Quality Accounts
Outline
• Why Quality Accounts
• Structure of Quality Accounts
• Aquifers
• Rivers
• How to define quality classes?
• Several country examples
• Issues
• Aggregation
• Measurement
Why quality accounts?
• Quality accounts describe the quality of water resources at
the beginning and end of the accounting period in terms of
chemical, physical and biological characteristics
• Important because
• Quality limits water availability for certain purposes
• It is a first step towards ecosystem accounting and its
variants
BUT
• Still experimental (few country experiences; little or no
standardization)
• Link with pressures due to human activities is not direct
Quality of what?
• Quality of water bodies, NOT waterbeds / riparian
zone
• Water body : “mass of water distinct from other
masses of water”
• Examples: rivers, lakes, aquifers …
Structure of quality accounts
QUALITY CLASSES
Quality 1
Quality 2
Opening
stocks
Changes in
stocks
Closing
stocks
Source: SEEAW
-
Physical
units
Quality n
Total
Aquifers: Australia
Groundwater quality in Victorian provinces (in million m3)
1995
Fresh
Marginal
Brackish
Saline
<500 mg/l
500-1500 mg/l
1500-5000 mg/l
>5000 mg/l
477.5
339.2
123.3
32.3
972.3
(566.6)
(141.1)
(n.a.)
(746.8)
1998
(39.1)
(incomplete)
Based on sustainable yield as a
proxy, NOT volume of storage
Source:
Water Account for Australia – 1993-94 to 1996-97 - Australian Bureau of Statistics, May 2000.
Total
Rivers: from point to monitoring
State A
State B
Quality
class
State
A
State
B
Change
12.5%
0.0%
-13%
18.8%
50.0%
+31%
56.2%
37.5%
-19%
13.5%
13.5%
+0%
100%
100%
0
Are these statistics
relevant?
Rivers
• Monitoring of points & generalisation to water systems
• Particular difficulty with water courses: how to account for their
relative size?
• Runoff is measured at the lowest point of a basin – the
quality varies along the stream
• The mere length confuses large rivers and small streams
• Statistics of points make sense only when the monitoring
system is dense – rarely the case
Stretches / Reaches
River group
Small
Medium
Large

Quality



Class1

Class2
Class3



Reach or stretch: a portion of a stream or river, as from one
turn to another, supposedly having constant characteristics
any distance between 2 monitoring points
Accounting unit: SRU (1)
• River reaches as basic accounting units for rivers
• Importance is best measured by length and discharge
• Best candidate is SRU (standard river unit) =
reach length  discharge in m3 s-1
• Large and small rivers can be aggregated when measured
in SRUs
• Can be classified or weighted with quality indexes
• Results comparables from basin to basin
• Robust and easy to compute
Accounting Unit: SRU (2)
Flow
Large river
Slow, medium
Fast, small
Qi
Qj
Qk
X
X
X
Length
Li
= a SRU
Lj
= b SRU
Lk
= c SRU
Summary
For compiling quality accounts we need:
• SRU value for each river reach for all rivers
• We need to assign a quality for each reach
for all rivers
Accounting Unit: SRU (2)
Flow
Large river
Qi
X
Length
Li
= 4 SRU
Q1
Slow, medium
Fast, small
Qj
Qk
X
Lj
= 0.5 SRU
Q2
X
Lk
= 1.5 SRU
Q2
Structure of quality accounts
QUALITY CLASSES
Opening
stocks
Quality 1
Quality 2
4
2
Changes in
stocks
Closing
stocks
Source: SEEAW
-
Physical
units
Quality n
Total
Ways of assessing water quality
• According to disturbances/perturbations to
functions
• Total hydraulic and osmotic power of river
basins
• Health of ecosystem approach (resilience)
Defining quality classes
• Normative values for “determinands” (parameters)
• Physical: temperature, colour
• Chemical: pH, NH4+ …
• Biological: bacteria, flora, fish …
• Etc..
• Allowable deviations from reference conditions
• European Water Framework Directive
Example: Malaysia (1)
WQI = 0.22*SI DO + 0.19*SI BOD + 0.16*SI COD
+ 0.15*SI AN + 0.16*SI SS + 0.12*SI pH
where SI is the subindex of each parameter.
DO - Dissolved Oxygen
BOD - Biological Oxygen Demand
COD - Chemical Oxygen Demand
AN - Ammoniacal Nitrogen
SS - Suspended Solid
pH - Acidity/Alkalinity
Example: Malaysia (2)
Usage
10
20
30
General
40
50
60
70
Very Polluted
80
90
Slightly Polluted
100
WQI
Clean
Water
Class
V
IV
III
II
I
Public
Water
Supply
Not Acceptable
Doubtful
Necessary Treatment Becoming
more Expensive
Minor
Purific
Required
Purification not
Necessary
Recreatio
n
Obvious
Pollution
Appearing
Not Acceptable
Only for
Boating
Doubtful
for Water
Contact
Becoming Polluted Still
Acceptable Need
Bacteria Count
Handy
Fish Only
Doubtful
for
Sensitive
Fish
Fish,
Shellfish
and
Wildlife
Not Acceptable
Coarse
Fish Only
Navigatio
n
Not Acceptable
Obvious
Pollution
Appearing
Treated
water
Transport
ation
Marginal
for Trout
Acceptable for all Fish
Acceptable
Not
Acceptabl
e
10
Acceptable for all Sports
Acceptable
20
30
40
50
60
70
80
90
100
WQI
Example: France (1)
• SEQ-eau
• Use-oriented
Recognizes: drinking water, leisure, irrigation,
livestock watering, aquaculture aquatic life
• Based on 15 suitability indicators
• Computed from 135 determinants
• Matrices:
• determinants X indicators (computed from)
• uses X indicators (significant for)
• determinants X classes (threshold values)
Source: Presentation User-Producer Conference by R. Lalement
Example: France (2)
Example: France (3)
Example: France (4)
• Results in
• a class of suitability for each use
• an index (and class) for overall quality
• For each indicator, the worst determinant wins
• For each use, the worst indicator wins
• For each determinant, apply the percentile 90 rule to
multiple samples (not the average)
[this is called “Rule of the worst”]
• ... an in depth assessment for uses,
• but little ecology : independent of « ecotype »
France: Monitoring Costs (5)
•
The estimated cost of the surveillance monitoring programme is
•
•
•
for a management plan, or
•
•
•
77 M€ for rivers and
8M€ for lakes
50 k€ for rivers
40 k€ for lakes
per site for a management plan, or
•
•
150 €/km2 (rivers and lakes), or
150 €/km (rivers).
Example: Canada
S = scope, number of failed determinands/total
F = frequency, number of failed tests/total
E = excursion, target value/observed value
Results: French Quality Accounts
River size
class
Main rivers
State 1992
1A
1B
2
3
Change 1994-1992
HC
5 1253 891 510 177
1A
1B
3 329
2
3
State 1994
HC
2 -152 -165
1A
1B
2
3
Adjustment
HC 1A 1B
2
3 HC
8 1583 893 358
12
0
6
7 -32
0
Main
tributaries
309 1228 1194 336
50
16 464 -275 -182
-22 325 1691 919 154
28
0
0
0
0
0
Rivers
260 615 451 128
47
46 134 -129
-17
-28 306 749 322 110
18
-1
-4
0
0
0
Brooks
860 1464 690 243
95
-51 -170 227
15
-23 810 1295 917 258
72
7
-6
1
0
0
Example:France 1992-1994
Results: organic matter indicator in SRU*1000
ISSUES
•
•
•
•
•
•
Choice of determinands
Classification of uses
Assessment: Rule of worst
Temporal issues
Aggregation over space (indicators)
Link with economic sphere
Choice of determinands
Number of determinands
Total
of which:
Specific to
Canada
of which:
Specific to
France
of which:
Specific to
South Africa
of which:
Common
determinands
Environmental
10
1
1
1
6
Gases dissolved
5
2
1
1
2
1
9
1
1
1
23
6
4
1
3
4
38
3
2
Determinand group
Metals (and metalloids)
24
3
Nutrients
5
Pesticides
68
22
Radioactivity
26
26
Salinity
14
Toxics (n-metal, n-pesticides)
104
36
• Country and context dependent
• Based on functions or uses
Classification of uses
• No standardized classification of uses or
functions
• Different uses for different type of water
bodies? (case of France)
• Different uses per water body? (USA)
• How to deal with multiple use?
• Choose the most stringent use? (AUS)
Assessment : Rule of the worst
• “One out, all out”
• Reason: assure equal weight to all parameters
• Applicable at level of determinands, indicators
or uses
• Problem:
• Extreme values; seasonal variations
• Improvement of monitoring leads to increased
probability of finding bad status
Rule of the worst: Application
Reach "2005"
Det 1 Det 2 Q
"2006"
Det 1 Det 2
RofW_05
QC 05
RofW_06
QC_06
SRU1
Q
Station
1
2
3
4
Opening stocks
Closing stocks
Changes in stocks
25
25
25
25
60
60
60
60
12
60
60
60
20
20
20
20
60
60
60
60
60
60
60
60
QC1 QC2 QC3 QC4 QC5
500
0 1500
0
0
0
0 2000
0
0
-500
0
500
0
0
20
20
20
20
12
60
60
60
1
3
3
3
60
60
60
60
3
3
3
3
500
500
500
500
Aggregation: space (1)
• Which rivers to include?
• Scale determines outcome
• River basin
• Weighted average indicator
• Hotspots
• Pattern index
Aggregation: space (2)
• River Quality Global Index (RQGI)
• Aggregates over river basin
• Weighted average of SRU according to quality class
• Scale 0-10
• n is number of classes
Aggregation: space (3)
• Pattern index
• Measures the variability in space in quality
of the River Basin
• Able to distinguish “hotspots”
Temporal issues
• How to reflect seasonal variations in the quality
accounts?
• What to do with inter-annual variations (wet
years..)
• Actual SRU or averages?
• How to deal with sudden events
• Frequency of monitoring
SEEAW advocates compilation of Quarterly
Accounts
Link with economic sphere (1)
• Water quality accounts
• Ideal is to measure efficiency of water quality
management programmes at basin level
• BUT: changes in water quality can have different causes
Water quality t1 = f(Water quality t0, ∆(uncontrolled
events), ∆(abstractions), ∆(emissions), ∆(expenditure))
• f() = unknown
• Therefore…….
Link with economic sphere (2)
QC1
Opening stock
Changes due
to economic
causes
Discharge of
waste water
Abstraction
Returns
Changes due
to natural
causes
accidents
Closing stock
QC2
-
QCn
Total
Questions
• Data availability?
• Frequency?
• Distribution of monitoring stations?
• Are flows and quality measured
simultaneously?
• Which determinands are measured?
• Economic data per river basin?
• Are different uses distinguished?
• Experience in compilation?