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Hydrology and Water Resources



Impacts of Climate Change on Water – Hydrology

The impacts of climate change on water affect both the natural and built ecosystems. This section deals with some of the hydrological impacts – flow, levels, volume, and the quality of water . Pollutants are featured with graphs.
Two integrated summary diagrams tie it all together. Finally there is water usage information and a challenge.

Recently, water levels in the Great Lakes have been lower than average. Property owners and businesses, such as marinas, have been affected by these lower levels. See Section 5.2.1b, Ontario section on precipitation. See Section 5.2.2b for aquatic ecosystems and terrestrial ecosystems that include groundwater and watersheds.

This is Macy’s Bay on Georgian Bay, May 15, 2000

Source: Environment Canada

1. Which Great Lake is shown here?
2. List 5 impacts this water level might have on the area.

ACTIVITY 2 Research
What percentage of the world’s fresh water is found in the Great Lakes?

The graph below shows the water levels(m) over the last century. The pattern is important to an understanding of the context of climate change, especially for the projections of future temperatures.

Mean monthly water levels in meters above sea level: Lake Huron from 1900-2000.

1. What is the range of meters above sea level shown on the y axis?
2. What is the difference in range of mean monthly water levels for year 1900 and the year 2000?
3. What might this pattern of highs and lows indicate about water levels in the Great Lakes and climate?

Source: Environment Canada, Burlington, Ontario.

1. Compare the low level periods in Lake Huron and Lake Ontario. What was built in the 1950s to influence lake levels?


Water, in all its forms, is cycled by energy from the sun. Heat energy from the sun is absorbed by the water and drives the water cycle. Changes of state must absorb or release heat energy. Snow cover, ice cover, precipitation and evapotranspiration, albedo, ground water, soil moisture, land use and vegetative cover, for example, all play a part in this sun-driven cycle. These topics are covered in other parts of this site.

The timing of precipitation events, loss of snow, and less absorption by soil all cause a reduction in the stream water base level flow, which recharges aquifers, wetlands, lakes, and rivers. (See Sections on Precipitation, Snow Cover.) As the annual air temperatures increase so does the temperature of our ground water. Warmer ground water eventually influences all bodies of water and aquatic life. According to Joan Klaassen, Environment Canada, climate models project regional reductions in ground water supply, as well as a 14% to 67% decrease in soil moisture in Southern Ontario. (See section on Ground Water.)

The Great Lakes system is the largest system of fresh water on Earth. If you stood on the moon, you could see the lakes and recognize the familiar wolf head shape of Lake Superior, and the “mitten” formed by Lakes Michigan, Huron and Erie. These freshwater seas hold about one-fifth of the world’s fresh surface water supply. Glacial rebound is slowly and unequally affecting the water levels also. (See section on Glaciers and Stream Recapture)
The Great Lakes moderate Ontario’s climate. There are fewer extremes in temperature and greater precipitation than the prairies. (See Canada-wide Temperature and Precipitation maps.)

Only 1% of the water in the Great Lakes is renewed each year. That means that if more than 1% of the volume is removed in a year, the levels will be reduced. Figure 1 shows the processes that remove and replace water in the lakes. Figure 2 shows how climate affects removal and replacement of water in the Great Lakes system.

Figure 1. The Water Cycle Figure 2. Great Lakes Water System


Source: Government of Canada and U.S. Environmental Protection Agency, 1995

ACTIVITY 5 Look at Figures 1 and 2 to answer the following questions:
1. Which processes represent natural removal of water? Which processes represent natural replacement?
2. How do changes in air temperature affect the rate of evaporation and precipitation?
3. As the climate gets warmer and drier, what will happen to our demand for water? Why?
4. What will be the effect on the level of the water table?
5. Make a list of effects it will it have on recreation, businesses.

Lower water levels increase the cost of commercial shipping due to reductions in cargo to maintain the draft or depth of water to the bottom of a ship. For example, intralake vessel 350 m long loses 270 tonnes of cargo for every 2.54 cm of draft loss. The competitive advantage of the cost of shipping over railway transportation may be threatened by dredging costs and increased risk of running aground. When lake water levels dropped in 1962-64 dredging to deepen canals and shipping lanes cost $3.2 million US per year – ten times more than before 1963.

The rate of evaporation from the surface of bodies of water increases with increases in temperature. The rate of the process of transpiration is also temperature sensitive. Increased temperature means that more heat energy is available for water to change from liquid to vapor – whether from the surface of a body of water, from the film of water on soil particles, or from plants. An example is the film of water on the cells inside the stomata of plants. The combination of these processes with reference to bodies of water and vegetation is called evapotranspiration. (See the section on terrestrial ecosystems for a detailed look at how soil works.)

Some applications that use the knowledge of changes of state of water are already in place. Canadian inventors are testing a blanket of an invisible, biogradable, molecular-thin film which, in trials on small tropical lakes, reduces evaporation by 45%. The long term effects on life in these lakes has yet to be determined.

Other Canadian inventors, working on mountain tops in South America, developed a mist net which catches molecules of water in the fog there and delivers liquid water to the village further down the mountain.

The graph below is based on 20 years of data from the area. This base data is used in the climate model to develop the scenario to assess future impacts on the area.

Relative Changes in monthly potential evapotranspiration for climate change scenarios for the Bay of Quinte Watershed showing percentage change from the base data 1971-1992.

Source: Walker, R.R., 1996. Assessment of Climate Change Impacts on the Bay of Quinte, Ontario:
A Report to Environment Canada,  Environmental Adaptation Research Group, Burlington, Ontario.

ACTIVITY 6 Locate the Bay of Quinte on a map of Ontario.
1. Describe the general pattern seen in all 3 projections during one year.
2. How does this pattern relate to the average?
3. What does the y axis tell you? What are the highest months for change? Why?

ACTIVITY 7 Research
1. What is the role of ice cover in this scenario?


Observations from 1846 to 1995 show that both the length of ice cover season and the area of the ice cover have decreased in the Great Lakes region. During this time the temperature also increased 1.2 C degrees per century. Ice break up is now an average of 6.5 days earlier and freeze up 5.8 days later. In the last 150 years lakes and rivers in Ontario have gained almost 2 weeks more of open water. (See sections on Libido effect, Lake Snow effect.)

The graph below shows the duration of the ice cover on Lake Simcoe. Notice that data collection began in the mid 1800s.

Source: Martyn Futter, Climate, Nature and People: Indicators of Canada’s Changing Climate

Canadian Council of Ministers of the Environment 2003 www.ccme.ca

1. Locate Lake Simcoe on a map of Ontario.
2. Describe the trend seen for the duration of ice cover. What effect has this had on fish populations?
3. How many years of data are represented on the graph?

ACTIVITY 9 Research
1. What are the freeze-thaw dates from 1993 to 2000? Does this data continue this trend?
2. Use a ruler and project the date when there might be no ice cover on Lake Simcoe.
3. Why is data available for this lake and not many other Ontario lakes? Hint: check the location and history of settlement of this area of Ontario.

Ports and commercial shipping schedules have changed. The Hudson’s Bay ice cover has decreased one-third since 1971. Shipping grain through Churchill as a port leading to the prairies and to the USA is cheaper than the ports on the St.Lawrence Seaway. Since 2002 one-third of all grains shipped have come through Churchill in spite of the fact that the port at Thunder Bay has an ice-free season that is twice as long. The change from Great Lakes ports to Churchill saved $10 million US in 2002.

The good news is that Canada has developed better ice-mapping systems and better ice detection. We are changing our behavior because of reduced ice cover.

Built systems and natural systems are both ecologically and economically affected by this change in ice cover. The less ice cover, the greater the total evaporation from open water and the resultant decrease inlake levels. A shorter ice cover season increases shoreline erosion.

Hudson’s Bay reduced ice cover has affected the populations of polar bears that use the sea ice as fishing platforms. Female polar bears cannot accumulate enough fat to nourish their young born later on the land. In the Great Lakes region, fish stock and fish egg survival rate, recreational boating, and beach access are all affected.

Environmental restoration programs for sensitive areas such as wetlands and shorelines could be vulnerable to climate change. The International Joint Commission for the Great Lakes has the responsibility to monitor and report on programs in the Great Lakes Basin and along the St. Lawrence River.

The present state of the Great Lakes is described as Areas of Concern. These identified areas are being studied and may already have remedial action plans underway. These plans, however, may have to be modified to include the impacts of climate change, especially those projected in sections 6 2. and 7.2.

Areas of Concern (AOCs) around the Great Lakes, agreed upon by the International Joint Commission (IJC) are listed below. An area where one or more beneficial uses listed by the IJC are impaired has been termed an Area of Concern (AOC). Annex 2 of the 1987 Protocol to the Agreement defines an AOC as “a geographic area that fails to meet the General or Specific Objectives of the Agreement where such failure has caused or is likely to cause impairment of beneficial use or of the area’s ability to support aquatic life”.

For each AOC, a Remedial Action Plan (RAP) is to be developed and implemented to restore and protect the beneficial uses. For open lake waters, Lakewide Management Plans (LAMPs) were developed to distinguish pollutants that could affect humans or aquatic life and to restore beneficial uses that were impaired.

There are currently 41 AOCs (there were 43). Collingwood Harbour (IJC, 1991) and Severn Sound (Kirschner, 2003) have been delisted. Remedial action Plans (RAPs) may have been written and implementation undertaken before the impacts of climate change for Ontario were considered. Each of the 12 beneficial uses potentially vulnerable to climate change is being reviewed.

For each AOC, a beneficial use is designated within the listed guidelines as impaired, unimpaired, under assessment, or restored. A use is identified as being under ‘assessment’ when environmental conditions are unknown or under review. ‘Restored’ indicates that the delisting guidelines have been achieved. In the following section the listing guideline for each use is described, and the potential impacts from climate change are identified.

The next diagram lists the Areas of Concern (AOCs) by lake. There are currently 41 AOCs (there were 43). Collingwood Harbour (IJC, 1991) and Severn Sound (Kirschner, 2003) have been delisted.

1. Which AOC numbers are in Ontario? How many of these are binational?

Research: What specifically must have occurred in order to delist an AOC, for example Collingwood?

These critical pollutants are considered to be the most extensive and persistent chemicals found in the Great Lakes in 1985. The presence of a contaminant indicates it came from the watershed. The contaminants listed all have toxic effects on living organisms at certain concentrations.

Critical Great Lakes Pollutants

Source: IJC


1. Choose one contaminants from the list and research its source and its use(s).
2. What is the chemical formula for the contaminant chosen? Is it an organic compound?
3. In what units are the concentrations of these contaminants usually measured?
4. What are the dangers of this Great Lakes contaminant as the rate of evaporation increases?

The graph below shows improvement in lake water quality for some of the contaminants.

Source: Environmental Signals National Environmental Indicator Series, E. Canada. 2003

1. Where do cormorants live? What do cormorants eat?
2. What actions helped to reduce the contaminant concentration in their eggs?

Water Phosphorus Levels

PWQOs are Provincial Water Quality Objectives. They represent the target levels or the highest levels that should occur. The government hopes to keep the concentrations of phosphorus below the target levels in lakes (0.02mg/l) and rivers(0.03mg/l). Some communities have tertiary sewage treatment plants that remove phosphorus before the treated water is discharged. The quickest and easiest way to reduce phosphorus loads is to treat sewage.

Runoff from agricultural and market garden areas is often high in phosphorus. The Southern Lake Simcoe area is planning additional facilities to open by 2006 to reduce the amount of phosphorus released into the lake from Holland Marsh, a large market garden area.

The projected decrease in runoff and the smaller percentage of phosphorus from easily managed sources will make it more difficult to meet targets under climate change conditions according to modeling scenarios. The graph below shows scenarios for the rest of the century.

Annual Average Phosphorus Concentration Scenarios for the Bay of Quinte at the Trent River.

Data from 1972-92 is used to establish the base case (1996)for the scenarios to 2090.

The horizontal line is the Bay of Quinte Remedial Action Plan (BQRAP) target concentration

0.02 mg/l is the Ontario target concentration of phosphorus in lakes.

0.03 mg/l is the Ontario target concentration of phosphorus in streams and rivers.

Source: Walker, R.R., 1996. Assessment of Climate Change Impacts on the Bay of Quinte, Ontario.

A report to Environment Canada,Environmental Adaptation Research Group, Burlington, Ontario.

1. What are the y axis units, in words, used to measure phosphorus concentration?
2. In what year is the greatest increase in concentration projected? Why?

The Great Lakes are a major influence on Ontario’s climate especially in summer and winter. This large volume of water modifies the climate. The water absorbs the heat of the summer sun and releases this heat as the water freezes causing milder winters. This process also is responsible for lake “seasonal turnovers” .*

ACTIVITY 14 Research
1. How does the density of water change as it cools from 10oC to 4oC to 0oC?
2. What is the specific heat* of water? How much heat is released per unit volume as water freezes? How does this affect the climate in the Great Lakes area?

The insert below is from a larger map of Lake Erie. It illustrates the consequences faced today of actions that have been taken in the past. Some of these impacts are still ongoing. The future of Lake Erie fisheries is put at risk because of these conditions. The stresses of the future impacts of climate change will add to the level of risk and vulnerability of the health of Lake Erie. See also “seasonal turnover”.

Rick Boychuk Editor, Lake Erie Map, Canadian Geographic Enterprises, 2003

1. What makes Lake Erie so different from the other Great Lakes? Hint: check its volume of water.
2. What topics would have to be considered in order to research the economic value of Lake Erie?
3. How important is the role of seasonal turnovers to the life in Lake Erie?

Pollutants can also land on the water from the atmosphere. The next graphs show eastern North America air borne depositions of sulphur and nitrogen. Note the area of highest concentration and the ripple effect of the lines drawn by joining areas receiving the same number of kilograms per hectare per year.

Sulphur dioxide emissions has been studied for some time but the effects of acid rain on fish, wildlife, and plants are not well known. Lakes are proving to be more sensitive now than earlier research indicated. An estimated 800,000 square kilometers from central Ontario to the Atlantic provinces will continue to receive sulphate deposition. At this level of deposition, ecosystems will be impaired even after current Canadian and U.S. control programs are fully implemented. Scientists estimate that a further 75% reduction beyond current commitments is needed in targeted regions.

Source: Environmental Signals National Environmental Indicator Series, E. Canada. 2003

1. What is the chemical formula for sulphate? In solution?
a. Compare the two maps. Describe the changes seen by 2000.
b. Where is the highest concentration located? Note the geographic location of Ontario.

ACTIVITY 17 Research
1. Scientist estimate that a further 75% reduction in sulphur dioxide emissions beyond our present commitment is needed in target regions. What does the above information have to do with fossil fuels?

Nitrogen oxide deposition is still not well understood. More monitoring and a review of “critical loadings” is needed. If nitrate deposition continues at the present levels, its contribution to acidification could offset any gains in sulphur dioxide reductions.

Individual impact studies of increased temperature, increased ultraviolet radiation, and changes in pH have all been found to affect fish and algae populations. Since these factors interact, studies of these and other factors such as additional pollutants in warmer water need to be carried out at the same time to determine the effect of the interactions all aquatic life.

Source: Environmental Signals National Environmental Indicator Series, E. Canada. 2003

1. The bar graph above shows the improvement in lake acidity in Ontario. What does this graph have to do with the graph showing sulphate levels in N.E. of North America?
2. What actions, undertaken in Ontario in the last 3 decades, are responsible for these improvements?

Source: Environmental Signals National Environmental Indicator Series, E. Canada. 2003

1. What is the source of the nitrates being deposited?
2. Compare these two maps and comment on the change seen since 1983.

ACTIVITY 20 Research
1. Check out the formulae of the common molecules containing nitrogen in our environment.
2. Research the connections between the nitrogen cycle, automobile exhausts, smog and agricultural practices.

One way of integrating the information on water or hydrology together is shown below as it examines the issue of lower water levels in the Great Lakes region. This diagram provides the basis for further research, role playing, etc., as well as a way of understanding the complexity of the issue of water levels in the Great Lakes Basin.

Lemmen, D.S., and Warren, F.J. (eds).  2004.  Climate Change Impacts and Adaptation: A Canadian Perspective. Natural Resources Canada, Ottawa

1. Chose one of the 7 sectors shown in the “sectors impacted” boxes. List the potential impact(s) shown for the sector. Add 2 more potential impacts that might affect this sector locally.
2. Explain how the “potential impacts” for the sector you chose in Question 1, might affect two other sectors shown in the diagram. For example: Fisheries – a loss of fish species would affect tourism and municipalities since fishing tourists might not come to the area and tourism dollars would not be spent in the municipalities. Note: there may also be conflicting demands between sectors.

The diagram below visually summarizes the potential changes in climate in the Great Lakes region. This provides the basis for the diagram of potential impacts on the Great Lakes seen in next section prepared by the same scientist.

Source: Linda Mortsch, Climate Change and Water Quality in the Great Lakes Basin, ijc.2002.

1. List the 4 areas of effects shown.
2. Why are the effects of climate change separated into these four areas?
3. What is missing when comparing the effects listed in the boxes and the landscape shown?
4. Imagine the sun’s heat energy or solar radiation driving the water molecules through this diagram. Draw arrows to show the water moving through the ecosystems – make sure to include at least ground water, run off, evaporation, precipitation, transpiration, photosynthesis, aquifer.

ACTIVITY 23 Research
Name 5 water-soluble pollutants likely to be carried in liquid water.

Water in Our Lives:

Water is critical to every aspect of our lives including our health, energy production, industry, and transportation. Reduced water levels will have the following effects:

  • Hydro power production will be reduced.
  • Shipping costs will increase because ships will have to make more trips with lighter loads.
  • Lower water levels create problems for cottagers, marine operators, and for launching, hauling out, and boat operation in shallow areas.
  • Higher water temperatures reduce water quality by creating a more favourable environment for microbes and algae blooms. Lower water levels can affect the ability of intakes to draw water. Water quality will be affected as supply intakes may not draw water properly.
  • Fish access to wetlands and other shore habitats will be affected.
  • Shoreline properties will have less flooding and erosion damage, but existing docking facilities will have to be changed.

Water Use

Source: Environmental Signals National Environmental Indicator Series, E. Canada. 2003

Ontario municipality water prices are among the lowest in the world and cover only about half of the actual costs of supplying water and treating wastewater or sewage. Municipalities use 11% of all surface and ground water in Canada. The remaining 89% of water usage is by agriculture, thermal power generation, manufacturing, and mining.

Canadian per capita water use is nearly three times that of European countries and second only to the U. S. In 1996, households in Ontario used 270 litres of water per person per day.
Ontarians have an extremely high water usage per person – about twice the rest of industrial world.

Residential use is more than 50% of the total water used. An increasing population is increasing the total water usage even though use per person may be declining slightly.

With climate change, falling water levels lower stream flow. Higher concentrations of chemicals in runoff may make it more expensive to meet and maintain drinking water quality standards.

Source: Environmental Signals National Environmental Indicator Series, E. Canada. 2003

As of 1999, about 57% of Canadian municipal water usage was metered. Canadian municipalities are slow to install water meters. Metered water installations increased less than 5% over 8 years, 1991-1999.

People on metered water lines use 50% less water.

Research has shown that water usage is reduced by about one-half when household water is metered.

Many metered water charges by municipalities are correlated with the sewage output to pay for the treatment of both water and sewage. Some municipalities, especially along the St. Lawrence River, historically charged households for water use by the number of taps in the home.

1. Find a recent bill from a municipality showing water usage charges.
2. What are the units used? What is the cost of water per litre? Total usage and cost for one year?
3. What is grey water? Is it being treated separately?

ACTIVITY 25 Research
What would a liter of water cost when based on a container of popular bottled water (mls)?

Table 1. Categories of Water Use in Ontario Homes


Source: Environment Canada

1. Construct a pie graph to represent household water using the above information.
2. Determine how many liters are used on average in Ontario households for each activity.
3. List five ways your household can reduce water consumption.

ACTIVITY 27 Research
What was the water use per household in Ontario for 2003? What is this as a percentage increase?

Table 2. Water uses and consumption:


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