Applying the polluter pays principle to quantify the environmental costs caused by large-dam flow regulation

• Autores: S. García de Jalón, Marta González del Tánago Del Río, D. García de Jalón
• Localización: X Congresso Ibérico de Gestão e Planeamento da Água: 20 Anos de continuidade de uma nova cultura da água. Fluxos de água, fluxos de vida / João Luís Mendes Pedroso de Lima (ed. lit.), Francesc La Roca Cervigón (ed. lit.), 2018, ISBN 978-84-944788-5-7, págs. 1-9
• Idioma: inglés
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• Resumen

  • Availability of water for irrigation, hydroelectric production and domestic or industrial supply usually require dams and reservoirs, which severely affect river ecosystems. Although the Water Framework Directive states that activities causing environmental damage are financially responsible, environmental costs associated to river damming are not being properly internalized in the current procedures of water pricing until now.We propose a methodology to evaluate the environmental costs of flow regulation based on the "polluter pays" principle, where the amount to be paid is proportional to the intensity, duration and frequency of the resulting hydrological change. This is a dynamic water pricing approach which is determined by the hydrologic alteration that the river suffers at every time instant (changes in river flow due to flow regulation). The procedure includes three steps: (i) assessing the admissible range of regulated flow variability, (ii) estimating the daily environmental impact of regulated flows, and (iii) calculating the environmental costs of flow regulation. This paper applies the proposed methodology in rivers regulated by large dams from North of Spain (Duero and Ebro Basins) and Central (Tajo Basin) and quantifies environmental costs for the flow regulation caused by 32 different dams. The advantages over other water cost valuation methodologies are discussed. The methodology was used to develop an R package called ‘FlowRegEnvCost: The Environmental Costs of Flow Regulation’ that is available online. The approach enlarges the current recognition of water environmental costs and represents a practical management tool for achieving the objectives of the WFD. It advocates for decreasing environmental impacts of flow regulation and increasing efficiency in water use as allows a clear visualization of the potential impacts and costs of the flow regulation, thus facilitating communication and discussion among environmental actors. Also, it can optimize (balance between sustainability and efficiency) the most appropriate time of the year for water releases from the dam, thus, minimizing the environmental cost and maintaining the profitability of the use. Therefore, this study may achieve sustainable water management functioning as a mechanism of self-control to avoid further degradation when regulating flows.