Impacts of land cover changes on extreme hydrological events

For tens of millennia, humans have been modifying natural ecosystems primarily to grow food, for wood and wood fuel. Currently, ~40% of the ice-free area is covered by crops and pasture, and in the coming years, globally and especially in Colombia, substantial increases in deforestation rates are projected. These land-cover changes (LCC) have a recognized effect on climate, both in terms of changes in greenhouse gas (GHG) emissions such as CO2, CH4, N2O (biochemical effects), and through variations in the energy balance to the surface mediated by albedo, evapotranspiration or roughness (biophysical effects). While the increase of GHG concentration in the atmosphere affects the climate in the long term and on a global scale, biophysical effects cause short-term changes in seasonal and/or annual temperatures, the carbon cycle or the hydrological cycle with a predominant effect at local and regional level.

However, (i) the effects of CCS on climate and its large-scale feedbacks are not consensual, (ii) the regional impacts of CCS need urgent research, particularly in countries that are prone to deforestation and internationally committed to conservation, biodiversity and climate change mitigation (e.g. Colombia), and (iii) the way in which climate extremes (major events and socio-economic impacts) modulate eco-physiological processes and how the latter (feedbacks) act on the water cycle is still poorly understood. This first study with the help of this Starter Fund aims to provide new elements, methods and expertise for the University, as well as to lay the concrete foundations for the Climate-Ecosystem Interactions (CEI) Research Group within the Earth System Science Programme.

The assistant will have regular (bi-weekly) supervision by the supervisor. The final product will be a handwritten document that fulfills the requirements of a master's thesis while having the structure of a scientific article. Since the professor-supervisor already has the data available, made the methodology and published a similar study on the impact of LULCCs on average rainfall (Quesada et al., GRL 2017), Objective #1 should not take long to obtain results with extreme precipitation rates (Month #1 -> #3). Objective #2 will be done in collaboration with the JRC and since the methodology is tested and published, it would be a matter of adapting correlations with hydrological products and discussing interpretations at global and regional levels (Month #4 -> #7.5). Given the hot topics and the strong impact of such studies, a publication in an international journal (Q2 or Q1) will be foreseen later on according to the student's projects. In the framework of this study (Objective #2), international collaborations are foreseen with Dr.Ramdane Alkama and Dr.Grégory Duveiller (confirmations obtained on 26/07/18, collaborators of the professor-supervisor in the European project LUC4C 2013-2017 and experts in the observational methodology of land cover change impacts - see Alkama and Cescatti, Science 2016 and Duveiller et al., Nature Communications 2018). Preliminary results will be presented to these collaborators after Month #5 via Skype to discuss progress, limitations and opportunities.