DEVELOPMENT OF A UNIT COST MODEL OF STRUCTURAL RIVER MANAGEMENT IN THE WORLD BASED ON MULTIVARIATE ANALYSIS OF CONSTRUCTION COST FACTORS - Daisuke SEKIYAMA; Masahiro TANOUE; Yugo TSUMURA; Yukiko HIRABAYASHI; 平林 由希子; 津村 悠虎; 田上 雅浩; 関山 大輔 (土木学会論文集B1（水工学）, 2022)