Mobile evaporite enhances the cycle of physical–chemical erosion in badlands

Abstract

Chemical weathering driven by physical erosion is a natural process that strongly affects chemical and solid matter budgets at the Earth's surface. However, the influence of extreme climatic erosion on chemical weathering dynamics is poorly understood. Badland landscapes formed in highly erodible substrates have the potential to respond to individual events on scales that are rapid enough for direct observation. Here, we assess the geochemical and grain-size composition of suspended sediment and riverine chemistry measurements collected from two catchments during the 2017 Nesat and Haitang typhoons in southwestern (SW) Taiwan. During the typhoons, the Na+ concentration covaried with suspended sediment concentration (SSC), which we attributed to sodium-induced deflocculation. Evaporite weathering at peak rainfall is succeeded by peak silicate weathering at maximum discharge. Overall, our observations suggest that initial weathering of near-surface evaporite enhances the physical erosion of silicate rock during extreme rainfall events.