SOIL HYDROLOGY AND MANAGEMENT EFFECTS ON EROSION AND WATER QUALITY
Location: National Soil Erosion Research Lab
Title: Evaluation of Interrill Erosion Under Wind-Driven Rain Events in Northern Burkina Faso
Submitted to: Meeting Abstract
Publication Type: Proceedings
Publication Acceptance Date: June 15, 2010
Publication Date: June 16, 2010
Citation: Visser, S., Erpul, G., Gabriels, D., Flanagan, D.C., Huang, C., Norton, L.D., Stroosnijder, L. 2010. Evaluation of Interrill Erosion Under Wind-Driven Rain Events in Northern Burkina Faso [abstract]. United Nations Educational, Scientific and Cultural Organization Chair on Eremology Workshop 'Action of Rain and Wind in Soil Degredation Processes.' June 16, 2010, Ghent, Belgium. 2010 CDROM.
Wind changes the velocity, frequency and angle of raindrop impact and hence affects rain splash detachment rates. Many soil erosion models underpredict interrill erosion because the contribution of the wind to raindrop detachment and wind-driven transport processes are not taken into account. In this research study, three approaches for the prediction of interrill sediment delivery rate were analyzed using field data from wind-driven rainfall events at three sites in northern Burkina Faso. The vertical rain intensity approach (I*qi) was the worst predictor for interrill sediment delivery rate (Di) at all three locations. At the Valley and at the Dunes sites, the kinetic energy approach (KEwd*qi) provided the best estimations of Di with r2 values of 0.71 for both sites. At both the Valley and Dunes sites, structural and erosion crusts were broken and consequently developing under influence of wind and water erosion processes. Comparing wind-driven saltating grains with wind-driven raindrops explains why KEwd*qi was a better estimator for Di than rainfall intensity for wind driven splash detachment of crusted soils. Di at the Degraded site was best predicted by the wind-driven rainfall intensity (Iwdr*qi). Here the presence of a strong, well-developed gravel crust protected the bare soil from the impacting wind-driven raindrops, making the effects of the increased kinetic energy as a result of the wind negligible. Di at the degraded site was thus a function of the surface runoff flowing around the gravel. Given that the infiltration rate at the degraded site was very low, Iwdr was the best predictor for the volume of runoff and hence for Di of soils with a well developed gravel crust. The results of our research highlight the importance of potentially including the kinetic energy of wind-driven rainfall for crusted soils without gravel in water erosion prediction models. For soils with a gravel crust, the effect of wind on the rainfall intensity could improve prediction of Di. Hence the role of the wind during wind-driven rainfall events should always be considered during the simulation of interrill erosion.