Faults and stratigraphic boundaries control evolution of the huge debris flows along the Jinjiang River, China

Abstract

This paper investigates the controlling factors of the evolution of debris flows along the Jinjiang River, which is located in an active orogen. The debris flows along the Jinjiang River are threatening nomads and pastures, as well as the power station on the river and its workers. Remote sensing images, geological maps, and field investigations were conducted to determine the distribution of the lithologies, faults, and debris flows. A total of 82.2 km of riverbank and 108 debris flows, including 22 huge flows, were investigated. The results indicate that the distribution of the huge debris flows is primarily controlled by either faults or boundaries between the sedimentary rocks and basalt. Both the faults and the stratigraphic boundaries play crucial roles in the evolution of the huge debris flows along the river. The fractured zone of faults and stratigraphic boundaries provides loose resource materials for the debris flows and is a weak strip prone to incision to become a debris flow valley. However, the lithology has relatively less impact on the evolution of the huge debris flows.