Page - 1285 - in Book of Full Papers - Symposium Hydro Engineering

3. ASSESSMENT RESULTS The performance of the above options was assessed during the winters of 2016, 2017 and early 2018. A number of extreme events occurred during those winters but no damages were observed on the dikes and they remained intact. The sand fences dike continued to build up and during the events, water did not penetrate through the dike body as no erosion was noted on the whole length of the dike. Water either formed a small pond in front of the dike or flowed within the gaps left between the three dike options. The clay core dike fences also continued to build up since the end of the construction. Vegetation also grows but at a different rate for each specie [1]. Current results show that Pancratium maritimum and Elymus farctus are of superior quality at the different locations on the dike (wind and leeward and crest) followed by both Sarcocorina fruticosa and Juncus rigidus. Monitoring of the five wells revealed that there is no significant increase the water level within each well even after the extreme events which is an indication that seepage is insignificant within the dike body. The Geo-tube core dike performance was similar to the above two dikes. No wet patches was observed on the back (dry) slope of the dike indicating that seepage is also insignificant within the dike body. The monitoring basin remained dry (apart from small wet batches due to rainfall) indicating that no significant overtopping occurred during the event. Fig. 7 a, b and c shows a photo of each dike option after a recent extreme event in 2018. Fig 8a shows that a second row of fences was constructed to widen the natural dike (or dune) that was created by capturing the blown sand by wind. Fig. 8b and c show that sea water accumulated in front of the dikes but caused no damage to them. a) Sand fences dike b) Clay core dike c) Geo-tube core dike Fig. 7 Dike options after a recent storm event 1285