FUNCTIONAL EVALUATION OF OPEN LEVEES IN THE OKAWANO AREA OF THE MATSUURA RIVER

Abstract

 There are several types of open levees, which are traditional river technologies. In the Matsuura River, it is common to find open levees with retarding zones in the downstream region.

 This study focuses on the Okawano area of the Matsuura River, where the form of an open levee is still evident. The area was flooded in August 2019, after which the function of the open levee was evaluated by two-dimensional plane calculations.

 From the evaluations, it was apparent that the flow velocity of the flood flowing into the retarding zone was extremely slow in the open levee of the Okawano area. In addition, it was verified that the water level inside the open levee at the time of the flood inflow was the same at all points. As a result, the paddy fields near the open levee were not seriously damaged by the inflow of the flood.

 Although a significant peak cut function could not be determined, the results of delaying the peak was obtained.