Geo Reviewer Surface Water Practice Exam

Hydraulic action is the process of erosion that primarily involves the force of moving water on rock and soil at a river's edge. This action occurs when water flows rapidly over these sediments, creating pressure differences that can dislodge particles from the riverbank. As the moving water pushes against the rocks and soil, it can exploit existing cracks and weaknesses, causing pieces to break off and be carried away by the current. This process is especially effective during periods of high flow or flooding, where the energy of the water is significantly increased.

In contrast, attrition refers to the wearing down of particles as they collide with each other and erode over time. Suspension involves the transport of fine particles within the water column but does not specifically refer to the erosion of the river's edge. Solution occurs when minerals dissolve in the water, contributing to erosion but not through physical removal of soil or rock from the banks. Each of these processes plays a role in river dynamics, but hydraulic action is the key mechanism for directly removing material from the river's edges.