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, roughlyCONSTRUCTIVE 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., 2006ABSTRACT

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.