西藏中南部侵蚀沟形态无人机航测与传统地面测量的对比分析

目的]分析无人机和传统地面方法测量侵蚀沟形态的差异,研究无人机影像提取西藏地区侵蚀沟形态的适宜性,以期准确、快速获取西藏地区沟蚀参数,为该地侵蚀沟快速调查与防治提供基础资料。方法]选取6个研究地点20条侵蚀沟,对实地测量与无人机正射影像提取的沟长、沟宽进行对比分析。结果]与实地测量相比,影像提取侵蚀沟沟长的平均偏差集中在2%～5%;沟宽的平均偏差集中在0～40%,其中实测沟宽范围在400～1 000 cm时,提取值和实测值的偏离程度最低。在6个研究地点中,影像提取值的偏离程度和侵蚀沟所处位置没有明显的关系。沟缘土质、沟缘线附近的植被及放牧对沟缘的踩踏是影响侵蚀沟形态提取的主要因素。结论]无人机遥感可为西藏地区沟蚀监测提供便捷、可靠的数据源。

Comparative Analysis on Morphological Characteristics of Erosion Gullies Measured by an Unmanned Aerial Vehicle and Traditional Ground Survey in South Central Tibet

Objective] The measurement differences between an unmanned aerial vehicle (UAV) and traditional ground methods were analyzed, and the suitability of extracting the morphological characteristics of erosion gullies by UAV orthophotos in Tibet was studied in order to obtain the parameters of erosion gullies accurately and quickly, with the aim to provide basic information for the prevention and control of gully erosion in the area.Methods] A total of 20 erosion gullies were selected from 6 research sites, to compare the lengths and widths of erosion gullies measured through field measurements and extraction from UAV orthophotos.Results] Compared to the results from the field measurements, the mean deviation extent of the erosion gullies'' length and width extracted by orthophotos was concentrated between 2%~5% and 0~40%, respectively. Additionally, when the measured width was in the range 400~1 000 cm, the deviation between the extracted and measured values was the lowest. Across the 6 research sites, there was no obvious relationship between the deviation extent of the erosion gullies'' morphological parameters extracted by orthophotos and the location. The soil and vegetation near the gully shoulder lines and the grazing damage to the gully shoulder lines were the main factors affecting the extraction of the erosion gullies'' morphological characteristics.Conclusion] UAV remote sensing can provide a convenient and reliable data source for gully erosion monitoring in Tibet.