Hyperconcentrated floods with more than 200–300 kg/m3 sediment concentrations often occur in the Lower Yellow River (LYR) during flood seasons, which leads to unique fluvial processes in the braided reach of the LYR. The investigation of channel geometry adjustments in response to hyperconcentrated floods can not only help to gain a better understanding of associated fluvial processes, but also is significant for making flood control strategies in the braided reach. In this study, pre- and post-flood bankfull channel dimensions in the braided reach were calculated based on the observed cross-sectional profiles in 15 years with the occurrence of hyperconcentrated flood events. Adjustments in channel geometry at section- and reach-scales were investigated, with several factors influencing adjustments in reach-scale channel geometry being analyzed. It indicates that the mean sediment transport rate was a key factor influencing the adjustment index, although pre-flood channel geometry and sediment deposition can also affect the index to some extent. An empirical relationship was developed between the characteristic parameter representing the pre- and post-flood channel geometries and mean sediment transport rate in hyperconcentrated floods. Eleven datasets were used to calibrate the parameters in the empirical relation, with the datasets in 1973, 1988, 1995, and 2002 verifying the relation. The calculated post-flood characteristic parameter of channel geometry using the empirical relation agreed well with observed data, and the proposed method can be used to predict the reach-scale adjustment of channel geometry during hyperconcentrated floods in alluvial rivers.
BatallaRJJongCDErgenzingerP. (1999) Field observations on hyperconcentrated flows in mountain torrents. Earth Surface Processes and Landforms24(3): 247–253.
2.
BreienHDe BlasioFVElverhøiA. (2008) Erosion and morphology of a debris flow caused by a glacial lake outburst flood, western Norway. Landslides5(3): 271–280.
3.
ChenJG (2012) Reservoir sedimentation and transformation of morphology in the lower Yellow River during 10 year’s initial operation of the Xiaolangdi reservoir. Journal of Hydrodynamics24(6): 914–924.
4.
ChengNHNguyenHT (2011) Hydraulic radius for evaluating resistance induced by simulated emergent vegetation in open-channel flows. Journal of Hydraulic Engineering137(9): 995–1004.
5.
ChienNWanZH (1998) Mechanics of Sediment Transport. Reston, VA: ASCE Press.
6.
ChuZX (2014) The dramatic changes and anthropogenic causes of erosion and deposition in the lower Yellow (Huanghe) River since 1952. Geomorphology216: 171–179.
7.
EnglundFWanZH (1984) Instability of hyperconcentrated flow. Journal of Hydraulic Engineering110(3): 219–233.
8.
FeiXJ (1998) Mechanics and application of sediment transport at long distance in hyperconcentrated floods. Journal of Sediment Research3: 55–61. (in Chinese).
9.
HarmanCStewardsonMDeroseR (2008) Variability and uncertainty in reach bankfull hydraulic geometry. Journal of Hydrology351(1): 13–25.
10.
JiangEHZhangHWZhaoLJ. (1999) Study of bed building law of hyperconcentrated flood and river facies relation. Yellow River21: 12–15. (in Chinese).
11.
JulienPYWargadalamJ (1995) Alluvial channel geometry: theory and applications. Journal of Hydraulic Engineering121(4): 312–325.
12.
KostaschukRJamesTRishiR (2003) Suspended sediment transport during tropical cyclone floods in Fiji. Hydrological Processes17(6): 1149–1164.
13.
LiWvan MarenDSWangZB. (2014) Peak discharge increase in hyperconcentrated floods. Advances in Water Resources67(4): 65–77.
14.
LirerLVinciAAlbericoI. (2001) Occurrence of inter-eruption debris flow and hyperconcentrated flood-flow deposits on Vesuvio volcano. Sediment Geology139(2): 151–167.
15.
MaizelsJ (1989) Sedimentology, paleoflow dynamics and flood history of jökulhlaup deposits: paleohydrology of Holocene sediment sequences in southern Iceland sandur deposits. Journal of Sedimentary Research59:(2) 204–223.
16.
MiaoCYKongDXWuJW. (2016) Functional degradation of the water–sediment regulation scheme in the lower Yellow River: spatial and temporal analyses. Science of the Total Environment551–552: 16–22.
17.
MiaoCYNiJRBorthwickAGL (2010) Recent changes of water discharge and sediment load in the Yellow River basin, China. Progress in Physical Geography34(4): 541–561.
18.
PiersonTCCostaJE (1987) A rheologic classification of sub-aerial sediment-water flows. In: CostaJEWieczorekGF (eds) Debris Flows/Avalanches: Process, Recognition, and Mitigation. Geological Society of America Reviews in Engineering Geology. Boulder, CO: Geological Society of America, 1–12.
19.
QiPLiWX (1996) Evolutional characteristics of hyper-concentrated flow in braided channel of the lower Yellow River. International Journal of Sediment Research11(3): 49–57.
20.
QiPYuXSunZY. (2008) Efficient sediment transport theory of the hyperconcentrated flow in the lower Yellow River. Journal of Sediment Research4: 74–82. (in Chinese).
21.
SchummSA (1977) The Fluvial System. New York: John Wiley and Sons.
22.
ShuAPFeiXJ (2008) Sediment transport capacity of hyperconcentrated flow. Science in China Series G: Physics, Mechanics & Astronomy51(8): 961–975.
23.
SmithGA (1986) Coarse-grained non-marine volcaniclastic sediment: terminology and depositional process. Geological Society of America Bulletin97(1): 1–10.
24.
SohnYKRheeCWKimBC (1999) Debris flow and hyperconcentrated flood-flow deposits in an alluvial fan, northwestern part of the Cretaceous Yongdong Basin, Central Korea. The Journal of Geology107(1): 111–132.
25.
StrelkoffTSClemmensAJ (2000) Approximating wetted perimeter in power-law cross section. Journal of Irrigation and Drainage Engineering126(2): 98–109.
26.
SunDPLiuMXZhangXL. (2014) Alluvial river adjusting response to the flood-sediment process: for the wandering reach of Yellow River as an example. Advances in Water Science25(5): 668–676. (in Chinese).
27.
Van MarenDSWinterwerpJCWangZY. (2009a) Suspended sediment dynamics and morphodynamics in the Yellow River, China. Sedimentology56(3): 785–806.
28.
Van MarenDSWinterwerpJCWuBS. (2009b) Modelling hyperconcentrated flow in the Yellow River. Earth Surface Processes and Landforms34(4): 596–612.
29.
WanZH (1985) Bed material movement in hyperconcentrated flow. Journal of Hydraulic Engineering111(6): 987–1002.
30.
WangHJYangZSSaitoY. (2007) Stepwise decreases of the Huanghe (Yellow River) sediment load (1950–2005): impacts of climate change and human activities. Global and Planetary Change57(3): 331–354.
31.
WangMFChenLZhouYL (2000) Analysis on characters and mechanism of fluvial processes of high sediment-laden flow in wandering channel. Journal of Sediment Research1: 1–6. (in Chinese).
32.
WangZJTaWQ (2016) Hyper-concentrated flow response to aeolian and fluvial interactions from a desert watershed upstream of the Yellow River. Catena147: 258–268.
33.
WangZYQiPMelchingCS (2009) Fluvial hydraulics of hyperconcentrated floods in Chinese rivers. Earth Surface Processes and Landforms34(7): 981–993.
34.
WilcoxACO’ConnorJEMajorJJ (2014) Rapid reservoir erosion, hyperconcentrated flow, and downstream deposition triggered by breaching of 38 m tall Condit Dam, White Salmon River, Washington. Journal of Geophysical Research: Earth Surface119(6): 1376–1394.
35.
WinterwerpJC (2006) Stratification effects by fine suspended sediment at low, medium and very high concentrations. Journal of Geophysical Research111: C05012.
36.
WohlEKuzmaJBrownNE (2004) Reach-scale channel geometry of a mountain river. Earth Surface Process and Landforms29(8): 969–981.
37.
WuBSWangGQMaJM. (2005) Case study: river training and its effects on fluvial processes in the Lower Yellow River, China. Journal of Hydraulic Engineering131(2): 85–96.
38.
WuBSWangGQXiaJQ. (2008a) Response of bankfull discharge to discharge and sediment load in the lower Yellow River. Geomorphology100(3): 366–376.
39.
WuBSXiaJQFuXD. (2008b) Effect of altered flow regime on bankfull area of the lower Yellow River, China. Earth Surface Processes and Landforms33(10): 1585–1601.
40.
XiaJQDengSSLuJY. (2016) Dynamic channel adjustments in the Jingjiang Reach of the Middle Yangtze River. Scientific Reports6: 22802.
41.
XiaJQLiXJLiT. (2014a) Response of reach-scale bankfull channel geometry in the Lower Yellow River to the altered flow and sediment regime. Geomorphology213: 255–265.
42.
XiaJQZongQLZhangY. (2014b) Prediction of recent bank retreat processes at typical sections in the Jingjiang Reach after the TGP operation. Science China Technological Sciences57(8): 1490–1499.
43.
XuJX (2004) Hyperconcentrated flows in the slope-channel systems in gullied hilly areas on the Loess Plateau, China. Geografiska Annaler86(4): 349–366.
44.
ZhangOYXuJXZhangHW (2002) Impact of flood events from different source areas on channel transects adjustment at the wandering-braided reach of the Lower Yellow River. Journal of Sediment Research6: 1–6. (in Chinese).
45.
ZhangYFWangPWuBS. (2015) An experimental study of fluvial processes at asymmetrical river confluences with hyperconcentrated tributary flows. Geomorphology230: 26–36.
