One such model suggests that channel size www.selleckchem.com/products/azd9291.html and incision depth influence post-incision processes, with controls on widening from accumulation of material at the base of eroding banks acting as a limit on lateral channel migration (Beechie et al., 2008). In Robinson Creek, the incision and bank erosion occurring is consistent

with the initial deepening stages of the cycle in relatively narrow portions and subsequent stages in the relatively wider portions of the channel, where erosion control measures have not been implemented. However, if incision continues, currently wider areas with bars and potential for vegetation establishment may destabilize as the incision–erosion cycle continues. Evidence for this scenario is evident from Robinson Creek field surveys that show upstream incision even in find more relatively wide zones over a three year period. In such an actively incising channel,

dynamic changes and complex responses may create spatial variability in geomorphic responses and complexity in channel recovery as multiple knickzones migrate upstream into reaches where cycles of local incision and aggradation have already occurred. Erosion control measures that limit widening may alter future channel adjustments. Both positive and negative feedback loops operate in coupled human–landscapes (Chin et al., 2013) such as incised alluvial systems. A positive feedback is an initial change to the system that causes more change in the same direction. In contrast, a negative feedback is a modification that limits the initial change. With respect to channel incision processes, positive feedback may occur because as a channel incises, high magnitude flood flows become confined (instead of spreading onto former floodplains) causing flow depth, transport capacity,

and shear stress to increase and further erode the bed of the channel. Negative feedback may occur when bank height increases GBA3 beyond a critical threshold, causing bank erosion and channel widening to occur, and limit flow depth and shear stress such that aggradation occurs. Considering coupled human–landscape feedbacks is critical in understanding how human activities contribute to positive feedback that may exacerbate incision versus negative feedback that may minimize incision and promote resilience over various time scales. For example, human responses such as constructing bank erosion control structures that address a symptom of incision—namely bank erosion—but not the cause (Spink et al., 2008), may intensify incision that can undercut the structure itself, and thus are not likely to be effective over the long term. Similar conclusions have been noted in other dynamic rivers (Miller and Kochel, 2010). Another problem is lack of attention, as structures intended to limit erosion are rarely monitored (Shields, 2009).