High-resolution terrestrial laser scanning (TLS) provides a unique opportunity to monitor short-term erosion and deposition processes in gully systems. This study quantified the pattern of erosion and deposition within an active gully in the sub-tropical environment of west Tennessee. Two TLS surveys were conducted on December 2014 and February 2015 to generate digital elevation models (DEMs) of different resolutions. The volumes of erosion and deposition were estimated by differencing the DEMs of these two dates with consideration of the spatially propagated errors associated with TLS-measured gully topography. The detected erosional and depositional volumes were 11.0 and 8.2 m³, respectively, with a net loss of 2.8 m³ of sediment at the DEM resolution of 2-cm. We found that both estimated volumes of erosion and deposition decrease as the DEM resolution becomes coarser. The estimated erosional volume decreases at a relatively high rate because erosion mainly occurs on steeper slopes where the propagated errors in TLS-measured topography are relatively higher, leading to rapid smoothing at coarser resolutions. In contrast, the depositional areas on gentler slopes have less propagated errors. This bias in the smoothing behavior of erosional and depositional areas appears to make coarser resolution DEMs dominated by deposition, a misleading interpretation of the sediment dynamics within the gully. We therefore suggest caution when using DEM difference to interpret the erosion-deposition processes within a gully system.

高分辨率地面激光扫描（TLS）提供了独特的机会来监控沟壑系统中的短期侵蚀和沉积过程。这项研究量化了田纳西州西部亚热带环境中活跃沟壑内侵蚀和沉积的模式。2014年12月和2015年2月进行了两次TLS调查，以生成不同分辨率的数字高程模型（DEM）。考虑到与TLS测量的沟渠地形相关的空间传播误差，通过区分这两个日期的DEM来估算侵蚀和沉积的量。测得的侵蚀和沉积量分别为11.0和8.2 m ³，净损失为2.8 m ³DEM分辨率为2厘米的沉积物数量。我们发现，随着DEM分辨率变粗，估计的侵蚀和沉积量都会减少。估计的侵蚀量以相对较高的速率减少，因为侵蚀主要发生在较陡峭的斜坡上，在该斜坡上TLS测量的地形中传播的误差相对较高，从而导致在较高分辨率下进行快速平滑。相反，较平缓的斜坡上的沉积区域传播误差较小。侵蚀和沉积区域的平滑行为上的这种偏差似乎使较粗分辨率的DEM受到沉积的支配，这是对沟内沉积动力学的误导性解释。因此，我们建议在使用DEM差异来解释沟壑系统内的侵蚀沉积过程时要谨慎。