Sediment Transport Dynamics in River Networks Induced by Water Diversion

A river network is a typical completely open system formed by interconnected river channels. The interactions between the imports of a river (water and sediment) and the channel will cause the change of the channel patterns. This is actually a feedback between the erosion and the sedimentation states of the channel via an adjustment of the sedimentcarrying capability of the stream. This feedback mechanism indicates that river network is a self-organized system (Rodriguez-Iturbe, 1997), and some dynamical laws lead its evolution and some statistic laws dominate its steady state (Leopold, 1953; Leopold & Maddock, 1953; Dodds & Rothman, 2000). So, river networks have attracted, in decades past, a good much attention of physicists and geophysicists (Banavar, et al., 1997; Manna & Subramanian, 1996; Manna, 1998; Sinclair & Ball, 1996; Kramer & Marder, 1992; Takayasu & Inaoka, 1996; Maritan, et al., 1996; Caldarelli, et al., 1997; Giacometti, 2000; Somfai & Sander, 1997; Rinaldo, et al., 1996, and so on). They focused mainly on the distributions of river parameters or the scaling relations between them, as well as the evolutionary mechanism, that is, what creates the distributions and scaling relations? The pioneering field investigation executed by Leopold revealed that the slope, width and depth of a channel respectively depend on the discharge in power functions (Leopold & Maddock, 1953). From then, some other scaling relations, in power functions, between river parameters were found (Hack, 1957; Flint, 1974). The theoretical studies for the purpose of getting deeper understandings of the reasons why the nature has selected these laws were conducted by the dynamic modeling based on the local erosion rules (for instance, Banavar, et al. ,1997) or the other considerations, such as erosion process based on the minimum energy dissipation (Sun, 1994; Dhar, 2006), evolution of a quasi-random spanning tree (Manna, 1996), statistical physics method based on the self-similarity theory (Banavar, et al. ,1997), and so on. Our previous modeling studies were focused on another process, that is, sediment transport in river networks (Wang, et al. 2008; Hao, et al., 2008; Huo, et al., 2009). The core spirit of the models embodies the feedback mechanism between erosion and sedimentation via the adjustment of sediment-carrying capability (SCC) of runoff. A steady state shows scaling law that the quantity of erosion or sedimentation (QES) distributes exponentially along the channel in the downriver direction. The response of a river to the abrupt change of the input shows self-organized and self-adaptive behaviors. The former is represented by opposite variation of the SCC to the QES as the discharge changes, which shows that the response of the river trends to depress the increase of erosion as water flow increases and that of