Accurate long wave generation in laboratories is of key interest in the field of coastal engineering. It allows for the study of long wave propagation, near-shore transformation, shoaling, run-up as well as the interaction with elements of urban development near the shoreline. In this context a novel method for the generation of long waves in the laboratory is presented. It bases on the application of high-capacity pipe pumps under the control of a loop-feedback control mechanism. This methodology yields accurate long wave forms which allow for a geophysical-correct representation of prototype tsunami.

INTRODUCTION

Against the background of many disastrous tsunami incidents such as the Indian Ocean tsunami in 2004 or the Tohoku tsunami in 2011, where thousands of casualties were counted, the understanding of tsunami propagating in deep water has grown rapidly in the last century. Both numerical and physical modeling techniques are applied to study either one part or the complete process of generation, propagation and run-up/surge flow either ocean-wide or in coastal waters. In laboratory-scaled experiments scientists face scaling problems when reproducing measured long wave time series from either moored ships (e.g Mercator Yacht, Thailand, 2004) or tidal gage records. In this context, applying solitary waves instead of prototype time series in physical modeling is a common approach. The generation of solitary waves is straightforward by means of basic wave maker theory (see e.g. Flick and Guza, 1980). Even though this approach covers a wide area of oceanographic and geophysical aspects, near-shore applications and the study of surge flow as well as wave run-up cannot be addressed appropriately. Wave lengths which are attainable in the laboratory are by far too short compared to geophysical length scales, e.g. prototype tsunami waves. Especially the study of time-dependent processes, e.g.

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