Monitoring to Detect Changes in Water Quality Series (Proceedings of the Budapest Symposium, July 1986). IAHS Publ. no. 157,1986.

Graphical presentation of water quality data

ADRIAN DEMAYO & SIMON WHITLOW Water Quality, Inland Waters Directorate, Environment Canada, Ottawa, Ontario, Canada K1A OE7

ABSTRACT The use of graphical presentations in the water quality field is not only increasing but also becoming a very efficient and effective way of presenting and interpreting data. A selection of graphs used in various water quality reports written by the staff of Environment Canada, is shown and discussed.

INTRODUCTION

Canada is a country with vast water resources. Major rivers such as the St Lawrence, Fraser, Mackenzie and Nelson combine with hundreds of smaller rivers and streams to discharge approximately 100 000 m3 s_1 towards the Atlantic, Pacific and Arctic Oceans, and Hudson Bay. Lakes are almost uncountable. An estimated 8% of the country is covered by lakes and if wetlands are taken into account the percentage of land covered by water increases to 20 (Pearseet al. 1985).

The Water Quality Branch (WQB) of Environment Canada (EC) is the principal federal agency collecting water quality data and disseminating water quality information. During its 50 year-history, the WQB has had to respond to policy changes and adapt to changing social and economic conditions (WQB, 1985).

The present role of the WQB is to provide scientific and technical information and.advice to government, private agencies and the public, and to promote the wise management of water from a quality perspective. This includes detecting emerging water quality problems, evaluating water quality conditions and addressing water quality issues on Canada's inland waters from both regional and national points of view.

DATA COLLECTION AND DATABASE

Collection of water quality data is the main activity and the basis for all other activities carried out by the WQB such as dissemination of water quality information, advice on water quality in Canada, establishment of water quality objectives and compliance monitoring.

All analytical results together with all relevant field data are stored in a computerized system known by the acronym NAQUADAT (National wAter QUAlity DATa bank). Presently the system contains approximately 3.2 million results from almost 160 000 samples and over 9000 locations. In 1983, for example, over 170 000 results from close to 10 000 samples from almost 2000 sites were added to the system. This rate of growth is expected to increase due to the

14 A

.Dem

ayo s

S.Whitlow

Graphical presentations 15

signing of Federal-Provincial Water Quality Agreements now underway and expected to be completed in 1987. These agreements, which provide for exchange of data between the two levels of government, are expected to almost double the number of sites for which water quality data are added to NAQUADAT each year. Figure 1 illustrates the sampling network in 1984, immediately after the agreement with the province of Quebec was signed.

NAQUADAT can produce a large variety of retrieval reports in the form of data listings, statistical summaries and graphs. Many users of water quality data receive the data in one of these forms or access the system directly via interactive terminals. In the last few years the Branch has been attempting to emphasize the interpretation of the data it collects and disseminate water quality information. In this context interpretation is defined as being the process of transforming environmental data and related information in information meaningful to the "general public", water resource managers and managers of other resources or programmes with environmental implications. In trying to obtain information from data as well as presenting information in a form easy to understand, the WQB's personnel have been increasingly using graphical techniques.

The paper will review some of the most commonly used graphs in the Water Quality Branch in the context of water quality data interpretation and presentation. All the examples illustrated are from work undertaken by scientists in Environment Canada. Many of the graphs were produced by direct computer processing of the data base; others have been drawn or enhanced by draftsmen to clarify and highlight features.

WATER QUALITY AREA ADDRESSED

Representativeness of samples

How well the samples reflect a hydrological system is an important consideration in water quality sampling and data interpretation. To characterize the water quality at a given point it is essential that the sampling covers the entire flow regime. Figure 2 shows a discharge duration curve to which information on the water quality sampling has been added. In this instance all flow classifications are represented and the flow variability is accounted for in the water quality data. If the data were bunched together only in certain parts of the curve they could not be considered to be representative of the flow regime at that location.

Another consideration, both in the planning and data interpretation phases of a water quality monitoring programme is the frequency and duration of the sampling record. Figure 3 provides a detailed look at sampling patterns for particular parameters. This information is needed to establish how appropriate descriptive statistics are for an extended period of time. The figure shows, for example, that while major ions have been sampled more or less uniformly over 20 years, DDT was measured only during the mid 1970s.

16 A.Demayo s S. Whitlow

"b.

STATION NO. 02YM001 FULL YEAR

DISCHARGES FOR 1954 - 1984

WATER QUALITY FOR 19» - 1983

LEGEND # OF WATER QUALITY SAMPLES IN 107. FLOW INTERVALS

MAXIMUM (234)

MINIMUM ( 0.835)

26

y/A < / ,\

</. —r-10

_L< — i — 70 20 30 40 50 60 70 80 90 100

TIME (%) DATA EQUALLED OR EXCEEDED

FIG.2 Discharge-duration curve with histogram of water quality samples.

Seasonality

River hydrology varies considerably with the seasons of the year. Figures 4-7 show different ways of plotting water quality data such that the seasonality is emphasized.

Figure 4 shows the mean monthly discharge and the concentration of the total dissolved solids (TDS) at a sampling station on the Athabasca River. The low winter discharge during the ice covered winter months is followed by the spring breakup and high flow freshette cycle. The concentration of TDS varies inversely with the flow during the same time period. Annual high TDS values occur from January-March. April values fall to an annual low due to dilution by increases in discharge. The TDS content rises steadily over the summer and fall as flows decline. This figure illustrates well the higher variability of water quality results during spring runoff as compared to the summer values, an important consideration in designing monitoring programmes.

Figure 5 combines water quality and flow data to explain the seasonal variations in ion concentrations. Arrows are used to suggest seasonal progressions. Cl~, Ca2+, K+, and HCO3- reach their highest annual concentration in the December-March period,

Graphical presentations 17

Ill HIIIIMlllllllllllll Illll|l llllllllll)ll Ijllllll Illll Mil IIHlllll) Il[l|ll[lllll Ml I I I I | I I IIIIIIIIMIIII Illll

NO; -NO;

I Hill Illl | "Hill I Mil III 111 II I I l l l I I I I l l l | l l |llllllllllll|

U. 3-

o ,. TOTAL PHOSPHORUS

ILL T 1 1 r

EXTRACTABLE Fe

141.111,11 _, 111,1 11,1 I l l l UN 11,1 IN 111,1 I I ,1 I I I ,

p.p-DDT

I 1,1 I N I I ,1 MM I I I , 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80

FIG.3 Frequency of sampling of selected parameters at Athabasca River at Athabasca (00AL07BE0001)(Blachford et al., 1985).

the time of lowest discharge. During this period, groundwater flow is expected to be the major ion supplier. Discharge increases dramatically in April and concentrations consequently decline. Concentrations continue to decline as background levels decrease through dilution and accumulated salts are flushed by increases in discharge. Declining discharges in the fall are accompanied by increasing levels of ions which return to baseflow concentrations in December. The potassium ion behaves differently: peak concentrations occur in April, possibly due to initial mobilization of K+ by increasing discharge, followed by the inverse concentration-discharge relationship observed for the other ions.

The seasonal trends of ion concentration in lakes differ significantly from those in rivers (Fig.6). In a large lake like Lake Ontario, the seasonal variations are largely determined by the climatic conditions. The annual temperature cycle is a regular occurrence and accounts for the yearly fall turnover as the surface layer becomes more dense than the bottom one. The seasonal behaviour of phosphorus follows a regular pattern. Low summer values are a result of biological uptake of soluble reactive phosphorus by algae during the warm summer months.

Figure 7 is one more attempt to show the seasonal changes in the concentration of a series of water quality variables, in this case nitrogen species. Particulate nitrogen (PN) comprises the lowest proportion of the total nitrogen content over the winter period.

18 A.Demayo s S.Whitlow

Since winter is a low energy regime, few materials are transported in suspension and mineralization of particulate to dissolved nitrogen forms during the low water periods may be occurring (Keeney, 1973).

2000

1000

500

100

50

-

i 1

'- • i

i

• i i - ! ' i

' J ! -

: i 1 I i -! i < 1 i

1 • i ' ! ; 1 i

' i : •• 1

j i i

J

i

J L J I I L j J

MONTH

J

J F M A M J J

MONTH

FIG.4 Seasonal variation of mean monthly discharge and total dissolved solids at Athabasca River at Athabasca, 1960-1979 (Blachford et al., 1985).

The particulate nitrogen content in spring is higher than in other seasons due to increases in discharge and suspended sediment transport. Dissolved organic nitrogen represents the difference between total Kjeldahl nitrogen (TKN) and NH3-NH4-1-. This component is at its greatest concentration over the year in the September-March period. This reflects compounds leached from decaying organic materials in the drainage basin and those from instream decomposition

Graphical presentations 19

- 1 — i — i — i — ; — i - -i—T~I—i—i—i—r—i—r-

CI"

Ca2

K +

HCO;

11. • 3

I I I I ' 1 I I l _ l L i

1000 10 50 100 500

MONTHLY MEAN DISCHARGE, rTV>.s'

FIG.5 Seasonal variation of Cl~, Ca2+, K+ and HCO3- at Athabasca River at Athabasca (00AL07BE0001). Numbers refer to month of the year. Bars indicate the range of data per month over the period of record (Blachford et al 1985).

20 A.Demayo & S. Whitlow

24

22

20

18

16

P ~ ^ 14 (D

3 a « & E ,0 10 h -

8

6

4

2

0

-

-

_

M

"

JAN

•. .

FEB

. #

• . —i 1

MAR APR 1

ff _l

~~,—

M .4

—L.

MAY

V

"

JUN 1 '

\

* • « •

• . /

•• •

: .*

1 L

JUL AUG 1

• • • •

. • •

SEP 1

• -

.••'• . .. •• *

# . *• . ••

".

•

Temperature of

maximum

1

density

J

1

»

• •'

•

_L__

OCT

• •

%

1

•

• • ••

—i—

NOV

7

DEC

'

-

-

-

_

•••. •

-

j

24

22

20

18

16

14

12

10

8

6

4

2

0 JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NO» DEC

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

FIG.6 Seasonal cycle of cruise mean surface temperatures and mean soluble phosphorus (1968-1972) in the offshore part of Lake Ontario (soundings > 100 m), 1966 to 1979 (Dobson, 1984)..

processes. Concentrations of NO^-NO" are slightly higher in winter and spring than in summer and fall. This likely reflects a groundwater source in winter and overland runoff of NO3 during rising flows in the spring (Logan, 1977), combined with biological use of NO3 during the period of growth in summer and fall (Blachford et al., 1985).

Oil field brines are sometimes high in ammonia. Regions of oil development occur throughout the Athabasca subbasin. Possible ammonia contributions from resource development, combined with the presence of dissolved organic compounds, may be responsible for the higher concentrations of ammonia than of N0g and NO3 during the summer and fall. These may also be partly due to the release of ammonia that accompanies algal die-off and a decline in the rate of

Graphical presentations 21

nitrification with decreasing temperatures.

Spatial variation

Maps One of the most basic graphical representations is to show the location of sampling sites on a geographical map. Such a map is used from the planning stages of a water quality monitoring programme to the data interpretation and report writing. The scale of the map and precision with which the sites are located depend on its eventual use.

Figure 1 shows a small scale map of Canada overprinted with the locations of the WQB's monitoring network. This map is useful to gain an appreciation of the extent of the monitoring programme. Since the overlay is computer generated from the data base, changes from year to year can readily be compared. Furthermore, wide area displays showing, for example, stations where high concentrations of trace metals have been detected, can be easily produced.

Geographical presentations are useful to show how conditions vary within a river system. Figure 8 illustrates schematically a reach of the St Lawrence River, on which the total hardness has been plotted in different screens of black. The figure shows, at a glance, the long distance from Montreal to Portneuf (approximately 200 km) taken for the water of the Ottawa River to completely mix with the water of the St Lawrence River above Montreal.

E o.:

• ) •

NOj- NO3 (44)

TKN (5)

NHj-NHlOl)

' //VfpN (7)

I JNH3-NH; I

NOJ-NOÔ (18)

N O j - N O ^ (37)

TKN (6)

NO2-NO3 (34)

TKN (7)

N H 3 - N H * ( 7 )

DECEMBER JANUARY

FEBRUARY MARCH

JUNE JULY

AUGUST

SEPTEMBER OCTOBER

NOVEMBER

FIG.7 Seasonal averages of nitrogen species concentrations, Athabasca River at Athabasca; numbers in parentheses are sample size (Blachford et al., 1985).

Bar graphs Figure 9 shows another way of representing concentration changes along a river. Turbidity, colour, TDS and specific conductivity increase gradually in the Peace River subbasin from the Bennett Dam outlet (site 1) to the river mouth (site 3) due to the additive effect of dissolved and suspended substances. The Smoky River contributes concentrations of all constituents that are notably elevated in comparison with those in the mainstem river water.

22 A.Demayo s S.Whitlow

The purpose of Fig.10 was to show how the total hardness changes from west to east. In this case the complete database has been used to calculate the minimum, median, and maximum values which are represented on the bar graph.

FIG.8 Total hardness in the St Lawrence River (Germain & Janson, 1984).

TURBIDITY

0 10 20 30 0 10 20 30 0 40 80 120 160 0 100 200 300

1. HWY 29

2. DUNVEGAN

3. PEACE POINT

4. SMOKY RIVER

FIG.9 Spatial variation of physical parameters (medians) at selected sites in the Peace River subbasin. See Fig.11 for locations. (Blachford et al., 1985).

Rosette diagrams Figure 11 illustrates the use of an ionic proportions diagram to represent spatial variations in the major ions concentrations. Carbonate rocks in the headwaters are responsible for the dominance of Ca2+ and HCO3 at sites 1 and 2. the Smoky River (site 4), located largely on marine Cretaceous

Graphical presentations 23

1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

11.

12.

13.

14.

15.

16.

17.

18.

19.

20.

21.

22.

23.

24.

25.

River Basin Region

Pacific Coastal

Fraser-Lower Mainland

Okanagan-Similkameen

Columbia

Yukon

Peace-Athabasca

Lower Mackenzie

Arctic Coast-Islands

Missouri

North Saskatchewan

South Saskatchewan

Assiniboine-Red

Winnipeg

Lower Saskatchewan-Nelson

Churchill

Keewatin

Northern Ontario

Northern Quebec

Great Lakes

Ottawa

St. Lawrence

North Shore-Gaspé

Saint John-St. Croix

Maritime Coastal

Newfoundland-Labrador

FIG.10 Hardness var (Pearse et al., 1985)

200 400 600 800 1000 1200 1400 3600 3800

CONCENTRATION (mg Cl)

iation from west to east of Canada

ŒKHEH KILOMETRES

FIG.11 Ionic proportion diagrams (expressing medians) for selected sites in the Peace River subbasin (Blachford et al., 1985).

24 A

.Dem

ayo &

S.W

hitlow

CO

'-H

« 0 W

0 in O

i •Q

S 01 +J n, 0) «0

o <N

o

•c: +

J

10

o CO

0) in 3 •u m

U 0

i

I 01 4

J

<t! +

J

s 01 A

; US

C5 H

E

t.

Graphical presentations 25

strata, contains elevated proportions of Na+ and Cl~ compared with those in the mainstem river water. Downstream increases in S0|~ and Mg2+ may be from anthropogenic sources and the Smoky River, respectively (Blachford et al., 1985).

Contour graphs and maps Contour graphs and maps are especially appropriate for summarizing high density data over large geographical areas. The data can be combined in a number of ways to emphasize particular aspects. The use of contours or isopleths make it possible to visualize spatial effects.

JUN JUL AUG SEP OCT

30

1

i'° 50

40

60

JUN JUL AUG SEP OCT

FIG.13 Nitrite ug Nl_1 versus time and depth: mean values for the offshore area (soundings > 100 mJ during 1966 (Dobson, 1984).

Figure 12 shows the temperature distribution of the surface of Lake Ontario. In Fig.13 time has been added as another dimension, but the spatial coverage has been reduced. In the depiction of nitrite values it can readily be seen that the maximum concentration occurs in mid-August at a depth of 30 m.

Figure 14 is a map of eastern Canada showing sulphate deposition levels. Superimposed on the deposition contours and cross-hatched areas are screened regions which indicate areas which are considered susceptible to acidic precipitation. The composite map clearly shows regions in the maritime provinces, for example, which are vulnerable to airborne deposition.

CONCLUSIONS

Graphs have been used in the water quality field for a long time. The current technological developments together with cultural changes in the North American society, which emphasize visual

26 A.Demayo & S.Whitlow

L E G E N D Wet S u l p h a t e D e p o s i t i o n ' 2 ' k g / h a . y r .

I I I I L e s s than 10

r r m 10-20 20-40 Greater than 40

Environment Canada has designated 20 kilograms per hectare . year as a target for sulphate deposition as part of an emissions reducing program.

Scale 200 400 600

kilometres

INQUIRY ON FEDERAL WATER POLICY

Caicite Saturation Index13'

I [ No data available

I I 0.0-3.0

S 3 3.1-5.0

Values greater than 3.0 reflect areas sensitive to acidification.

FIG.14 Sulphate deposition and sensitivity of waters to acid precipitation in eastern Canada. Sensitivity is characterized as the potential of a receiving body of water to be stressed by acid deposition and can be quantified using the caicite saturation index (Pearse et al., 1985).

presentations over the written word, are leading us towards water quality reports in which graphs play the major role. This paper presents some simple and effective ways in which water quality data and related information can be displayed. The staff of the Water Quality Branch of Environment Canada together with other colleagues in the Department are continuing their efforts to develop even more effective graphs to present the results of their work.

REFERENCES

Blachford, D.P., Demayo, A. & Gummer, W. (1985) Water Quality.

Graphical presentations 27

Mackenzie River Basin Study Report, Supplement 9. Minister of Supply and Services, Ottawa, Canada.

Dobson, H.F.H. (1984) Lake Ontario Water Chemistry Atlas. Scientific Series No.139. National Water Research Institute, Inland Waters Directorate, Burlington, Ontario.

Germain, A. & Janson, M. (1984) Qualité des eaux du fleuve Saint-Laurent du Cornwall a Quebec. Section des relevés de qualité, Region du Quebec, Environment Canada.

Keeney, D.R. (1973) The nitrogen cycles in sediment-water systems. J. Environ. Quai. 2(1); 15-29.

Logan, T. (1977) Transport of sediment. In: The Fluvial Transport of Sediment, Associated Nutrients and Contaminants. (Ed. H-Shear and A.Watson), I.J.C., 181-195.

Pearse, P.H., Bertrand, F. & MacLaren, J.W. (1985) Currents of Change. Final Report, Inquiry on Federal Water Policy, Ottawa, Canada.

WQB (1985) The Business of the Water Quality Branch. Water Quality Branch, Inland Waters Directorate, Ottawa.