Megacities structure and water security: Past and future

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Conference Presentation

Reference

Megacities structure and water security: Past and future

BOLOGNESI, Thomas

BOLOGNESI, Thomas. Megacities structure and water security: Past and future. In:

Global Water Century: Looking ahead 100 Years

, Boulder (USA), 12th June, 2018

Available at:

http://archive-ouverte.unige.ch/unige:109705

Disclaimer: layout of this document may differ from the published version.

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Introduction Megacities structure Looking backward Looking ahead Implication for Utilities

Megacities Structure and Water Security

Past and Future

T. Bolognesi^†

†University of Geneva School of Public Affairs, CU Denver

thomas.bolognesi@unige.ch

Global Water Century: Looking ahead 100 Years June 12, 2018

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Where in the world are the megacities?

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Why focusing on megacities?

1. An urban and concentrated world (UN, World Urbanization Prospect 2018):

• Urban population: 30% (1950), 55% (2018), and 68% by 2050

• 1 in 8 people live in 33 megacitites (> 10 M inhab.)

2. Intense interactions between human and nature

Critical challenge of floods and droughts management

• “Day Zero” challenge : Cape Town, Sao-Paulo... California?

• > 70% of pop affected by water disaster in 2017 (EM-DAT, 2018)

• severe droughts costlier than floods (Damania et al., 2017)

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Why focusing on megacities?

1. An urban and concentrated world (UN, World Urbanization Prospect 2018):

• Urban population: 30% (1950), 55% (2018), and 68% by 2050

• 1 in 8 people live in 33 megacitites (> 10 M inhab.)

2. Intense interactions between human and nature

Critical challenge of floods and droughts management

• “Day Zero” challenge : Cape Town, Sao-Paulo... California?

• > 70% of pop affected by water disaster in 2017 (EM-DAT, 2018)

• severe droughts costlier than floods (Damania et al., 2017)

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Vulnerability to water-related disasters

Short-term perspective: How water-related disasters impact on megacities?

Long term perspective:

How megacities structure impacts on their vulnerability to water-related disasters?

Megacities Water shocks

Structure megacities

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Vulnerability to water-related disasters

Short-term perspective: How water-related disasters impact on megacities?

Long term perspective:

How megacities structure impacts on their vulnerability to water-related disasters?

Megacities Water shocks

Structure megacities

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A measure of urban structure

(Bolognesi, 2013, 2015)

• 595 megacities, with 192 in the 154 largest watersheds

• 3 structural characteristics 1. Maturity (33.4%) 2. Antropization (29.8%) 3. Centrality (18.8%)

• 6 Regional profiles

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A measure of urban structure

(Bolognesi, 2013, 2015)

• 595 megacities, with 192 in the 154 largest watersheds

• 3 structural characteristics 1. Maturity (33.4%) 2. Antropization (29.8%) 3. Centrality (18.8%)

• 6 Regional profiles

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Macro structure of cities

(Bolognesi, 2015)

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Macro structure of cities

(Bolognesi, 2015)

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Structural characteristics and vulnerability 1980-2009

Maturity Anthropization Centrality

Floods -0.06 0.26** -0.42**

Deaths 0.04 0.07 0.15*

People affected -0.22** 0.30** -0.28**

Damage in $ -0.1 0.25** -0.28

Droughts -0.22** 0.08 -0.2**

Deaths -0.05 0 0.1

People affected -0.25** 0.34** -0.24

Damage in $ -0.18 0.1 -0.29**

N=192

OLS estimation,^∗p<0.05,^∗∗p<0.01

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Future Water Deficit 2041-2070

(Flörke et al., 2018)

• + 80% urban water demand by 2050

• 27% studied cites with demand > water availability

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Structural characteristics and Future Water Deficit 2041-2070

Deficit Magnitude

Robust Boostrap Robust Boostrap maturity -0.439^∗∗∗ -0.439^∗∗∗ -0.409^∗∗∗ -0.409^∗∗

centrality -0.315^∗ -0.315⁺ -0.188 -0.188 bigbv -0.617⁺ -0.617⁺ -0.567⁺ -0.567

cut1 -0.188 -0.188

cut2 0.840^∗∗∗ 0.840^∗∗∗

_cons 0.264 0.264

N 144

pseudoR² 0.115 0.071

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Implications for water profession and management practices

Embeddeness & connectedness:

• Spatial: widen the diagnosis (Bergsma, 2018)

• Time and path dependency: transition pathways(Renou and Bolognesi, 2018)

• Social-ecological systems: nested habitats and components, and vice-versa (Ostrom, 2009; Ostrom et al., 2007)

Management practices:

• Plan according to your state (structure) not only your outcome(vulnerability)

• The world is diverse, so should be management

• Regulatory entanglement, pay attention to the overall

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Appendix References

Megacities Structure and Water Security

Past and Future

T. Bolognesi^†

†University of Geneva School of Public Affairs, CU Denver

thomas.bolognesi@unige.ch

Global Water Century: Looking ahead 100 Years June 12, 2018

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Bergsma, E. (2018). Expert-influence in adapting flood governance: An institutional analysis of the spatial turns in the United States and the Netherlands.Journal of Institutional Economics, 14(3):449–471.

Bolognesi, T. (2013). Caractéristiques structurelles des mégapoles et vulnérabilité hydrique.Economie Appliquée, LXVI(1):95–123.

Bolognesi, T. (2015). The water vulnerability of metro and megacities: An

investigation of structural determinants. Natural Resources Forum, 39(2):123–133.

Damania, R., Desbureaux, S., Hyland, M., Islam, A., Moore, S., Rodella, A.-S., Russ, J., and Zaveri, E. (2017). Uncharted Waters : The New Economics of Water Scarcity and Variability. World Bank, Washington, DC.

Flörke, M., Schneider, C., and McDonald, R. I. (2018). Water competition between cities and agriculture driven by climate change and urban growth.Nature Sustainability, 1(1):51–58.

Ostrom, E. (2009). A General Framework for Analyzing Sustainability of Social-Ecological Systems.Science, 325(5939):419–422.

Ostrom, E., Janssen, M. A., and Anderies, J. M. (2007). Going beyond panaceas.

Proceedings of the National Academy of Sciences, 104(39):15176–15178.

Renou, Y. and Bolognesi, T. (2018). Governing urban water services in Europe:

Towards sustainable synchronous regimes.Journal of Hydrology.