Ecosystem Services: impact of a dam on Opihi river

photo - Opuha Water Partnership

1

Key contributors

Dr Ed Hearnshaw – now Senior Analyst, Ministry for the Environment.

Edward.Hearnshaw@mfe.govt.nz

Dr Jean Tompkins – now Biodiversity Officer, Environment Canterbury.

Jean-Marie.Tompkins@ecan.govt.nz

Professor Ken Hughey, Lincoln University

Pressures

• Water becoming scarce and rivers stressed by abstraction for irrigation

• Water - multiple uses and society needs to consider all uses, not just consumptive uses

• Evaluations of water projects need to consider all values to be valid, accepted

• Economic evaluations struggle to include all values for water if they are not readily monetised

• Ecosystem Services approaches have arisen as a consequence.

Opihi Catchment• Irrigation abstraction, dry river in

summers• Levels Plains irrigation began

1936, 3700ha • Declining health of river ecology &

loss of river values• Opuha Dam built 1997-98, $34

million• 710 ha lake, water storage for

irrigation, electricity generation, boating, fishing, recreation, required to maintain summer flows in Opihi River

• Negative effects expected: increased algal growth, loss of natural character

Opuha dam

Opihi river

Known outcomes from Opuha Dam

• Minimum flow levels maintained in river• Water storage in dam allows much greater water

supply for irrigation and industrial uses• Opihi catchment irrigated area - 16,000 ha• Additional $12 million surplus/annum to farmers• Additional $123 million/annum spillover benefits• Estimated 480 additional jobs (Harris et al, 2006)• 2008 resource management award from

Environment Canterbury

Minimum river flows, river mouth closures

Opihi River: Waipopo

Opihi River - Confluence: Rockwood

Opuha River: Skipton Bridge

Monitoring site Biophysical indicator

Unit

2007 Trend 2007 Trend 2007 Trend Minimum River Flows

m3/s 7.67 + 2.95 0 4.45 +

Table 6: Trends in the average minimum river flows on the Opihi River and its tributaries 1989 - 2007 (Ministry for the Environment, 2009).

Period Biophysical indicator

Pre-Opuha Dam Post-Opuha Dam

Number of Days River Mouth Closed

100+ 4-5

Table 7: The average annual number of days the mouth of the Opihi River is closed.

Average water

temperatures

Annual faecal coliform levels

Salmon spawning numbers

The ecosystem services approach• Step 1: Ecosystem services (ES) are identified

• Step 2: Stakeholder representatives preferentially weight each ecosystem service.

• Step 3: Indicators which represent each ecosystem service are collated.

• Step 4: The preferential weights and indicator scores of each service are incorporated into a multi-criteria analysis which will produce the ESI.

Monitored over time the ESI can indicate sustainability

Disease Regulation

Pest Regulation

Erosion Control

Water Regulation

Water Purification

Educational Values

Aesthetic Values

Conservation Values

Spiritual Values

Provisioning Ecosystem Services

Fibre

Abiotic Products

Freshwater Supply

Natural Hazard Regulation

Ecosystem Services Index

Biophysical

Indicator A

Biophysical

Indicator B

Socio-Economic

Indicator A

Cultural Ecosystem Services

Regulating Ecosystem Services

Classes are preferentially weighted by stakeholders

ES are preferentially weighted by stakeholders(w)

Expertly verified indicators monitor the state of each ES (normalised scores are aggregated). (s)

The ESI is monitored over time. An increasing index value indicates ‘weak’ sustainability (or a movement towards it)

ESI = ∑wnsn

Step 1: Ecosystem services of the river are identified

15 ES are identified for the Opihi River

Class of ES Ecosystem service Examples of ecosystem service

Provisioning

Abiotic ProductsGravel extraction for road chip and concrete

Biological Products Not applicableFibre Flax, driftwood

FoodGame fisheries (e.g. salmon, trout), native fisheries (e.g. eel, whitebait, flounder)

Water SupplyIrrigation, hydroelectric production, municipal water use, industrial water use, stock water use

Regulating

Climate Regulation Not applicableDisease Regulation Parasite and toxic algae regulation

Erosion Control Stabilization of river banksNatural Hazard Regulation Flood and drought protection

Pest Regulation Invasive non-native species (e.g. Algae)Water Purification Removal of pollutants

Water Regulation River flow regulation (e.g. minimum river flows)

Cultural

Aesthetic Values Perceived beauty

Conservation Values Endangered native species (e.g. black-billed gull), significant landscapes (e.g. Opihi Lagoon)

Educational ValuesHistorical/archaeological values & knowledge systems

Recreational Values Sailing, rowing, kayaking, fishing, duck hunting, picnicking, swimming, walking

Spiritual Values Māori values (e.g. mauri)

Data

• Pre and post dam time series data needed

• Main sources NIWA, MfE, ECan, Fish and Game (CSI)

• 42 indicators used

• Indicator selection criteria: data availability, communicability, indicator cost

Step 2: Stakeholder preferences

• A one-to-nine scale was used, where one represents neutrality or indifference between the pairing and nine represents an overwhelming preference for one ES over the other.

Stakeholder Preferences

• 15 regional stakeholders representatives

• 6 local stakeholder representatives

• Asked to provide preferences from perspective of present needs of stakeholders they represent

• Analysed using Expert Choice software

Step 3: Expertly verified indicators which represent each ecosystem service are

collated and their safe minimum standards recorded.

-The evaluation period was 1989 to 2008. -(Dam construction 1997)

An example using the provisioning class of ecosystem services...

*Light blue sections reflect available indicators.

Class Ecosystem service Environmental indicators Socio-economic

indicators

Provisioning ecosystem

services

Abiotic Products

Mean River Bed Level (m) Profitability of Gravel Resource ($)

Volume of Gravel Extracted (m3)

Fibre

Number of Fibrous Species Number of People Actively Collecting Fibrous Materials

Total Biomass of Fibrous Species (kg)

Food

Annual Periphyton Cover (%) Commercial Fishery Employment

Average Weight of Fish Caught (kg) Cultural Health Index

Benthic Community Metabolism (R2) Fish Taste

Biochemical Oxygen Demand (mg/l) Number of People Actively Collecting Food

Days River Mouth ClosedDissolved Oxygen Level (ml/l)

Number of Mahinga Kai Species

Number of Salmonids Caught

pH LevelPresence of Riparian Vegetation

Spawning Numbers Turbidity (NTU)

Water Temperature (0C)

Water Supply

Irrigated Area (ha) Economic Impact from Irrigation ($)

River Flow Variability (σ2)Total Volume of Water Takes (m3)

Double counting

Indicator Ecosystem

service

Communicability

(1-9 scale)

Data availability (1-9 scale)

Annual cost(1-9

scale)

Indicator cost-

effectiveness

E. coli LevelRecreational Values 6.3

7.67 52.79

Water Purification 7 2.93

Irrigated AreaWater Supply 8

9 28.5

Natural Hazard Regulation

3 6

Minimum River Flows

Water Regulation 57 3

4Recreational Values 5 4

Number of Flood Flows

Natural Hazard Regulation

98.33 4.33

4

Water Regulation 6.33 3.39Qualitative Macroinvertebrate Community Index

Conservation Values

77 6.33

2.21

Water Purification 6.33 2.11

pH LevelWater Purification 7

7 34.67

Food 5 4

Step 4: Using the ESI to evaluate for weak sustainability

ESI = ∑wnsn ESI / # indicators in that year

Pre-dam Post-dam

Key findings from case study

• Fifteen ES were identified from the river

• Since dam construction the river has progressed towards weak sustainability in its provision of ES.

(Interpretation - needs to acknowledge the state of the river pre-dam)

• There is a need to develop a standardised set of effective indicators of river ES-Alternatively ES could be decomposed into more tangible benefits, allowing improved correlation with indicators.

Discussion

• Biophysical, economic and social data availability is patchy• Indicators for Regulating and Cultural ES often rely upon

biophysical data

• Can capture trends in ES if have time series data• Multiple uses of some indicators, danger of double

counting

• Investment in appropriate time series data a key decision• If can overcome data challenges, ES approaches could be

useful to evaluate potential new project

Opuha project papers• Hearnshaw, E, Cullen, R and Hughey, K. 2010. Ecosystem services

review of water storage projects in Canterbury: The Opihi River case. Report to Environment Canterbury. http://www.canterburywater.org.nz/downloads/e cosystem-services-review-the-opihi-river-case.pdf

• Hearnshaw, EJS, Tompkins, J-M, Cullen, R. 2011. The sustainability and cost effectiveness of water storage projects on Canterbury rivers: The Opihi River case. Australian Agricultural and Resource Economics Society annual conference, Melbourne, 9-11 February.

http://ageconsearch.umn.edu/bitstream/100720/2/Tompkins.pdf• Hearnshaw, EJS, Tompkins, J-M, Cullen, R. 2011. Addressing the

wicked problem of water resource management on Canterbury rivers. Australian Agricultural and Resource Economics Society annual conference, Melbourne, 9-11 February.

http://ageconsearch.umn.edu/bitstream/100556/2/Hearnshaw.pdf

Thanks

ross.cullen@lincoln.ac.nz