Sediment transport under increasing anthropogenic stress: Regime shifts within the Yellow River, China
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RESEARCH ARTICLE
Sediment transport under increasing anthropogenic stress: Regime shifts within the Yellow River, China Shuang Song, Shuai Wang , Bojie Fu, Yanxu Liu, Kevin Wang, Yikai Li, Yaping Wang
Received: 24 July 2019 / Revised: 30 November 2019 / Accepted: 19 May 2020
Abstract Ecosystems respond to climatic and anthropogenic forcings with regime shifts and reorganizations of their system structures. In river basins, changes in sediment transport can have cascading effects that cause ecosystem regime shifts. The Yellow River, once the world’s most sediment-rich river, has experienced dramatic regime shifts. Although recent intervention has returned sediment discharge in the Yellow River to pristine levels, our understanding of previous regime shifts remains inadequate, particularly for the regime shift to a sediment rich period during early historical time. We reanalyzed previous datasets to clarify the first historical sediment transport regime shift in the Yellow River. Our results show that while historical climatic changes (e.g., the Medieval Warm Period, about 900–1100 AD) caused changes in sediment transport, a regime shift occurred only under increased forcing from anthropogenic stresses (started from about 1350 AD, reached the tipping point after 1900 AD). This unique behavior of the Yellow River under increasing anthropogenic forces may provide perspective for sustainable river basin management. Keywords Anthropogenic stresses Climate change Regime shift Sediment transport Yellow River
INTRODUCTION Regime shifts are reorganizations of a system’s structure and function; they can be caused endogenously by gradual or cumulative changes within an ecosystem, or be triggered exogenously by anthropogenic or natural disturbances (Collie et al. 2004; Rocha et al. 2018). Due to the complex feedbacks between climate, human activities and sediment transport processes in large river basin systems, changes in
sediment discharge often initiate cascading regime shifts (Hughes et al. 2013; Best 2019). Therefore, by understanding the drivers of changes in sediment transport and their impacts on regime shift development, we can develop strategies to bolster the resilience of river basin systems. The Yellow River, China, is one of the most sedimentrich rivers in the world and has experienced two large-scale regime shifts as a result of changes in sediment transport, generating attentions from around the world (Fig. 1) (Wang et al. 2007; Wei et al. 2016; Lappalainen et al. 2018). Around 2000 years ago, China entered a more unified period of human history that saw more extensive use of the Yellow River Basin. Increasing anthropogenic stresses throughout the historical period caused the sediment discharge of the Yellow River to increase from pristine levels to a sediment-rich regime by the mid-20th century (Ren and Zhu 1994). However, human intervention in the Yellow River Basin has made structural changes and led to a dramatic decrease of the sediment discharge during the past 60 years (Yu et al. 2013; Wang e
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