A Lagrangian drifter for surveys of water surface roughness in streams

Water surface roughness in rivers and streams is mainly driven by flow, turbulence and riverbed conditions. Conversely, water surface roughness gives easy access to information about hydrodynamics – provided that measurements are possible at sufficient spatial-temporal resolution and accuracy. We present a novel small-size (diameter 28 mm) drifter, which detects water surface roughness through acceleration measurements while floating on the water surface. Laboratory tests revealed a good agreement between drifter-based measurements and optical characterization of surface roughness. Only very short waves with periods河流与溪流的水面粗糙度（water surface roughness）主要受水流、湍流与河床条件的影响。反之，只要能够以足够的时空分辨率与精度开展测量，水面粗糙度便可便捷地提供流体动力学（hydrodynamics）相关信息。本研究提出一款新型小型漂流浮标（drifter，直径28 mm），该浮标可在水面漂浮的同时通过加速度测量（acceleration measurements）检测水面粗糙度。实验室测试结果显示，基于该浮标的测量结果与水面粗糙度的光学表征（optical characterization）结果具有良好的一致性。仅周期为[原文未完整给出]的极短水波。