Quantifying sediment transport across an undisturbed prairie landscape using cesium-137 and high resolution topography James M. Kaste a, ⁎ , Arjun M. Heimsath a , Matthew Hohmann b a Department of Earth Sciences, 6105 Fairchild Hall, Dartmouth College, Hanover, NH 03755, USA b U.S. Army Engineer Research and Development Center, Construction Engineering Research Laboratory, PO Box 9005, Champaign, IL 61826-9005, USA Received 20 June 2005; received in revised form 7 December 2005; accepted 9 December 2005 Available online 17 February 2006 Abstract Soil erosion is a global environmental problem, and anthropogenic fallout radionuclides offer a promising tool for describing and quantifying soil redistribution on decadal time scales. To date, applications of radioactive fallout to trace upland sediment transport have been developed primarily on lands disturbed by agriculture, grazing, and logging. Here we use 137 Cs to characterize and quantify soil erosion at the Konza Prairie Long-Term Ecological Research (LTER) site, an undisturbed grassland in northeastern Kansas. We report on the small scale (b 10 m) and landscape scale (10 to 1000 m) distribution of fallout 137 Cs, and show significant variability in the concentrations and amounts of 137 Cs in soils at our site. 137 Cs soil concentrations and amounts typically vary by 10% to 30% on small scales, which most likely represents the spatial heterogeneity of the depositional processes. Landscape scale variability of soil 137 Cs was significantly higher than small scale variability. Most notably, soils collected on convex (divergent) landforms had 137 Cs inventories of 2500 to 3000 Bq m - 2 , which is consistent with the expected atmospheric inputs to the study area during the 1950s and 1960s. Concave landforms, however, had statistically lower inventories of 1800 to 2300 Bq m - 2 . The distribution of 137 Cs on this undisturbed landscape contrasts significantly with distributions observed across disturbed sites, which generally have accumulations of radioactive fallout in valley bottoms. Because the upslope contributing area at each sampling point had a significant negative correlation with the soil inventory of 137 Cs, we suggest that overland flow in convergent areas dominates soil erosion at Konza on time scales of decades. Very few points on our landscape had 137 Cs inventories significantly above that which would be predicted from direct deposition of 137 Cs on the soil surface; we conclude therefore that there is little net sediment storage on this undisturbed landscape. © 2005 Elsevier B.V. All rights reserved. Keywords: Erosion; Overland flow; Konza Prairie; Grassland; Geomorphology 1. Introduction Each year the world loses billions of tons of soil from erosion, a flux that is likely to exceed natural soil production rates (Pimentel et al., 1995). Soil erosion has been accelerated in recent years from cultivation, logging, and other effects of anthropogenic manipula- tion of the landscape (Hooke, 2000; Hewawasam et al., 2003). As soil is transported off of the land surface, it can damage aquatic ecosystems (Osmundson et al., 2002) and it can reduce this global resource for food, fiber, and timber production. A detailed understanding of soil erosion across different types of landscapes is critical, therefore, for developing sustainable land management practices. Geomorphology 76 (2006) 430 – 440 www.elsevier.com/locate/geomorph ⁎ Corresponding author. E-mail address: James.Kaste@Dartmouth.edu (J.M. Kaste). 0169-555X/$ - see front matter © 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.geomorph.2005.12.007