Assessment of lidar data for instream flow type classification

The information of instrem biotype, i.e., types, location, distribution, etc, are important for estuary environment management. Field observations carry out by ecology surveyor is the standard procedure to gather that information, which is time consuming and is difficult to be applied to a large spatial extend. The instream biotype is classified according to the flow type, water depth, substrate material, and bottom topography. The roughness characteristic of the water surface can be extracted from the high density point cloud acquired by airborne topographic lidar, which can then be used for flow type classification. This implies a great potential of using lidar for instream biotype classification to a large spatial extend in a timely manner. We employed semi-variogram for the water surface roughness characterization. The principle component analysis is then used for the flow type classification. The results show that the first and second principle components are closely related to the flow type considered in this study, i.e., unbroken standing wave, ripple and no perceptible flow.