Presentation by Shaimaa Abd Al-Amear Theol, IHE Delft Institute for Water Education, The Netherlands, at the Delft3D - User Days (Day 1: Hydrology and hydrodynamics), during Delft Software Days - Edition 2018. Monday, 12 November 2018, Delft.

1. SIMULATING SEDIMENT TRANSPORT IN
IRRIGATION SYSTEMS USING DELFT3D
Case study: Gizera irrigation scheme, Sudan
Shaimaa A. Theol
Bert Jagers*
Suryadi, Charlotte de Fraiture
*Deltares

2. PRESENTATION OUTLINE
• PROBLEM STATEMENT
• JUSTIFICATION
• STUDY AREA
• METHODOLOGYAND CHALLENGES
• SCENARIOS
• RESULTS
• CONCLUSIONS
• RECOMMENDATIONS

3. PROBLEM STATEMENT
Sedimentation is a major problem in irrigation
systems since it may cause:
• Raising canals bed levels
• Disruption of water distribution - “ unfair water
distribution”
• Blockage of outlets
• Structure functions elimination
• High maintenance costs for sediment removal

4. JUSTIFICATION
• Typically 1D models are used to study
irrigation canals as they are computationally
most efficient;
• The use of 2D model has been chosen to study
sediment patterns near offtakes and
structures in more details.
Other studies
and models
Delft3D
model
Cohesive and non-
cohesive
Multi-dimensions
(2D, 3D) models
Networks (DD) tool
Operations practice
(RTC) tool
Non-cohesive
sediment mostly
1D models

5. STUDY AREA
Zanada, width = 6m, length=17 Km, S=0.00002, SS=1:1, there are weirs and two contractions.
Toman, width=2 m, length=6 Km, S=0.00001, SS=1:1 with gate

6. METHODOLOGY AND CHALLENGES
• Getting the details of case study from Google Earth, data was in spherical
coordinates.
• Constructing the grid with coarse resolution where the selected canals have a
small width.
• Validate Delft3D with other 1D-model which is used in irrigation canals.
• Adapting wall roughness for the canals.
• Using DD tool close to the area of interest to avoid the long simulations periods.
• Applying different scenarios.

7. SCENARIOS
• Reference case (gate full open, weir1=weir2=0.3 m)
• Upstream weir (raising and lowering the weir height)
• Downstream weir (raising and lowering the weir height)
• Fixed gate openings (0.2, 0.4, 0.6, 0.8) m.
• Operation (Plan 1 and Plan 2)

8. RESULTS

11. Cont. Results
(-): The reduction in
sediments deposition, (+):
The increase in sediments
deposition.
1 = strongly not satisfied,
2= poor, 3= satisfied, 4=
quite satisfied, 5=
strongly satisfied
Scenarios Description
Main Branch Meeting
Cohesive Non-cohesive Cohesive Non-cohesive CWR
Scenario 2 Weir effects
Upstream weir
w1=0 -0.50% -0.50% No change No change 5
w1=0.6 1% 1% 2% 2% 4
Downstream
weir
w2=0 No change No change 3% 3% 4
w2=0.6 No change No change -12% -12% 5
Scenario 3 Gate effect
Fixed gate height
g=0.2 4% 4% -99% -99% 1
g=0.4 4% 4% -96% -96% 2
g=0.6 3% 3% -71% -71% 3
g=0.8 1% 1% -19% -19% 4
Operation
Plan1 -0.10% -0.10% No change No change 5
Plan2 3% 3% -54% -55% 4

12. G=0.2 m G=0.8 m Plan 1 Plan 2

13. Conclusions
• Delft3D 4 has been helpful in the analysis, however, I had to use a
rather coarse model to keep run times acceptable.
• The position of the controlled weirs has a significant influence on their
effectiveness.
• By adjusting the gate of the branch canal depending on the upstream
discharge I was able to meet (CWR) in a satisfactory manner while
significantly reducing the overall sedimentation.
• For variable sediment concentrations, OP2 is vital to be used. The gate
can be closed when high concentrations enter the canals and opened
with less concentrations.

14. Recommendations
• Delft3D 4 can be efficiently used in simulations of sediment transport
in irrigation systems.
• For future studies I propose to use the Delft3D FM Suite as it will
allow to keep run times short by using 1D mode for the long straight
canals while simulating the areas of interest at higher resolution in 2D
or 3D.

15. THANK YOU FOR YOUR ATTENTION