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Systems Dynamic Model of Horowhenu- Workshop 1

Toheroa gatherers hunting the shellfish on Hokio South beach (30th September 1974)


Manaaki Taha Moana Manaaki Taha Moana is a six year research programme primarily funded by the Foundation of Research Science and Technology ($6.6 million). It runs from October 2009 to October 2015. It has two case study regions Tauranga Harbour, and the Horowhenua coast. The aims of the research programme are: Restoring and enhancing coastal ecosystems that are important to Iwi. This will achieved through a better knowledge of these ecosystems and the degradation processes that affect them, and then using that knowledge to influence decision-making by councils and others. Iwi/hapū Capacity Building. This will be achieved by a strong focus on developing iwi-based researchers and to build hapū/iwi future leaders in the area of coastal management. Research Providers: - School of People Environment and Planning, Massey University - Taiao Raukawa Trust - Manaaki Te Awanui Trust - Waka Digital Ltd - Cawthron Institute

Systems Dynamic Modelling– Horowhenua 2013 The aim of this systems dynamic modelling project is to understand the broad interrelationships between ecological "issues/problems" and their "causes" on Toheroa in the Horowhenua. Key representatives from Horowhenua, including local iwi participants, will provide a robust set of perspectives in the system dynamic workshops, defining the ecological, economic, social and cultural impacts on Toheroa in the Horowhenua. What is System Dynamic Modelling System dynamics is an approach to understanding the behaviour of complex systems over time. It uses a computer simulation modelling technique to deal with internal feedback loops and time delays that affect the behaviour of the entire system, incorporating feedback loops and stocks and flows. This approach allows us to frame, understand, and discuss complex issues and problems to help us better understand the dynamic behaviour of complex systems. The basis of the method is the recognition that the structure of any system — the many circular, interlocking, sometimes time-delayed relationships among its components — is often just as important in determining its behaviour as the individual components themselves. It is also claimed that

because there are often properties-of-the-whole, which cannot be found among the properties-of-theelements, in some cases the behaviour of the 'whole' cannot be explained in terms of the behaviour of its parts. Thus, a systems dynamics approach to examination of an issue considers all the aspects of that issue, taking holistic view of how changes in one component impact on the other components within the system, which may then in turn impact back upon the original component that underwent a change. What is a 'system'? A system is an organised collection of parts (or subsystems) that are highly integrated to accomplish an overall goal. The system has various inputs, which go through certain processes to produce certain outputs, which together, accomplish the overall desired goal for the system. So a system is usually made up of many smaller systems, or subsystems. Systems range from simple to complex. Complex systems, such as social systems, are comprised of numerous subsystems, as well. These subsystems are arranged in hierarchies, and integrated to accomplish the overall goal of the overall system. Each subsystem has its own boundaries of sorts, and includes various inputs, processes, outputs and outcomes geared to accomplish an overall goal for the subsystem. Complex systems usually interact with their environments and are, thus, open systems. A highfunctioning system continually exchanges feedback among its various parts to ensure that they remain closely aligned and focused on achieving the goal of the system. If any of the parts or activities in the system seems weakened or misaligned, the system makes necessary adjustments to more effectively achieve its goals. Systems Thinking: The approach of systems thinking is fundamentally different from that of traditional forms of analysis. Traditional analysis focuses on the separating the individual pieces of what is being studied; in fact, the word "analysis" actually comes from the root meaning "to break into constituent parts." Systems thinking, in contrast, focuses on how the thing being studied interacts with the other constituents of the system, a set of elements that interact to produce behaviour, of which it is a part. This means that instead of isolating smaller and smaller parts of the system being studied, systems thinking works by expanding its view to take into account larger and larger numbers of interactions as an issue is being studied. This results in sometimes strikingly different conclusions than those generated by traditional forms of analysis, especially when what is being studied is dynamically complex or has a great deal of feedback from other sources, internal or external.

Stella Software: For this project we will be using Stella software. Stella supports a wide range of storytelling features. We will use STELLA to: •

Simulate a system over time

Enable participants to creatively change systems

Teach participants to look for relationships – see the Big Picture

Clearly communicate system inputs and outputs and demonstrate outcomes

Key Features of Stella include; 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

Horowhenua Project Team – Systems Dynamic Modelling 

Huhana Smith

Aaron McCAllion

Moira Poutama

Aroha Spinks

Nigel Thomas

Steven Mason

Wider Manaaki Taha Moana Research Group

Information gatherers and Experts as needed

Framework for the Horowhenua Systems Dynamic Model The group decided that the Model Simulation Specifications would be based on Temporal scale: Time steps: Spatial scale:

Annual time step from 1950 to 2070 Model to run in annual time steps Hokio Stream to South Otaki River

Model Questions: The main question we want the current model to answer. 1.

How do Kaitiaki establish a sustainable harvest for Toheroa Shellfish – Model may at a later date be extended to include other harvestable species- Cockles, Tuatua and Pipi?


What are the factors that most threaten the Population and Health of Horowhenua


What solutions (policies), to identified root causes, can make an impact and how much? (ie what actions can produce the most positive overall outcomes, to address root causes of problems). We want the model to help us prioritise the underlying issues that we need to tackle first.


What social values can we modify to effect solutions?


Will Reseeding efforts assist in establishing a sustainable harvest?


What factors influence sea food, water quality?


Seafood as an ecosystem service and its value?


What sea food is found along the Horowhenua Coast?


Nitrogen runoff in Horowhenua?

10. What is the area in hectares this study covers? 11. Rainfall in Horowhenua? 12. Population in study area?

The big issues (symptoms) that seem to be emerging from discussion are: Wormholes/Ghost Shrimps (Predators) Loss of fish species that attack Toheroa predators. Eutrofication; 

Increased industrial/economic activity depleting ecosystems and their services; coastal development and urban pressures and associated pollution;

Sedimentation (Tidal Zone impact)

River and Stream Plumes (Nutrient, hormones, applications of fertiliser, photochemical, ground water contamination and Effluent)- Water Quality

Vehicle access to Dunes and Tidal Zone

Climate and Oceanic issues Proposed Construction of the Model, and Associated Discussion: 

Catchment Population Model

Horowhenua Population model

Land Use

Ecosystem Values

Socio Economic  Food Resource Index

Pollutant Loads

Actions, Solutions and Agency Spend Module  Major External Factors climate Change (sea level rise)  Tsunami

CATCHMENT HUMAN POPULATION MODEL This module will simulate the Human Population of the Catchment Data Inputs needed TBC

Possible Graphical Output: TBC

Data Sources:

HOROWHENAU BIOMASS MODEL This module will simulate the Biomass of Toheroa in Units Data Inputs needed TBC

Possible Graphical Output: TBC

Data Sources: TBC

Land Cover and Use Module: This module will simulate the predominant and projected land use and land cover changes from 1950 till 2070. It also will show the contribution of different land uses to the total sediment loads into the Tidal Zone. This module may also estimate the total sediment trapping from wetlands. The ‘total sediment’ may be linked with ‘sediment impact on Toheroa’ from the ‘Ecosystem Services’ module, and ‘Pollutant Loads’ from the ‘Total Pollutant Loads Toheroa Catchment’ module to simulate the possible impacts. Data Inputs needed • Main land use categories and their area in Ha • Need accurate trend data of land use changes since 1950 to Current • Wetlands in Ha • Sediment trapping values of Wetlands

Possible Graphical Output: Changes in Land use overtime and effect on Sedimentation & Wetlands 

Sedimentation in Tonnes 1950-2070

Riparian maps

Wetland growth/Decline

Data Sources: TBC

Ecosystem Services Module: This module will simulate the services that ecosystems provide humans and the impact of sedimentation, Toxins, Pollutants on these ecosystems. One way of doing this, is to place a monetary value on the 'services' that 'ecosystems' provide humans. Wetlands, for example, provide a number of ecosystem services including trapping and stabilizing sediments, nutrient recycling, nursery for fisheries, 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 Toheroa. The annual harvested values of these species could be measured and the impact of food resource loss via predators, toxins, bans and other impacts could be measured over the Scenario period (1950-2070). Data needs: Any relevant information/data associated with the following: 

Customary gathering data

Legal or illegal gathering

Sediment Impacts on Toheroa

Biomass and Land catch data of Toheroa.

Values of Ecosystem services in USD$

Wetland, Indigenous forest area in Ha

Bird Species

Health (health reports)

Estimates of Customary and Recreational Food Gathering

Predator identification (Ghost shrimp) eradication program data???

Fisheries data ( For fish that are predators to crabs who in turn are predators to ghost shrimp) Q- Is the ghost shrimp a predator or only displaces Toheroa

Possible Graphical Outputs: 

Ecosystem valuations

Biomass valuation

Harvested valuations overtime

Socio-Economic Module: • Vehicle Access (Recreational Strategy) • Nutrient Loads

• Food Resource Indicator • Water Quality

Pollutant Load Module Urban Wastewater Loads: This module may estimate the pollutants loads from all urban waste water discharges in the catchment. Need to find the number of urban wastewater treatment plants which discharge in to the catchment area. 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 Industrial Wastewater Loads: This module estimates the pollutants loads from all industrial wastewater discharges. Need to find the number of industrial wastewater discharges into the catchment. 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 Urban Stormwater Loads: This module may estimate the pollutants loads from stormwater from urban areas. Data Needs: - List of all major pollutants to be considered from Storm water

- Stormwater consents - investment Calculations Needs: - Aggregate the storm water discharges and loadings (total quantity with weight average concentrations) per pollutant 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 Horticulture and Cropping Loads: This module may estimate 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!) Total Pollutants Loads: This module will add up all the pollutants estimated from all point and non-point sources.

Actions, Solutions and Agency Spend Module: Data Needs: - Identify the major actions/spend already underway in the Catchment; and collect their details (what, where, when, and what are the monitored or expected impacts!) - Identify the proposed actions in the catchment and estimate their details (what, where, when, and what are their expected impacts!) example – RESEEDING Annual Plans of Councils and agencies in the Catchment Indicators: This module will simulate 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. Ghost Shrimp Population – Growth of Ghost Shrimp is an indication of a problem somewhere else in the system. Major External Factors Climatic and Oceanic factors 

Beach Morphology

Breach community dynamics

Toxic Algal Blooms


Storm events


Phytoplankton concentration

Temperature and Salinity Shock

Sea Level Rise

Tsunami Risk

Reports Collected to Date 

Factors Affecting Toheroa: Lit Review MTM Report No10

Review of factors affecting the abundance of toheroa (Paphies ventricosa) New Zealand Aquatic Environment and Biodiversity Report No. 114

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