Swash, Beauty and Loosestrife
Art about Finn Slough: What we
were thinking…2011
Overview: The Place
Finn Slough
• Finn Slough (sometimes Tiffin Slough) is on the south
arm of the mighty Fraser River in Richmond, British
Columbia, Canada. The Slough is bounded on the
Fraser River side by Whitworth Island and on the north
by a dyke (Dyke Road) built to protect Richmond from
the river. Access to homes on the Gilmour Island side of
the Slough is by a wooden draw bridge, creating a
definite sense of difference from nearby urban areas.
a bit of background …
• About Finn Slough, about this Art Show, and
about what having talks at Art Shows is for…
We are pleased to have been presenting this event
since 2000!
We began because we noticed a lot of people
made art about Finn Slough but didn’t show it all
together or even know each other did this.
We wanted to give back to the community of
Richmond BC by creating an event at which
artists could all speak together about their
subject! We are very grateful to those who said
yes! to our request to speak.
In 2005…
…we thought, maybe it would be interesting
to everyone, artists, visitors, and residents
alike to include talks at the Art about Finn
Slough Show from people who have
connections to the history and the
ecological features of this place. There is
no shortage of people who have
something to say that relates to Finn
Slough, and interesting ways in which to
say it, we found.
Here is the list of speakers we have heard from, so far:
• 2007: Daphne Marlatt: her book of poetry, Steveston, that
documents historically, elegaically and with great care, Finn
Slough,“channel or by-water” and its people at a particular point in
time
• 2008: Councillor Harold Steves: our topic of “Bridges”, metaphorical
and real; an amazing story teller with a depth of history locally
(Steves of Steveson, yes! That one)
• 2009: Terry Glavin: Canadian author and journalist, passionate
exponent of ideas to do with salmon. Terry spoke along with Mary:
• 2009: (two speakers in 2009) Mary Gazetas: journalist, artist, and
terrific story teller, recounting events to do with the Fraser,
especially a sturgeon tagging expedition!
• 2010: Mark Forsythe: CBC radio one host, who gave us a view of
his work on the history of the Fraser River (Cariboo) Gold rush.
Many connections to history of Finn Slough at that time: he
emphasized the importance of the stories of individuals as what we
must have to understand history
Boats, Plants, Fish, Water, and Historical
Buildings and People in Harmonious
Juxtapositions: These are Typical Topics
Tonight’s Talk
• Why is this year’s show called “Swash”?
• What is it about loosestrife?
• How do these connect?
Swash: What the River Brings
• Finn Slough as an area, a community, a place, is
more water than land. Remember that Whitworth
Island, a narrow strip of land, is what separates the
Fraser River from the Slough itself and the Slough is
between Whitworth Island and Dyke Road, Richmond.
This positioning is important and makes us think about
water all the time, especially during high tides and
storms!
Note that the Fraser river “brought” Whitworth Island, made
it from silt from upstream…as rivers do make islands in
their deltas.
• And rivers “take”, too. (Floods like the one of 1948 took
15 odd acres away from Whitworth Island)
• Main Idea here: the give and take of rivers is a natural
process, nature at work, dynamic, and having complex
and unlooked for surprises for humans.
But humans impact rivers too
• You could say the river brought humans to
live there: originally to do with boat
moorage, it became home for fishers too.
• Now the Fraser is a major freight route,
and the shipping on it has many impacts.
• Historically, many kinds of plants and
animals arrived by boat; of interest
particularly are the unintentionally ones,
like loosestrife. This is why we will be
hearing about purple loosestrife soon.
Complications when considering rivers
• The Fraser is tidal (in and out twice daily)
• The Fraser flows out to the sea.
• The Fraser is affected by wind that either
reinforces the outflow or the inflowing tide.
• The Fraser additionally is affected by the
movement of water from shipping.
• Seasonal melt water amplifies various
effects.
• RESULT: a lot of complex waves adding
and subtracting.
In addition, rivers like the Fraser are traditionally seen as the
“free” road/transport system… they don’t require paving,
they head in the right direction, and since people locate
settlements on their banks, they are already in the right
place. However, maintenance such as dredging has
historically been the equivalent of regular road
maintenance, to keep channels available. This, however,
is a less frequent process than in the past, and has
negative consequences for shipping and for how well the
river can flow. (image from Pitt Meadows area)
But shipping also increases erosion of river
edges (the riparian zone, where water
and land interact), as far up the Fraser as
shipping typically goes.
The effect of boats and shipping on the
riparian zone (the part of rivers humans
most like to live on) is profound.
• What the river gives and takes in terms of soil
(accretion and erosion) is an organic process, of
redistribution, renewal, of rebirth, but mostly of
change.
• Sometimes human interventions “change the
change” process, speeding up, slowing down.
To understand how humans participate in this it
is helpful to think about how waves work:
How do waves work?
SWASH The water that rushes up on shore is called
SWASH . The SWASH carries various materials with
it. The friction and the pull of gravity then cause the
water to flow out. Some material gets left behind.
BACKWASH The flow back after the wave has broken is
called BACKWASH. The backwash carries material back
out, sometimes much more than swash brought in.
Two Kinds of Waves, roughly
CONSTRUCTIVE WAVES: low energy waves that deposit
materials.
As these waves approach, the friction between the waves
and the bed causes the waves to slow down at some
distance from the edge. The swash is more powerful
than the backwash; more materials are carried up and
deposited on the coast than are removed. Over time,
the water’s “edge” is built up.
DESTRUCTIVE WAVES: high energy waves that erode
These are common along steep sloping “edges” where
they break with great force over a short distance. The
backwash of such waves is more powerful than the
swash. More materials are removed than are deposited.
Over time , the “edge” is eroded away.
• This is how they look…
• Even more complications…
The Effects of Wave Action and
What to Do about It…
• Is a subject of MUCH study, research, debate
and disagreement
• There are legal constraints on shipping, boat
speeds, etc. but little ability to enforce, or
funding for enforcement
• At the same time, there is an increasing sense of
urgency, as climate change puts more water in
rivers, which in turn offers more scope for all the
kinds of wave and flow actions already
mentioned.
Experimental Measurements of River-Bank Erosion Caused
by Boat-Generated Waves on the Gordon River, Tasmania
By:
Gerald C. Nanson, G. C., Von Krusenstierna, A. , Bryant, E. A., &
Renilson, M. R., 2006
ABSTRACT
Erosion of natural river banks by boat-generated waves is an
increasingly serious problem on the navigable reaches of many
rivers, particularly on the middle and estuarine reaches. An
experiment designed to link bank erosion rates with easily
measured wave characteristics, conducted on the scenic lower
Gordon River in Tasmania, provides information useful for river
management. Within a boat-generated wave train a number of
characteristics were measured and most showed a high correlation
with measured rates of bank retreat. Maximum wave height within
the train is the simplest measure and is associated with a major
threshold in erosive energy on unconsolidated sandy alluvium at
wave heights of 30 to 35 cm. At maximum wave heights above 35
cm all but the most resistant bank sediments erode. Reducing
maximum wave heights to < 30 cm by limiting boat speeds, and
reducing the frequency of boat passages, caused a dramatic decline
in bank erosion along the river.
• Effects of water action can be beautiful…
(canyon image, not Finn Slough!)
• Wash and wake make beautiful (but
potentially very destructive) patterns…
Transport Canada is charged with regulating against the
negative effects of shipping, boating, and wash/wave
action…but swash remains a powerful and destructive
riparian feature
And how does swash relate to Art and to Loosestrife?
• Purple loosestrife is a very beautiful plant, makes a nice
cut-flower bouquet, and is the star of really stunning
photographs. It has begun to turn up and be admired
and photographed at Finn Slough. What can knowing
more about such a beautiful plant do to our sense of
beauty or how we aesthetically value things in our
environment?
• It is as well an invasive plant that no-one really intended
to turn loose on the riverside environment. Loosestrife
came with European settlers who used the river ;
loosestrife used and still uses the river to get around,
spreading with amazing vigour, unlike the native flora like
black lilies (frittilaria camchatkensis) that are transported
by the river but are not invasive. Finn Slough remains a
pocket of habitat that still supports the native flora,
supporting plants that used to be common throughout
the Fraser delta, but now exist only in fragile pockets like
Finn Slough that change has washed over in a gentler,
slower way.