Carbon fluxes in a mediterranean reservoir under a scenario of changing hydrology

Abstract

Inland waters have been related to human development from ancient times supporting us with a wide range of ecosystem services. Recently, it has been highlighted the key role that these systems play in the global carbon cycle becoming a key element in weather regulation and climate change mitigation policies. Within inland waters, reservoirs have been reported as one of the most active compartments in the global carbon cycle. The number of reservoirs is in expansion due to population growth, linked to an increase in water and energy demand. Besides that, climate change and direct anthropogenic pressures (irrigation, water diversion, aquifer overexploitation, land use changes, etc.) trigger alterations in hydrology and thermal structure which could modify carbon fluxes in aquatic ecosystems. Furthermore, the last report of IPCC (AR6) points out the Mediterranean region as one of the most affected by these pressures. Although there has been an important improvement in the scientific knowledge about carbon fluxes in reservoirs, there is still a lack of information due to its high spatial and temporal variability and this is especially conspicuous for Mediterranean ecosystems. Therefore, more research is necessary to understand the effects of hydrological and thermal structure changes on carbon fluxes in Mediterranean reservoirs in order to be able to improve predictions and anticipate and reduce climate changes effects. This thesis tackles the effect of hydrological and thermal structure changes in carbon fluxes in a Mediterranean reservoir (El Gergal, Seville) measuring both CO₂ and CH₄ fluxes from water surface, CO₂ fluxes from drawdown areas and the accumulation of CO₂ and CH₄ in the hypolimnion.