Headward erosion is a process in which the upper part of a stream or river valley erodes back towards its source, effectively lengthening the river. This process is significant in understanding river dynamics, landscape evolution, and the development of drainage networks.
Reference: Ferguson, R. I., & Werritty, A. (1983). Headward Erosion in a Small Scottish Catchment. Earth Surface Processes and Landforms, 8(4), 391-395.