Numerical Investigations of Flood Level Reduction via Securing Lateral River Space for Extreme Flood

Mountain Flood Control Reservoir (MFC Reservoir) is used to reduce the flood level in the mountainous area and protect settlements downstream. The special feature of this MFC Reservoir is the fast filling during 1-2 days, short storage time at the maximum level and speed falling of the water level. Simulation of the MFC Reservoir operation was carried out on the software Midas GTS NX. Two rockfill dam models were developed: with the core and with the screen. The fluctuation of the water level in the MFC Reservoir was taken as the transformed flood from 1% to 10% probability. The fast water level change in the MCF Reservoir creates the transient seepage condition during the flood. During the water level rising in the MFC Reservoir, the upstream slope stability gradually increases because of hydrostatic pressure. After the water level begins to fall with rate of 0.7 m/hour, the slope stability decreases. The core or screen location significantly affects the stability of the upstream dam slope. The simulation showed that the upstream slope of the dam with the core was more stable. Due to the high hydraulic conductivity, the upstream dam prism with the berm significantly dampens the pore pressure in the dam and increases the stability of the upstream slope.

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Investigating an Innovative Sea-Based Strategy to Mitigate Coastal City Flood Disasters and Its Feasibility Study for Brisbane, Australia

Water ◽

10.3390/w12102744 ◽

2020 ◽

Vol 12 (10) ◽

pp. 2744

Author(s):

Usman Khalil ◽

Shu-Qing Yang ◽

Muttucumaru Sivakumar ◽

Keith Enever ◽

Mariam Sajid ◽

...

Keyword(s):

Water Level ◽

Feasible Solution ◽

River Estuary ◽

Gate Operation ◽

Flood Peak ◽

Coastal City ◽

Flood Level ◽

Height Datum ◽

Level Reduction ◽

Management Operation

This study examines an innovative Coastal Reservoir (CR) technique as a feasible solution for flood adaptation and mitigation in the Brisbane River Estuary (BRE), Australia, which is vulnerable to coastal flooding. The study analysed the operation of a CR by using the MIKE 21 hydrodynamic modelling package. The 2D hydrodynamic model was calibrated and validated for the 2013 and 2011 flood events respectively, with a Nash-Sutcliffe coefficient (Ens) between 0.87 to 0.97 at all gauges. River right branch widening and dredging produced a 0.16 m reduction in water level at the Brisbane city gauge. The results show that by suitable gate operation of CR, the 2011 flood normal observed level of 4.46 m, with reference to the Australian Height Datum (AHD) at Brisbane city, could have been reduced to 3.88 m AHD, while under the improved management operation of the Wivenhoe Dam, the flood level could be lowered to 4 m AHD at Brisbane city, which could have been reduced with CR to 2.87 m AHD with an overall water level reduction below the maximum flood level. The results demonstrated that the innovative use of a CR could considerably decrease the overall flood peak and lessen flood severity in the coastal city of Brisbane.

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