Cornelis, W.M.

Erpul, G.

Gabriels, D.

Samray, H.

English

Wageningen UR (University & Research Centre): Publication System

Changes in Kinetic Energy Flux of Wind-Driven Rains (WDR) with Different 
Slope Gradients and Aspects  
H. Samray 1,2,3, G. Erpul2, D. Gabriels 3, W.M. Cornelis3 
1Department of Foreign Relations and EU Coordination, Ministry of Agriculture and Rural Affairs, 06100, Lodumlu- 
  Ankara, Turkey 
2Department of Soil Science, Faculty of Agriculture, University of Ankara, 06110 Diskapi-Ankara, Turkey 
3Department of Soil Management and UNESCO Chair on Eremology, Ghent University, Coupure Links 653, B 9000 
 Ghent, Belgium 
 
ABSTRACT 
Recent studies have shown that the vector physics of wind-driven rain (WDR) varies with the angle of rain incidence, 
and especially under high rain inclinations, the slope aspect makes significant differences in the vectoral partitioning of 
the total rain energy flux. Since such interrill erosion processes of WDR as soil detachment by raindrop impact and 
particle transport by raindrop-impacted thin flow transport require a component-wise evaluation of fall vectors of both 
rainfall intensity and raindrop impact velocity, knowing energy flux distribution over a soil surface with a given slope 
gradient and aspect play a key role to model the sub-processes physically. In this study, vectoral distribution of kinetic 
energy flux of the wind-driven rains with different slope gradients and aspects were measured using two-dimensional 
experimental setups at the wind and rain simulation facility of the International Center for Eremology (ICE) in Ghent 
University in Belgium. Varying fall incidences were obtained by the rains driven by the wind speeds of 0, 6, 10, 12 ms-1 
over a test surface placed on windward and leeward slopes of 2, 3, 4, 5, 7, 9, 11°.  In the experiments, the WDR 
incidence angles, calculated by integrating the degrees of rain inclination, slope gradients and aspects, ranged between 
2o and 72o and 2o and 85o for windward and leeward slopes, respectively. Depending upon the wide range of the 
incidence angles, the partition of the total kinetic energy flux (KET, J m-2 s-1)  into its components also changed highly; 
for example, although the highest normal rain energy flux (KEN = 0.247 J m-2 s-1) was obtained with the wind free rains 
incident on windward slope of 2o, the lowest was with the wind-driven rains driven by 12 ms-1 wind speed and incident 
on leeward slope of 11o (KEN = 0.025 J m-2 s-1). On the other hand, for the same WDR incidences, the values of the 
along-surface rain energy flux (KES) were 0.0003 and 0.602 J m-2 s-1, respectively. For these extreme conditions the 
changes for KEN and KES were in the order of magnitudes of 10 and 103, respectively. Given the fact that the sub-
processes of interrill erosion under WDR are closely related to the vector field to be formed at the impact-flow 
boundary and the differences in the distribution of KEN and KES would result in diverse sediment delivery rates as the 
angle of WDR incidence vary. 
 
Keywords: wind driven rain, vector physics, kinetic energy, angle of rain incidence, 
 


Changes in Kinetic Energy Flux of Wind-Driven Rains (WDR) with Different Slope Gradients and Aspects

https://library.wur.nl/ojs/index.php/AE2012/article/download/12467/11967

Changes in Kinetic Energy Flux of Wind-Driven Rains (WDR) with Different Slope Gradients and Aspects

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