HOW DO SCIENTISTS IN THE REAL WORLD USE TIME-SERIES DATA?

• Who collects data?

• What are some stories behind data?

• How much data is enough?

• How is the data being used?

• What is different to what we teach?

WHO COLLECTS DATA?

Many different organisations…

• Regional and local councils.

• Transit NZ.

• Research institutes e.g. NIWA

• Consulting firms e.g. BECA

• Schools.

OVERVIEW

• Importance of long term trend.

• Contexts for correlation and interpolation.

• Using one set of data to create another.

• Importance of data over long time periods.

• Different analysis techniques.

• Think about and question what we teach.

MAHURANGI HARBOUR

LONG TERM TREND

Horse mussel numbers

Wedge shell numbers

Cockle numbers

Population decline – examples1994 - 2003

Monitoring

DATA TOLD SCIENTISTS…

• Health of Mahurangi Harbour in decline.

• Increased sedimentation was smothering marine life and causing a decline in diversity.

• Common shellfish no longer found in some areas.

• Boating had become more difficult because of reduced water depths.

MAHURANGI ACTION PLAN

Goal: Halt, slow or reverse the adverse effects of sedimentation.

• Fence-off streams, waterways and wetlands.

• Undertake riparian planting.

• Conduct a sediment source assessment.

• Change land management practices.

• Extensive environmental education.

TRENDS IN LAKE TAUPO

0

100

200

300

400

500

600

700

1970 1975 1980 1985 1990 1995 2000 2005 2010

NO

3-N

(to

nn

es

)

r2 = 0.58

Trend = 11.15 t y-1

NO3-N increasing trend

ANNUAL NITRATE ACCUMULATIONTREND OR CYCLE?

A polynomial model with a 9-year cycle gives a good fit .. r2 = 0.9

0

100

200

300

400

500

600

700

800

1970 1975 1980 1985 1990 1995 2000 2005 2010

NO

3-N

(to

nn

es

)

Mo

del

pre

dic

tio

n

?

WHAT MODEL IS THE BEST FIT?

0.0

0.5

1.0

1.5

2.0

2.5

3.0

1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005

Ch

loro

ph

yll a

(m

g m

-3)

In the last 10 years, mean chlorophyll a concentrations have more than doubled

OTHER EVIDENCE

0.0

0.5

1.0

1.5

2.0

2.5

3.0

1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005

Ch

loro

ph

yll a

(m

g m

-3)

Maximum

Average

Minimum0.18 ± 0.07 mg m-3 y-1

0.072 ± 0.027 mg m-3 y-1

Summer(r2 = 0.57)

Winter(r2 = 0.78)

Annual Average(r2 = 0.77)

FURTHER ANALYSIS

Goal: Reduce nitrogen run off by 20%.

• Regional plan change.

• Launch an $81.5 million fund.

• Encourage and assist land use change.

• More restrictive wastewater practices.

PROTECTING LAKE TAUPO STRATEGY

SH20 WATERVIEW CONNECTION

A 3.2 km tunnel to connect SH20 at Maioro St in Mt Roskill to the northwestern motorway SH16 at Waterview by Great South Rd

PRIOR KNOWLEDGE TO INFORM PLANNING

• In drilling this tunnel, how much ground water will be removed?

• What effects will this have on the flow and ecosystem of Oakley Creek?

• What are the usual flow levels in Oakley Creek?

• What monitoring information is available on flow rates of Oakley Creek?

USING ONE SET OF TIME-SERIES DATA TO CREATE ANOTHER

• Use flow rates from a monitored creek in a nearby catchment.

• Check relationship with the small amount of flow data from Oakley Creek.

• Generate Oakley Creek flow data set.

• Use this as input for groundwater models.

• Establish impact on ecosystem.

CORRELATING DATA

WHAT IS THE NORMAL ANNUAL CYCLE?

ANOMALIES

HOW MUCH DATA IS ENOUGH?

JUST USE THE MOST RECENT DATA?

SEA LEVEL RISE - PROJECTIONS

SEA LEVEL ANOMALIES 1974 - 2006

SEA LEVEL ANOMALIES 2001 -2007

SEA LEVEL ANOMALIES 1973 - 1994

WITHIN OUR CURRICULUM - DO WE TEACH THIS?

• Establish a relationship between two data sets and then use one set to complete another.

• Graphs or diagrams based on anomalies.

• Different time – series analysis.

ANOMALIES

WAS MAY HOTTER THAN USUAL?

• http://www.niwa.co.nz/edu/resources/climate

• http://cliflo-niwa.niwa.co.nz/

DateTemp

Ma x (C)Anomalyfor May

1 21.7 4.3

2 19.3 1.9

3 18.9 1.5

4 17.7 0.3

5 16.9 -0.5

6 20.2 2.8

7 17.3 -0.1

8 17.9 0.5

9 19.2 1.8

10 17.6 0.2

YES!

26 days were warmer than average for May and only 5 days were colder than average.

DENDROCHRONOLOGY TREE + TIME-STUDY

• Oxygen isotope signal correlates to temperature.

• Ring-width correlates to periods of low river flow.

• Useful for improving climate model results.