The document evaluates the LandSoil model's ability to map erosion in an agricultural catchment. The objective is to represent runoff, erosion, and deposition patterns around connectivity points. The study area uses a 1m DEM of a region in Wallonia. The model operates using expert rules to model runoff based on infiltration rates and an modified D8 flow algorithm, as well as rill, interrill, and tillage erosion. Inputs include soil characteristics, infiltration capacities from measurements, and sediment concentrations from expert rules. Measurements of runoff and erosion are compared to modeling results, showing close correspondence for runoff volumes and satisfying validation for erosion measurements. The model captures the influence of land use and field boundaries on erosion amounts.

1. Is an expert-based model
able to map erosion in an
agricultural catchment?
Vincent Cantreul - Université de Liège, Gembloux
Agro-Bio Tech
Gilles Swerts, Charles Bielders, Aurore Degré
1

2. 2
To evaluate the capacity of the LandSoil
model to represent runoff, erosion and
deposition patterns in an agricultural
catchment with a particular attention
to spatial patterns around major
connectivity points
Objective

3. 3
Study area

4. 4
Study area

5. 5
Model operation
 Runoff
• Soil roughness, Soil crusting and vegetation cover  Steady-state soil
infiltration rate
• B = T - W – I*t
B = infiltration/runoff balance (mm), T = total rainfall event amount
(mm), W= imbibition rainfall (mm), I = steady-state soil infiltration rate
(mm.h^-1), t = runoff event duration (h)
• Modified D8 flow direction with tillage direction
 Erosion
• Rill erosion considering soil surface properties, slope, modeled runoff volume
and observed rill sections
• Interrill erosion : expert-rule assigning a potential sediment concentration
• Tillage erosion

6. 6
Model inputs
 DEM 1m (Walloon Region)
 Soil characteristics observed each month
 Infiltration capacity : expert-rule updated with a measurement campaign in June
2018
 Potential sediment concentration : expert-rule from Evrard et al. (2008)
 Imbibition rainfall updated with measured runoff height and debits

7. 7
Measurements

8. 8
Runoff

9. 9
Erosion

10. 10
Erosion

11. 11
Conclusion
• Rainfall selection = 92 % of the erosivity in the model
• Comparison between measured and modeled runoff volumes showed
very close correspondence. 3 events out of the adjustment for point1
 high quotient between rainfall amount and effective duration.
• Graduated rulers permitted to validate modeling at some locations in
the watershed. The comparison for the 15 measurement zones was
satisfying even if standard deviations of measurements and modeling
remained high.
• Field limits did not seem to have big impact on amount of eroded and
deposited particles. But it played a role in the transport acting as a
channel for small erosion rates lower than 0.5 T/event or around.
• For our study, land use, field allocations and linear features positions
showed strong influence in the erosion amount.