Integrated approach for estimating the alteration in the CO 2 sink capacity of an inland waterbody due to climate change - Case study: Wadi El-Rayan Lakes, Egypt

Abstract An essential regulatory ecosystem function of inland Lakes is their ability to dissolve atmospheric carbon dioxide (CO2), therefore, they serve as CO2 sinks. Wadi El-Rayan Lakes are two lakes (Upper and Lower) in Fayoum, Egypt at different levels in respect to mean sea level (MSL) and are connected through a waterfall. Their CO2 sink capacity depends on their water temperature and salinity as well as their water volume which are all highly sensitive to climate conditions. Consequently, any slight change in climate conditions would affect their CO2 sink capacities. This paper aims to quantitatively estimate the change in the CO2 sink capacity of Wadi El-Rayan Lakes under climate change scenarios. For the purpose, an integrated approach is developed assimilating CO2 solubility model, hydrodynamic simulation and geographical information systems (GIS). According to the developed approach, CO2 solubility under variable temperature and salinity is mathematically modelled and this model is further used with hydrodynamically simulated data for Wadi El-Rayan Lakes' temperature, salinity and water depth to estimate their CO2 sink capacities. CO2 sink capacity is estimated for 2014 and 2050 under two Representative Concentration Pathways (RCPs) 2.6 and 8.5. Afterwards, the alteration in CO2 sink capacities due to climate change is determined. The results revealed that by 2050, the lakes would lose about 23–25% of their capacities compared to that of 2014 according to RCP 2.6 and 8.5, respectively.