Evaluation of Rehabilitation of Tidal Flat System at the Ibi River Mouth

Abstract

Wide-spread ebb tidal flat has been lost around the river mouth area of the Kiso, Nagara and Ibi Rivers due to the ground subsidence in the Nobi Plains since 1965. Recovery of ebb tidal flat once lost to create the waterfront with a variety of lives without hindrance in river rehabilitation can contribute rehabilitation of river environment. To this purpose, beach nourishment by using sand dredged from the river channel was planned and carried out in front of the river revetment in the regions separated by groins. As a result, the intertidal zone with much biodiversity between mean tide level and mean low water level was widened due to the action of wind waves. Stable beach was formed by the construction of groins and river environment with a variety of lives was recovered corresponding to the distribution of well-sorted bed materials and water depth of the intertidal zone.