Coupling within fluvial systems is a fundamental property affecting the down-system transmission. The coupling concept was originally introduced to geomorphology with widespread attention by Brunsden and Thornes [1]. Recently, it has received attention in the context of coupling between hillslopes and channels [2-6]. The coupled connectivity reflects how the channel network responds to hillslope-derived disturbance in the fluvial system, and is therefore important in determining the geomorphic response to human-induced environmental change [71]. The transmission of sediment governs the coupling relationships between hillslopes and headwater sources, and from reach to reach of the channel system [8]. At zonal scale, coupling mechanisms affect the transfer