Repairs of concrete irrigation channels in Japan are guided to a large extent by the degree to which their walls have degraded over decades of use. Current methods of estimating Manning roughness coefficients from the roughness of the channel wall are based on linear profiles of arithmetic mean roughness. This study developed a method to estimate Manning roughness coefficients for a planar region directly from the peak-to-peak value of a reflected aerial ultrasonic wave, using a transceiver-based ultrasonic device. Model channel experiments using manufactured materials of known roughness were undertaken to confirm the strong correlation between peak-to-peak values and Manning roughness coefficients and to derive a conversion equation that was incorporated in the ultrasonic device. The device yielded Manning roughness coefficients for handmade concrete panels that matched estimates made by a conventional moulage gauge technique. It also matched the results of estimates by the commonly used Manning–Strickler equation. A field experiment in an operating irrigation channel confirmed these results, showing that aerial ultrasonic measurements of surface roughness are as accurate as those by existing techniques.

中文翻译：

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基于航空超声反射的表面粗糙度测量装置的开发与测试

在日本，混凝土灌溉渠道的维修在很大程度上取决于其墙壁在使用数十年后退化的程度。从通道壁的粗糙度估计曼宁粗糙度系数的当前方法是基于算术平均粗糙度的线性分布。这项研究开发了一种方法，该方法使用基于收发器的超声波设备直接从反射的空中超声波的峰峰值估算平面区域的曼宁粗糙度系数。进行了使用已知粗糙度的制造材料进行的模型通道实验，以确认峰峰值与Manning粗糙度系数之间的强相关性，并得出转换公式，该转换公式已包含在超声设备中。该设备得出的手工混凝土面板的曼宁粗糙度系数与传统的量规技术得出的估算值相符。它也与常用的Manning–Strickler方程的估计结果相匹配。在运行中的灌溉渠中进行的野外实验证实了这些结果，表明航空超声对表面粗糙度的测量与现有技术一样准确。