To link an Input-output (I-O) model to a System Dynamics (SD) model in order to build an ecological-economic model that: â Benefits from the dynamic properties ...
AN INPUT-OUTPUT ECONOMIC MODEL INTEGRATED WITHIN A SYSTEM DYNAMICS ECOLOGICAL MODEL: A METHODOLOGY FOR FEEDBACK LOOP APPLIED TO FISH NURSERY RESTORATION
MATEO CORDIER, TAKURO UEHARA, BERTRAND HAMAIDE, JEFFREY WEIH
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Objectives • To link an Input-output (I-O) model to a System Dynamics (SD) model in order to build an ecological-economic model that: – – – –
Benefits from the dynamic properties of SD Benefits from the detailed economic structures of I-O Captures the complexity of an ecological-economic system Incorporates feedback loops between the ecosystem and the economic system – Reverses Isard’s (1968) model types: we model the economic system within the ecosystem (not the contrary), as one of the ecosystem’s components. This way, interactions inside the ecosystem can be covered in a dynamic way, which is very rare in ecological-economic models (and especially in environmental I-O models)
• Apply the model to the Seine Estuary, France 2
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Motivation (1) 1) Environmentally Extended Input-Output models (I-O) capture detailed economic structures but not fully the dynamics: • Constant technical coefficients; Lack of feedback loops • Investments and household consumption are given exogenously : profits and incomes earned in year t-1 do not influence respectively investments and household consumptions in year t • Environmental variables entered in the I-O model are static and evolve linearly
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Motivation (2) 2)
System Dynamics (SD) models capture the complex behavior of a system such as nonlinear dynamics and feedbacks but is not suited for detailed (disaggregated) structures such as an economy
SD models are a computer-aided approach to solving a system of nonlinear first-order differential equations
Population Net Birth Rate +
+
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Code for the model:
Food per Capita Fractional Birth Rate +
B
+
Food
Population = INTEGRAL(Net Birth Rate, Populationt0) Net Birth Rate = Population*Fractional Birth Rate Fractional Birth Rate =f(Food per Capita) Food per Capita = Food/Population
Sterman, J. (2000). Business dynamics. Irwin-McGraw-Hill.
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Motivation (3) • With a SD tool, it is technically possible to integrate SD and I-O It is highly compatible with other tools: it can be synchronized with SAP, Oracle, Microsoft Excel, GIS, etc. Aim: to build a dynamic model (SD property) with detailed economic structure (I-O property)
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Study Area: The Seine Estuary • The nursery area for sole has been decreasing due to economic activities Nursery areas (km2) 190 181.91 180 170
160 150 140
139.67 127.94
130
122.77
120 110 Years
111.74
100 1830 1850 1870 1890 1910 1930 1950 1970 1990 2010 Source: Cuvilliez et al. (2008)
Nurseries are a natural habitat that has been continually destroyed since 1834 by the construction of dykes and harbour extensions for maritime transport, and by the Normandy bridge.
Source of data: Rochette et al. (2010)
Evolution of nursery areas of the internal part of the Seine estuary 6
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Two components interacting in the Model Surrounding ecosystem (SD modelling on Powersim®)
Impact of supply (= f(catch)) and income (= f(GDP)) on prices of sole fish
Nursery areas Restoration rate
Destruction rate
Common soles total
Restoration Policy Age 1 common soles Abundance Multiplier
Catch Rate
Common soles Natural Mortality Rate
Converter to kg Aging in Catch Rate Catch in the internal area Fractional Catch Rate
Economic component (I-O on Excel®)
Aging out Natural Mortality Rate Fractional Natural Mortality Rate
Final Demand for Sole (= Catch) Nursery area restored Restaurant/transport/hotel services sold to recreational fishermen (to be included in forthcoming work)
Household income variation 7
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The economic component (I-O equations on Excel)
2. Salaries and dividends when estuary companies invest in nursery restoration
such as investors
3. Household purchasing power (payments for goods and services) with investments in nursery restoration
1. Final consumption with investments in nursery restoration
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The Surrounding ecosystem Total surface of high density areas
Total surface of nursery areas
(SD modelling on Powersim)
Nursery areas Total surface area restored
Restoration rate
Destruction rate
Abundance Multiplier
Restoration Policy
Common soles total Age 1 common soles Sole stock internal of the Seine
Sole stock external of the Seine Fishing quota
Delay Time Weight converter
Aging in Caught in the internal area Catch Rate
Catchable stock Export rate Sole exports
Catch Rate
Adjusted Fractional Catch Rate Weight of Common soles from the internal area
Intermediate rate Total demand Change in demand Intermediate allow ed for the internal area Reference Fractional domestic Catch Rate consumptions
Final domestic demand for sole fish
Natural Mortality Rate Aging out Natural Mortality Rate Fractional Natural Mortality Rate
Economic component (I-O sub-model in Excel)
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How the economic system (I-O) is embedded within the ecosystem modeling (SD)?
Five variables are endogenised in a dynamic way: their value depends on the results given by the model in previous year.
Two feedback impacts are simulated in the model:
Ecosystem
Impact
Feedback Impact
Economy
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Simulation results over 2007 – 2020 With restoration of 23.7km2 (2007-2017)
Without nursery restoration
km 2 2 Km
k Km m2 2
128
128
Total surface of high density areas
Total surface of high density areas
Nursery areas in the Seine Estuary
124 120 116 112 108 104 100 1/1/2007
1/1/2011
1/1/2015
1/1/2019
124 120 116 112 108 104 100 1/1/2007
1/1/2011
Non-commercial use only!
1/1/2015
1/1/2019
Non-commercial use only!
Population of soles originating from the Seine estuary Number ls of individua 6,700,000
individuals
Numberlsof individua 6,700,000
Common soles total
6,500,000
total
6,300,000 6,100,000 5,900,000 5,700,000 1/1/2007
1/1/2011
1/1/2015
1/1/2019
individuals
6,500,000 6,300,000 6,100,000 5,900,000 5,700,000 1/1/2007
1/1/2011
1/1/2015
1/1/2019
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Simulation results over 2007 – 2020
Catch of soles fish base 100 = 2007 (%)
Catch of soles in the Eastern channel (zone VIId) by fishermen from the Seine estuary 105 103.8 With nursery restoration 104 103 Without nursery restoration 103.2 102 101 100 99 Years 98 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020
GDP base 100 = 2007 (%)
Gross Domestic Product (GDP) of the Seine estuary (region Haute-Normandie) With nursery restoration
120.7 119.0
118 Without nursery restoration 114 110 106 102 98 Years 94 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020
06/02/1994 18/09/1994 30/04/1995 10/12/1995 21/07/1996 02/03/1997 12/10/1997 24/05/1998 03/01/1999 15/08/1999 26/03/2000 05/11/2000 17/06/2001 27/01/2002 08/09/2002 20/04/2003 30/11/2003 11/07/2004 20/02/2005 02/10/2005 14/05/2006 24/12/2006 05/08/2007 16/03/2008 26/10/2008 07/06/2009 17/01/2010 29/08/2010 10/04/2011 20/11/2011 01/07/2012 10/02/2013 22/09/2013
Sole price (€/kg)
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Retro-validation of the I-O/SD model Price of sole fish per kilogram
17 16 15 14 13 12 11 10 9 8 7 6 5
Calculated by the I-O/SD model
Observed data
R2 = 0.52
𝑃𝑟𝑖𝑐𝑒 𝑡 = 𝑒 −4.488086793 × 𝑉𝐴𝑡−1 0.777322352
× 𝑇𝑜𝑡𝑎𝑙 𝐶𝑎𝑡𝑐ℎ𝑡 −0.130727997 13
Acknowledgments We would like to thank Olivier Le Pape, Benoit Archambault and Etienne Rivot from Agrocampus Ouest in France (UMR ESE). Thanks also to Thomas Poitelon from Université de Versailles-Saint-Quentin-en-Yvelines (CEARC) in France. This study has been funded by the Sumitomo Foundation, the Asahi Glass Foundation, the Yamada Fund for Scientific Research, and the Grants-in-Aid for Scientific Research in Japan.
