Effect of Cascade Reservoirs on Flood Routing in the Hongshui River, Southern China

Kang Zhang,Wenming Zhang,Shaobo Wang,Yanyan Zhang,Shenguang Fang

doi:10.1051/matecconf/20152501012

Abstract

Hongshui River, with a length of 659 km and drainage area of 130,870 km 2 , is the upstream reach of Xijiang River, which is the dominant branch river of the Pearl River system in Southern China. There are 9 dams with a total storage capacity of 384.9×10 8 m 3 constructed on the Hongshui River and its upstream reach Nanpan River since 1980s (the annual water discharge of Hongshui River is 696×10 8 m 3 ). The water level of the 9 reservoirs is connected together, which causes the riverbed channelizing and the flood characteristic changing during the processes of flood routing. To study the effect of the cascade reservoirs on flood routing, 363 flood peaks data of two hydrologic stations on the Hongshui River during 1971–2007 are collected to analyze the flood characteristics changing before or after construction of the large dam Yantan. The flood peak travel time is the main factor which is taken into consideration in this study. Statistics results show: (1) The flood peak travel time which varies with flood magnitude shows different trends before and after construction of the Yantan dam; (2) the average flood peak travel time with a smaller flood magnitude ( P=50% ) is shorter in the post-Yantan dam period than in the pre-Yantan dam period. However, the flood peak travel time with a relatively larger flood magnitude (> Q P=50% ) has no obvious differences before and after the construction of Yantan dam.

Highlights

Dam construction can supply human fresh water, irrigation, navigation, hydropower generation, and can help human to control the flood and storage of sediment
The construction of dams disrupts the balance of natural rivers, which commonly cause a series of changes, such as water discharge or hydrology circles (Dynesius and Nilsson, 1994; Poff and Hart, 2002; Toping et al 2003), sediment load (Topping et al 2000), water quality (Poff et al 1997), ecological connectivity (Ward and Stanford, 1995; Whol 2004), river ecology (Ligon et al 1995), geomorphology (Turner 1971; Graf 2006), fluvial processes (Williams and Wolman, 1984), riparian plants (Turner and Karpiscak, 1980)
This study mainly focused on the Hongshui River, where 6 dams centralized are arranged on the reach whose length is approximately 420 km from Longtan dam to Qiaogong dam

Summary

Introduction

Dam construction can supply human fresh water, irrigation, navigation, hydropower generation, and can help human to control the flood and storage of sediment. The hydrological regime is a central important factor in river systems, which is taken much attention of researchers. Most researches focus on the magnitude, frequency, duration, timing, and rate of change of hydrologic regimes (Walker et al 1995; Magilligan and Graber, 1996; Poff et al 1997; Yang et al 2004; Magilligan and Nislow, 2005; Graf, 2006). How about the effect of dam construction on the propagation time of flood peak and flood magnitude? How about the effect of dam construction on the propagation time of flood peak and flood magnitude? How about the al-

Methods

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Discussion

Conclusion