11th International Drainage Symposium August 30-September 2, 2022 Des Moines, Iowa

1. 2022 IDS Oral Presentation
R Caleb Bruhn, Jorge Guzman, Prasanta K Kalita, Richard A Cooke
Seepage Considerations
in Drainage Canal Design
for Groundwater Quality

2. Why is it important to
consider seepage in
drainage ditch design?
Introduction

3. Surficial aquifers are important
Fresh groundwater withdrawals in Iowa, Michigan, Minnesota, and
Wisconsin during 1985, million gallons per day (USGS, 2000)
Surficial aquifer system – 1,495
Cretaceous aquifer – 87
Pennsylvanian aquifer – 88
Mississippian aquifer – 67
Silurian–Devonian aquifer – 224
Upper carbonate aquifer – 20
Cambrian–Ordovician aquifer system – 548
Jacobsville and crystalline-rock aquifers – 16
Fresh groundwater withdrawals in Illinois, Indiana, Kentucky, Ohio, and
Tennessee during 1985, million gallons per day (USGS, 2000)
Surficial aquifer system – 1,488
Mississippian embayment aquifer system – 308
Pennsylvanian aquifers – 164
Mississippian aquifers – 71
Silurian–Devonian aquifer – 488
Ordovician aquifers – 45
Cambrian–Ordovician aquifer system – 396
Blue Ridge aquifers – 12

4. Surficial aquifers are being polluted
Kumar, 2017
Tang et al., 2021
Ouedraogo et al., 2016
Blocks (%) in District reporting
groundwater nitrate > 45 ppm

5. Agricultural drainage is one source

6. Often, through canal seepage

7. How does canal
shape affect
seepage rate?
d = water depth in canal
s = bank slope horizontal
w = ½ water surface width

8. Field work in Sierra Leone
Njala University

9. The local context

10. Conceptual Model

11. Numerical analysis using
finite element discretization
Method

12. HYDRUS 2D/3D simulations
d = water depth in canal
s = bank slope horizontal
w = ½ water surface width
Hydraulic
radius (m)
Wetted Perimeter &
Cross-section Area
Bank slope
(#H:1V)*
*H - Horizontal, V - Vertical
R = 0.354
P = 2.828 m
A = 1.0 m
2 1
R = 0.447
P = 4.472 m
A = 2.0 m2 2
P = 3.578 m
A = 1.6 m2 1
R = 0.474
P = 6.325 m
A = 3.0 m
2 3
P = 4.743 m
A = 2.25 m2 2
P = 3.795 m
A = 1.8 m2 1

13. Surprising behavior!
Results

14. Seepage not function of R alone
[CELLRANGE]
[CELLRANGE] [CELLRANGE]
10.0
11.0
12.0
13.0
14.0
15.0
16.0
1 2 3
Water
table
location
below
ground
surface
(cm)
Nominal bank slope ( _H:1V)
Canals with Hydraulic Radius = 0.474 m
Triangle Trapezoid Rectangle
[CELLRANGE]
[CELLRANGE]
10.0
11.0
12.0
13.0
14.0
15.0
16.0
1 2 3
Water
table
location
below
ground
surface
(cm)
Nominal bank slope ( _H:1V)
Canals with Hydraulic Radius = 0.447 m
Triangle Trapezoid Rectangle
[CELLRANGE]
10.0
11.0
12.0
13.0
14.0
15.0
16.0
1 2 3
Water
table
location
below
ground
surface
(cm)
Nominal bank slope ( _H:1V)
Canals with Hydraulic Radius = 0.354 m
Triangle Trapezoid Rectangle

15. Seepage not function of A, P alone
11.0
11.5
12.0
12.5
13.0
13.5
14.0
14.5
15.0
15.5
16.0
1 1.2 1.4 1.6 1.8 2 2.2 2.4 2.6 2.8 3
Water
table
location
below
ground
surface
(cm)
Area (m2)
Influence of cross-sectional area
Triangle
Trapezoid
Rectangle

16. 11.0
11.5
12.0
12.5
13.0
13.5
14.0
14.5
15.0
15.5
16.0
0.600 1.100 1.600 2.100 2.600 3.100
Water
table
location
below
ground
surface
(cm)
(m)
Influence of canal surface width
Triangle
Trapezoid
Rectangle
Seepage not function of width alone

17. 11.0
11.5
12.0
12.5
13.0
13.5
14.0
14.5
15.0
15.5
16.0
0.500 0.600 0.700 0.800 0.900 1.000 1.100 1.200 1.300 1.400
Water
table
location
below
ground
surface
(cm)
(m)
Influence of water depth in canal
Triangle
Trapezoid
Rectangle
Seepage not function of depth alone
Size of data point
corresponds to
cross-section area

18. Do these results match
others’?
Why does this pattern
occur?
Discussion

19. Others’ Work

20. Circular Arc
𝑧 ∝
𝜋 − acot 𝑆 × 𝑃𝑠𝑙𝑜𝑝𝑒 + 𝜋 × 𝑃𝑓𝑙𝑎𝑡
𝑃𝑡𝑜𝑡𝑎𝑙
11
12
13
14
15
16
11 12 13 14 15 16
Predicted
water
table
depth
(cm)
Actual water table depth (cm)

21. Conclusions

22. Conclusions
• Shape changes seepage rate by changing the streamline paths
• This changes the head loss: Ernst’s concept of “radial resistance”
• The difference in seepage can result in almost 3 cm difference in the
steady state location of water table midway between canals

23. Acknowledgements
• College of ACES International Graduate Research Grant
• Dr. Richard Cooke
• Richard Williams
• Navo

24. References
Bouwer, H. (1965). Theoretical Aspects of Seepage from Open Channels. Journal of the Hydraulics Division, 91(3), 37–59.
https://doi.org/10.1061/JYCEAJ.0001259
Feick, S., Siebert, S. and Döll, P. (2005): A Digital Global Map of Artificially Drained Agricultural Areas. Frankfurt Hydrology Paper 04,
Institute of Physical Geography, Frankfurt University, Frankfurt am Main, Germany
Jägermeyr, Jonas & Gerten, Dieter & Heinke, Jens & Schaphoff, Sibyll & Kummu, Matti & Lucht, W. (2015). Water savings potentials of
irrigation systems: Global simulation of processes and linkages. Hydrology and Earth System Sciences. 19. 3073-3091.
10.5194/hess-19-3073-2015.
Kumar, M. D. (2017). Market Analysis: Desalinated Water for Irrigation and Domestic Use in India. U.S. Global Development Lab.
http://rgdoi.net/10.13140/RG.2.2.25518.72006
Ouedraogo, I., Defourny, P., & Vanclooster, M. (2016). Mapping the groundwater vulnerability for pollution at the pan African scale.
Science of The Total Environment, 544, 939–953. https://doi.org/10.1016/j.scitotenv.2015.11.135
Richts, A., Struckmeier, W. & Zaepke, M. (2011): WHYMAP and the Groundwater Resources of the World 1:25,000,000. In: Jones J.
(Eds.): Sustaining Groundwater Resources. International Year of Planet Earth; Springer. doi: 10.1007/978-90-481-3426-7_10
Swamee, P. K., Mishra, G. C., & Chahar, B. R. (2000). Design of Minimum Seepage Loss Canal Sections. Journal of Irrigation and
Drainage Engineering, 126(1), 28–32. https://doi.org/10.1061/(ASCE)0733-9437(2000)126:1(28)
Tang, F. H. M., Lenzen, M., McBratney, A., & Maggi, F. (2021). Risk of pesticide pollution at the global scale. Nature Geoscience, 14(4),
206–210. https://doi.org/10.1038/s41561-021-00712-5
U. S. Geological Survey. (2000). Ground Water Atlas of the United States. In Hydrologic Atlas (No. 730). U.S. Geological Survey.
https://doi.org/10.3133/ha730

25. Thank you!
Questions