Studying mangroves in the field can be very difficult; therefore it is in some situations better to model in a flume. The question is, to what extend are the situation in the field and the situation in the flume comparable with each other? This study focusses on reflection in the wave flume. Wave energy in a flume can be damped by placing a wave absorber at the back of the flume, which absorbs part of the wave energy; part of the waves is reflected. In this study rock is used to build the wave absorber. Two aspects are studied: the influence of the lay-out of the wave absorber on the reflection in the flume, with as goal to find an optimal lay-out, fitting on a maximum horizontal length of 3.00 m, to minimise reflection; and the method of measuring the amount of reflection in a wave flume.