Figure 1D and 1E from Rathburn et al.: Flood impacts in the North St. Vrain Creek catchment, northern Colorado, USA. Images D and E are from Google Earth.

Sara Rathburn of Colorado State University and colleagues have developed an integrated sediment, wood, and organic carbon budget for North St. Vrain Creek in the semi-arid Colorado Front Range following an extreme flooding event in September of 2013. Erosion of more than 500,000 cubic meters, or up to ~115-years-worth of weathering products, occurred through landsliding and channel erosion during this event. More than half of the eroded sediment was deposited at the inlet and delta of a water supply reservoir, resulting in the equivalent of 100 years of reservoir sedimentation and 2% loss in water storage capacity. The flood discharged 28 mega-grams of carbon from one square kilometer of land (28 Mg C/km2), which is more like what would happen in humid, tectonically active areas. To get an idea of what that means, Rathburn explains, a mega-gram of carbon (C) eroded from one square kilometer of land is equivalent to about a million paper clips covering an 18-hole golf course. So in this scenario, the flood discharged 28 million paper clips from just a golf course-sized area.