumi-Tei), a Traditional Japanese River Technology on the Matsuura River, from an Ecosystem-Based Disaster Risk Reduction Perspective

Abstract

Large-scale disasters, such as hurricanes, cyclones, tsunamis, and forest fires, have caused considerable damage in recent years. This study investigated two case studies of discontinuous open levees (kasumi-tei), which are a traditional Japanese river technology, on the Matsuura River at the sites of Okawano and Azame-no-se, and evaluated the advantages of these levees from the perspective of ecosystem-based disaster risk reduction (Eco-DRR). These case studies were conducted through literature surveys, flood observations, and oral interviews. The systems in both the cases were flood control systems utilizing ecosystem services. The traditional river technology (the flood plain open levee) served as an effective Eco-DRR in both cases. Additionally, the flood plain levee technology enhanced the ecosystem services at both sites, including not only flood control capabilities, but also other ecosystem services. Furthermore, the open levees offered substantial cost advantages over their alternatives. These results suggest that other traditional Japanese river technologies may also be effective in strengthening Eco-DRR.