Sand Heads Changes 2018-2022

Sand Heads - Fraser Prodelta Seabed Changes
CSL Heron Surveys 2018-2022

page generated, July 19th 2022
by John E. Hughes Clarke

The following images and links show the surveys conducted on the prodelta slope of the Fraser by the CSL Heron during the period 2018 to 2022.

These were primarily conducted in transit between IOS and Squamish and thus done before and after the summer freshet. Sometimes, but not always, we overnighted in Steveston, and thus there were two opportunities to cover the delta front (weather being a significant issue for a small vessel in April and October).

There is, of course, a major data gap for the two COVID summer freshets when the Heron was inaccessible. Apparently the Vector did a survey in the summer of 2020, but not unfortunately in the summer of 2021(?). Thus all assessments of the impact of the 100 year flood on the Fraser can only compare changes with the whole 2021 summer freshet activity overprinted.

Post COVID a new focus is in the Fraser estuary, so more time will probably be spent there.

Epoch	Bathymetric Coverage	Difference w.r.t previous survey epoch
Spring 2018 JD095 April 5, 6th	overnighted at Steveston reduced using observed Sand Heads tides.	there are previous Heron surveys: 2017 2015 2013 2012 but I don't have the data with me right now. All difference maps have a greyscale that extends from -4m (black) to +4m (white)
Fall 2018 JD291 October 17, 18th	overnighted at Steveston reduced using WebTide model	difference - over summer 2018 +ve bias because the spring survey had a bad SV extension below 100m (MVP max depth)
Spring 2019 JD110 April 20, 21st	overnighted at Steveston reduced using WebTide model	difference - over winter 2018-2019
Fall 2019 JD279 October 6th	transit home without Steveston stop -weather too bad to do more than canyon reduced using WebTide model	difference - over summer 2019
	....... PANDEMIC DATA GAP ....... apparently there was: a summer 2020 survey (Vector?) but no summer 2021 survey (?)
Winter 2021 JD340 December 14-15-16th	about two weeks after the once-a-century flood reduced using Sand Heads predicted tides	cumulative difference - two summers - 2020 and 2021 I'd like to believe the distal Fraser Canyon activity (first since 2012) is due to the 100 year flood but could be anytime in summer 2020/1
Spring 2022 JD140 May 23, 24,25th	river had just started to rise.. reduced using Sand Heads predicted tides	difference - over winter 2021-2022 striping is due to kmall PU bug not applying surface sound speed (needs reintegrating SVP)
mid- summer 2022 JD17X June 26,27,28,29th	river at full mid-summer freshet (> 10,000 m3/s) reduced using Sand Heads predicted tides ASCII lat--lon-depth file 2m grid spacing	difference - first half of summer 2022 surprisingly active distal Fraser canyon..

page made by JEHC - July 2022