An Input-Output/ System Dynamics Approach to
Ecological Economic Modeling:
An application to the Seine Estuary in France
Takuro Ueharaa, Mateo Cordier b, c, Bertrand Hamaided and
Jeffrey Weihe
a
College of Policy Science, Ritsumeikan University, Kyoto, Japan
Européen Arctique, Université de Versailles Saint-Quentin-en-Yvelines (CEARC-UVSQ), France.
c Centre d’Etudes Economiques et Sociales de l’Environnement, Centre Emile Bernheim, Université Libre de Bruxelles,
(CEESE-CEB-ULB), Brussels, Belgium.
d Centre de Recherche en Economie, Université Saint-Louis (CEREC-FUSL), Brussels, Belgium.
e Senior Adult Learning Center, Portland State University, USA.
b Centre
1
Objectives
• Build a model which links an Input-output (I-O) table
to a System Dynamics (SD) model to capture the
complexity of an ecological-economic system
• Apply the method to the Seine Estuary, France
• For this paper, policy implications for the restoration
of the estuary are NOT the main focus
– (we will address these in the next step!)
2
Motivation
• We need modeling techniques which can capture
the complexity of an ecological-economic system.
• Environmentally Extended I-O
– Well-developed; an I-O is often readily available
– Captures detailed economic structures, but not dynamics
• Constant technical coefficients; Lack of feedback loops
• SD(a computer-aided approach to solving a system of nonlinear first-order differential equations)
• Captures nonlinear dynamics and feedback loops, but not detailed
(disaggregated) economic structures
• It is technically possible to integrate I-O and SD.
• SD can be synchronized with SAP, Oracle, Microsoft Excel, GIS, etc.
3
Study Area: The Seine Estuary
• The nursery area for sole has been decreasing due to
economic activities (Rochette et al, 2010; Culliviez et al, 2008).
190
181.91
180
Nursery areas (km2)
170
160
150
139.67
140
127.94
130
122.77
120
111.74
110
100
1830
1850
1870
1890
1910
1930
1950
1970
1990
Nursery habitats have been continually destroyed since
1834 by the construction of dikes and harbor
extensions for maritime transport, and by the
Normandy bridge.
Evolution of nursery areas of the internal part of the
Seine estuary
Source: Cuvilliez (2008).
Source: Rochette, S. (2010)
2010
Years
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The Schematic Model
• SD on Powersim® is synchronized with I-O on Excel®.
Ecological System
(SD on Powersim)
Economic System
(I-O on Excel)
Commodity ↓
Nursery Area in the
Seine Estuary
Total Output
Initial Nursery Area
Restoration Policy
Carrying Capacity of
Sole
Fractional
Destruction Rate
Destruction Rate
Restoration Rate
Maximum Number of
Sole per km2 of
Nursery Area
Sole in the Seine
Estuary
Initial Stock of Sole
Net Birth
Average Weight per
Catch
Price of Sole per kg
Catch Rate
Fractional Catch
Rate
Weight of Caught
Sole
Change in Total
Output
Final Demand for
Sole
Initial Total Output
Mining products & services
Products from other industries
2009
2010
2011
2012
2013
1,781.3
1,837.0
1,891.1
1,951.7
2,015.3
117.1
111.2
114.4
117.9
121.6
125.5
58.3
56.6
58.1
59.6
61.3
63.0
318.4
298.4
312.4
323.8
336.4
349.6
25,751.8 24,545.5 25,427.9 26,222.4 27,113.8 28,052.2
2,139.6
1,975.3
2,095.4
2,178.0
2,269.1
2,364.9
Other non-metallic mineral products
1,429.7
1,373.1
1,411.0
1,453.7
1,501.6
1,552.5
Electrical energy, gas, steam and hot
water
3,791.0
3,451.5
3,695.0
3,854.8
4,029.4
4,213.1
Construction work
Final Demand
for Sole
2008
1,856.3
Coke, refined petroleum products and
nuclear fuels
Services from other tertiary sectors
Intrinsic Growth
Rate of Sole
Total Output
Year →
Products of agriculture, hunting and
related services
Products of forestry, logging and
related services
Fish and other fishing products;
services incidental of fishing
Water transport services
Supporting and auxiliary transport
services; travel agency services
Soles
TOTAL OUTPUT →
49,374.8 47,865.1 49,193.5 50,449.8 51,926.8 53,475.1
7,344.0
7,214.6
7,128.2
7,356.0
7,592.6
417.8
370.5
403.7
424.1
446.1
7,854.9
469.4
2,408.1
2,291.6
2,379.9
2,454.8
2,539.5
2,628.6
1.9
1.7
1.6
1.6
1.5
1.5
95,009
91,336
94,058
96,788
99,892
103,166
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Simulation Results
• Preliminary results with three scenarios.
– 0% Restoration Every Year, from 2018 to 2028 (as a baseline)
– 2% Restoration Every Year, from 2018 to 2028
– 10% Restoration Every 5 Years, from 2018 to 2028
140.00
120.00
100.00
80.00
60.00
40.00
20.00
0.00
2008 2010 2012 2014 2016 2018 2020 2022 2024 2026
Final demand for sole
Final Demand for Soles (millions of
Euro)
Nursery Area in the Seine Estuary (km2)
Nursery area in the Seine Estuary
2.50
2.00
1.50
1.00
0.50
0.00
2008 2010 2012 2014 2016 2018 2020 2022 2024 2026
Baseline (No Restoration)
Baseline (No Restoration)
2% Restoration from 2018
2% Restoration from 2018
10% Restoration Every 5 Years from 2018
10% Restoration Every 5 Years from 2018
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Future Research Directions
• Feedback loops between an economic system and an ecological system
– E.g., impacts of economic activities on the destruction of the nursery
• Delays
– E.g., dike construction impacts that linger for several years (Cuvilliez, 2009)
• Ecological System
– Need natural scientists’ advice to sophisticate the structure of the ecological
system model
• Data Collection
– Collect “soft data” through, for example, expert meetings
• Scale Mismatch?
– Is the economy too big (monetarily) relative to the size of the ecological system?
– Boundary of Economic System? Adjust I-O using RAS method?
• Optimal Restoration Policies
– SD offers optimization techniques for analytically unsolvable models
– SOPS (Stochastic Optimization in Policy Space)
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