Long-term morphodynamic changes of a desert reach of the Yellow River following upstream large reservoirs' operation

Abstract China's Yellow River has experienced its dramatically decreasing trend for the flow discharge since the construction and operation of large reservoirs located upstream. This low flow regulation has triggered a severe aggradation of the Ulan Buh Desert channel of the Yellow River because the declining flow exhibits no capability to scour and carry away large amount input of desert sands from the Ulan Buh Desert. Twenty monitoring cross-sections documented the Ulan Buh Desert channel has experienced its increasing aggradational trend in conjunction with its lateral migration decreasing trend from 1966 to 2005, which is opposite to the normal pattern of aggradation with deepening or symmetrical infilling for a channel located downstream of a reservoir. The channel aggradation can also be identified two stages: slow aggradation and rapid aggradation. Slow aggradation is characterized by the channel bed elevation rising 9.5 cm on average between 1968 and 1985, which responded to the operation of the Liujiaxia reservoir. During this period, the flow discharge was similar to pre-dam flow conditions but the sediment transport reduced to half of its pre-dam value. Because of about 0.24 × 108 t of desert sands entering the channel from the Ulan Buh Desert annually, this dilute flow indicated not to scour the channel as expected, but contrarily to cause the channel aggraded. Rapid aggradation followed completion of the Longyangxia reservoir with the channel bed elevation rising by 73 cm on average between 1986 and 2005. In this period, the combined regulation of Liujiaxia and Longyangxia reservoirs has caused the flow discharge decreasing dramatically, which is more beneficial for accumulation of the desert sands (0.19 × 108 t yr− 1 on average) in the desert channel, and led to the channel aggradation rate accelerated rapidly.

[1]  Yoshiki Saito,et al.  Man's Influence on the Erosion and Transport of Sediment by Asian Rivers: The Yellow River (Huanghe) Example , 1987, The Journal of Geology.

[2]  Yoshiki Saito,et al.  Interannual and seasonal variation of the Huanghe (Yellow River) water discharge over the past 50 years: Connections to impacts from ENSO events and dams , 2006 .

[3]  N. Chien.  Changes in river regime after the construction of upstream reservoirs , 1985 .

[4]  Huang Hai.  MONITORING CHANGES OF NEARSHORE ZONES IN THE HUANGHE (YELLOW RIVER) DELTA SINCE 1976 , 2004 .

[5]  M. Wolman,et al.  Downstream effects of dams on alluvial rivers. , 1984 .

[6]  R. H. Meade,et al.  World-Wide Delivery of River Sediment to the Oceans , 1983, The Journal of Geology.

[7]  C. Park,et al.  Adjustment of river channel capacity downstream from a reservoir , 1974 .

[8]  E. Stanley,et al.  Channel adjustments following two dam removals in Wisconsin , 2003 .

[9]  Tao Wang,et al.  The effect of the coarse aeolian sand on siltation of the Inner Mongolian Reach of the Yellow River , 2003 .

[10]  A. Brookes.  Challenges and objectives for geomorphology in U.K. river management , 1995 .

[11]  L. James.  Channel incision on the Lower American River, California, from streamflow gage records , 1997 .

[12]  Avijit Gupta,et al.  Effects of high‐magnitude floods on channel form: A case study in Maryland Piedmont , 1974 .

[13]  K. Richards,et al.  Discharge and sediment supply controls on erosion and deposition in a dynamic alluvial channel , 1996 .

[14]  G. Petts.  Complex response of river channel morphology subsequent to reservoir construction , 1979 .

[15]  Yan Wang,et al.  Stepwise decreases of the Huanghe (Yellow River) sediment load (1950–2005): Impacts of climate change and human activities , 2007 .

[16]  D. Jing.  STUDY ON FISHERY BIODIVERSITY AND ITS CONSERVATION IN LAIZHOU BAY AND YELLOW RIVER ESTUARY , 2000 .

[17]  Men,et al.  Genetic diversity and its seasonal variation of Jiaozhou Bay phytoplankton determined by rbcL gene sequencing , 2006 .

[18]  G. Brierley,et al.  Channel bed adjustments following major aggradation in a steep headwater setting: findings from Oyabu Creek, Kyushu, Japan , 2004 .

[19]  B. Everitt.  Channel responses to declining flow on the Rio Grande between Ft. Quitman and Presidio, Texas , 1993 .

[20]  Z. L. Hales,et al.  Riverbed Degradation Prediction , 1970 .

[21]  C. Renshaw,et al.  Short and long-term changes to bed mobility and bed composition under altered sediment regimes , 2006 .

[22]  Jiongxin Xu.  Complex behaviour of natural sediment‐carrying streamflows and the geomorphological implications , 2002 .

[23]  T. Dunne,et al.  Identifying eroding and depositional reaches of valley by analysis of suspended sediment Transport in the Sacramento River, California , 2001 .

[24]  M. Doyle,et al.  Modelling the effect of form and profile adjustments on channel equilibrium timescales , 2003 .

[25]  J. Schmidt,et al.  Streamflow regulation and multi-level flood plain formation: channel narrowing on the aggrading Green River in the eastern Uinta Mountains, Colorado and Utah , 2002 .

[26]  J. Milliman,et al.  Yellow River's water and sediment discharge decreasing steadily , 1998 .

[27]  Implications of the fluvial process—channel morphology interaction below British reservoirs for stream habitats , 1980 .

[28]  J. Hooke.  Styles of channel change , 1997 .

[29]  K. Gregory.  The human role in changing river channels , 2006 .

[30]  Peter W. Downs,et al.  River Channel Management: Towards sustainable catchment hydrosystems , 2004 .

[31]  Xu Jiong-xin.  Sediment flux into the sea as influenced by the changing human activities and precipitation: example of the Huanghe River, China , 2003 .

[32]  K. Richards,et al.  River Channels: Environment and Process , 1989 .

[33]  S. Kempe,et al.  Sediment and nutrient transport to the coastal zone , 1998 .

[34]  J. Knox.  HUMAN IMPACTS ON WISCONSIN STREAM CHANNELS , 1977 .