Fig. 12 illustrates simplified geomorphic feedbacks related to incision in a coupled human–landscape system. Both positive and negative feedbacks occur when thresholds are exceeded. Initially, the channel can accommodate some incision and still maintain Doxorubicin mw connectivity. After incision begins, positive feedbacks may arise because bank height (h) increases relative to flow depth (d)—when a threshold is crossed between the condition where flow depth may increase

relative to bank height (d > h) and the condition where flow depth remains lower than bank height, precluding overbank flow (d < h). Once the threshold is crossed, flows are contained within the channel, channel-floodplain connectivity is lost, and transport capacity and excess shear stress increase, leading to more incision. Negative feedbacks arise if slope flattens, or if bank height exceeds a critical height. For example, in the case where positive feedback leads to more incision—with bank height still less than the critical height (hc)—then the positive feedback cycle will dominate geomorphic changes and bank height will increase further. However, once incision progresses

to the point where bank height exceeds a critical height threshold (h > hc), bank erosion will occur, ZD6474 concentration leading to widening, sediment deposition, and eventual stabilization of the channel, assuming that incision ceases. Human responses may then take two disparate approaches to address geomorphic changes: (1) accommodate the dynamic series of adjustments including widening and bank erosion that eventually lead to a stable channel, with connectivity between the channel and newly formed floodplain at a

lower elevation than the terrace; or (2) attempt to arrest the dynamic adjustments such as widening that follow incision, with no connectivity between the channel and adjacent terrace. In the first condition, riparian vegetation may establish and be GNAT2 viable on the new floodplain that is closer to the water table relative to remnant riparian vegetation on the terrace, but raised above the bed elevation where shear stresses are greatest. In the second case, any vegetation established at the margins of the channel would be more easily eroded by flows with high shear stresses contained within the incised channel. Selecting the appropriate management response for modern incised rivers requires a new understanding and conceptualization of complex feedbacks within the context of coupled human–landscape systems. Identifying and quantifying the extent of incision is not a straightforward matter of measuring bank height, since stable alluvial channels create a distinctive size and shape by incising, aggrading, and redistributing sediment depending on the balance between their flow, sediment discharge, bank composition, and riparian vegetation characteristics.