A detailed laboratory study was conducted to examine the effects of particle size on hysteretic sediment transport under time-varying rainfall. A rainfall pattern composed of seven sequential stepwise varying rainfall intensities, each of 20 min duration, was applied to a soil erosion flume. Flow rates and sediment concentration data for seven particle size classes were measured in the flume effluent. Clockwise hysteresis loops in the sediment concentration versus discharge curves were measured for the total eroded soil and the finer particle sizes. Overall, it is found that hysteresis varies amongst particle sizes and that the predictions of the HR model are consistent with hysteretic behavior of different sediment size classes.

1. Ecological Engineering Laboratory
ECOL
17th International Conference on Transport & Sedimentation of Solid Particles, The Netherlands
Hysteresis Effects in Splash Sediment Transport
Mohsen Cheraghi a, Seifeddine Jomaa b, Graham C. Sander c, D. A. Barry a
a Ecological Englineering Laboratory, EPFL, Lausanne, Switzerland
b Helmholtz Centre for Environmental Research – UFZ, Magdeburg, Germany
c Department of Civil Engineering, Loughborough University, Loughborough, United
Kingdom.

2. ECOL 2/10
A.M. De Girolamo et al. / Catena 128 (2015) 135–143
Hysteresis loop in catchments
Celone river (Italy)

3. ECOL 3/10
Hysteresis loop in catchments

4. ECOL 4/10
The Main Questions
 Hysteresis Effects in Rainfall Driven Sediment Transport
 Capability of the Hairsine and Rose Erosion Model

5. ECOL 5/10
ECOL Flume

6. ECOL 6/10
HR model 𝜕(𝐶𝑖 𝑞
𝜕𝑥
+
𝜕(𝐶𝑖 𝐷
𝜕𝑡
= 𝑟𝑖 + 𝑟𝑟𝑖 − 𝑑𝑖
Hairsine and Rose Model
𝜕𝑚 𝑖
𝜕𝑡
= 𝑑𝑖 - 𝑟𝑟𝑖
𝐶𝑖 = concentration
𝑚𝑖 = deposited mass
𝑟𝑖 entrainment rate =
1 − 𝐻 𝑎𝑃 𝑝
𝐼
𝑟𝑟𝑖 reentrainment rate =
𝐻𝑎 𝑑
𝑃 𝑝
𝐼
𝑑𝑖 reentrainment rate = 𝑣𝑖 𝐶𝑖
′

7. ECOL 7/10
Results
Collector 1Collector 2
Discharge

8. ECOL 8/10
Results
Total Sediment Concentration

9. ECOL 9/10
Results
Hysteresis loops

10. ECOL 10/10
Results
Deposited Mass

11. ECOL 11/10
Concentration of Different Particle Size ClassesFuture works
Hysteresis Effects of Different Particle Size Classes
C1 : < 2 µm
C2 : 2 - 20 µm
C3: 20 - 50 µm
C4: 50-100 µm
C5: 100-315 µm
C6: 315-1000 µm
C7: > 1000 µm

12. ECOL 12/10
Concentration of Different Particle Size ClassesFuture works
 Droplet size: 4 mm (Vt = 7.65 ms-1)
 Particle size: 1 mm
*The simulation is done for 50 ms splash

13. ECOL 13/10
Concentration of Different Particle Size ClassesConclusion
Conclusions
 There is a Clockwise Hysteresis Effects in Rainfall Driven Sediment Transport with
initially loose sediments
 HR Model Has the Capability of Predicting the Erosion Rate under a Temporally
Variable Rainfall