Siavash Zamiran
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​Erosion and Scour Evaluation of Levees Due to Floodwall Overtopping

Southern Illinois University
2013-2015
​
Project Description:
Scours due to overtopping behind the floodwalls on levees undermine the wall and result in failures. Estimating the erosion rate is critical. The erosion rate depends on hydraulic parameters of overtopping flow, geometry, and soil parameters. In this research, different scaled levee-floodwall systems are constructed to investigate the erosion rate of levees. EFA and JET erosion tests are also conducted on similar soil material to identify methodologies that can link the lab tests with scaled levee-floodwall tests. Silty clay to low plastic clayey material with plasticity indices ranging from 0% to 40% was utilized in this research.
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Levee floodwall system before and after scouring test

Related Publications:

Scour Characteristics of Saturated Levees Due to Floodwall Overtopping
American Society of Civil Engineering, ​International Foundation Conference and Equipment Exposition. San Antonio, TX (IFCEE 2015)

Levee Erosion and Scour Potential Due to Floodwall Overtopping
XV Danube - European Conference on Geotechnical Engineering. Vienna, Austria.


Introduction:
Levees are earthen structures constructed across rivers or adjacent to lakes to protect lands while floods, storm surges and hurricanes occur. Due to global warming and changes in sea level and weather, the number and the intensity of these natural disasters have increased demand for more stable and stronger protection structures on the bank of the rivers. Levee failures during hurricane Katrina in 2005 in New Orleans are the famous classical examples. There were some other failure examples such as levee failures due to 2013 flooding in Sichuan province in China; Typhoon Morakat in Taiwan in 2008 (Chang et al.2011); the 2008 Hurricane Ike in the Caribbean Islands and Gulf Coast (Tirpak 2009); Midwest floods in the U.S. in 2008 (Villarini et al. 2011); Wilnis Flood in the Netherlands in 2003 (Baars 2004); the 1976 Belgium Flood (Elskens 1995); and the Hurricane Camille in Mississippi (Smith 2011).
 
Among various failure mechanisms that cause levee breaches, soil erosion is found to be one of the most important factors (Kamalzareet al. 2013, Seed et al. 2008). Predicting soil erosion and scour generation when overtopping happens is important in order to design stable levee and floodwalls. There have been numerous studies to investigate the erodibility of soils. Briaud et al. (2008) used Erosion Function Apparatus (EFA) test to measure the erodibility of the soils and afterwards by using Chen 3D software (Chen 2002), numerical simulations were performed on the levee to find out the velocity vectors in the overtopping water and the generated scour when the overtopping water impinges the levee. By analyzing the results from EFA test, an erosion chart to categorize erodibility of the soils was developed.  Hughes and Nadal (2009) studied the effect of combination of wave overtopping and storm surge overflow on the erosion and scour generation in levees. The study included hydraulic parameters and flow characteristics such as flow thickness, wave intervals, surge level above levee crown in analyzing scour development. According to the laboratory tests, empirical correlations related to average overtopping discharge were derived to analyze the resistance of levee against erosion. These equations could only fit to the situation similar to the experimental tests while they can give a reasonable estimation if applied to other conditions.
 
There are also some studies that investigated on the erosion mitigation methods. Johnson et al. (2013) performed laboratory test models on scaled levees to study the scour dynamics and the effect of scour protection measures on the generation of scour. Their results show that using different types of armoring on landside of the levee can decrease the amount of created scour. They also found out the equilibrium in scour width is obtained faster than the equilibrium in scour depth. Also, Li et al. (2012) studied the effect of overtopping on levee crests armored by roller compaction concrete using a full-scale experimental study. Their results show a more stable levee when they are armored.
 
The effect of soil specifications including plasticity index and compaction levels on scour generation on the crest and the body of the levee are also viable while there is a lack of comparable systematic data. In this study various tests were conducted on levees with various compaction and plasticity to identify scour rates and the results were compared to scour potentials concluded from Erosion Function Apparatus (EFA) tests.

REFRENCES
Baars, S. (2004). Peat Dike Failure in the Netherlands. Official Publication of the European Water Association (EWA).
Briaud, J., Chen, H., Govindasamy, A., Storesund, R. (2008). Levee erosion by overtopping in New Orleans during the Katrina Hurricane. Journal of Geotechnical and Geoenvironmental Engineering. 134 (5): 618–632.
Chang, T., Chen, S., Huang, S. (2011). Shelter effect evaluation of the willow works bank protection method: a case study for Beinn River Reach 2009 Typhoon Morakot event. Paddy and Water Environment. 11: 15-33.
Chen, H. C. (2002). Numerical simulation of scour around complex piers in cohesive soil. In: Chen, H.C., Briuad, J.L. (eds). Proc. 1st Int. Conf. on Scour of Foundations; November 17-20, 2002, Texas, United States. pp. 14-33
Elskens, F. (1995). Protecting Overflow Dikes for Controlled Flood Areas in Belgium. Proc. One-day conference: Inland Waterways and Flood Control; October 23, 1995, Brussels, Belguim. 11 pp.
Hughes, S.A., Nadal, N.C. (2009). Laboratory study of combined wave overtopping and storm surge overflow of a levee. Coastal Engineering.56: 244–259
Jang, W., Song, C. R., Kim, J., Cheng, A. H. –D., Al-Ostaz, A. (2011). Erosion Study of New Orleans Levee materials subjected to Plunging Water.Journal of Geotechnical and Geoenvironmental. 137:398-404.
Johnson, E. B., Testik, F. Y.,Ravichandran, N., Schooler, J. (2012). Levee scour from overtopping storm waves and scour counter measures. Ocean Engineering, 57:72-78.
Kamalzare, M., Han, T., McMullan, M., Stuetzle, C., Zimmie, T., Cutler, B., and Franklin, W. (2013) Computer Simulation of Levee Erosion and Overtopping. In: Meehan, C., Pradel, D., Pando, M.A., Labuz J.F. (eds).Proc. Geo-Congress at Stability and Performance of Slopes and Embankments; March 3-7, 2013, San Diego, United States. pp. 1851-1860.
Li, L., Pan, Y., Amini, F., Kuang, C. (2012) Full scale study of combined wave and surge overtopping of a levee with RCC strengthening system. Ocean Engineering.54:70–86
Seed, R. B., Bea, R. G., Athanasopoulos-Zekkos, A., Boutwell, G. P.,  Bray, J. D., Cheung, C., Cobos-Roa, D., Harder Jr. L. F., Moss, R. E. S., Pestana, J. M., Riemer, M. F.,Rogers,J. D. Storesund, R.,Vera-Grunauer,X.andWartman, J. (2008) New Orleans and Hurricane Katrina.III: The 17th Street Drainage Canal. Journal of Geotechnical and Geoenvironmental. 134:740-761.
Smith, M. (2011). Camille 1969: History of a Hurricane. University of Georgia Press.
Tirpak, S.M. (2009). United States army corps of engineers, Galveston district operational experiences and response to Hurricane Ike. Shore and Beach. 77 (2): 60–70.
Villarini, G., Smith, J.A., Baeck, M.L., Krajewski, W. (2011). Examining flood frequency distributions in the Midwest U.S. American water resources association. 47 (3): 447–4


Affiliations
•  Committee Member, ASCE GI Geophysics Committee, 2017-Present
•  Committee Member, ASCE GI Deep Foundations Committee, 2017-Present

•  Committee Member, ASCE GI Rock Mechanics Committee, 2016-Present
•  Member, American Society of Civil Engineering, 2015-Present
• Committee Member, Geomate Technical Program, 2015-Present
• Councilor-at-Large, Illinois State Academy of Science, 2017-2019
• Individual Member, Deep Foundation Institute, 2015-2016
•  Member, St. Louis Engineer Club, 2015-2017

•  President & Founder, Geo-Institute SIUE Student Chapter, 2015-2017
•  Member, Chi Epsilon National Civil Engineering Honor Society in the US, 2015-Present
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Siavash Zamiran, Ph.D., P.E.
Senior Project Engineer, Marino Engineering Asscoiates, Inc.