Colorado Plateau Riparian Complex Perennial (Valley Type IV - C5/F5 Stream Types)

Description

The reference channels are E4 or C4. There are two community phases in this state, an E4 channel and C4 channel phase. E4 channel has well vegetated stream banks with plant roots that hold the stream bank together. The C4 channel can occur where flooding has deposited sediment and the channel has widened. The same plant community components are present in both community phases.

Submodel

Description

This state occurs when disturbances in state 1 or 3 remove bank stabilizing vegetation, or there is above normal flooding. Vegetation removal can cause the fine sediment on the banks to lose cohesion, making it easier for sediment to be eroded on the banks. Above normal flooding can also cause channel degradation. Scour of the channel bed typically lead to a “G” type channel that is disconnected from the flood plain. When flood water is unable to disperse over a flood plain is contained within the channel, more erosion on the banks may occur because of greater shear stress. Increased erosion of banks and bed may result in vertical and lateral instability. PCC1 is typically absent from this state, or may be patchy. PCC2 and PCC3 may increase in this state.

Submodel

Description

The channels in this state are stable analogues (stable channels that have similar morphology as state 1 channels) that have re-established some floodplain connection during bankfull flows. These channels also have the potential to express all plant community components. The lower channel may have established after several incremental entrenchment and widening events, as evidenced by floodplains and terraces.

Stable analogue E4 channel. This channel succession within state 3 is similar to state 1, but at a lower elevation. These stable analogue channel types are at risk of crossing a threshold back to state 2 if sediment and flow do not remain in balance.

Submodel