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Integrated modelling for economic valuation of the role of forests and woodlands in drinking water provision to two African cities

Integrated modelling for economic valuation of the role of forests and woodlands in drinking water provision to two African cities
Integrated modelling for economic valuation of the role of forests and woodlands in drinking water provision to two African cities
Rapidly growing economies often have high population growth, resulting in agricultural expansion in rural areas and increased water demand in urban areas. Conversion of forests and woodlands to agriculture may threaten safe and reliable water supply in cities. This study assesses the regulating functions and economic values of forests and woodlands in meeting the water needs of two major cities in Tanzania and proposes an integrated modelling approach with a scenario-based analysis to estimate costs of water supply avoided by forest conservation. We use the process-based hydrological Soil and Water Assessment Tool (SWAT) to simulate the role of woody habitats in the regulation of hydrological flow and sediment control. We find that the forests and woodlands play a significant role in regulating sediment load in rivers and reducing peak flows, with implications for the water supply from the Ruvu River to Dar es Salaam and Morogoro. A cost-based value assessment under water treatment works conditions up to 2016 suggests that water supply failure due to deforestation would cost Dar es Salaam USD 4.6–17.6 million per year and Morogoro USD 308 thousand per year. Stronger enforcement of forest and woodland protection in Tanzania must balance water policy objectives and food security.
2212-0416
50-61
Ashagre, Biniam B.
b6b9ab8c-9548-47fc-ab72-08364dad5226
Platts, Philip J.
a389d869-ad8d-4904-a983-234d324bafc4
Njana, Marco
2b358bbd-0a8a-49fb-82e4-9cdac8526da1
Burgess, Neil D.
c56742a9-4441-4c6e-92e7-fb69c487ee54
Balmford, Andrew
b66d76a7-4e7d-435b-a1b8-2d61883c8166
Turner, R. Kerry
c1905718-7796-4563-a014-f456d154921f
Schaafsma, Marije
937ac629-0fa2-4a11-bdf7-c3688405467d
Ashagre, Biniam B.
b6b9ab8c-9548-47fc-ab72-08364dad5226
Platts, Philip J.
a389d869-ad8d-4904-a983-234d324bafc4
Njana, Marco
2b358bbd-0a8a-49fb-82e4-9cdac8526da1
Burgess, Neil D.
c56742a9-4441-4c6e-92e7-fb69c487ee54
Balmford, Andrew
b66d76a7-4e7d-435b-a1b8-2d61883c8166
Turner, R. Kerry
c1905718-7796-4563-a014-f456d154921f
Schaafsma, Marije
937ac629-0fa2-4a11-bdf7-c3688405467d

Ashagre, Biniam B., Platts, Philip J., Njana, Marco, Burgess, Neil D., Balmford, Andrew, Turner, R. Kerry and Schaafsma, Marije (2018) Integrated modelling for economic valuation of the role of forests and woodlands in drinking water provision to two African cities. Ecosystem Services, 32 (Part A), 50-61. (doi:10.1016/j.ecoser.2018.05.004).

Record type: Article

Abstract

Rapidly growing economies often have high population growth, resulting in agricultural expansion in rural areas and increased water demand in urban areas. Conversion of forests and woodlands to agriculture may threaten safe and reliable water supply in cities. This study assesses the regulating functions and economic values of forests and woodlands in meeting the water needs of two major cities in Tanzania and proposes an integrated modelling approach with a scenario-based analysis to estimate costs of water supply avoided by forest conservation. We use the process-based hydrological Soil and Water Assessment Tool (SWAT) to simulate the role of woody habitats in the regulation of hydrological flow and sediment control. We find that the forests and woodlands play a significant role in regulating sediment load in rivers and reducing peak flows, with implications for the water supply from the Ruvu River to Dar es Salaam and Morogoro. A cost-based value assessment under water treatment works conditions up to 2016 suggests that water supply failure due to deforestation would cost Dar es Salaam USD 4.6–17.6 million per year and Morogoro USD 308 thousand per year. Stronger enforcement of forest and woodland protection in Tanzania must balance water policy objectives and food security.

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Water_valuation_Dar_paper_2018_05_02_accepted_version - Accepted Manuscript
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More information

Accepted/In Press date: 10 May 2018
e-pub ahead of print date: 7 June 2018
Published date: August 2018

Identifiers

Local EPrints ID: 421644
URI: http://eprints.soton.ac.uk/id/eprint/421644
ISSN: 2212-0416
PURE UUID: 5ba5d468-1375-46a0-a7d1-2cca9e305852
ORCID for Marije Schaafsma: ORCID iD orcid.org/0000-0003-0878-069X

Catalogue record

Date deposited: 19 Jun 2018 16:30
Last modified: 17 Dec 2019 05:22

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