Since our lives are relatively, so short, we tend to think our common landscape features change little over time. Who would think for example, that the Nooksack River was once a tributary of the Fraser river, or that 10,000 or so years ago almost none of our favorite fishing spots in the Valley and LM existed. They would have been covered by hundreds of feet of seawater. The valley up to Hope was a saltwater sound. Both Harrison and Pitt lakes were not lakes but saltwater inlets of the Salish Sea.
There are 3 spots on the Fraser I used to fish for cutthroat in the winter and spring which basically disappeared, became unfishable, mostly due not to floods, but to flood remediation. By gravel mining and riprap structures that both changed the river course and left them all but inaccessible. These days the riprap is made using boulders that are the size of small cars. A couple of years ago on my return to one place I found a sloped field of riprap about 40 yards wide, up to six feet high with chasms as deep and if I slipped, wide enough to swallow my leg. It terminated in deep water where once there was a gravel beach.
I went back the next year and most of the gaps between the riprap were filled with silt and a muddy beach skirted the edge. In one season of flooding the river had all but covered that riprap.