On a hot early Summer day in the Valley, anyone who jumped into the ice cold Merced from one of the Valley Bridges did so from the downstream side because below the Bridge there the River was deeper...I'd peer over the edge to see if any Trout about...that deep part I learned is called a Scour Hole...the Bridges restrict the flow of the River, and the speeded up current makes these holes on the downstream side of the Bridge...on the upstream side, when the River is flooding, the restriction makes the River sprawl out and want to go around the Bridge, so new channels, and new areas of erosion take place...I guess that's the reason for wanting removal of the Bridges, Sugar Pine in particular, where I remember negotiating the new channels when they were flooded...the goal is to have the River in equilibrium, where new sediments being deposited balance erosion...factors involved are human trampling, the Bridges, woody debris, ripraps, etc....and I gather all this from glancing at this article from the Merced River Plan study, which is very good...here's link to Analysis of the Bank Erosion of the Merced River, the particular article, and here's link to the study, Merced River Plan documents....rainy gloomy out, site has a 'there are park alerts in effect' note up...good day to be inside warm...in the water color sketch, a long Snag Tree has gotten stuck under Sentinel Bridge, somewhat lost in today's charcoal sketch!...class was set up on the south bank upstream...the Bridges catch snags...and the stump...that's a stump being reflected in the water in the foreground!...the stump may be from a long while ago when the River was going a bit different in its channel...the River moves around, and Trees get engulfed, and when that happens, for safety, they were cut down, which left stumps out in the River...Sentinel Bridge was redone after the '97 flood too, and they didn't stick with the exact 'park's rustic look' in the old Bridges facing stones, but went for a more uniform facing...why they couldn't have stuck with the old look I dunno...a much earlier version of Sentinel Bridge had Lanterns...Lanterns would be nice!...oh, one factor I didn't see in the report is that the Valley is now much more wooded than before, fewer Meadow plants along the banks...though I don't know if Meadow growth hinders erosion...grasses are at Cottonwood Bend, and erosion 'on the outside of the oxbow' is moving right along!...but I think that likely because of the use path thereabout, and 'trampling', which I did some too!...oh...the pics below were taken by Burton Frasher...he followed through on the notion of making postcards!
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