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Wageningen University (2013)

Soil surface roughnesss measurements and erosion modelling

Thomsen, L.M. 

Titre : Soil surface roughnesss measurements and erosion modelling

Auteur : Thomsen, L.M. 

Université de soutenance : Wageningen University

Grade : Master of Science (MS) 2013

This study compared five methods for measuring soil surface roughness, two contact methods : pinboard and roller chain, and three non-contact methods : laser scanner, stereophotogrammetry and the “Kinect”. The latter is a 3D depth sensor originally developed for gaming consoles, which recently was proved to be applicable for Earth Sciences (Mankoff and Russo, 2012). Roughness was in this study defined as irregularities in the surface related to soil type and tillage practice. The index random roughness (RR), calculated as the standard deviation of a number of elevation recordings, was used for comparison. The methods were compared in terms of accuracy, precision, resolution, ease of usage, price and land use. Further, the obtained average roughness values were used as input in a physical-based spatially-distributed erosion model, LISEM. This facilitated a one-at-atime parameter sensitivity analysis. Results showed that the various methods have different pros and cons and since the methods used different principles to obtain roughness data, they are prone to different errors. The “Kinect” proved to be a useful sensor. The erosion model was relatively sensitive to the roughness input data. Interestingly, roughness data obtained with different methods, which in statistical terms were not significantly different from each other (RR 0.81 versus 1.18±0.33) , were still causing a 50% change in hydrograph peak, indicating that the model sensitivity is not adjusted for the accuracy of measured roughness data. For improved model performance it is suggested to determine the required accuracy and precision as well as the preferred method of measured roughness data when used as input to an erosion model like LISEM.

Mots clés : surface roughness / soil properties / soil physics / erosion / modeling


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