Author(s): Xudong Fu; Liwei Jiang; Baosheng Wu; Guangqian Wang; Chunhong Hu
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Keywords: Lower Yellow River; Optimization; Sediment delivery ratio; Reservoir regulation; Flood event; In-stream flow; Sediment load
Abstract: The Lower Yellow River is characterized by heavy sediment load that results in a naturally aggrading and suspended river. Great concerns have been raised in recent years on prevention from flood hazard and river aggradation. One of the great challenges is how to design an optimized series of water and sediment discharges that could be generated from the Xiaolangdi Reservoir during the flood season and result in minor aggradation in the downstream reach. To meet this need, an optimization approach was proposed based on the properties of flood events that transport the majority of sediment load. An objective function was designed to minimize the in-stream flow volume needed to transport a given sediment load during the flood season, being subject to constraints including allowable sediment deposition, total sediment load transported, and the sediment delivery ratio that relates sediment deposition to inflowing sediment load carried by a flood event. An example was then presented for the Lower Yellow River to quantify the minimum in-stream flow volume that maintains the bank-full discharge of 4000 m3/s at the current stage. The effects of uncertainty in quantifying sediment transport were finally explored. The probability density distribution of the minimum in-stream flow volume was found to have a positive-skewed profile in the case where the two parameters in the sediment delivery ratio formula for non-overbank flood event took a uniform or triangular distribution.
Year: 2009