Investigation of the mechanism of the generation of rip current and development of the procedure for predicting rip current using remote sencing.

每年有100多人在海里游泳时发生事故而丧生。据报道，很大一部分事故是由激流造成的。如果我们能够提前预报裂流的发生，就有可能通过预警系统来减少事故的发生。然而，突然有一种激流。在一个非常狭窄的区域中存在，它的寿命并不是那么长。通常不可能预测这种激流的发生。不用说，这种激流对游泳者来说是极其危险的，同时，激流也成为极浅水域底质向近海输送的媒介。本研究的目的是开发一种利用气球局部遥感的激流观测系统，并对激流的发生条件进行研究。开发了基于立体相机图像的地表位移测量系统和基于K-GPS的海底地形测量系统，几乎所有已报道的地形撕裂流形态都能在野外观测中得到记录。利用K-GPS对测量的海底地形上的波场和波流进行了数值模拟，再现了部分测量的流态。开发了中尺度海底地形和波场的测量系统，并通过现场观测进行了验证，这些结果为极浅水域波场和波流的测量建立了有效的程序。

More than 100 lives were lost by accidents during swimming in the sea every year. It is reported that large part of the accidents were caused by the rip current. If we can predict the occurrence of rip current in advance, it is possible to reduce number of accident through the warning system. However, a certain kind of rip current suddenly. comes in to existence in a very narrow region and its lifetime is not so long. It is generally impossible to predict the occurrence of this kind of rip current. It is needless to say that this kind of rip current is extremely dangerous for swimmers.At the same time, rip current becomes transporting agency of bed material in the very shallow water region towards offshore.The aim of this study is to develop a rip current observation system by using local remote sensing from the balloon and to investigate the occurrence condition of rip currents. Surface displacement measuring system by stereo-camera images and bottom topography measuring system using K-GPS are also developed.Almost all patterns of orographic rip currents reported until now can be recorded in the field observations. Some of the measured flow patterns are reproduced by the numerical simulations of wave fields and wave induced current on the measured bottom topography by K-GPS. Measuring systems of mesoscale bottom topography and wave field are also developed and verified through the field observations.These results surely set up effective procedures for measuring wave fields and wave induced current in very shallow water regions.