Author(s): Yuko Ishida; Kento Okunishi; Masashi Harada; Yoshiya Ogawa; Masato Maegawa
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Keywords: Green infrastructure; Integrated watershed management; Biodiversity; Land conservation; Habitat evaluation
Abstract: Once, the Ogura-Ike Pond (area of 794 ha, and maximum water depth of 1.1 m), located in the southern part of Kyoto Prefecture, possessed a flood control function because of being connected to the Uji River through a braided channel, and inhabited various organisms of the Yodo River basin. After being diked in 1941, the pond lost its flood control function and living things disappeared from it. Recently, heavy rainfall has been occurring more frequently than expected in various areas in Japan. Flood disaster risk is increasing in the middle basin of the Yodo River, which acts as the junction of three rivers (Katsura, Uji, and Kizu), including the former Ogura- Ike Pond basin. Thus, besides the current river improvement plan, the Yodo River basin requires new flood control measures. Through the analyses conducted using iRIC, a two-dimensional flood flow analysis software, we considered plans to confirm the effect on both flood control and environmental conservation measures to see if the retarding basin can be developed in the current Ogura-Ike drained land. The retarding basin was established on iRIC Nays2D Flood (ver.5.0). The flow rate used for the flood analysis using iRIC Nays2D Flood was the flow rate that is 1.2 times the estimated high-water flow rate of the Uji River. The result of the flood analysis showed the flood water was found to be stored in the retarding basin. At that time, fish habitats were created in the retarding basin through the habitat evaluation analysis, using the Maxent model. It was shown that the retarding basin can also be utilized as an evacuation site for aquatic organisms in case of flooding.
Year: 2020