Assessment of the impacts of dynamic soil properties and vegetation
cover on soil erosion using distributed hydrological model
Tan
1
Zi ,
Ciaran
2
Lewis ,
Gerard
2
Kiely ,
and John D.
GC11A-0968
1
Albertson
1.Civil and Environmental Engineering, Duke University, Durham, US
2.Civil and Environmental Engineering, University College Cork, Cork, Ireland
Contact Information
Tan Zi tan.zi@duke.edu
I. Introduction
III. Scenarios
Soil erosion is a common environmental problem in certain mountainous
regions. Heterogeneity of soil properties and complex vegetation-soil
interactions raise challenges in accurately simulating soil erosion
processes.
Six scenarios were selected to investigate the impacts of soil and vegetation.
Time
Soil Erosion
+
+
Soil
Degradation
BVS2=B+V+S2
BVS1=B+V+S1
BV=B+V
BS2=B+S2
BS1=B+S1
B
Vegetation
Loss
Fig.1 Positive feedbacks of soil erosion
VI. Conclusion and Application
The erosion model was tested at an experimental watershed in Ireland.

Area:1542 ha

AAP:1400mm

Vegetation: perenial ryegrassland

Soil: gleys/podzols

Measurement: Flux tower, flow gauge,
and water sampler
Fig.8 The DEM map of Dripsey watershed
• The erosion model has expected behavior on soil particles movement
by water on hillslope.
• The temporal changes of both soil properties and vegetation covers
have considerable impacts on soil erosion processes.
• Temporal changes of vegetation covers have dominant effects on soil
erosion simulations in short time simulation.
• Temporal changes of soil properties should be considered in long time
simulation, e.g. climate change application.
• The coupled soil and vegetation model has the best performance
compare with observed data, the spatial distribution of soil erosion
also improved in coupled model.
Fig. 4 Major components of erosion model
BS
+
+






V. Watershed Simulation
BS2
IV. 1D Hillslope Tests
The model was tested on a 1D hillslope. The driven meteorological data
were generated by Wather generator according to the climate condition
of experimental watershed. Three points were selected to show the soil
texture changes due to erosion and deposition processes applied on the
hillslope.
1. How to represent these feedbacks using modeling tools?
2. How important are those feedbacks in long term simulations?
Fig.11 Soil conservation(left) and sediment transport(right), images
acquired by using google search engine
II. Model Structure
GEOtop
VII. Future work
Typical Erosion
Module
• Vegetation dynamics
• Spatial verification
• Soil organic matter/nutrition losses by water erosion
• Estimate the impacts of soil properties on soil erosion under
climate change scenarios
D50
Fig.5 The soil texture changes at different locations during simulation
BS1
Fig.2 The structure of GEOtop model and typical soil erosion module
Fig.9 Simulated soil erosion/deposition map of Dripsey watershed of year 2002
In order to capture the influences of changing soil
properties on soil erosion, this model assumes a thin
detached soil layer lays on the top of soil column, and
this erosion process will occur on this layer.
S2
Key References
BS2
Scenarios
B
BV
BS1
BS2
BVS1
BVS2
BVS2
Fig.6 The time series of soil erosion rate(E) of different scenarios
NS
0.8807
0.8795
0.8802
0.8806
0.9477
0.9477
1. Rigon, R., Bertoldi, G. & Over, T. M. GEOtop: A distributed hydrological model
with coupled water and energy budgets. J Hydrometeorol 7, 371-388 (2006).
2. Govers, G. Empirical relationships for the transport capacity of overland
flow. Erosion,Transport and Deposition Processes 189, 45-63 (1990).
3. Everaert, W. Empirical Relations for the Sediment Transport Capacity of
Interrill Flow. Earth Surf Proc Land 16, 513-532 (1991).
4. Lewis, C. Phosphorus, Nitrogen and Suspended Sediment loss from Soil to Water
from Agricultural Grassland Master of Engineering Science thesis, University
College Cork, (2003).
Fig.10 Normalized cumulative soil loss of different scenarios
Acknowledgement
Tab.1 Annual soil erosion of Dripsey watershed
S1
E (kg/ha)
Fig.3 The structure of dynamic soil properties module
Fig.7 Normalized cumulative soil losses of different scenarios
BS1
111.2742
BS2
110.9986
BVS1
60.8619
BVS2
60.86053
This study is part of the Science, Technology, Research and Innovation for the
Environment (STRIVE) Programme 2007-2013. We are appreciative of the
financial support of Irish Government under the National Development Plan
2007-2013.