A natural experiment reveals the impact of hydroelectric dams on the estuaries of tropical rivers

Abstract

We tested how sediment trapping by hydroelectric dams affects tropical estuaries by comparing two dammed and two undammed rivers on Mexico’s Pacific coast. We found that dams demonstrably affected the stability and productivity of the estuaries. The two rivers dammed for hydroelectricity had a rapid coastal recession (between 7.9 and 21.5 ha year−1) in what should otherwise be an accretional coastline. The economic consequences of this dam-induced coastal erosion include loss of habitat for fisheries, loss of coastal protection, release of carbon sequestered in coastal sediments, loss of biodiversity, and the decline of estuarine livelihoods. We estimate that the cost of the environmental damages a dam can cause in the lower part of basin almost doubles the purported benefits of emission reductions from hydroelectric generation.

Frequency of occurrence of flow regime components: a hydrology-based approach for environmental flow assessments and water allocation for the environment

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The dynamics of farmer migration and resettlement in the Dhidhessa River Basin, Ethiopia

“…Climate change, population growth and deforestation have significantly affected water resources management and the development of the country (Tena et al 2015). Studies in Ethiopia, Mexico's Pacific coasts and elsewhere in the world have shown that large-scale dam and irrigation projects usually cause serious environmental and social consequences (Tilt et al 2009, Eguavoen and Tesfai 2012, Ezcurra et al 2019. Though such water resource development schemes are intended to bring economic and social benefits, their construction and operation are usually followed by flooding, degradation, environmental change, loss of land and economic instability to the communities living, for example, around the Arjo-Dhidhessa large-scale dam in the Dhidhessa River Basin (DRB) (Tena et al 2015).…”

Remote Sensing for the Quantification of Land Surface Dynamics in Large River Delta Regions—A Review

“…Another recent study by Ezcurra et al [148] performed shoreline mapping based on the full Landsat archive to test how sediment trapping by hydroelectric dams affects the stability of the coastlines of estuaries on the Mexican Pacific coast. They found that the estuaries of the two rivers that were dammed for hydroelectricity experienced rapid coastal recessions of between 7.9 and 21.5 ha per year, in what should be an accreting coastline.…”