Within the first few waves sandbags that are situated at the lower, slope downwards end of the damaged spot were washed away. We lost sandbags on the lashing straps-side, the jute ribbon side preforms well. After about 60 - 90 minutes, the anchor pins of several fascines are turning towards the water flow and so destabilizing some fascines and make them flutter. The first fascine comes loose but will lay on the damaged spot. At 195 minutes, the second fascine comes loose but will lay on the damaged spot. The remaining fascines have to endure hard poundings of the waves but are holding and still act as breakwaters. At 230 minutes, the third fascine came loose. The bottom fascine (closest to the scape of the damage) is holding and still acts as breakwater. At 267 minutes, this fascine becomes loose. At 273 minutes, the wig with the lashing straps becomes loose. At 284 minutes the lashing straps part of the wig is washed away but the jute ribbon part is just holding on. At 360 minutes, the last wave of the challenge was delivered. The situation at the end of the challenge is depicted in figure 10 and 11. Notice that there are still sandbags present and the condition of the jute ribbons. There was some slope instability of the right hand side of the scarp (see figure 10) and an erosion pit on the right hand side of the damaged area (where the lashing straps were) with a depth of about 40-50cm.

After the end of the challenge, there was some more testing (not part of the challenge). 20 waves with the full capacity of the simulator and only the jute layering on the slope and damaged area left. There was no significant increase of slope instability or erosion in the erosion pit; the erosion pit reached a maximum depth of about 120 cm.

1. The two fascines that are positioned closeted to the wave overtopping simulator. We saw that the waves overshoots these fascines for the most part. These fascines could be more effective when they are placed a bit further downslope, in the area where the first fascines were lost. 2. The ribbons of lashing straps. These ribbons are too narrow in width to cover the damaged area and provide protection against the force of the waves. Hence, all the sandbags underneath the wig of lashing straps were lost/washed away. 3. The steel anchor pins that were used for the fascines. The anchor pins that were facing slope upwards turned in such a way that they were facing slope downwards after a period of wave action (see figure 12). The fascines than could start to flutter and come loose. The anchor pins placed in pairs, facing slope upwards and slope downwards and tied together with an iron wire is recommended. 4. The structural integrity of the jute ribbons. The ribbons were made by cutting ribbons of a cloth of jute with a knife. Therefore, the ribbons could fray and the ribbons couldn’t cover as much as whole ones, but still they could protect the area. Perhaps jute ribbons (about 30cm wide) could be prepared in advance with sides hemmed. 5. The jute layering of the slope and the damaged area performed well. The jute didn’t rupture despite heave wave action and pounding waves on it. However the jute was delivered in strips of about 1m wide, the strip layering of the jute on the slope and damaged area did hold with enough anchor pins placed. Preferably jute layering as much from a whole is recommended. 6. The jute ribbons protected the damaged area well. The sandbags underneath stayed in place despite heave wave action and pounding waves on it, especially the sandbags close to the scarp of the damage. Jute has the property of soaking up water, hence getting more weight. The heavy jute ribbons stay in place and cover the damaged area. Also a next wave will be more guided/speeded up by the wet, heavy jute ribbons. 7. After 360 minutes of waves (end of the challenge), there was a slight erosion pit (elongated hole, cigar like, of about 40 – 50cm in depth). Figures 13 to 15 shows the damaged area. The other areas of the damaged section were not affected by erosion. Above the erosion pit, some slope instability occurred. Figures 13 to 15 shows the damaged area. In the corner of the scarp and right hand side of the damaged area, the jute layers were not overlapping enough so the water flow could get underneath of some of the layers. And therefore erosion took place, resulting in slope instability and the erosion pit.

See Report for figures and more information. The presented solutions preformed in such a way that the whole time period of increasing wave action could be bridged without total failure of the damaged area and direct surroundings of the damaged area. The wig made of jute ribbons performed very well. There were still sandbags underneath this part of the wig after full duration and full wave action. The ribbons must have a certain width to be effective (cover the area/sandbags), at least 30-40cm wide. The ribbons should be long enough to bridge the damage plus an extra 1–1,5m below the damaged area; this ensures that the ribbons stay more in place. The benefit of jute is also that it soaks up water, becomes heavy and stays in place. The structural integrity of the jute ribbons was lower than expected. The ribbons should be hammed or several layers of ribbons should be applied to make up for the loss of structural integrity of the top ones. The wig of plastic lashing straps performed not well. The ribbons were to narrow so they could not cover the damaged area enough and all the sandbags underneath this part of the wig were lost. The structural integrity of the plastic ribbons held well compared with the jute ribbons. The fascines performed well. They took a lot of beating but stayed in place for a longer time that expected. The anchoring of the fascines is very important to ensure that they stay in place as long as possible. The anchor pins should cover both sides of the fascine so that flutter can not take place or in case of two anchor pins to put them on either side and tie together with an iron wire. The jute layering on the inner slope and on the bottom of the damaged area preform beyond expectation. The jute layers did not rupture even during the whole 360 minutes of the challenge with heavy wave action/pounding. Preferably jute layering as much from a whole is recommended (as wide a strips as possible). Solely using jute layers on the inner slope or bottom of a damaged area is a distinct possibility as an emergency measure if there is a limited time window.