infiltration and soil erosion modelling on lausatian … · 2018. 4. 17. · into soil ersion model...
TRANSCRIPT
Results of rainfall experiments
(overview):
INTRODUCTION
Reclaimed lignite mine sites require long-term and safe structuring of
recultivation areas. Lignite burden dumps contain hydrophobic
substances that cover soil particles. Consequently, these soils show
strong water repellency, which influences the processes of infiltration.
Erosion by water leads to explicit soil losses, especially on heavily
endangered water repellent and non-vegetated post mining soil
surfaces. Erosion processes are involved in acidification of surface
waters by input of pyrite containing sediment.
INFILTRATION AND SOIL EROSION MODELLING ON LAUSATIAN POST MINE SITES Franziska Kunth, Jürgen Schmidt TU Bergakademie Freiberg | Soil and water conservation unit | Agricolastraße 22 | 09599 Freiberg | Phone: 03731 / 39- 2679 | [email protected] | EGU Vienna 2013
Study site 1
Study site 2
Study site 3
Rainfall intensity [mm/min]
0.63 0.63 0.65
Endinfiltration [mm/min]
0.03 0.13 0.22
Runoff coefficient
0.87 0.66 0.29
Mean sediment concentration [g/l]
27.1 29.4 0.74
Net Erosion [t/ha]
2.8 2.1 0.03
PRELIMINARY RESULTS
Measured infiltration rates on non-vegetated water repellent sites were
extremely low. Therefore, a newly developed water repellency-factor
(calibration factor Fphob) was applied to depict infiltration and erosion
processes on water repellent dump soils. For infiltration modelling with
EROSION 2D/3D calibration factors (e.g. water repellency factor, skin-
factor, etc.) were determined in different steps by calibrating computer
modelled infiltration, respectively volume rate of flow to the measured
data.
Computer model
Model input-parameters:
Relief data (DEM)
Rainfall data
(duration, intensity)
Soil parameters
(e.g. bulk density, grain size
distribution, calibration factors,
etc.)
REFERENCES
Schmidt, J. (1991) A mathematical Model to Simulate Rainfall Erosion. Catena Supplement (19) 101-109 / Schmidt, J. (1992) Modeling long term soil loss and landform change. A.J. Parson and A.D. Abrahams (eds.) Overland flow - Hydraulics and Erosion
Mechanics. UCL Press. London. 409-433 / VON WERNER, M. (1995): GIS-orientierte Methoden der digitalen Reliefanalyse zur Modellierung von Bodenerosion in kleinen Einzugsgebieten. Dissertation Thesis, Freie Universität Berlin, Berlin / SCHINDEWOLF, M. &
SCHMIDT, J. (2012): Parameterization of the EROSION 2D/3D soil erosion model using a small-scale rainfall simulator and upstream runoff simulation, in: Catena 91, p. 47–55
Rainfall experiments on reclaimed lignite mine sites
- Event and raster-based physical soil erosion model (cellular automata
type) (Schmidt, 1991, 1992; v. Werner, 1995)
- Prediction of runoff and particle detachment, transport and deposition
- Infiltration modelling according to GREEN&T (1911) approach
- Momentum flux approach by SCHMIDT (1996) describes particle
detachment and transport
- Validation of newly implemented calibration factor Fphob within this study
Study site 1 Study site 2 Study site 3
Non vegetated
Strongly water repellent
Soil crust
Water repellent
Vegetated
Non water repellent
METHODS
Influence of water repellency had to be considered and implemented
into soil ersion model EROSION 3D. Validation of new E3D-calibration
factor Fphob within this ongoing study. Required input data for soil erosion
modelling (e.g. physical soil parameters, infiltration rates, calibration
factors, etc.) were gained by soil sampling and rainfall experiments.
STUDY AREA
Non-vegetated as well as recultivated reclaimed mine sites in the
Lusatia lignite mining region (southeast of Berlin, Germany)
Rainfall simulator
- Three linked rainfall modules (height: 2 m, plot size: 3x1 m) with
oscillating nozzels
- Collection of runoff and sediment (SCHINDEWOLF, 2012)
OBJECTIVE
- Reliable assessment of soil erosion risks in post mining sites
- Modelling of effectiveness of different recultivation scenarios
- Model-based approach to conceptions of near-surface slope protection
measures as a result of this ongoing study
0,00
0,10
0,20
0,30
0,40
0,50
1 6 11 16 21 26 31 36 41 46 51 56 Rainfall duration [min]
Infiltra
tio
n [m
m/m
in]
Calibration of calculated infiltration rates by
water repellency factor
Infiltration [mm/min]: ● Rainfall experiment ― Simulation (with skin-factor) --- Simulation (with skin-factor and water repellency factor)
Effect of water repellency
CONCLUSION
Infiltration and runoff experiments on non-vegetated reclaimed lignite
mine sites showed that water repellency reduces infiltration to a
minimum. Wetting front infiltrates only few millimetres after 1 hour of rain
with an intensity of 0.6 mm/min (See figure “Study site 1”). Soil erosion
model EROSION 2D/3D is able to depict infiltration processes that are
limited by water repellency by using the new implemented water
repellency factor Fphob.
Results will be used for modelling different (recultivation) scenarios and
assessment of erosion risks of reclaimed lignite mine sites.
Model output-parameters:
Spatial parameters
(Erosion, Deposition, Sediment
concentration, Net erosion, etc.)
Cross section parameters
(Surface runoff volume, Outflow
from the catchment, Sediment
output from the catchment)