Sensitivity analysis of EUROSEM using Monte Carlo simulation II::the effect of rills and rock fragments

A sensitivity analysis of the surface and catchment characteristics in the European soil erosion model (EUROSEM) was carried out with special emphasis on rills and rock fragment cover. The analysis focused on the use of Monte Carlo simulation but was supplemented by a simple sensitivity analysis where input variables were increased and decreased by 10%. The study showed that rock fragments have a significant effect upon the static output parameters of total runoff, peak flow rate, total soil loss and peak sediment discharge, but with a high coefficient of variation. The same applied to the average hydrographs and sedigraphs although the peak of the graphs was associated with a low coefficient of variation. On average, however, the model was able to simulate the effect of rock fragment cover quite well. The sensitivity analysis through the Monte Carlo simulation showed that the model is particularly sensitive to changes in parameters describing rills and the length of the plane when no rock fragments are simulated but that the model also is sensitive to changes in the fraction of non-erodible material and interrill slope when rock fragments were embedded in the topsoil. For rock fragments resting on the surface, changes in parameter values did not affect model output significantly. The simple sensitivity analysis supported the findings from the Monte Carlo simulation and illustrates the importance when choosing input parameters to describe both rills and rock fragment cover when modelling with EUROSEM

Promoting global watershed management towards rural communities: the May Zeg-zeg initiativeLength: pp.192-195

Watershed managementRural development

Recent developments in gully erosion research and their implications for controlling soil loss and sediment yield

Resumen del trabajo presentado al IV International Symposium on Gully Erosion, celebrado en la Universidad Pública de Navarra del 17 al 19 de septiembre de 2007.Soil erosion by water causes significant soil degradation worldwide. Most erosion process research and erosion control has focussed on sheet and rill erosion. Relatively little research has dealt with (ephemeral) gully erosion which is illustrated, for instance, by a recent review of soil erosion studies in Europe (Boardman and Poesen 2006). Gullies typically occupy less than 5 % of the upland area, but gully erosion may be held responsible for relatively large soil losses (up to 80 %) by water erosion and related sediment production with significant on and off site consequences. Hence, controlling soil erosion in concentrated flow zones pays of. However, innovation in research on gully erosion control is rather limited compared to progress in research on gully (or more generally concentrated flow) erosion processes (Poesen et al. 2003). The objectives of this study are therefore to review recent developments in gully erosion research that have implications for improving the effectiveness of (ephemeral) gully erosion control measures and to formulate some important challenges

Simulation and experimental verification of W-band finite frequency selective surfaces on infinite background with 3D full wave solver NSPWMLFMA

We present the design, processing and testing of a W-band finite by infinite and a finite by finite Grounded Frequency Selective Surfaces (FSSs) on infinite background. The 3D full wave solver Nondirective Stable Plane Wave Multilevel Fast Multipole Algorithm (NSPWMLFMA) is used to simulate the FSSs. As NSPWMLFMA solver improves the complexity matrix-vector product in an iterative solver from O(N(2)) to O(N log N) which enables the solver to simulate finite arrays with faster execution time and manageable memory requirements. The simulation results were verified by comparing them with the experimental results. The comparisons demonstrate the accuracy of the NSPWMLFMA solver. We fabricated the corresponding FSS arrays on quartz substrate with photolithographic etching techniques and characterized the vector S-parameters with a free space Millimeter Wave Vector Network Analyzer (MVNA)