Presentation by Sam de Roover, HydroLogic, The Netherlands, at the wflow - User Day (Developments in distributed hydrological modelling), during Delft Software Days - Edition 2019. Friday, 08 November 2019, Delft.

1. Wetland restoration
modelling
A case study in the German
Middle Mountains

2. Contents
• Introduction
• Methods - 3 stage
rocket
• Results
– Stage 1: micro scale
analysis
– Stage 2: translation
– Stage 3: macro scale
analysis
• Conclusions

3. Wetland restoration - the idea
• Restoration of wetland
areas in valleys of
German Middle
Mountains
• Remove constructed
drainage networks
• Change surface water
flow regime:
– increase storage
– retain water
– slow down discharge
• Potential area: 7% of
highlighted areas ->

4. Introduction project
• The impact of wetland
restoration measures
• Peak flow reduction
• German Middle
Mountains
• Small time scale for
project: Assess the
potential

5. 3-stage rocket
1. Microscale
SWAT+ model
2. Translation
3. Macroscale
wflow_sbm model
SWAT+ model
Kylldal
wflow
Kylldal
wflow
Rhine + Mosel

6. First stage: methods micro scale
SWAT+ model (Acacia)
• Change in land cover and stream
characteristics
– Vegetation flood plain
– Stream characteristics
• increase width
• decrease depth
• increase roughness
coefficient
SWAT+ model
Kylldal
wflow
Kylldal
wflow
Rhine + Mosel

7. First stage: results micro scale
• Lower peak flows
• Increase in baseflow
recessions
• Increase of low flows
(less drought risk)

8. Second stage: methods translation
• wflow_sbm - existing model Rhine area
• Sensitivity analysis
• Comparison statistics SWAT+ <-> wflow
• Wetland effect:
200% increase
Manning
coefficient
SWAT+ model
Kylldal
wflow
Kylldal
wflow
Rhine + Mosel

9. Third stage: methods macro scale
wflow_sbm
• 7% of area fit for
restoration
• We looked at cells:
– Within selected
area
– Contains stream
order 2
– Random number
to get to 7%
• Change Manning
coefficient for
those cells
SWAT+ model
Kylldal
wflow
Kylldal
wflow
Rhine + Mosel

10. Third stage: results macro scale
Results on frequency of high discharges
MoselRhine

11. Overview assessment effects of wetland
restoration
Kylldal Mosel Rhine
Wetland
restoration
intensity
45 % 50 % 50 %
Annual maximum
peak discharge
change
-13 % -2.9 % -1.1 %
Annual 95th
percentile change
-3 % -0.9 % -0.1 %
Annual median
change
9 % 0.6 % 0.1 %

12. Conclusion use of wflow in the project
• Use existing model to assess impact of
large scale measure.
1. Translation
2. Calibration
3. Wetland modelling
wflowMicroscale model
Wetland restoration
effects
New map data
1
2 3
Discharge

13. Wetland restoration
modelling
A case study in the German
Middle Mountains