Coastal Management and Erosion
Interpretations and analysis: Our results show that the Jetty side of Changing Spit had the highest gradient followed by the end of spit and the seaward side of Changing Spit. This suggests that the Jetty side was the most eroded among the three points. A probable reason for this might be the artificial waves (wake) created by the boats frequenting the Jetty side. The artificial waves generated add significantly to the wave energy of the waves reaching the Jetty side.
Moreover, the distance between the boats passing and the shore of the Jetty side is small and hence little of the wave energy is lost before it reaches the hornlike and thus the Jetty side was the most eroded as compared to the other two. The end of spit was the second most eroded. This Is due to Its large fetch. Due to the fetch of the end of spit the waves reaching the shore will have greater wave energy resulting in erosion. Moreover, the end of spit also experiences the effect of the artificial waves generated by the Jetties that pass by.
However, the artificial waves’ energy Is not as high as the Jetty side waves since the distance between the
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Thus, the only source of waves reaching the shore of the seaward side of Changing spit will be from the open waters which could have resulted In a low erosion rate accounting for the low beach gradient of the seaward side of the change spit. In Dalton, while the wave height at the seaward side was mostly insistently small, the wave height at the Jetty side was periodically much higher than the seaward side, due to the nature of Jetties appearing from time to time. This also suggests that the wave energy of the Jetty side of the spit is greater than the wave energy of the seaward side spit.
This also accounts for the slow erosion rate of the seaward side of the Changing spit. The number of swashes at each side per minute was much higher at the jetty side (38 swashes/min) than at the seaward side (19 swashes/ml). This shows that the energy of the waves of the Jetty side Is higher than he seaward side leading to a greater erosion rate. This high frequency of waves will result in more waves hitting the shore which in turn causes erosion. Thus, the higher the frequency of the waves the greater the erosion rate is.
Therefore, due to the fact that the Jetty side has a higher wave energy and frequency the Jetty side erodes the fastest. Recommendations: Since, the fetch of the Jetty side is extremely small, building a seawall is impractical and not feasible. Building breakwaters are also is not feasible since it will obstruct the movement of the Jetties. Hence, protection measures such as stabilizing the horses, planting mangrove trees and rip-raps might be an alternate solution. We can stabilize It by planting vegetation such as marry grass. The roots of the vegetation trap and bind the sand together preventing it from eroding.
However, shores to be 1 OFF minimized along the coast which is not possible for the Changing spit since Changing spit is heavily frequented by people for recreational activities and minimizing it will defeat the purpose of the Changing spit. Another possible costal protection for the Jetty side might be mangrove trees. The mangrove trees have prop roots or kneed roots that anchor the trees firmly. These roots also bind the loose soil, and protect it from erosion. However, the mangrove trees can be an eyesore to the people coming there and it also reduces accessibility. The last coastal protection will be the ripsaw.
Rapid works by absorbing and deflecting the energy of waves before they reach the defended structure. The gaps between the rocks trap and slow the flow of water, lessening its ability to erode soil or structures on the coast. Even though ripsaw are the most feasible coastal measure for the Jetty side they are an eyesore and limit the accessibility for people visiting the Champs Spit. Now moving on to the end of spit. Even though the end of spit has a longer fetch, building a breakwater is not feasible since it obstructs the path of the boats. Hence, stabilizing coastal dunes will be the only convenient coastal measure.
The seaward side of the beach has pretty long fetch and thus we can build breakwaters. Breakwaters are relatively cheap as compared to sea walls and are easier to maintain. The breakwaters absorb the impact and effects of ocean waves, creating a calm, quiet waterway behind it thus reducing erosion rates. However, erosion will still occur in the area not protected by the breakwater. Reflections: Our data was collected between 3 to 5 p. M. Hence, the frequenting of Jetties might have increased or decreased and thus we could have measured an anomalous data.
However, we used our beach profiling to support our conclusion that the frequenting of Jetty is actually a key reason for the high erosion rate of the Jetty side of the Changing spit. Another possible defect might be the wind direction. The wind direction on that could have been different from other days or particular periods of the year (South- West monsoon). However, due to the lack of information we were not able to find the direction of wind. Hence, this might be a possible problem since this would have affected the wave frequency that we measured.
We could also have taken the readings again on another day and could have compared the results to make sure that the readings were constant but due to lack of time we were unable to do so. When we were measuring the number of swashes for the Jetty side boats were frequenting the place. I feel we could also have measured the wave frequency when the Jetties were not passing so that we might know the erosion rates when there is less Jetties frequenting. We could also have collected the beach profiles at different actions in the same area to make sure that we did not collect anomalous data but due to lack of time we were unable to do so.
Conclusion: Relation to our hypothesis: The conclusion that we arrived was different form our hypothesis. We hypothesized that the seaward side will be the one will be the one that will be most eroded but it turned out to be the Jetty side. Based on our background research we realized that the seaward side had the largest fetch and thus will have the largest wave energy which in turn will result in the highest erosion rate. However, we did not consider the Jetties’ movement and thus our hypothesis was wrong. However, part of our due to its second largest fetch.