The effects of nourishment material size, wave and berm heights on artificial nourishment


Karasu S., Kömürcü M. I. , YÜKSEK Ö., Özölçer I. H. , Kankal M.

7th International Conference on the Mediterranean Coastal Environment, MEDCOAST 2005, Kusadasi, Turkey, 25 - 29 October 2005, vol.2, pp.963-972 identifier

  • Publication Type: Conference Paper / Full Text
  • Volume: 2
  • City: Kusadasi
  • Country: Turkey
  • Page Numbers: pp.963-972

Abstract

Coastal erosion is one of the most important problems of beaches. Traditional methods, including groins, detached breakwaters, revetments and seawalls, can be effective at local scale and generally cause erosion problems in the vicinity (especially at the down drift sides) of the coasts on which they are applied, while protecting the coasts near them. Artificial beach nourishment is one of the modern methods to be employed in protecting coasts from erosion. The performance of a nourishment project is generally determined by percent remaining material (the ratio of material volume remained at a time to the total material volume used in the nourishment). This ratio (M) depends on various wave, coast and material parameters. In this study, the results of a series of experimental studies, performed to study the effects of wave height (H), nourishing berm height (B) and nourishment material size (D) on M are presented. Experimental studies were performed at the Hydraulic Laboratory Basin, with the dimensions 30*12*1.2 m, in the Civil Engineering Department of Karadeniz Technical University (KTU), Trabzon. The initial bed slope (m=1/15) and wave period (T=1.2s) were constant for each experiment. The length and width of nourishing berm were 2.15 m and 0.30 m. The duration of an experiment was t=90 minutes. During each experiment, bed profiles were measured at 5, 10, 20, 30, 45, 60 and 90 minutes. The measuring area was divided 20*20 cm measuring grids. The remaining material volume and remaining ratio were calculated by using the results of the measurements. Three kinds of material (D=0.18, 0.40 and 0.80 mm), three wave heights (H=4.0, 5.5 and 7.0 cm) and two berm heights (B=5 and 8 cm) were employed. According to the results of the experiments, M decreases with H. This decrease is especially significant for fine material (D=0.18mm). For medium (D=0.40 mm) and coarse (D=0.80 mm) material, M values also significantly decrease for high waves (H=7 cm), however, for medium (H=5.5 cm) and small (H=4 cm) waves, the changes in M values are small. For all wave and berm conditions, M increases with D and B. But, the dependence of M to B is less than that to D.