画像処理による河床粒度分布情報の高空間解像度化  [in Japanese] HIGH SPATIAL RESOLUTION SURVEY OF GRAIN SIZE INFORMATION ON RIVER BED BY IMAGE PROCESSING  [in Japanese]

Access this Article

Abstract

効率の良い調査・分析が可能な画像処理法による河床粒度分布調査を用いて高空間解像度の河床粒度情報の取得を試み,短時間調査によって流況と一致する粒度情報の取得可能性を検証した.調査対象は縦断距離50mの山地河川の砂防堰堤堆砂区間であり,その領域内で26箇所という高い空間解像度の調査を実施した.一方,地形測量に基づき,直近の推定出水流量から水理計算によって移動限界粒径<i>d<sub>m<sub>c</sub></sub></i>を導いた.<i>d<sub>m<sub>c</sub></sub></i>と粒度調査結果<i>d<sub>m</sub></i>の比較では,堆砂デルタ付近では概ね一致したが,堰堤近傍では<i>d<sub>m<sub>c</sub></sub></i>より大きな<i>d<sub>m</sub></i>が観測された.この調査では,断面毎の流れの変化に伴う<i>d<sub>m<sub>c</sub></sub></i>敏感な応答は認められなかった.画像処理法による粗粒成分分析とふるい分け試験による細粒成分分析を組み合わせた結果では,それぞれの分析法の閾値とした13.2mm付近に存在確率の不連続なピークが認められ,分析方法を分ける粒径の閾値の重要性が示唆された.

 We tried a method of grain sizing by image processing which is available to survey and analyze in short time. The high-efficiency method actualizes high spatial resolution information of grain size distribution. Thus, the information has a vailability to express a situation of stream flow better than traditional grain sizing methods. For this reason, we paid attention to 50 m reservoir area upper from the check dam in mountainous region and surveyed the grain distribution at 26 sites and river channel landform. The grain sizing by image processing provided the appropriate result qualitatively. Moreover we estimated the critical diameter of moving from hydraulic information simultaneously. A qualitative appropriate result is showed less than 50 mm error as a result, however, quantitative response is not found between the critical diameter of moving and the grain size distribution surveyed. Meanwhile,the different grain sizing methods that are image processing and traditional sieving are used to cover the bilateral weak point. Thereby, a peak of grain existence probability is found in the threshold diameter between image processing and sieving. This result indicates that it is necessary to change the threshold diameter much larger than the limit of image processing grain sizing.

Journal

  • Journal of Japan Society of Civil Engineers, Ser. F3 (Civil Engineering Informatics)

    Journal of Japan Society of Civil Engineers, Ser. F3 (Civil Engineering Informatics) 67(2), I_111-I_118, 2011

    Japan Society of Civil Engineers

Codes

Page Top