chapter 1 the importance of rivers - sfu.ca - simon …hickin/rivers/rivers1(introduction).pdf ·...

Chapter 1 The Importance of Rivers

1. Why Study Rivers? 2. Rivers as Landscape Elements in the Arts 3. Rivers as Hazards 4. Rivers as Resources 5. Rivers as Recreational Assets 6. Rivers as Transportation Corridors 7. Rivers as Habitat 8. Rivers as Legal Boundaries 9. Rivers as Geomorphic Elements and Agents 10. The River System 11. Some Further Reading 12. What’s next?

1. Why Study Rivers? Because they’re there! This may seem like a flippantly glib answer to the question but it is truly

why rivers are important to geographers and to geomorphologists. Rivers and their drainage

basins constitute a basic building block of our planet’s physical landscape and societies

everywhere are deeply influenced by their presence. Rivers are both a virtue and a curse to

society and understanding how and why they function as they do is a very important challenge to

both the physical and social sciences as well as to planning and river engineering. This chapter

is a preamble that will touch briefly on some of the roles played by rivers before we begin to

delve into the physical science of fluvial geomorphology. It is designed to offer you some

examples of the importance of rivers and is not meant to be exhaustively comprehensive; you are

encouraged to think about these things and to add your own examples as we go along.

2. Rivers as Landscape Elements in the Arts

Rivers are a pervasive element in the landscape and for many people represent the defining

quality of particular places. Writers and visual artists have been captivated by rivers forever it

seems and have for as long as humans have been recording their feelings about their environment

sought ways to express the aesthetic and romantic images that rivers seem to conjur up. Perhaps

this fascination with rivers reflects the notion that the water they carry is essential to life itself.

Perhaps part of the fascination also derives from the movement of water (like the captivating

movement of fire) that seems to invest rivers with the quality of life. For whatever reasons,

Hickin: River Geomorphology: Chapter 1

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writers and artists are drawn to rivers and our literature and painting are heavy with their

presence.

Perhaps one of the most famous purveyors of stories about river life (in English) is Samuel

Langhorne Clemens (Mark Twain) whose 19th century novels (particularly Adventures of

Huckleberry Finn) and short stories about the Mississippi River and the river communities along

its wandering course are such an important part of American literature. The Mississippi River is

of course, one of the most written-about rivers in the world. Closer to home, and more recently,

we see rivers as the centrepiece of Canadian novels such as Cheryl Tardif’s The River (set on the

Nahanni River in the Northwest Territories) and images of rivers are used as a literary device in

works such as Margaret Laurence’s The Diviners among many others. Rivers have a similar

place in French language works. For example, the St. Lawrence River is at the heart of many

Quebec novels (Anne Hébert's Kamouraska, Réjean Ducharme's L'avalée des avalés), poems (in

works of Pierre Morency, Bernard Pozier), and songs (Leonard Cohen's Suzanne, Michel

Rivard's L'oubli). A recent Australian historical novel set in the Hawkesbury River Valley is

Kate Grenville’s The Secret River. Non-fiction books on rivers are also abundant with Hugh

Maclennan’s Seven Rivers of Canada being a notable Canadian contribution along with

American John McPhee’s The Control of Nature. Even Environment Canada makes the

water/culture connection on its WEB page concerned with Canadian water resources!

(http://www.ec.gc.ca/water/en/culture/ident/e_words.htm).

But it is in landscape painting that rivers perhaps claim their most significant cultural presence.

They almost constitute a genre of their own in art history and a visit to any art gallery will almost

certainly produce an encounter with a riverscape. In Britain landscape painting of the 18th

century evolved from an elitist form (catering to wealthy landowners) into a rather poetic vision

and painters provided a romantic ideal of landscape as a source of timeless values which could

be enjoyed by everyone. Famous landscape artists like Gainsborough and Constable present the

landscape as a place of rest and solace and this comforting mood is often set by capturing the

gentle transit of rivers through the countryside (Figure 1.1).


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Figure 1.1: Examples of the landscape paintings of John Constable in which rivers and riverscapes form the central theme of his work.

Closer to home we see fine examples of the work of the Group of Seven similarly engaged with

rivers in various parts of Canada (Figure 1.2). Particularly relevant to us here in the lower

mainland of British Columbia are Frederick Varley’s paintings of Lynn Creek (Moonlight at

Lynn) and Cheakamus River (Cheakamus Gorge).

Movies represent another visual-art form that have drawn significantly on rivers for subject

matter. Examples that come readily to my mind include Apocalypse Now, The African Queen,

Show Boat, A River Runs Through It, The River Wild, River of No Return, The Man From Snowy

River and Wrath of God. TV movies of a more documentary nature include the 1999 movie

Amazing Streams and Rivers (check it out at http://www.spout.com/films/155255/default.aspx).

John Constable, English landscape painter (1776-1828)

Boatbuilding Near Flatford Mill

Flatford Mill

Valley Of The Stour

View On The Stour

Bridge Over The Stour

The Hay Wain


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Figure 1.2: Examples of river-themed paintings by the Canadian Group of Seven.

A.Y. Jackson (1882-1974) The Red Maple

J.E.H. MacDonald (1873-1932) Falls - Montreal River

Tom Thomson (1877-1917) Woodland Waterfall

Frederick Varley (1881-1969) Cheakamus Gorge

Frederick Varley (1881-1969) Moonlight at Lynn


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Poetry and music can also lay claim to rivers as artistic vehicles. You can compile your own list

but at the risk of dating myself and making my ancient musical tastes public, my list of poems

and songs would include ‘Banjo’ Paterson’s The Man from Snowy River, Jerome Kern and Oscar

Hammerstein’s ‘Ol Man River, Jimmy Cliff’s Many Rivers to Cross, and Henry Mancini and

Johnny Mercer’s Moon River. You can also check out another of my favourites: Alberta-born

Joni Mitchell’s River at (http://www.youtube.com/watch?v=bVwo9IQMWM0) if you need to relax before

moving to the next section dealing with rivers as hazards! She sees a river as an avenue of escape

from life’s troubles:

Oh I wish I had a river I could skate away on But it don’t snow here It stays pretty green I’m going to make a lot of money Then I’m going to quit this crazy scene I wish I had a river I could skate away on I wish I had a river so long I would teach my feet to fly Oh I wish I had a river I could skate away on I made my baby cry

Before we leave this section on rivers and the arts we should note that rivers have been granted a

quite special place in the Canadian identity through the activities of the Canadian Heritage River

Board (CHRB). The CHRB was created to recognize the powerful part that rivers play in

defining the Canadian landscape and in turn what it is to be Canadian. Examples of rivers

declared by the CHRB to be special enough to be given heritage status in western Canada are

shown in Figure 1. 3. The Fraser River was declared a heritage river in 1998.

3. Rivers as Hazards

In contrast to the calm and soothing imagery of the riverscapes created by artists the reality is

that many rivers are dangerous, every year taking thousands of lives and destroying property

worldwide.

Flooding is perhaps the most obvious river hazard. All natural rivers flood as part of their

normal behaviour. It is by flooding that rivers build floodplains and in many places entire


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Figure 1.3: Examples of rivers in western Canada that have been declared heritage rivers by the Canadian Heritage River Board.

ecologies are dependent on the regular seasonal overflowing of the channel to fill adjacent

floodways and lakes. But humans also have a knack for building on floodplains and the results

are often disastrous. We are all familiar with the tragic loss of life that occurs almost every year

on the huge river systems (Jamuna, Padma (Ganges), Brahmaputra and Meghna rivers) draining

the melting Himalayan snows and the rains from monsoonal and cyclonic storms across

Bangladesh (http://www.youtube.com/watch?v=y9hw1V8YrFc) to the Bay of Bengal. But most

places have rivers that flood and cause havoc. Here in BC Fraser River has a history of flooding

its banks, sometimes just locally but also occasionally extensively enough to affect most of the

Fraser Valley. One of the largest floods occurred in 1948, inundating much of the Fraser Valley

(http://www.ec.gc.ca/water/en/manage/floodgen/e_bc.htm#1948) and isolating Vancouver for

weeks (Figure 1.4). It was after this event that a system of dykes was built along much of the

South Nahanni River, NWT

Alsek River, Yukon Yukon River, Yukon

Clearwater River, Saskatchewan

Kicking Horse River near Field, BC Fraser River, BC


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Figure 1.4: The Fraser Valley town of Mission in flood in 1948

length of the Lower Fraser in order to contain a future flood of this magnitude.

It is an interesting comment on our perception of hazards that flooding of the Fraser River is not

seen today by politicians and planners to represent as much of a threat as history suggests. Yet

little has changed since 1948, apart from the raising of barely adequate dykes and the

construction of a dam on the Nechako River, a tributary that joins the Fraser River near Prince

George. Essentially the flood of 1948 will be repeated in due course but in Vancouver we seem

to be far more concerned about earthquakes that have never happened in hundreds of years than

we are with what is almost a certain flooding disaster waiting to happen.

Dyking rivers is the normal engineering response to coping with floods but they are not the

simple fix as they might at first seem. Quite apart from the great expense of building them there

is another problem. If the dyke is not high enough to contain a flood the floodwaters will surge

onto the floodplain and be held back from rejoining the river further downstream because of –

you guessed it – the dykes that line the river! This has happened many times during flooding on

the Mississippi River and the US Army Corps of Engineers routinely in times of flood have to

use explosives to create breaches in the dykes to let the water flow back into the river!


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Scouring of bridge piers is another consequence of rivers in flood. Although most bridges

today are designed to withstand a major flood the engineering design work required is not a

precise science and bridges do continue to fail. Often associated with flooding on our local

mountain rivers are debris flows, slurries of sediment and often large woody debris that move

down the channel with such momentum that they are capable of knocking out bridge piers

without first scouring the footings. A tragic example of this natural hazard is M-Creek on

Highway 99 in Howe Sound. Here in 1981 a debris flow knocked out the bridge at night and ten

people died as drivers of cars, unaware that the bridge had collapsed, drove into the channel.

Excavation of building footings and buried structures (such as riverside buildings and pool

foundations and sub-bed pipelines) by flood waters is also a widely reported destructive effect of

flooding on all types of rivers.

Erosion of riparian land by lateral migration is a related problem encountered mainly in river

bends of meandering rivers. Such erosion of the outside (or concave side) of bends often takes

Figure 1.4: These houses are the victims of lateral migration and undercutting by the Hope River in Tavern, St Andrew, taken two days after the passage of Tropical Storm Gustav on August 28, 2008. (Observer file photos).


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out riverside roads (as happens frequently on Squamish River north of Vancouver). Again, the

lateral migration of river bends in meandering rivers is entirely normal and can only be arrested

by protecting the eroding banks by the emplacement of revetment (rip-rap) on the concave

banks. This problem is exacerbated by developers who create housing projects on the edge of

floodplains for that coveted “waterfront” status. Unfortunately waterfront on a migrating river is

a rather dynamic concept (Figure 1.4)!

4. Rivers as Resources

Rivers may have a hazardous and destructive side but they are also fundamentally one of our

greatest resources. Rivers provide fresh water for many purposes:

Domestic water use (drinking, cooking and washing) hardly needs explanation. In many parts

of the world rivers are dammed to store water while elsewhere water is drawn directly from

rivers for domestic water use. Rivers supply water directly or indirectly (from lakes) for urban

gardens, pools and parks. Similarly, river water nourishes agriculture, sometimes being

directly pumped to nearby fields and elsewhere being transported through pipes and aqueducts of

irrigation schemes to distant fields. Industrial use of water can be rapacious and in most places

depends on the availability of abundant river water. This connection is no more evident than

here in British Columbia where pulp mills, for example, are always located near plentiful

supplies of freshwater from rivers or lakes. Indeed, there are few industrial processes that do not

consume large volumes of fresh water.

Many regions draw their fresh water for domestic and industrial use from groundwater but this

source is also dependent on water from rivers. Much of the water in the ground gets there by

groundwater recharge from rivers on the surface. There is in fact an exchange of water that

takes place between the groundwater and the river water. During dry periods river discharge

declines and is sustained by groundwater seeping through the channel boundary to the river.

During wet periods, on the other hand, the rivers fill and the elevated hydrostatic pressure forces

water through the channel boundary to be stored in the ground below (in the aquifer).

Hydro power is another obvious industrial dependency on river water. In British Columbia a

number of our rivers are dammed so that the stored water can be used to drive the turbines in


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hydro-electric generating plants. Indeed the Province is almost entirely dependent on rivers for

its electricity and this dependency increases every year with the construction of the new low-

head run-of-the-river hydro power plants in the headwaters of mountain streams.

The commercial and native fishery also depends on rivers. The health of salmon runs in

particular is intimately connected to the health of our rivers and the role of rivers in the

freshwater fishery is obvious. A related activity dependent on rivers is trapping. Of course

trapping of fur-bearing animals is not the huge industry it was during historical times in Canada

but trapping of beaver in particular remains an active enterprise in northern communities.

Placer minerals are minerals that have been transported by the flowing water of rivers to

depositional sites where they may be mined. In British Columbia and the Yukon the most

important placer mineral is gold (alluvial gold) and it is found in the contemporary deposits of

rivers and in older sediments such as those forming river terraces and abandoned channels.

Elsewhere rivers have been the agent for transporting and concentrating alluvial diamonds. For

example, the Orange River that separates South Africa from Namibia has transported diamonds

from the interior kimberlites to the southwest coast of Africa where they were further

concentrated by coastal processes to become what is today a commercially exploited very rich

alluvial diamond field.

5. Rivers as Tourism and Recreational Assets

Rivers attract tourists and have become increasingly important to the economies of many

countries. Large rivers like the Mississippi, Nile, Rhone and the Amazon, for example, support

fleets of high-priced tourist shipping while smaller more lively streams (like Squamish and

Thompson rivers here in BC) have become ecotourism attractions or draw adventure tourists to

white-water rafting and kayaking.

Riverside parks are popular places (the lower Fraser River has many, for example) for camping

and recreational fishing, boating and waterskiing or just simply river-watching. I’m sure that

you can, with little difficulty, add to this list of riverside recreational activities.


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6. Rivers as Transportation Corridors

The role of rivers in the early exploration of Canada by the voyageurs needs no explanation to a

student at Simon Fraser University! Rivers provided access to the interior of Canada and

enabled the westward exploration of the country as the early explorers traveled the rivers by

canoe to the coast.

Today rivers continue to be important transportation corridors. Here in Canada rivers such as the

Mackenzie in the North are critical for travel and commerce and rivers are used in the industrial

centres as shipping routes. Much of Canada’s international trading is done by shipping that

passes through the St Lawrence River in Quebec and Ontario in the east or through lower Fraser

River in the west. In Canada rivers are used to transport log booms from the forests to the mills

in many regions and barge traffic in most estuaries represent lifelines to coastal communities.

All major roads follow river valleys. This correlation is particularly evident in the Coast and

Rocky Mountains where highways and railroads cross the grain of the mountains via east-west

river valleys. The route of the Trans Canada Highway (Highway 1) is dictated by the access

provided by rivers such as the Fraser, Kicking Horse and Bow. Indeed the entire road system in

British Columbia is laid out in river valleys.

A river-dependent transportation issue that most of us likely do not think about is air travel! In

mountainous areas such as western Canada recreational and small commercial aircraft follow

routes over river valleys. Aircraft cannot fly above about 3000 m without oxygen being supplied

to the cabin and this alone tends to limit routes to low-elevation passes (ie, river valleys).

Weather is another factor: river valleys often provide an air route below the cloud ceiling.

7. Rivers as Habitat

Rivers and their floodplains constitute one of the world’s great biosystems. It provides habitat

for a huge range of animals and plants and most of the world’s birds, especially water fowl such

as ducks and geese. Many river animals, like beaver, river otter, muskrat and mink were

important commercial species and are historically important in Canada as the backbone of the

early fur trade. Rivers are vital habitat to many species of fish, of course none more important


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than salmon and trout here in Canada. Even mammals such as beluga whales that we usually

associate with the oceans come into estuaries of rivers like the Mackenzie to calve. Other

animals most of us will readily associate with rivers include moose, bear, caribou and elk. In BC

the gathering of salmon and eagles on Squamish River has become an annual celebration!

8. Rivers as Legal Boundaries

Again, not something most of us think about but rivers in many parts of the world are used as

legal boundaries. At a local level rivers can form municipal and county boundaries such as the

Capilano River that separates West and North Vancouver or the Squamish River that defines one

of the boundaries of the Squamish Nation Reserve in Squamish. In North America many

Provincial and State boundaries are defined by river courses. For example, in Canada, Quebec

and Ontario share a boundary on the Ottawa River. In the US a number of states (for example,

Minnesota/Wisconsin, Iowa/Wisconsin, Iowa/Illinois, Missouri/Illinois, Illinois/Indiana,

Indiana/Kentucky, Arkansas/Tennessee, Arkansas/Mississippi, Louisana/Mississippi, among

others) have borders formed by the Mississippi/Missouri system rivers. Rivers forming

international borders include the St Lawrence (Canada/US), the Rio Grande (US/Mexico), the

Putumayo River (Colombia/Peru), the Mekong River (Burma/Thailand/Laos), the Orange River

(Namibia/South Africa), the Amur River (Russia/China), the Oder River (Germany/Poland) and

the Rhine River (France/Germany), among many others.

One of the interesting problems that arises from using a river course to define a legal boundary is

that rivers move so there is a question about what that means for the boundary! For example, in

the case of the US and Mexico, the border between the two countries is defined by a very mobile

Rio Grande River and this has led to the establishment of the International Boundary and Water

Commission whose mandate includes monitoring the position of the Rio Grande River and

resolving the resulting territorial disputes (http://www.ibwc.state.gov/home.html). A principle

well established in law now is that legal boundaries move with rivers if the channel migrates

incrementally (gradually) over time but are left behind if the channel moves by avulsion

(catastrophically). As you can imagine, this arbitrary legal principle creates as many problems as

it solves!


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9. Rivers as Geomorphic Elements and Agents

This brief survey of the importance of rivers brings us to the matter at hand: the role of rivers in

making and shaping the landscape. Most of the earth’s surface consists of the nested basins

(drainage basins) that accommodate and supply rivers with water and sediment. Indeed,

drainage basins are regarded by most geomorphologists as the fundamental geomorphic unit.

Even in glaciated landscapes and in deserts, rivers and their valleys are the dominating landscape

element. It is fair to say that, almost everywhere on the land, rivers represent the most important

set of processes shaping the surface of the earth. In the long term (millions of years) they

undertake the surface erosion (Figure 1.5) that balances the creation of new land by tectonics

Figure 1.5: The erosive power of rivers is clearly evident on Fraser River at Hell’s Gate (A), on Lilloett River near Pemberton BC (B) and on the Athabasca River in the Canadian Rockies (C).

A

B

C


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(uplift) and therefore are integral in the processes that maintain crustal equilibrium and mass

balance. Rivers transport to oceans the water and sediment eroded from the continental

highlands. They form a central element of the hydrologic cycle (Figure 1.6). They are like a

global system of geomorphic conveyor belts moving water and sediment from the mountains to

Figure 1.6: Rivers are important components of the hydrologic cycle.

the sea. In the shorter term they create valleys and build floodplains and they build deltas that

store sediment eroded from the continents (Figures 1.7 and 1.8).

Figure 1.7: Deltas are sites where rivers store sediments transported from the continental highlands. A: Buchan’s Brook delta in Red Indian Lake, Newfoundland, and B: the bird’s foot delta of Scotts Brook, Cape Bretton Island.

A B


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Figure 1.8: The Fraser River delta at Vancouver, British Columbia.

10. The River System One of the important principles that you will have encountered in earlier courses is that rivers

form a part of the interrelated environment that we sometimes refer to as the earth system. But

here we need to recognize that rivers themselves are part of a smaller nested system that also

functions as an interdependent set of forms and processes; geomorphologists have named this the

fluvial system.

The fluvial system is a concept that draws our attention to the fact that rivers are complex and

form part of a dynamic system in which all parts are interdependent. This notion is captured in

the diagram of relationships described in Figure 1.9. This diagram is from David Knighton’s

book Fluvial Forms and Processes (1998) and you will find it a useful place to revisit as we

continue our exploration of the ways of rivers.


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Figure 1.9: “The fluvial system” from Knighton (1998: Figure 1.1). Knighton’s diagram recognizes that all aspects of river channel morphology (for example,

channel slope, width, depth and planform character) and flow (velocity, for example) are related

and that they, in turn, depend on several independent channel controls (such as valley slope, river

discharge, input of sediment, and bank material type and strength). These channel controls are in

turn dependent on basin controls such as physiography, vegetation and soils which in turn

ultimately depend on regional climate and geology.

We do not fully understand the details of many of the processes that control these relationships

but most geomorphologists have no doubt about the existence of such complex

interdependencies even if we have yet to fully specify them. One of the important implications

of this diagram of the fluvial system is that, if one or more components change, many others will

be affected in some way. Local changes (such as building a dam and diverting water from the

basin) will set in motion changes in the rest of the system. The more general the change (such as

a shift in climate) the more profound will be the impact on the fluvial system. Some of you may

not be surprised at the nature of these interdependencies but most of us would be surprised to


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learn how often they are ignored by planners and engineers and geomorphologists responsible

for managing our rivers.

11. Some Further Reading

At this early stage in our discussion of fluvial processes you might find it most useful to consult

a general textbook on geomorphology and refer to the chapter(s) on rivers and fluvial

geomorphology. Three good sources in the Library are Easterbrook (1999), Ritter et al (2002)

and Trenhaile (2006):

Easterbrook, D.J. 1999 Surface Processes and Landforms, Prentice Hall.

Ritter, D. F. Kochel, C. and Miller, J.R. 2002 Process Geomorphology, Waveland Press.

Trenhaile, A.S. 2006 Geomorphology of Canada, Oxford University Press.

More advanced (but less readable) accounts are the introductory chapter in Knighton (1999) and

Richards (1982):

Knighton, D. 1998 Fluvial Forms and Processes: A New Perspective, Hodder Arnold Publication, Chapter 1.

Richards, K.S. 1982 Rivers: Forms and Processes in Alluvial Channels, Blackburn, Chapter 1.

The SFU Library has both of these advanced texts.

12. What’s Next?

Now that we have finished our preamble on rivers we can get on with the next step of getting

down into the river channel to see what makes it tick! What is it that determines the size of a

river and how do we measure it? These are some of the basic questions of fluvial

geomorphology and are the subjects of Chapter 2.

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