![]() ![]() Wave forecasting was made in terms of the significant wave, and the propagation and transformation of the significant wave were analyzed with the then-available knowledge on the behavior of regular waves. They took the arithmetic means of the heights and periods of the highest one-third waves among a record of many waves, and called the wave having the averaged height and period of the highest one-third waves as the significant wave: the notations of H 1/3 and T 1/3 have been used since then. Through laboratory measurements of waves generated by winds, Sverdrup and Munk were fully aware of wave randomness, but they needed a simple definition of wave height and period to correlate observed wave data with wind characteristics. Under an urgent request of the US Armed Forces, Sverdrup and Munk 1), 2) succeeded in developing a scientific method of wave forecasting with the new concept of significant wave, which was widely applied in many amphibious operations during World War II. No reliable wave recorders were available in the early 20th century. Engineers and mariners described the magnitude of sea waves with a single height and single period through their visual judgment. Before 1942, harbor engineers employed some empirical formulas to correlate the height of sea waves with the wind speed and the fetch length (sea distance over which winds blow). The Second World War also produced an innovation in wave forecasting method. The Allied Force’s landing operation at Normandy Coast in June 1944 was a special example of artificial harbor construction in a very short time. Where coastal topography provides no adequate harbors, people developed artificial harbors by constructing breakwaters and quays. People made use of natural harbors for fishing, commerce and daily living. ![]() They built coastal dikes, seawalls, jetties, and other structures. ![]() Since old times, people have been aware of morphological changes of coastal areas and tried to protect the land from coastal erosion. Introduction - Start of coastal engineering ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |