Programme  OS5f Governance of water quality  abstract 917

Estimation of environmental flows at the Orange River mouth using an improved spatial interpolation approach.

Author(s): Billy Troy, Jean Marie Fritsch
(1) : IRD- Institut de Recherche pour le Développement, UMR G-eau, PO Box 542, Newtown 2113, Johannesburg, South Africa.

Keyword(s): environmental flows, flow duration curves, Orange River Mouth, Ramsar site, spatial interpolation approach, wetlands

Article: abs917_article.pdf
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Session: OS5f Governance of water quality
AbstractEnvironmental flow requirements are often difficult to

estimate due to missing or incomplete observed flow time series at the sites concerned. A spatial interpolation

approach for daily flow regime simulation at ungauged sites was designed to address this matter and other

hydrological issues. This paper presents improvements of this method, applied at the Orange River Mouth site

(South Africa and Namibia), which shelters endangered wetlands of international importance. This modified spatial

interpolation approach allowed to calculate simulated daily flow time series that better matched with observed water

levels than the original method. These results were then used to estimate the flooding frequency at the mouth required

to support wetlands conservation. These methodological developments are generic and could easily be included in

future applications of this spatial interpolation approach.

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