Is Natural Flood Management feasible in large catchments?

According to the Wildlife Trust "Now is the time for UK Governments to prioritise investment in wilder landscapes which could provide the natural solutions  to help prevent flooding in future.  Habitats such as upland bogs and moors, woodlands, wetlands and species-rich grasslands act as giant sponges, absorbing and holding water and slowing down water run-off into rivers"

However there is a lot of debate about whether these practices can realitically be implemented in enough number/ at large enough scales to significantly reduce flood risk in large catchments. 

Is NFM a viable practice in large catchments?