Spatial and Temporal Variations of Suspended Sediment Deposition in the Alluvial Reach of the Upper Yellow River from 1952 to 2007

Catena 92 (2012) 30–37

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Spatial and temporal variations of suspended sediment deposition in the alluvial reach of the upper Yellow River from 1952 to 2007

Suiji Wang a,⁎, Yunxia Yan a, Yingkui Li b a Key Laboratory of Water Cycle and Related Land Surface Processes, Institute of Geographical Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China b Department of Geography, University of Tennessee, Knoxville, TN 37996, USA article info abstract

Article history: The suspended sediment deposition (SSD) in the alluvial reach between the Qingtongxia station and the Toudaoguai Received 28 May 2011 station of the upper Yellow River has shown a dramatic variation since 1952. However, its spatial and temporal Received in revised form 28 October 2011 changing pattern and driving factors are still not clear. This paper examines the detailed spatial and temporal var- Accepted 22 November 2011 iations of the SSD based on the annual suspended sediment load at five gaging stations located in this alluvial reach in 1952–2007. The mean annual SSDs in four sub-reaches (Qingtongxia–Shizuishan, Shizuishan–Bayangaole, Keywords: Bayangaole–Sanhuhekou, and Sanhuhekou–Toudaoguai) were calculated and analyzed for different periods. The Suspended sediment deposition (SSD) – − ∗ 5 ∗ 5 ∗ 5 ∗ 5 −1 −1 Human impact mean annual kilometric SSDs in 1952 2007 were 0.228 10 ,0.97 10 ,0.165 10 and 0.006 10 ta km Reservoir construction and operation in the four sub-reaches, respectively, with the highest SSD occurred in the Shizuishan–Bayangaole sub-reach. Re- Water and soil conservation sults also suggested that SSD was mainly accumulated in 1952–1959 before major reservoirs were constructed Alluvial channel and in 1986–2007 after three major reservoirs (Qingtongxia, Liujiaxia and Longyangxia) were constructed in the Yellow River main stream. During 1960–1985, all sub-reaches except the Shizuishan–Bayangaole sub-reach experienced channel erosion. Although climate change may play some roles, the changes in SSD were mainly influenced by human activities. In particular, the water and soil conservation actions, such as the construction of check dams from 1958 in upper stream tributaries, intercepted significant amount of suspended sediment and cause the net erosion of the main channel in the 1960s. The operation of the Qingtongxia reservoir reduced the SSD in this downstream reach in the 1970s and 1980s because upper stream suspended sediment was trapped by the reservoir and reservoir-released relative clear water scoured the downstream channel. Although the Liujiaxia and Longyangxia reservoirs trapped relatively small amount of suspended sediment, they stored a large amount of water during the flood season, reducing the discharge and the erosion capability of the downstream flow.Therefore,thisopera- tion mode may increase the SSD in this river reach. In addition, with the gradual loss of the Qingtongxia reservoir's capacity in sediment storage, more suspended sediment was released to the downstream channel, causing strong SSD in this reach after 1990. © 2011 Elsevier B.V. All rights reserved.

1. Introduction 2004; Kesel, 2003; Surian, 1999; Surian and Rinaldi, 2003; Wellmeyer et al., 2005). River channel evolution occurs primarily in response to the changes Human impacts on channel morphology and fluvial processes in- of natural factors such as climate, surface material, sediment supply, clude both indirect and direct influences (Kiss et al., 2008). For example, and so on. However, with the population increase, human activities be- as indirect influences, land-use change and river regulation in a river come a more and more important influencing factor. For example, basin can alter runoff and sediment yield. As a direct influence, the con- Brown (1997) indicated that there is a long history of human–riverine struction of dams can intercept upstream sediment and fundamentally interactions throughout the Holocene. The influence of human activities change the fluvial hydrology (Draut et al., 2011; Kiss et al., 2008). Al- on river channel dynamics was intensified with the continuous increase though much progress has been made in the study of channel dynamics in population and human activities, especially after the industrial revo- in response to human activities, the changes in ways and by degrees of lution in the 1800s. Human activities, such as reservoir construction, sediment transportation and the response of river channels down- sand mining, bank revetments, and land use alterations, have signifi- stream from the constructed dams are still not clear (e.g., Draut et al., cantly changed the natural dynamics of river channels (Batalla et al., 2011; Grant et al., 2003; Kummu et al., 2010; Renwick et al., 2005; Walling and Fang, 2003; Wang and Li, 2011; Williams and Wolman, 1984; Yang et al., 2007). Here, we examine the spatial and temporal variations of the suspended sediment deposition (SSD) in the alluvial reach fl ⁎ Corresponding author. Tel.: +86 10 64889036; fax: +86 10 64851844. of the upper Yellow River and discuss their major in uence factors asso- E-mail address: [email protected] (S. Wang). ciated with human activities.

The Yellow River is well-known in the world due to its high sedi- upstream reservoirs (e.g. Wang et al., 1996; Zhao et al., 1999). Other ment concentration and rapid sedimentation rate in the lower reach. studies suggested that the channel aggradation was induced by perenni- The average sediment deposition in the lower reach is 1.58∗108 t/a al sediment input from the surrounding deserts (Ta et al., 2008; Yang, from 1950 to 2004 (Wang et al., 2006b). Sedimentation in the lower 2002). For example, Ta et al. (2008) emphasized that the channel in Yellow River causes the channel bed to rise continuously as a “hanging the Ningmeng reach have been degraded in the past four decades with- river”, exerting great pressure on flood protection (Xu, 2002). In recent out eolian sediment supply. These studies indicated that the pattern of decades, the channel of the Ningmeng (Ningxia–Inner Mongolia) alluvi- channel changes and its driving factors are still not clear in this reach. al reach in the upper Yellow River (Fig. 1) rose evidently and nearly Furthermore, channel variations in different sub-reaches and periods 150 km long channel has appeared as a “hanging river”. It exerts un- may also be different because of the complexity of suspended sediment precedented pressure on flood management in this reach. Furthermore, supply and human activities. The purpose of this paper is to (1) docu- frequent channel shifts in the braided section and migration in the ment variations of the annual runoff and suspended sediment load in meandering section resulted in bank erosion and channel crevasse different sub-reaches from 1952 to 2007; (2) calculate the total annual that imperil nearby settlements and infrastructures (Yao et al., 2010). suspended sediment deposition (SSD) and annual kilometric SSD for In addition, human occupation (housing and economic activity) in the each sub-reach; (3) examine the spatial and temporal pattern of SSD floodplains also increased, causing the rising economic losses of flood di- variations in this reach from 1952 to 2007; and (4) identify main driving sasters (Hoffmann et al., 2010). Therefore, the channel changes in the factors affecting the spatial and temporal SSD variations. Ningmeng reach have created substantial social, economic, and environ- mental problems (Ta et al., 2008; Wu et al., 2006). For instance, the flood 2. Study area and environment setting which occurred in the August of 1981 with a peak discharge of 5450 m3/s and a water level elevation of 1019.63 m at the Sanhuhekou station cre- The Yellow River originates from the Tibetan Plateau and flows ated 9 crevasses, submerged 18,480 hectares of cropland, and destroyed into the Bohai Sea (Fig. 1) with a drainage area of 0.75 million km2, numerous buildings, bridges, irrigation ditches and roads (YRWCC, a total length of 5464 km, a mean annual runoff of 46.4 billion m3, 1991). Contrastively, the flood which occurred in March of 1996 with a and a relief of 4830 m (Wang et al., 2006a). Most of the drainage peak discharge of only 1490 m3/s reached a similar water level elevation area is controlled by arid to semi-arid climate with a mean annual of 1020 m at the Sanhuhekou station and resulted in loss that was almost precipitation of 478 mm. Traditionally, the Yellow River is divided into identical to that of the 1981 flood. Furthermore, flood disasters in this three reaches: the upper (from the headwater to Toudaoguai with a reach have also been more frequent since the 1980s. channel length of 3472 km and a relief of 3496 m), the middle (between Some studies ascribed the channel aggradation in the Ningmeng Toudaoguai and Taohuayu with a channel length of 1206 km and a relief reach to the deposition of sediment eroded from the tributaries in of 890 m), and the lower (from Taohuayu to the river mouth with a the Loess Plateau under the condition of low flow regulation of the channel length of 786 km and a relief of 94 m) reaches.

Fig. 1. Sketch map of the Ningmeng reach of the upper Yellow River and the locations of the 5 gaging stations. The three large reservoirs Qingtongxia, Liujiaxia and Longyangxia were constructed in 1968, 1968 and 1986, respectively. Download English Version: https://daneshyari.com/en/article/4571885

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