Tracking watershed change using lake sediments on the Bruce Peninsula, Ontario, Canada

Abstract

Sediment transports nutrients to lakes through overland runoff and streamflow, influenced by watershed weather and land use/management. Understanding climatic and land use influences on sediment transport rates is important for ongoing and future erosion control strategies, though difficult to disentangle. Using a paleolimnological approach in a watershed with consistent land use over time, insight can be gained on past sediment yields. In this study, lake sediment cores were collected from a lake draining a small watershed on the Bruce Peninsula. Sediment grain size was measured at a fine-scale in five sediment cores and compared to instrumental and historical records. High-flow timings have changed from a spring-dominated regime to more frequent high-flow events throughout the winter. Since the 1960s, sediment accumulation rates decreased. From this work, it was concluded that sediment yield from Judges Creek watershed decreased as a result of earlier streamflow peaks occurring when less sediment is available.