Book Review on Flood Discharge and Sediment Transport of the Yellow River (by Pu Qi)

Recently, as an important book of Henan Province sponsored by the publishing fund of Managing the Yellow River from the Yellow River Conservancy Commission, China, Flood Discharge and Sediment Transport Positional of the Lower Yellow River and Development of an Efficient Flood Discharge Channel, was officially published by Yellow River Conservancy Press. Former Minister of the Ministry of Water Resources, China, Mr. Wang Shucheng, former Deputy Director of Chinese Academy of Engineering, Mr. Pan Jiazheng, and former Director of Yellow River Conservancy Commission, Mr. Li Guoying, wrote prefaces for this book, respectively.

The Yellow River, the second largest river in China, is well known as a highly sediment-laden river. The average annual sediment inflow entering the Lower Yellow River is 1.6 billion tons. Every year, there are around 400 million tons of sediment deposited on the lower reach of the Yellow River, which results in raising of river bed with a speed of 10 cm per year. Unbalanced relationship between water and sediment with less water but more sediment is the outstanding issue of the Yellow River. The main direction of managing the Yellow River should focus on developing a harmony relationship between water and sediment. With the implementation of Water and Soil Conservation Project of the Loss Plateau, sediment that comes into Yellow River can be reduced significantly. At the same time, how to make full use of the sediment transport characteristics of the hyperconcentrated flood, and the potential sediment transport capacity of the natural channel to transport as much sediment as possible to sea, becomes the key technical issue when dealing with the hyperconcentrated flood.

There are four parts, seventeen chapters in total in this book. It demonstrates the research results of one decade from the 1980’s to the operations of Xiaolangdi Reservoir, as the followings:

1.        Part One (five chapters) introduces flood discharge/sediment transport characteristics and potentials of the narrow and deep channel. With the analysis on the mechanism and the condition of a phenomenon called “the more sediment comes in, the more sediment will be transported.”,  it also explains the dynamics and evolution rules of the hyperconcentrated flood, reasons for abrupt increase of flood peaks, friction characteristics of hyperconcentrated flow, influences of the change in sediment concentration and energy slope on sediment transport, erosion during rising and deposition during falling of a flood event in an alluvial river, and reasons for the powerful flood discharge and sediment transport capacity of narrow and deep channel.

2.        Part Two (two chapters) illustrates the principles of variation in the meandering reaches, and conditions of the river pattern transformation, and it provides methods to regulate the meandering reaches.

3.        Part Three (four chapters) explains the key technologies of flow and sediment regulation by the reservoir, application rules and control conditions of multi-year sediment regulations,   mechanical properties of reservoir sediment, possibilities that the hyperconcentrated flood can be created during reservoir emptying, flow and sediment regulation by combined reservoir operations, results of the reduced sediment deposition after multi-year sediment regulations, and the amount of water required for sediment transport that can be saved.

4.        Part Four (four chapters) explains the outstanding issues in harnessing meandering reaches, causes for the secondary suspended river, analysis on whether the production dykes should be demolished or not, comparisons of the pros and cons between various river training plans, and the necessities of two-bank training. It also provides theories and technologies of how to construct an efficient channel for flood discharge and sediment transport.

5.        Chapter 16 analyzes the favorable condition of transporting sediment of Yellow River to the ocean by floods.

6.        Chapter 17 illustrates the bright prospects of managing the lower Yellow River channel.

This book summaries the author’s research results for years, and it illustrates in greater details the fundamental characteristics of the hyperconcentrated flood, and the analysis on comparing the field data collected along the main stem and tributaries. From the results of this study, the channel with narrow and deep shape was found suitable for transporting hyperconcentrated flow. The necessity of developing the hyperconcentrated flood was also proposed. With the research on the operation mode of Xiaolangdi Reservoir, the authors proposed “sediment should be regulated on a multi-year basis, and it should be released at the right time”, and they proved the feasibility of creating hyperconcentrated flood by combined reservoir operations. Sediment in Yellow River comes from the floods, so let the floods carry it away is the best solution. If we can make full use of sediment transport by flood, even when Xiaolangdi Reservoir cannot be used for flushing sediment by clear water, the downstream channel can still be scoured. With the research on regulations of meandering reaches in the lower Yellow River, the authors proposed the two-bank training strategy to stabilize the main channel, and they studied on developing an efficient flood discharge and sediment transport channel.

This book analyzed the new problems and significant changes of the lower Yellow River channel after the operations of Xiaolangdi reservoir for a decade. Since October, 1999, when Xiaolangdi Reservoir began operations for storing sediment, creating flood to scour downstream channel, the total amount of sediment that was scoured in the downstream channel has reached 1.3 billion m³. The water surface elevation in the channel upstream of Gaocun has decreased 2 m for the same discharge. Bankfull discharge at Gaocun has reached 5,300 m³/s or more. The water depth also reduced 1 m in the channel downstream of Aishan. But the river reach upstream of Jiahetan is still shallow and wide, which needs two-bank regulation urgently to develop a narrow and deep channel. The operations of this reservoir is also creating beneficial conditions for the multi-year sediment regulations, sediment transport into the ocean by flood, and the non-rising of the river bed elevation. If the above regulation measures can be successful, then the outstanding issues of the Yellow River, the so-called “unbalanced relationship between water and sediment with less water but more sediment” can be totally overcome.

The Yellow River is the most sediment-laden and the most difficult river to manage in the world, yet there is great hope to harness it. The publication of this book clearly points out the most crucial points for managing the downstream Yellow River channel. If the proposed multi-year sediment regulations and an efficient flood discharge and sediment transport channel in the lower reach can be achieved, the complete removal of the flood hazards, the development of the water resources and the control of the downstream channel will all be accomplished. The appendix of this book contains seven important documents, including the proposal by ten Chinese Academy of Science and Engineering members, with Mr. Pan Jiazheng, and etc. in 1996.

The preface by Mr. Wang Shucheng emphasized the necessary technical measures to achieve the non-river bed rising of the lower Yellow River. The preface by Mr. Pan Jiazheng emphasized the four major problems that need to be overcome for managing the lower Yellow River channel. The preface by Mr. Li Guoying underlined the important research results obtained by the author throughout years, and at the same time he indicated that some views and opinions in this book are still in debate at the theoretical and practical level of studying the Yellow River issues. In the postscripts of this book, the author introduced how the understandings of the Yellow River were developed throughout the years, and he pointed out the reason that the management measures can not be applied for the Yellow River is, traditional river managers do not want to recognize the powerful sediment carrying capacities of the lower Yellow River in reality. If they admit this, the famous saying of “less water but more sediment” will not hold any more! This will definitely shake the theoretical foundations of the traditional river management strategies on the Yellow River!