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- Stendahl, Johan, et al.
(författare)
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The stone and boulder content of Swedish forest soils
- 2009
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Ingår i: CATENA. - : Elsevier BV. - 0341-8162. ; 77, s. 285-291
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Tidskriftsartikel (refereegranskat)abstract
- Stone and boulder content has a strong influence on many soil processes and is a crucial factor to take into account when estimating element pools. In this paper we present the results of a large scale inventory of the stone and boulder content of forest soils, which employed a surface penetration method (Viro's method) in 1943 plots across Sweden. The volume of stones and boulders was 43.4%, on average, although it was 47.6% for the most common soil type on glacial till parent material. The variation was spatially correlated and there were regional patterns, which were related to bedrock composition and Quaternary development. A stoniness function was developed for the upper 30 cm of the mineral soil and this was used to translate the penetration depths into stone and boulder content. The function was based on a reference data set of 200 soil pits. A relationship was found between stone and boulder content and surface boulder frequency, but the strength of the relationship varied regionally. In some regions surface boulders may provide an indicator of stone and boulder content in the soil. (C) 2009 Elsevier B.V. All rights reserved.
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| 2. |
- Vigiak, Olga, et al.
(författare)
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A semi-empirical model to assess uncertainty of spatial patterns of erosion
- 2006
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Ingår i: Catena (Cremlingen. Print). - : Elsevier. - 0341-8162 .- 1872-6887. ; 66:3, s. 198-210
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Tidskriftsartikel (refereegranskat)abstract
- Distributed erosion models are potentially good tools for locating soil sediment sources and guiding efficient Soil and Water Conservation (SWC) planning, but the uncertainty of model predictions may be high. In this study, the distribution of erosion within a catchment was predicted with a semi-empirical erosion model that combined a semi-distributed hydrological model with the Morgan, Morgan and Finney (MMF) empirical erosion model. The model was tested in a small catchment of the West Usambara Mountains (Kwalei catchment, Tanzania). Soil detachability rates measured in splash cups (0.48-1.16gJ(-1)) were close to model simulations (0.30-0.35gJ(-1)). Net erosion rates measured in Gerlach troughs (0.01-1.05kgm(-2) per event) were used to calibrate the sediment transport capacity of overland flow. Uncertainties of model simulations due to parameterisation of overland flow sediment transport capacity were assessed with the Generalized Likelihood Uncertainty Estimation (GLUE) methodology. The quality of the spatial predictions was assessed by comparing the simulated erosion pattern with the field-observed erosion pattern, measuring the agreement with the weighted Kappa coefficient of the contingency table. Behavioural parameter sets (weighted Kappa > 0.50) were those with short reinfiltration length (< 1.5m) and ratio of overland flow power a to local topography power close to 0.5. In the dynamic Hortonian hydrologic regime and the dissected terrain of Kwalei catchment, topography controlled the distribution of erosion more than overland flow. Simulated erosion rates varied from -4 to +2kgm(-2) per season. The model simulated correctly around 75% of erosion pattern. The uncertainty of model predictions due to sediment transport capacity was high; around 10% of the fields were attributed to either slight or severe erosion. The difficult characterisation of catchment-scale effective sediment transport capacity parameters poses a major limit to distributed erosion modelling predicting capabilities. Crown Copyright (c) 2006 Published by Elsevier B.V. All rights reserved.
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