Gully morphological characteristics in the loess hilly‐gully region based on 3D laser scanning technique

Abstract Gully morphology characteristics can be used effectively to describe the status of gully development. The Chabagou watershed, located in the hilly‐gully region of the Loess Plateau in China, was selected to investigate gully morphological characteristics using a 3D laser scanning technique (LIDAR). Thirty‐one representative gullies located at different watershed locations and gully orders were chosen to quantitatively describe gully morphology and establish empirical equations for estimating gully volume based on gully length and gully surface area. Images and point cloud data for the 31 gullies were collected, and digital elevation models (DEMs) with 10‐cm resolution were generated. ArcGIS 10.1 was then used to extract fundamental gully morphological parameters covering gully length ( L ), gully width ( W T ) and gully depth ( D ), and some derivative morphological parameters, including gully head curvature ( C ), gully width–depth ratio ( w/d ), gully bottom‐to‐top width ratio ( W B /W T ), gully surface area ( A g ) and gully volume ( V g ). The results indicated that gullies in the upper watershed and the second order were more developed based on their high values of gully head curvature. The potential for gully development increased from the second order to the fourth order. Within the same gully orders, gullies in the lower watershed were more active with more development potential. A method for differentiating between gully head and gully sidewalls based on the gully head curvature value was proposed with a mean relative error of 8.77%. U‐shaped cross‐sections were widely distributed in the upper watershed and upper positions of a gully, while V‐shaped cross‐sections were widely distributed in the lower watershed and lower positions of a gully. V–L and V–A g empirical equations with acceptable accuracy were established and can be used to estimate gully erosion in the Loess hilly‐gully region. Copyright © 2017 John Wiley & Sons, Ltd.