This paper summarizes field trials to evaluate the performance of a prototype compact topo‐bathymetric lidar sensor for surveying rivers. The sensor uses a novel polarization technique to distinguish between laser returns from the water surface and streambed and its size and weight permit deployment from a small unmanned aerial system (sUAS) or a boat. Field testing was designed to identify the range of operational conditions under which the sensor can provide accurate information on river depths. For accuracy assessment, conventional, field‐based depth measurements were collected by wading and sonar. Additionally, optical properties of the rivers were measured in situ. Wading and lidar bathymetry comparisons in relatively shallow channels yielded observed versus predicted (OP) regression R² values ranging from 0.60 to 0.97. A comparison between sonar and lidar bathymetry in a deeper river resulted in an OP R² of 0.72. Absorption and attenuation coefficients at the 532 nm wavelength of the lidar were recorded in the field and the highest values of these inherent optical properties were at sites with the highest turbidity and highest concentrations of colored dissolved organic matter, chlorophyll, and suspended sediment. At these sites, which included both sand and gravel/cobble beds, the point density of riverbed returns was not uniform, with areas of sparse coverage occurring primarily in deeper water. However, submerged objects and slopes could be resolved in the lidar point clouds.

中文翻译：

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在各种河流条件下的紧凑型极化极化测深激光雷达的现场评估

本文总结了野外试验，以评估用于测量河流的原型紧凑型地形测深激光雷达传感器的性能。该传感器使用一种新颖的偏振技术来区分来自水面和河床的激光返回，其尺寸和重量允许从小型无人机系统（sUAS）或船上部署。现场测试旨在确定传感器可以提供有关河深的准确信息的操作条件范围。为了进行准确性评估，通过涉水和声纳收集了常规的，基于现场的深度测量值。另外，河流的光学特性是在原位测量的。在相对较浅的通道中进行涉水和激光雷达测深的比较，得出观测值与预测值（OP）的回归R ²值范围从0.60到0.97。较深河中声纳和激光雷达测深的比较得出OP R ²为0.72。现场记录了激光雷达在532 nm波长处的吸收系数和衰减系数，这些固有光学特性的最高值出现在浊度最高，有色溶解有机物，叶绿素和悬浮沉积物浓度最高的位置。在包括砂砾床和卵石/卵石床在内的这些地点，河床回流的点密度不均匀，稀疏覆盖的区域主要发生在较深的水中。但是，可以在激光雷达点云中解决淹没的物体和坡度。