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Manaaki Taha Moana (MTM) Mediated Modelling of Tauranga Coastal Ecosystem Services: Systems Dynamics Model Description

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Index

 

1.0 Background:
2.0 MTM Model Development:
2.1 Program Used – Stella:
2.2 Model Simulation Specifications:
2.3 Model Modules:
2.3.1 Population Pressures Module:
2.3.2 Land Cover and Use Module:
2.3.3 Ecosystem Services Module:
2.3.4 Socio-Economic Module:
2.3.5 Recreation Value of Tauranga Harbour Module:
2.3.6 Urban Wastewater Loads:
2.3.7 Industrial Wastewater Loads:
2.3.8 Urban Stormwater Loads:
2.3.9 Pastural Farming Loads Module:
2.3.10 Horticulture and Cropping Loads:
2.3.11 Total Pollutants Loads:
2.3.12 Actions, Solutions and Agency Spend Module:
2.3.13 Indicators:
2.3.14 Major External Factors
3.0 Reports to Date

1.0 Background:

The Manaaki Taha Moana (MTM) research team is building a systems dynamics model (MTM Model) for Tauranga Harbour and its catchments.  The model is being developed with stakeholders during and in between the MTM project workshops. This document is a recording the development of the MTM model along the process. The ultimate goal of the Manaaki Taha Moana project is to enhance and restore ecosystems of importance to Tauranga Moana (in that case study). Local iwi participants and Stakeholders of the harbour will provide a robust set of perspectives into the Mediated Modelling workshops, defining the social and cultural impacts of the degradation of the health of Tauranga Harbour and the life force it brings to tangata whenua. Only through understanding and cooperation between tangata whenua and all stakeholders in the Moana could this possibly be achieved. The tangata whenua participants, along with the MTM research team here in Tauranga welcome the opportunity to engage in the Mediated Modelling sessions as a platform to bring this to fruition.

1.1 Team Developing the Model:

Marjan Van den Belt, Aaron McCallion, Sarah Wairepo, Mark Berry, Derrylea Hardy

1.2 Model Questions:

The main question we want the model to answer. Preliminary answers from Workshop 1&2 are added.

1.     What are the 3 factors that most threaten the health of the harbour?

The 3 big issues (symptoms) that seem to be emerging from the workshops are:

1) Sedimentation;

2) Eutrofication;

3) Loss of things such as kaimoana, habitat loss. The inherent processes/factors that are causing these issues are: 1) increased industrial/economic activity depleting ecosystems and their services; coastal development and urban pressures and associated pollution; system not “counting” ecosystem services.

2.     What are the desired outcomes of a sustainable harbour with respect to economic, cultural, social, and environmental wellbeing?

Ecological (natural): Water in harbour that is same quality as at uppermost part of catchment, ie clear, drinkable, sustains life.

Social: Valued uses of harbour can still occur. Eg fishing; Mana-enhancing social systems reliant on the harbour, such as ability to collect kaimoana, are intact.

Cultural: Mauri of harbour is sustained?

Economic: The value of ecosystem services is accounted for in the economic system, with appropriate incentives and regulations, so that use of natural resources is sustainable and does not erode natural capital upon which the economy depends, thus enabling ongoing but sustainable “economic” activity in region.

3.     What actions can produce the most positive overall outcomes, to address root causes of problems?

Heavy “users” of ecosystems, or groups/industries that benefit from ecosystem services provided by the harbour, should also contribute to the maintenance/restoration of those ecosystems. Eg through funds set up specifically for ecosystem services, via taxation or levies on ecosystem goods and services. System adapted via incentives/taxes to encourage individuals/groups to engage in restoration efforts, or limit unsustainable use of ecosystems.

4.     What social values can we modify to effect solutions?

Better integration, so people see “whole picture” and how parts of the system influence each other – eg how economic/social/cultural activities impact on the environment, and vice versa. We want society to be conscious of the services they ARE getting from ecosystems, that they have value – so society will WANT to support them and ensure sustainable natural capital levels. Thus, people to better understanding the whole system, interactions between parts of the system, how economic/social activities impact on environment and how environment provides “services” to humans that are not necessarily “free” forever.

2.0 MTM Model Development:

2.1 Program Used – Stella:

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Free isee Player Version

Mapping and Modelling:

• Icon-based graphical interface simplifies model building
• Stock and Flow diagrams support the common language of Systems Thinking and provide insight into how systems work
• Enhanced stock types enable discrete and continuous processes with support for queues, ovens, and enhanced conveyors
• Causal Loop Diagrams present overall causal relationships
• Model equations are automatically generated and made accessible beneath the model layer
• Built-in functions facilitate mathematical, statistical, and logical operations
• Arrays simply represent repeated model structure
• Modules support multi-level, hierarchical model structures that can serve as “building blocks” for model construction

Simulation and Analysis:

• Simulations "run" systems over time
• Sensitivity analysis reveals key leverage points and optimal conditions
• Partial model simulations focus analysis on specific sectors or modules of the model
• Results presented as graphs, tables, animations, QuickTime movies, and files
• Dynamic data import/export links to Microsoft® Excel

Communication:

• Flight simulators and dashboards describe model components and facilitate manipulation
• Input devices include knobs, sliders, switches, and buttons
• Output devices highlight outcomes with warning flashers, text, graphs, tables, and reports
• Storytelling supports step-by-step model unveiling
• Causal Loop Diagrams present dominant feedback loops within structure
• Sketchable graphs allow easy comparison of expected results with actual simulations
• Export for NetSim support publishing and sharing model over the web using isee NetSim add-on software
• Save as Runtime option creates full-screen, runtime models
• Multimedia support triggers graphics, movies, sounds, and text messages based on model conditions

2.2 Model Simulation Specifications:

• Temporal scale: Annual time step from 1950 to 2070
• Spatial scale: Tauranga Harbour and its catchments

2.3 Model Modules:

• Tauranga Harbour Catchment Population Pressures
• Land Use
• Ecosystem Values
• Socio Economic
• Recreational Value of Tauranga Harbour
• Pollutant Loads on Tauranga Harbour
• Actions Solutions and Agency Spend
• Major External Factors
• Tauranga Harbour Indicators
• Water Dynamics of Tauranga Harbour and its Catchments

2.3.1 Population Pressures Module:

This module simulates the population changes from 1950 till 2070. It includes the resident population and inbound tourists in the Tauranga Harbour catchment to calculate the effective population pressure, tourist numbers and the value of the Tourism to the region. The module also has the potential for a tax take from tourism a beneficiary of Tauranga Harbour eco system services that could be distributed to

The population pressure is linked to the urban water demand in the water availability and use for Tauranga Harbour catchments module.

Data Inputs:

Tauranga Harbour Catchment Population

Visitor Numbers to Western Bay of Plenty 2009-2010

Data Sources:

Tourism BOP website
Statistics NZ - Tauranga and western Bay of Plenty Population Statistics 1986-2006.

Data Calculations:

Outputs: (graphical)

• Population projections using various growth rates
• Tourism projections using various growth rates
• Value of Tourism to Catchment region up to 2070 using Tourism number projections (Visitor numbers, average stay, average value per day)
• What a potential inbound tourist regional tax could bring to region for ecosystem restoration using various rates.

2.3.2 Land Cover and Use Module:

This module simulates the predominant and projected land use and land cover changes from 1950 till 2070. It also shows the contribution of different land uses to the total sediment loads into the Tauranga Harbour. This module also estimates the total sediment trapping from mangroves and wetlands. The ‘total sediment’ will be linked with ‘sediment impact on shellfish’ from the ‘Ecosystem Services’ module, ‘recreation value of Tauranga Harbour’ module, and ‘Pollutant Loads’ from the ‘Total Pollutant Loads Tauranga Harbour Catchment’ module to simulate the possible impacts.

The amount or rate of sedimentation in Tauranga Harbour has increased over the years because of population growth, changing land use and soil disturbance related to development.

Data Inputs:

• Main land use categories and their area in Ha since year as at 2008.
• Need accurate trend data of land use changes since 1950 to 2008
• Projected/ expected growth rates of mangroves and the cutting event of mangroves.
• Wetlands in Ha
• Sediment trapping values of Mangroves and Wetlands
• Sea Grass in Ha, factors affecting sea grass death rate (sea lettuce, storm, Black Swans, toxins, nutrient runoff (feedback loop needed with pollutant loading of harbour module) , ozone impact, sediment impact on sea grass and pulse event of Ruahihi canal collapse in 1981.
• History of Sea grass & Mangroves.

Data Calculations: 

Graphical Output:

Changes in Land use overtime and effect on Sedimentation/Wetlands/Sea-grass and Mangroves

• Sedimentation in Tonnes 1950-2070
• Mangrove Growth
• Wetland growth/Decline
• Sea grass Growth Decline

Data Sources:

Wildlands Kaimai Catchment Report (2010)
Bay of Plenty Maritime Wetlands Database Environmental Report 2000/21
Tauranga Harbour Integrated Management Strategy 2006/7, Bay of Plenty regional council.
Environmental Report 2004/16 Aspects of Mangrove Distribution and Abundance in Tauranga Harbour Stephen Parks, Bay of Plenty regional council

2.3.3 Ecosystem Services Module:

This module simulates the services that ecosystems provide humans and the impact of sedimentation, Toxins, Pollutants and Dredging on these ecosystems. One way of doing this, is to place a monetary value on the 'services' that 'ecosystems' provide humans.  Seagrass, for example, provides a number of ecosystem services including trapping and stabilizing sediments, nutrient recycling, creation of high primary productivity and the provision of habitat for animal and plant species.  By placing a monetary value on these ecosystem services, their value becomes 'visible' and decision makers can appreciate their true worth. A further monetary valuation can be put on the food resource of commonly gathered species of Tauranga harbour. The annual harvested values of these species could be measured and the impact of food resource loss via dredging, toxins, shellfish bans and other impacts could be measured over the Scenario period (1950-2070).

Data Inputs:

Any relevant information/data associated with the following:

• Sediment Impacts on Shellfish
• Dredging Impacts on Shellfish
• Biomass and Land catch data of commonly harvested for food species in Tauranga harbour -Whitebait, Oysters, Eels, Snapper, Tuata, Pipi, Cockle, Green lipped Mussel, Scallops, Flounder.
• Fish Species
• Values of Ecosystem services in USD$
• Mangrove, Wetland, Sea grass, Indigenous forest area in Ha

To be included:

• Bird Species
• Forest Health Factors
• Bio security risks
• Health and feedback loops to pollutant loading of harbour

Data needs:

• Estimates of Native and Non-Native fish population in the Tauranga Harbour.
• Annual growth rate
• Annual harvest rate
• Estimates of Native and Non-Native birds population
• Estimates of Customary and Recreational Food Gathering
• Forest Health data
• Pest eradication program data

Data Calculations: 

Outputs: (graphical)

Ecosystem valuations

Biomass valuation

Harvested valuations overtime

Data Sources:

• Costanza, R., d'Arge, R., de Groot, R., Farber, S., Grasso, M., Hannon, B., Limburg, K., Naeems, S., O'Neill, R.V., Paruelo, J., Raskin, R.G., Sutton, P., van den Belt (1997).  The Value of the World's Ecosystem Service and Natural Capital.  Nature 387: 253-260.
• Environment Bay of Plenty.  2010.  Mangroves.  Tauranga Harbour Fact Sheet 3.  Environment Bay of Plenty, Whakatane.
• National Institute of Water and Atmosphere.  2010.  Comparing Seagrass Meadows across New Zealand.  NIWA, Wellington.
• Statistics New Zealand Website

2.3.4 Socio-Economic Module:

Data Needs:

• Standard of living data
• Employment Data – Number of jobs, unemployment rate....
• Mining was mentioned
• Cost of unemployment
• Cost of crime
• Bio-security risk – Pest species....
• Ships and ballast
• Global/National Economy
• Interest rates
• Inflation

2.3.5 Recreation Value of Tauranga Harbour Module: This module simulates the recreational value of Tauranga Harbour.

The recreational opportunities available on and around the harbour are a significant attraction for people to live and visit the Bay of Plenty region. The quality of the physical environment and leisure/recreation opportunities are some of the main reasons why people move to this area.

Data Needs: Any relevant information/data associated with the following:

• Harbour Margins
• Navigation safety
• Boating Facilities
• Nutrient Loads
• Water Quality
• Sea Lettuce in Tonnes
• Recreational Fishing
• Environmental Food Resource Indicator

Data Sources:

Recreational Strategy Tauranga Harbour, 2009, EBOP

2.3.6 Urban Wastewater Loads: This module estimates the pollutants loads from all urban waste water discharges.

There are a number of urban wastewater treatment plants which discharge in to the harbour. As expected, they will have different amounts of loadings both in terms of quantity and concentrations of pollutants.

Data Needs:
-  List of all major pollutants to be considered from urban wastewater discharges
-  All urban discharge consents and their loading rates of identified pollutants: Quantity discharges (e.g. cubic m per day or year) and concentrations of different pollutants (g per cubic m)

Calculations Needs:
-  Aggregate the urban wastewater discharges and loadings (total quantity with weight average concentrations) per pollutant

Module Developments:
-  Further develop the module according to the identified pollutants in urban wastewater discharges
-  Populate the module with collected and estimated town wastewater discharges data

• Port of Tauranga.  2009.  Port of Tauranga Financial Information.  Annual Report 2009.  Prepared by KPMG on Behalf of the Auditor General of New Zealand.  http://port-tauranga.co.nz/Investors/Financial-Information.

2.3.7 Industrial Wastewater Loads: This module estimates the pollutants loads from all industrial wastewater discharges.

There are a number of industrial wastewater discharges into the harbour. As expected, they will have different amounts of discharges and pollutant loadings both in terms of quantity and concentrations.

Data Needs:
-  List of all major pollutants to be considered from Industrial wastewater discharges
-  All Industrial discharge consents and their loading rates of identified pollutants: Quantity discharges (e.g. cubic m per day or year) and concentrations of different pollutants (g per cubic m)

Calculations Needs:
-  Aggregate the industrial discharges and loadings (total quantity with weight average concentrations) per pollutant

Module Developments:
-  Further develop the module according to the identified pollutants in industrial wastewater discharges
-  Populate the module with collected and estimated industrial wastewater discharges data

2.3.8 Urban Stormwater Loads: This module will estimate the pollutants loads from stormwater from urban areas.

Data Needs:
-  List of all major pollutants to be considered from Stormwater
-  Stormwater consents
-  investment

Calculations Needs:
-  Aggregate the stormwater discharges and loadings (total quantity with weight average concentrations) per pollutant

Module Developments:
-  Further develop the module according to the identified pollutants in stormwater discharges
-  Populate the module with collected and estimated stormwater discharges data

2.3.9 Pastural Farming Loads Module: This module estimates the pollutants loads from Pastural farming sector.  The approach of ‘cows per ha’ would allow us to simulate the impact of dairy intensification (increasing stock per ha) as well as increase in dairy farming in hectares.

If there are proposed changes, it would require determining what proposed changes mean, i.e. % reduction in different pollutant loadings rates from % of dairy farming area!

Data Needs:
-  List of all major pollutants to be considered from Pastural farming sector
-  Identified pollutant loading rates, in e.g. kg N per cow per year (these loading rates should consider the attenuation coefficients!)

Calculations Needs:
-  How to calculate E-coli concentrations and loads!

Module Developments:
-  Further develop the module according to the identified pollutants from the Pastural farming sector
-  Populate the module with collected and estimated Pastural farming data

2.3.10 Horticulture and Cropping Loads: This module estimates the pollutants loads from Horticulture and Cropping farming sector.

Data Needs:
-  List of all major pollutants to be considered from Horticulture and Cropping farming sector
-  Identified pollutant loading rates, in e.g. kg N per ha per year (these loading rates should consider the attenuation coefficients!)

Module Developments:
-  Further develop the module according to the identified pollutants from the Horticulture and Cropping farming sector
-  Populate the module with collected and estimated Cropping farming data

2.3.11 Total Pollutants Loads: This module adds up all the pollutants estimated from all point and non-point sources.

2.3.12 Actions, Solutions and Agency Spend Module:

Data Needs:
-  Identify the major actions already underway in the Tauranga Harbour and its catchments; and collect their details (what, where, when, and what are the monitored or expected impacts!)
-  Identify the major proposed actions in the Tauranga Harbour and its catchments; and estimate their details (what, where, when, and what are their expected impacts!)

Module Developments:
-  Populate the module with the collected and estimated data
-  Further develop the module according to the identified actions to be simulated.

2.3.13 Indicators: This module simulates the measures that reflect or indicate the state of the health of Tauranga Harbour and its catchments.

What are the indicators that there is a problem? e.g. wading bird habitat – loss of bird life is an indication of a problem somewhere else in the system.

2.3.14 Major External Factors

Climatic Events - The effects of climate on vegetation and habitats across the project area results from a complex set of interactions with altitude, vegetation and land use, distance from the coast, and landforms and soils.

• Drought events in the early and middle parts of the 20th Century triggered widespread dieback of indigenous vegetation in ‘cloud forest‘, and these effects are still very evident along the highest ridges today. This has resulted in the ―scruffy vegetation that is present in these areas.

3.0 Reports to Date

• Assessment of Environmental Effects for Port of Tauranga Channel Deepening & Widening. (2009)
• 9912 - Changes in abundance of Seagrass in Sth Tauranga Harbour (EBOP 1999) 9930 - Change in abundance of Seagrass in Tauranga Harbour from 1959 - 1996
• State of the Environment Assessment for the Catchments of the Kaimai Range & Northern Mamaku Plateau (Feb 2010)
• Tauranga Harbour Integrated Management Strategy - Lawrie 2006
• The New Zealand Mangrove: review of the current state of knowledge - Morrisey 2007
• Aspects of Mangrove Distribution & abundance in Tauranga Harbour - Park 2004
• Expansion Dynamics of Monospecific, Temperate Mangroves and Sedimentation in 2 Embayments of a Barrier-Enclosed Lagoon, Tauranga Harbour, New Zealand - Stokes 2010
• Hydrological & Ecological Baseline Study of the Wetland South East of Kuka Road (Wildland Nov 2009)
• Environmental Assessment of the Wider Te Puna and Waipapa Catchments, Western Bay of Plenty (Wildland Sept 2009)
• MiscReport-091119-MicrobiologicalQualityofShellfishinEstuarineareas
• Report-0411-ComplianceReportForVegetationRemovalAndLandClearance
• Report-0608-WastewaterTreatmentSystemComplianceRpt
• Report-0711-SeaLettuceMonitoringInTheTaurangaHarbour
• Report-070500-WaterUseandAvailabilityAssessmentfortheWesternBayofPlenty
• Report-091015-BOPAMABiologicalSurvey
• Report-091221-WaterQualityBOPRivers89to08
• Strategy-090528-StormwaterStrategyForTheBayOfPlentyRegion

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