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Parameter One of a set of measurable factors (e.g. temperature, pH), that define a system and determine its behavior. PowerPoint Presentation
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Parameter One of a set of measurable factors (e.g. temperature, pH), that define a system and determine its behavior. - PowerPoint PPT Presentation


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Parameter One of a set of measurable factors (e.g. temperature, pH), that define a system and determine its behavior. Indicator A measurable feature that provides useful evidence of system quality or reliable evidence of trends in quality. Metric - a standard of measurement

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slide1

Parameter

One of a set of measurable factors (e.g. temperature, pH), that define a system and determine its behavior.

Indicator

A measurable feature that provides useful evidence of system quality or reliable evidence of trends in quality

Metric

- a standard of measurement

- an attribute with empirical change in value along a gradient of human disturbance.

- a measure of (a biological) attribute.

- data analysis summary

slide2

Types, examples of metrics

Biological

EPT

% Sensitive Diatoms

plant/animal condition

Physical

(river) channel length, sinuosity

(land use type) area, density

Chemical

pH

Temperature

DO PPM

DO %Sat

etc.

slide3

Index

an aggregated number used to judge condition (e.g. IBI, RBP)

A water quality index is a means to summarize large amounts of water quality data into simple terms (e.g., good, fair, poor) for reporting to management and the public in a consistent manner.

slide4

Indices

Can tell whether overall WQ poses threat to uses - e.g.

habitat for aquatic life

irrigation water for agriculture and livestock

recreation and aesthetics

drinking water supplies.

slide5

Multimetric Indices (EPA, Bio example)

numbers that integrate several biological metrics to indicate a site’s condition.

designed to be sensitive to a range of factors (physical, chemical, and biological) that stress biological systems,

are relatively easy to measure and interpret.

slide6

Indices - Multimetric approach

each metric is given a rating according to whether its value

approximates,

deviatessomewhatfrom, or

deviates stronglyfrom

values measured in least-disturbed ecosystems of a particular type within a region.

These ratings (e.g., excellent, moderate, fair, and poor) can be used to make decisions about whether the water body condition indicates that aquatic life is being supported.

slide7

Advantages of an index include

ability to represent a variety of variables in a single number,

ability to combine various measurements in a variety of different

measurement units in a single metric

effectiveness as a communication tool.

can be used to convey relative differences in water quality between sites (or @ one site) over time

slide10

Air Quality Index

Good:

simple

number and color easy to remember

succinct

underlying explanation pertaining to issue important to audience (public health).

slide11

AQI Caveats:

  • How AQI Calculated:
  • monitors record concentrations of major pollutants at many locations
    • ground-level ozone
    • particle pollution
    • carbon monoxide
    • sulfur dioxide
    • nitrogen dioxide
  • formula used to convert raw values into numeric scale.
  • Highest – rated pollutant becomes AQI for that day.
  • E.g. ozone = 90, Sulfur dioxide = 88; AQI = 90.
  • Problems. If:
  • Sensitivity to one type of pollution.
  • OR: need to know where pollution types are coming from.
  • AQI alone not helpful. Underlying information useful
slide12

Indices - Good general rule

When presenting indices,

The overall “score” is valuable

but make supporting detailed information accessible.

AQI Presentation tip:

Print score/color on web site home page, familiar icon/box (like weather info)

Clickable links to more detailed table, information.

slide13

Carlson’s Trophic State Index

Trophic State Indices (TSIs) are an attempt to provide a single quantitative index for the purpose of classifying and ranking lakes, from standpoint of nutrient influence on water quality .

Carlson TSI commonly used by Volunteer Monitors

slide14

Carlson TSI assumption:

major assumption is that suspended particulate material in the water controls Secchi depth and that algal biomass is the major source of particulates;Increased nutrients (phosphorus):

Produce increased algal biomass (chlorophyll a)

Produce decreased water clarity (Secchi disk)

Carlson TSI quantifies this relationship.

Ranges along a scale from 0-100.

slide15

Carlson TSI useful for

comparing lakes within a region

assessing changes in trophic status over time.

Higher values correspond to increased trophic state.

An increase in TSI of 10 units corresponds to a halving of Secchi depth and a doubling of phosphorus concentration.

slide16

Carlson TSI Formulae:

TSI = 60 - 14.41 Ln Secchi disk (meters)

TSI = 9.81 Ln Chlorophyll a (ug/L) + 30.6

TSI = 14.42 Ln Total phosphorus (ug/L) + 4.15

Because these are interrelated by linear regression models, any one of the variables can be used to derive a TSI score.

slide18

Carlson TSI Caveats:

Chlorophyll best for classification: most accurate at predicting algal biomass.

Carlson states total phosphorus may be better than chlorophyll at predicting summer trophic state from winter samples

Transparency should only be used if there are no better methods available.

Use Carlson TSI with lakes with few rooted aquatic plants and little non-algal turbidity.

Not appropriate for other lakes.

slide19

River Network Macroinvertebrate metrics, index

From Living Waters Manual

http://www2.rivernetwork.org/index.cfm

Two levels of sampling, analysis.

Level 1: Order. 6 metrics

Level 2: Family 10 metrics.

Level 2 uses 7 of the metrics to calculate

Overall Percent Similarity Index (to reference)

slide21

Steps to calculate River Network % Similarity Index:

Step 1: Calculate each metric for reference and for target collection. (Instructions in Living Waters manual)

Step 2. Convert each metric score to % similarity (*use Dominance, CSI directly)

Example

slide24

River Network Macroinvertebrate Index

Step 5. Divide Total Score:

Target population / Reference

18 / 42 = 43% similarity between target and reference collections.

Step 6. Categorize results

> 79%: Non-impaired.

29-72%: Moderately impaired

< 21% Severely impaired

Observations/caveats:

Use with different sites within similar geographic area, stream order, etc.

Information in each metric may provide additional insight, depth to overall index: i.e. aid in data interpretation.

slide25

Selecting/Creating metrics and indices

Multimetric Indices to Prepare and Analyze Data

http://www.epa.gov/bioindicators/html/multimetric.html

Five activities are central to making multimetric biological indexes effective:

Classifying environments to define homogeneous sets within or across ecoregions (e.g., streams, lakes, or wetlands; large or small streams; warm-water or cold-water lakes; high- or low-gradient streams).

Selecting measurable attributes that provide reliable and relevant signals about the biological effects of human activities.

Developing sampling protocols and designs that ensure that those biological attributes are measured accurately and precisely.

Devising analytical procedures to extract and understand relevant patterns in those data.

Communicating the results to citizens and policymakers so that all concerned communities can contribute to environmental policy.

slide26

Selecting/Creating metrics and indices

Good Metrics:

Sensitive to change

Predictable, consistent

Metrics vary in their scale--they can be:

integers

percentages

dimensionless numbers

qualitative observations (e.g. grassland vs. forest).

Translation into unitless scores must address this.

Standardization assumes that each metric

has the same value and importance (i.e., they are weighted the same),

and that a 50% change in one metric is of equal value to assessment as a 50% change in another.

slide27

Most IBIs contain between 8 and 12 metrics.

Metrics must be tested to ensure their precision and accuracy. (see discussion in Wisconsin DNR “Development of a Wetlands Biological Index…” report)

Metrics to Indices: Attributes to consider:

Scope - How many? - The number of water quality variables that do not meet objectives, relative to the total number of variables measured.

Frequency – How often? - The number of individual measurements that do not meet objectives, relative to the total number of measurements made.

Amplitude – How much? – The amount by which measurements depart from those objectives.

slide28

Presenting Indices

  • General tips:
  • Know your target audience
    • Expertise level
    • Particular interest
  • Use objective
    • Personal: resource use
    • Education
    • Resource management/regulation
      • Where to target resources
      • Impaired waters designation
      • TMDL development
      • Etc.
slide30

Make your own indices. Examples.

Trout comfort zone (Combine DO, temperature, volume of lake containing suitable values. … add duration/frequency of excursions?

Boating recreation index (Number of days when water levels, water quality, weather, etc. (absence of duckweed on lake surface, open channels) combine for “pleasant” boating experiences… add economic impact?)

Fishing recreation index. (Similar to boating - # of days when water levels, bug hatches, etc. afford quality fishing)

Beach closure days (see fishing, boating above… for added economic impact, consider extra weight for scores on holiday / high traffic periods).

Water clarity / home value index (Combine Secchi disk data with real estate prices).

slide31

Haikus as water quality indices?

Shattering the stillness

Of an ancient pond

A frog jumps into water

- - Basho