Simulation of event-based and long-term spatial redistribution of Chernobyl-derived radiocaesium within catchments using geographical information system embedded models

✍ Scribed by Marcel van der Perk; Ondrej Slávik

• Publisher: John Wiley and Sons
• Year: 2003
• Tongue: English
• Weight: 503 KB
• Volume: 17
• Category: Article
• ISSN: 0885-6087
• DOI: 10.1002/hyp.1172

✦ Synopsis

Abstract

The Chernobyl accident contaminated vast areas of Europe with radiocaesium (^137^Cs) in 1986. To evaluate long‐term and event‐based redistribution of Chernobyl‐derived ^137^Cs at the catchment scale, two geographical information system embedded models have been developed. The first model simulates ^137^Cs redistribution using a monthly time step based on a long‐term soil erosion model. The second model simulates lateral radiocaesium transport at the event scale based on the existing Limburg soil erosion model. This model accounts for surface runoff, soil erosion and deposition, and radiocaesium exchange between the topsoil layer, runoff water, and suspended sediment. Both models have been tested and applied to the Mochovce catchment, western Slovakia. The spatial distribution of ^137^Cs activity in soil simulated by the long‐term model was used as input for the event‐based model to assess the changes in ^137^Cs transport during rainfall events between 1986 and 2002. Soil erosion events in the first months after initial fallout input before ploughing caused a considerable decline in the ^137^Cs soil inventories, which were estimated at 8·9% of the total initial inventory. The majority of ^137^Cs transport during rainfall events occurs in particulate form. Both the absolute amounts of particulate ^137^Cs transport and the fraction of particulate ^137^Cs transport were shown to be positively related to suspended sediment transport. Between 1986 and 2002, dissolved ^137^Cs transport has declined by a factor of about 26, which can be largely attributed to the increased sorption to sediment particles. Particulate ^137^Cs transport has declined by a factor of about two, which can be largely attributed to the decrease in soil ^137^Cs. The ^137^Cs inventories in soil have decreased by a factor between three and four at the steep hillslopes, but have remained at about the same level as the initial fallout input at the valley bottoms. Copyright © 2003 John Wiley & Sons, Ltd.