River Morphodynamics and Stream Ecology of the Qinghai-Tibet Plateau

Based on a thorough understanding of changing facts on fluvial morphodynamics and ecology on the Qinghai-Tibet Plateau, the research projects in this book study the effect of the plateau uplift on river network morphology, fluvial processes, aquatic ecology (i.e. wetland, lake and benthic invertebrates) and desertification in the local region. The research focusses on analyzing the causes and mechanism underlying these changes during a comprehensive field survey in 2007-2014, and in the meantime proposes suitable management strategies for protection and rehabilitation of this region. Main research contents include: 1) hydrological and geomorphic processes of stream network development under the geological background of the plateau uplift; 2) modern fluvial processes (i.e. river pattern diversity and spatial changes, meandering rivers migration, natural cutoff and oxbow lakes evolution); 3) benthic invertebrate assemblages in different aquatic habitat (i.e. alluvial and mountain rivers, saltwater and freshwater lake, oxbow lake); 4) wetland types, evolvement and shrinkage mechanisms on the plateau; 5) distribution and evolution of desertification and control methods.

This book focuses on the river morphodynamics and stream ecology of the Qinghai-Tibet Plateau. The objective of the book is to summarize and synthesize the recent studies based on field surveys undertaken in the period 2007-2014. This book was written to serve as a graduate-level text for a course in river dynamics and stream ecology and as a reference text for engineers and researchers engaged in hydropower engineering, fluvial geomorphology and aquatic ecology. The first two chapters serve as an introduction of geomorphological characteristics as well as uplift and its impact on river morphology of the Qinghai-Tibet Plateau. Chapters 3-5 cover meandering rivers and cutoff, wetlands and wetland shrinkage,desertification and restoration strategies in the Sanjiangyuan region. Chapter 6 discusses the interaction between erosion and vegetation, and Chapter 7 characterizes the aquatic ecology of the Yarlung Tsangpo and the Sanjiangyuan region.

Preface 1 Geomorphology of the Qinghai – Tibet Plateau1.1 Uplift of the Qinghai–Tibet Plateau1.1.1 Geomorphological characteristics1.1.2 Geological background1.1.3 Uplift process and mechanism1.2 Impacts of the uplift of the plateau on stream networks1.2.1 Stream ordering system and Horton’s Laws1.2.2 River networks on the Qinghai–Tibet Plateau1.2.3 Influence of plateau uplift on topologic structure of the river networks1.3 Impacts of tectonic motion on river morphology1.3.1 Development of the Yarlung Tsangpo River1.3.2 Massive sediment storage in the Yarlung Tsangpo1.4 Morphological characteristics of rivers in the Tongde basin1.4.1 Development of the Baqu River elongating stream network1.4.2 Characteristics of the Daheba River 35 2 Fluvial processes of incised rivers in Tibet2.1 Landslides and debris flows2.1.1 Spatial distribution of landslides and debris flows2.1.2 Effects of the Yigong landslides on fluvial processes2.1.3 Debris flow dams2.2 Glacial processes2.2.1 Glaciers in the Palong Tsangpo basin2.2.2 Effects of glaciers on fluvial morphology2.2.3 Impacts of glaciers on the Palong Tsangpo2.3 Streambed structures controlling riverbed incision2.3.1 Streambed structures2.3.2 Equivalency principle of bed structure and bedload motion 3 Meandering rivers in Sanjiangyuan3.1 Meandering rivers3.1.1 Meandering tributaries of the Yellow River3.1.2 Sinuosity of the Bai and Hei Rivers3.1.3 Oxbow lakes3.2 Development process of meanders3.2.1 Meandering river in alpine meadow3.2.2 Physical characters of slump blocks3.2.3 Bank failure in the meandering process3.2.4 Transverse migration rate of meanders3.3 Cutoff of meanders3.3.1 Types of cutoff3.3.2 Neck cutoff3.3.3 Mechanism of cutoff3.4 Evolution of oxbow lakes3.4.1 Formation of oxbow lakes3.4.2 Long-term evolution of oxbow lakes 4 Wetlands and wetland shrinkage4.1 Wetlands in Yellow River source4.2 Shrinkage of the Ruoergai Swamp4.2.1 The Ruoergai Basin4.2.2 Shrinkage of the Ruoergai Swamp4.2.3 Shrinkage mechanisms of the Ruoergai Swamp4.3 Crescent lakes in the Maduo desert4.3.1 Crescent lakes4.3.2 Formation mechanisms of crescent lakes4.3.3 Ecological effect of crescent lakes 4.4 Wetland protection and restoration 5 Desertification and restoration strategies5.1 Desertification in Sanjiangyuan5.1.1 Sanjiangyuan and desertification5.1.2 Characteristics of aeolian sand5.2 Vegetation development on sand dunes5.2.1 Interaction of fixed sand dunes and vegetation5.2.2 Vegetation succession in desertification areas5.3 Vegetation-aeolian erosion dynamics 5.3.1 Interaction of aeolian sand dune and vegetation development5.3.2 Vegetation-aeolian erosion model 5.3.3 Application of the model to the Mugetan desert 6 Erosion and vegetation6.1 Erosion in the Yarlung Tsangpo basin6.1.1 Various types of erosion 6.1.2 Glacier erosion 6.2 Vegetation in the Yarlung Tsangpo basin 6.2.1 Various types of vegetation 6.2.2 Effects of elevation and erosion on vegetation6.3 Grain erosion and control strategies 6.3.1 Grain erosion6.3.2 Mechanisms of grain erosion6.3.3 Control strategies 7 Aquatic ecology 7.1 Aquatic ecology in the Yarlung Tsangpo basin 7.1.1 Investigation of benthic macroinvertebrates7.1.2 Environmental parameters 7.1.3 Composition of macroinvertebrate assemblages 7.1.4 Effect of elevation gradients on biodiversity of macroinvertebrates7.1.5 Effect of environmental parameters on macroinvertebrate 7.2 Aquatic ecology in Sangjiangyuan 7.2.1 Ecological conditions in Sanjiangyuan 7.2.2 Field investigations of macroinvertebrates 7.2.3 Taxa and biodiversity7.2.4 Densities, biomass and functional structure of macroinvertebrates 7.2.5 Effect of human disturbances 7.3 Aquatic ecology of abandoned channels 7.3.1 Typical types of abandoned channels 7.3.2 Taxa composition and biodiversity7.3.3 Management of abandoned channels Subject index

Zhaoyin Wang is professorat Tsinghua University andchairman of the Advisory Council of the International Research and Training Center on Erosion and Sedimentation (UNESCO). He is vice president of the International Association of Hydraulic Engineering Research (IAHR) and chairman of the division of Hydro-environment of IAHR, chief editor of the International Journal of Sediment Research; and vice president of the World Association for Sedimentation and Erosion Research (WASER).His research interests include sediment transportation, river ecology and integrated river management. He has published more than 300 papers in international and Chinese journals. His scientific achievements include the theory of hyperconcentrated flows, debris flows and control strategies, development of vegetation-erosion dynamics, research in eco-sedimentation, theory and methods of integrated river management. In recognition of Zhaoyin Wang’s scientific contributions, the Chinese government has awarded him several prizes.The American Society of Civil Engineers awarded him the 2011 Hans Albert Einstein Award. Zhiwei Li is a post-doctoral research fellow of Tsinghua University. His research interests include fluvial processes, meandering river and wetland. He has published more than 30 papers in international and Chinese journals as the first author. His current efforts focus on fluvial processes of theYangtze River Source and Yellow River Source and wetland degradation mechanisms of the Ruoergai basin on theQinghai-Tibet Plateau. Mengzhen Xu is doctor and assistant professor of Tsinghua University. Her research interest include eco-hydraulics and eco-sedimentation, restoration of river ecosystems, and the impact of hydraulic engineering on aquatic ecosystems. She has published and co-authored more than 40 papers in international and Chinese journals. Doctor Guoan Yu is Alexander von Humboldt Research Fellow and assistant professor of Institute of Geographic Sciences and Natural Resources Research, CAS. His research interest include fluvial processes, bedload transport and geomorphology.