The Guadalquivir Estuary: A Hot Spot for Environmental and Human Conflicts

Abstract

The Guadalquivir estuary has an important place in history as mainland Europe’s most southern large river-estuary-delta system. Intensification of human pressure combined with a limited understanding of its functioning have resulted in increasing socio-economic and environmental conflicts over the estuary. Within this context, the existing scientific framework could not answer the concerns raised about the consequences of dredging to substantially increase its depth, allowing large ships to serve the port of Seville. A holistic approach to understanding the estuarine ecosystem, including it’s physical and biogeochemical dynamics and how these act to control biodiversity, was identified as the first step towards making knowledge-based decisions about its sustainable use. Intensive use of satellites and remotely operated sensors was critical to this endeavour, allowing a detailed diagnosis to be produced quickly (within 30 months). A real-time monitoring network allowed the critical spatio-temporal scales (intratidal to inter-annual) necessary to provide a baseline understanding of the major processes to be resolved. Discrete sampling of variables, such as nutrients and dissolved inorganic carbon, helped to fill in the gaps and synoptic satellite images allowed the estuaries influence on the inner shelf to be evaluated. The overall diagnosis depicts an estuary in a poor condition. Numerous human interventions have drastically altered the geomorphology, tidal dynamics and freshwater inputs of the system. Physical conditions favour high residence times that interact with the perturbation of upstream sediment supply by dams and local organic matter loading to create poor water quality. The present day conditions are a system where low dissolved O2, high CO2, high suspended solids and a lack of stable benthic-intertidal habitats limits biodiversity, more than is typical of other estuaries. Recovery of the ecosystem-services supplied by the Guadalquivir is a challenge, but entirely possible, given careful balancing of the cultural, social, economic and environmental demands of all stakeholders within a knowledge-based framework. This study demonstrates that the application of robust and cost-efficient technology to estuarine monitoring can quickly generate the scientific foundations necessary to meet these societal and legal demands, and can provide a suitable tool by which the cost-effectiveness of remedial solutions can quickly be evaluated.