Environ Earth Sci (2013) 70:97–106 DOI 10.1007/s12665-012-2106-0 ORIGINAL ARTICLE Planform channel dynamics along the Ningxia–Inner Mongolia reaches of the Yellow River from 1958 to 2008: analysis using Landsat images and topographic maps Zhengyi Yao • Jianhua Xiao • Wanquan Ta • Xiaopeng Jia Received: 15 February 2012 / Accepted: 30 October 2012 / Published online: 15 November 2012 Ó Springer-Verlag Berlin Heidelberg 2012 Abstract Channel planform dynamics were analyzed for 64.3 m to the right from 1990 to 2000, and 2.8 m to the the Ningxia–Inner Mongolia reaches of the Yellow River. right from 2000 to 2008. Map data were analyzed by means of GIS and used to determine the planform characteristics and changes in Keywords Channel planform dynamics Á Channel width, sinuosity, and shoreline migration rates between shifting Á Yellow River Á Ningxia Á Inner Mongolia 1958 and 2008. The study was based on topographic maps of 1958 and 1967, which had been derived from aerial photos and a field survey and from satellite imagery of Introduction 1977, 1990, 2000, and 2008. The channel planform dynamics were determined by comparing sequential The Yellow River is China’s second-longest river, and is changes in the position of the shorelines in these years. famous for its high sand content, frequent floods, unique Sinuosity adjustments were small during the study (range: channel characteristics in the lower reaches (the riverbed is 1.34–1.45). The initial sinuosity (1.45 in 1958) gradually higher than the land outside the banks), and currently decreased to 1.34 in 1990, and then increased to 1.40 in overused water resources (Yu 2002; Fu et al. 2004; Sato 2008. Channel contraction had been the dominant planform et al. 2008). In the lower reaches of the Yellow River, the process, but periodic floods resulted in channel expansion channel changes frequently; 26 large channel changes have (1958–1990). The river’s channel area expanded substan- occurred since 602 B.C. and these changes and the tially from 1958 to 1990 (by 42.1 %), then sharply con- dynamics of the lower reaches of the Yellow River have tracted from 1990 to 2000 (by 45.8 %), with no subsequent been well studied (Xu 2002; Chu et al. 2006). changes. The bank erosion and accretion rates were severe. Many researchers have noticed that the channel plan- The mean erosion rates ranged from 30.7 to 68.3 m/year on form along the Ningxia–Inner Mongolia reaches of the the left side and 27.1 to 58.3 m/year on the right side. The Yellow River changed frequently and dramatically during mean accretion rates ranged from 44.4 to 68.3 m/year on the past half century. the left side and 30.5 to 60.4 m/year on the right side. The Due to a low gradient, loose riverbed materials, and a mean channel midline shifted by 57.8 m toward the right high sediment load, the Ningxia–Inner Mongolia reaches of from 1958 to 2008. The mean channel midline moved the Yellow River are characterized by large channel shifts 4.8 m to right from 1958 to 1967, 54.3 m to the left from and frequent morphological changes (Hou 1996; Hou et al. 1967 to 1977, 44.2 m to the right from 1977 to 1990, 2007). Historically, there have been large channel changes as a result of channel shifts to the right (facing down- stream) along these reaches (Wang 1984; Li et al. 2003). Z. Yao (&) Á J. Xiao Á W. Ta Á X. Jia The resulting bank erosion has become a serious problem Key Laboratory of Desert and Desertification, Cold and Arid at many sites along these reaches, imperiling nearby set- Regions Environmental and Engineering Research Institute, tlements and infrastructure. Recent damage caused by bank Chinese Academy of Sciences, 320 Donggang West Road, Lanzhou 730000, People’s Republic of China erosion has been frequently reported, and river channel e-mail: [email protected] changes have created substantial social, economic, and 123 98 Environ Earth Sci (2013) 70:97–106 environmental problems (Wu et al. 2006;Taetal.2008). In the study reaches, there are six gauging stations: For example, the Flood Prevention Office of Bayan Nor Qingtongxia, Shizuishan, Bayan Gol, Sanhuhekou, Zhao- City reported that about 215 km2 of arable land, grass- junfeng, and Toudaoguai. These stations divide the study land, and woodland were lost to erosion and that reaches into five sections. At the Qingtongxia gauging numerous infrastructures (e.g., irrigation ditches, station, mean annual runoff is 238 9 108 m3 and the mean bridges, roads, ports, and buildings) were destroyed from annual sediment load is 1.2 9 108 t (Fig. 2). The sediment 1953 to 2000. transport is mainly concentrated in the flood season. For River channel changes such as bank erosion, down- example, the runoff in flood season is only 1.2 times of that cutting, and bank accretion are natural processes for an in non-flood season, but sediment load in flood season is alluvial river. However, regional developments such as 9.0 times of that in non-flood season. sand mining, infrastructure construction on the riverbank, From Qingtongxia to Shizuishan, the Yellow River artificial cutoffs, bank revetment, reservoir construction, flows over the wide Yinchuan Plain. The river course is and land use alterations have changed the natural geo- 199.0 km long, and the water level falls 47 m along a morphologic dynamics of rivers (Surian 1999; Kesel 2003; gradient of 0.24 %. The width of the riverbed ranges from Surian and Rinaldi 2003; Batalla et al. 2004; Vanacker 200 to 5000 m; the riverbed material is silt and gravel et al. 2005; Wellmeyer et al. 2005). Therefore, channel (mainly coming from mainstream). At the eastern end of stability is often threatened. Such human activities may this section, about 87 km of river runs beside the Hedong even become stronger forces for change than natural events Sandyland. From Shizuishan to Bayan Gol, the Yellow such as floods and droughts. The resulting channel changes River flows along the margin of the Ulan Buh Desert, over cause various environmental and socioeconomic conse- a distance of 150.8 km, and the water level falls 35 m, over quences in terms of navigation, loss of riparian land and a gradient of 0.23 %. The river course narrows to between infrastructure, flood hazards, and the alteration of aquatic 300 and 700 m, and the riverbed material becomes mainly and riparian ecosystems. The purpose of this paper is to alluvial silt, with gravel and even rock in some sections describe the planform geometry and migration behavior of (mainly coming from tributaries). To the west of the river, confined meandering section of the Yellow River and to large areas of dunes exist, and about 6.1 9 108 t of sand relate the channel-migration rate of these rivers to basic poured into the Yellow River from 1954 to 2000 (Yang hydrologic and geomorphic controls. Although the new et al. 2003). From Bayan Gol to Hekou, the Yellow River data presented here are clearly of scientific interest to those wriggles its way through the Hetao Plain over a distance of seeking to understand the dynamics of meander migration, 563.7 km, and the water level falls 63 m over a gradient of they are also significant to practical issues such as pre- 0.11 %. The width of the riverbed ranges from 500 to dicting channel-migration rates for engineering and plan- 2500 m, and the riverbed material is loose silt. On the ning purposes. southern bank of this section, there are ten tributaries, named the ‘‘Ten Great Gullies’’. These tributaries origi- nated at the center of the Ordos Plateau (which also is the Study area center of rainstorms of Ordos Plateau) and flows through the Hobq Desert. In the windy season, large amounts of The study area is located along the Ningxia–Inner Mon- dune sand pour into the valleys of the Ten Great Gullies golia reaches of the Yellow River, starting at Qingtongxia and are carried by flooding during the rainy season into the (Ningxia Hui Autonomous Region) and ending at Hekou Yellow River; these sediments usually block the river’s (Inner Mongolia Autonomous Region), with a total channel flow, causing dikes to burst and flooding the Hetao Plain length of 913.5 km (Fig. 1). Although this area represents (Zhao et al. 2001; Feng and Zhang 2008). In addition, cold the upper reaches of the river, it resembles the lower winters create ice jams that lead to winter and spring floods reaches because of the low gradient, meandering channel, that cause great losses to the local people (Chen and Ji loose riverbed materials, high sediment load, and large area 2005; Jiang et al. 2008). of surrounding alluvial plains (the Yinchuan Plain and the Since the Liujiaxia Dam (584 km from Qingtongxia, Hetao Plain). The region is characterized by a dry climate, channel distance) began operation in 1968 and the Long- with rare rainfall; the mean annual rainfall ranges from 200 yangxia Dam(918 km from Qingtongxia, channel distance) to 250 mm, with a potential evapotranspiration of began operation in 1986, large dams and reservoirs have 1000–2000 mm. The study reaches have few tributaries increasingly controlled the Yellow River’s discharge and that contribute relatively little discharge to the Yellow attenuated water and sediment yields in the Ningxia–Inner River. The tributaries, which cover a drainage area greater Mongolia reaches (only an important tributary of Huang- than 5000 km2, are the Kushui River, the Dusitu River, and shui River is not control by the great reservoirs).