Around 6% of the Earth''s land surface is covered by wetlands. Wetlands play a key role in hydrological and biogeochemical cycles, delivering multiple benefits to society: sources of water supply, flood regulation, water purification, agriculture, fisheries, and biodiversity. Hence, wetland systems are of immense socio-economic as well as ecological importance. In this research, the focus was on the Abras de Mantequilla (AdM) wetland in the tropical coastal region of Ecuador, a RAMSAR site and case study area for the EU-FP7 WETwin project.

The research in this thesis involves a combination of field data collection, multivariate analysis techniques, as well as numerical modelling studies. The goal was to explore the effects of changes in hydrological forcing on the hydrodynamic and ecohydraulic responses of the wetland. The study aims to contribute to the understanding of how a tropical river-wetland system functions in terms of hydrodynamics, water quality, primary production, and biotic communities. Spatial patterns of biotic communities and environmental variables are obtained as well as spatio-temporal variability of hydrodynamics, water quality, primary productivity and fish habitat-suitability conditions.

In data scarce areas and countries with financial constraints, the combination of field measurements with numerical models was extremely useful and relevant, confirming that these techniques complement each other in obtaining a better understanding of the dynamics of freshwater river–wetland systems. Studies like the present research can be used to enhance awareness about the environmental services of wetlands and stimulate cooperation between all stakeholders in order to achieve more sustainable wetland management.