A comparison of the performance of nine soil organic matter models using datasets from seven long-term experiments

Information on sediment and nutrient export from catchments and about related erosive processes is required by catchment managers and decision-makers. Many models exist for the consideration of these processes. However, these models differ greatly in terms of their complexity, their inputs and requirements, the processes they represent and the manner in which these processes are represented, the scale of their intended use and the types of output information they provide. This paper reviews several different erosion and sediment and sediment-associated nutrient transport models with regard to these factors. The review of models is limited to those models with explicit considerations of either the sediment generation or transport process.

A review of erosion and sediment transport models

Vegetation controls soil erosion rates significantly. The decrease of water erosion rates with increasing vegetation cover is exponential. This review reveals that the decrease in water erosion rates with increasing root mass is also exponential, according to the equation SEP e b RP where SEP is a soil erosion parameter (e.g., interrill or rill erosion rates relative to erosion rates of bare topsoils without roots), RP is a root parameter (e.g., root density or root length density) and b is a constant that indicates the effectiveness of the plant roots in reducing soil erosion rates. Whatever rooting parameter is used, for splash erosion b equals zero. For interrill erosion the average b-value is 0.1195 when root density (kg m 3) is used as root parameter, and 0.0022 when root length density (km m 3) is used. For rill erosion these average b-values are 0.5930 and 0.0460, respectively. The similarity of this equation for root effects with the equation for vegetation cover effects is striking, but it is yet...

Impact of plant roots on the resistance of soils to erosion by water: a review

Parameterisation, calibration and validation of distributed hydrological models

Predicting soil erosion and sediment yield at the basin scale: Scale issues and semi-quantitative models

The European Soil Erosion Model (EUROSEM) is a dynamic distributed model, able to simulate sediment transport, erosion and deposition over the land surface by rill and interill processes in single storms for both individual fields and small catchments. Model output includes total runoff, total soil loss, the storm hydrograph and storm sediment graph. Compared with other erosion models, EUROSEM has explicit simulation of interill and rill flow; plant cover effects on interception and rainfall energy; rock fragment (stoniness) effects on infiltration, flow velocity and splash erosion; and changes in the shape and size of rill channels as a result of erosion and deposition. The transport capacity of runoff is modelled using relationships based on over 500 experimental observations of shallow surface flows. EUROSEM can be applied to smooth slope planes without rills, rilled surfaces and surfaces with furrows. Examples are given of model output and of the unique capabilities of dynamic erosion modelling in general. © 1998 John Wiley & Sons, Ltd.

https://gruenland.wzw.tum.de/fileadmin/auerswald/1998_Morgan-ESPL.pdf

The European Soil Erosion Model (EUROSEM): A dynamic approach for predicting sediment transport from fields and small catchments.

The European Soil Erosion Model (EUROSEM): documentation and user guide. Silsoe College, Cranfield University

The European soil erosion model (EUROSEM): documentation and user guide.

The modelling system described by Styczen and Storm (1993) simulates nitrogen transformation as well as water and nitrogen transport on a regional scale and can be used to evaluate effects of changes in the land use or in agricultural practices on the water quality in the groundwater and in the streams. It may be used to evaluate variations in time and space, and to predict the time lag from new strategies are implemented until measurable results are obtained. A case study was carried out on the 425 km2 large Karup River catchment in Denmark for the period 1968–88, and the paper presents the data required to set up the model and results from the simulations. Most of the data and information required could be extracted from existing databases, reports, and statistical yearbooks while information on changes in management practices came from local agricultural advisers. The simulations are compared to measurements in part of the Karup River catchment.

Modelling of N-movements on catchment scale - a tool for analysis and decision making

The leaching of soil particles and surface applied 14 C-Iabeled glyphosate and pendimethalin from intact soil columns (height: 50 cm; diameter: 30 cm) were investigated, and the relative significance of particle-facilitated pesticide transport was quantified. Investigations were performed with a recently plowed (four columns) and an untilled (five columns) sandy loam soil. Leaching was driven by three irrigation events (15 mm h -1 ; 2 h each). Samples of the leachate were filtered immediately (within 1.5 minutes) using 20 nm filters, and the 14 C-pesticide content was determined for filtered and unfiltered samples. Pesticide leaching was driven by preferential water flow in macropores. For the plowed structure, 68 ± 10% of the leached glyphosate (average of 6 events ± std.) was bound to particles whereas significantly less glyphosate was bound to particles in leachate from minimally disturbed columns (17 ± 12%). Thus, the results suggest that soil structure affected the mode of transport of glyphosate. It is likely that glyphosate sorbed strongly when applied on recently plowed soil (K d = 503 L kg -1 for the soil), and that it could be mobilized and transported independently of soil particles more easily when applied on the minimally disturbed soil covered in part with crop residues (K a < 1 L kg -1 for straw). Significantly less amounts of soil particles were leached from minimally disturbed (119—247 mg) than from recently plowed (441—731 mg) columns. The significance of particle-facilitated pendimethalin leaching could not be accurately quantified due to disagreement between control measurements based on both 14 C-activiry and chemical analyses.

Merete Styczen

Papers

The European Soil Erosion Model (EUROSEM): A dynamic approach for predicting sediment transport from fields and small catchments.

The European Soil Erosion Model (EUROSEM): documentation and user guide. Silsoe College, Cranfield University

The European soil erosion model (EUROSEM): documentation and user guide.

Modelling of N-movements on catchment scale - a tool for analysis and decision making

Particle-facilitated pesticide leaching from differently structured soil monoliths.