Economic analysis: Riprap with geo-filter vs collar as scour protections around submerged vanes

The strongest circulation gives the maximum effects of submerged vanes at optimal angle of attack and at the same time local scour holes develop around the submerged vanes, which may dislodge the submerged vanes. With the introduction of collar or riprap with geo-filter at the leading edge of submerged vane, the local scour may be reduced. A comparison of the cost of riprap with geo-filter and collar has been attempted to get a general idea of economics. This paper explains theoretically how to compare the cost of riprap with geo-filter and collar.