Table 4 Geomorphic principles that work with river process (Truth 2)

Don’t fight the river. Locked-in mentalities that strive to control a river are unsustainable. Rivers that are fixed in place and locked in time are expensive to maintain. Nature fights back. Eventually it wins!

A living river ethos recognises rivers as disturbance-driven systems. Rivers are never static. Adjustment is the norm

A riverscape ethos works with the process regime that creates and regenerates the dynamic physical habitat mosaic

Erosion and sedimentation are integral parts of a healthy, living river – in the right place, at the right time and rate

Rivers create their own resistance (roughness) and are really good at using their own energy

Ecosystem engineers modify rivers for their own benefit, creating living rivers just as they like them

The balance of impelling and resisting forces, and the spatial distribution of unit stream power, influence the frequency of sediment movement through the system

River morphodynamics at the reach scale vary markedly for differing types of river, with significant differences in capacity for adjustment (sensitivity; rivers love sand) and range of variability (process regime). Different types of river adjust in different ways over differing timescales

The assemblage of geomorphic units along a reach reflects the suite of process–form interactions and magnitude–frequency relations that determine forms and rates of river adjustment (vertical, lateral and wholesale adjustment)

Different combinations of erosional and depositional processes occur at different flow stages, with marked variability in magnitude–frequency relations for different types of rivers. Some rivers are adjusted to extreme events, others are not

Channel geometry (size and shape) and channel–floodplain relationships (channel planform) are products of differing mixes of erosional and depositional processes on the bed and banks

Channels and floodplains tell different stories. When interpreting a river, it is important to get your head out of the channel

Reach-scale behaviour varies in differing process zones and is affected by (dis)connectivity relationships (controls upon the flow/sediment regime) at the catchment scale. Tributary-trunk stream relationships and network configuration control patterns of river reaches and the distribution of geomorphic hotspots

Controls upon process interactions vary at differing positions along a river (relative role of slope, valley width, discharge regime, stream power, sediment inputs (amount, calibre), bank strength, etc.). Different types of disturbance event, and upstream–downstream relationships, influence the pattern and range of variability of reaches along the river