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Open AccessArticle

Experimental Investigation of Flood Energy Dissipation by Single and Hybrid Defense System

1
Faculty of Civil and Environmental Engineering, University of Engineering & Technology Taxila, Rawalpindi 47080, Pakistan
2
Civil Engineering Department, College of Engineering, Qassim University, Al-Mulida 51431, Saudi Arabia
*
Author to whom correspondence should be addressed.
Water 2019, 11(10), 1971; https://doi.org/10.3390/w11101971
Received: 15 July 2019 / Revised: 13 September 2019 / Accepted: 17 September 2019 / Published: 21 September 2019
(This article belongs to the Section Hydraulics and Hydrodynamics)
In this study, a series of laboratory experiments were conducted to investigate the energy loss through the hybrid defense system (HDS) in the order of dike, moat, and emergent vegetation in steady subcritical flow conditions. The results of HDS were compared with a single defense system (SDS) comprising only vegetation (OV). The dimensions of dike were kept constant while two different shapes (trapezoidal and rectangular) of moat were considered. The impacts of vegetation of variable thickness and density were investigated. Two combinations of HDS were investigated including the combination of dike and vegetation (DV) and the combination of dike, moat, and vegetation (DMV). The effect of backwater rise due to the vegetation, hydraulic jump formation and the impact of the arrival time of floodwater on energy dissipation were investigated. It was observed that on the upstream side of obstructions, the backwater depth increased by increasing the Froude number in both the SDS and HDS. The hydraulic jump observed in HDS was classified and the energy dissipation due to it was calculated. Under various conditions investigated in this paper, the maximum average energy dissipation was 32% in SDS and 46% in HDS. The trapezoidal moat performed better than rectangular moat as energy dissipater. The delay time was also greater with trapezoidal moat as compared to that in rectangular one. The maximum delay time was 140 s in the case of HDS. Hence, the hybrid defense system offered maximum resistance to the flow of water, thus causing a significant energy loss. For each case of SDS and HDS, empirical equations were developed by regression analysis to estimate the energy dissipation amounts. View Full-Text
Keywords: floods; defense system; vegetation; dike; backwater rise; hydraulic jump; energy reduction floods; defense system; vegetation; dike; backwater rise; hydraulic jump; energy reduction
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MDPI and ACS Style

Ahmed, A.; Ghumman, A.R. Experimental Investigation of Flood Energy Dissipation by Single and Hybrid Defense System. Water 2019, 11, 1971. https://doi.org/10.3390/w11101971

AMA Style

Ahmed A, Ghumman AR. Experimental Investigation of Flood Energy Dissipation by Single and Hybrid Defense System. Water. 2019; 11(10):1971. https://doi.org/10.3390/w11101971

Chicago/Turabian Style

Ahmed, Afzal; Ghumman, Abdul R. 2019. "Experimental Investigation of Flood Energy Dissipation by Single and Hybrid Defense System" Water 11, no. 10: 1971. https://doi.org/10.3390/w11101971

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