Estimation of soil loss by the WATEM/SEDEM model using an automatic parameter estimation procedure

Abstract

Soil degradation is a major environmental problem in many parts of the world, including Slovenia. The spatially distributed WATEM/SEDEM model can be used to identify the most critical parts of the catchment with regard to soil erosion. Five Slovenian (Central Europe) catchments with inhomogeneous topography, land use, geological conditions, hydro-meteorological properties and sizes (catchment areas between 1 and 2000 km 2 ) were modeled with calibrated parameters, while the WATEM/ SEDEM model was calibrated with an automatic parameter estimation procedure, which is model independent. Both direct and indirect information regarding sediment yields, including turbidity measurements, daily suspended sediment concentration observations and bed load observations, were used for the WATEM/SEDEM model's calibration. A detailed rainfall erosivity (R) factor map, which was constructed from 5-min rainfall data from 31 pluviographic meteorological stations, was used as one of the inputs for the WATEM/SEDEM model. The calculated mean annual soil loss was between 0.3 and 7.4 t/ha/year, and the sediment delivery ratio (SDR) ranged from 0.07 to 0.22 for 5 modeled catchments. The results indicate that the SDR decreases with increasing catchment area; however, the ratio between the average sediment yield and mean soil erosion obviously depends on many other factors, e.g., topography, climatic and geological conditions. The parcel trap efficiency parameter for forests had the greatest influence on the WATEM/SEDEM model's outputs in all five case studies.

Geomorphic response detection and quantification in a steep forested torrent

“…It should be noted that in this time period no extreme event happened in the Kuzlovec torrent. Further, various estimated values of suspended material can be obtained by considering different time periods of measurements and using different methodologies for estimating suspended sediment values (Bezak et al, 2015b). This agrees with the large variability in the measured suspended sediment and bed load delivery from the steep forested torrents (e.g., Rickenmann, 1997).…”

“…Bed load was not included in this estimation; for torrential streams the proportion between bed load and total load can be between 20 and 90% (Lenzi and Marchi, 2000). Notably, this estimated value (5 t ~ 0.1 t/ha/year) can be regarded as relatively low related to the mean annual soil erosion rates at a catchment scale for Slovenia, which can be up to approximately 7 t/ha/year due to high rainfall erosivity and steep slopes (Bezak et al, 2015b;Panagos et al, 2015). It should be noted that in this time period no extreme event happened in the Kuzlovec torrent.…”

Modelling of Soil Erosion and Accumulation in an Agricultural Landscape—A Comparison of Selected Approaches Applied at the Small Stream Basin Level in the Czech Republic

“…The algorithms used are listed in the program manual [52]. This software generally belongs to relatively frequently used tools-in Central Europe, its outputs were presented, for example, by Bezak et al [53] or in the Czech Republic by Van Rompaey et al [31] and by Krása [54], which describes in more detail the individual algorithms of the model.…”

Impact of a Random Sequence of Debris Flows on Torrential Fan Formation

“…The RAMMS modelling procedure (i.e., one sequence that was composed from 62 model runs) was performed automatically using a set of Autoit and R functions/scripts. This kind of combination was previously used for the automatic calibration of the Water and Tillage Erosion Model (WaTEM)/Sediment Delivery model (SEDEM) WaTEM/SEDEM model that can be used for soil erosion modelling [32]. For the Suhelj fan we adopted the triangular hydrograph shape with a total duration of 250 s where the peak was positioned 125 s after the start.…”