Space observations of hydrological change in semi-arid regions – TERRA

Hydrological models are amongst the best tools for understanding the past and future development of water resources. However, the modeling of the hydrological response of a system to environmental changes is still a scientific challenge. Particularly interesting but difficult to model aspects are: i) the possible feedbacks between hydrological changes and environmental changes and ii ) the complex response of an integrated water system ( surface and underground ) to several environmental changes. Remote sensing observations could provide important support to the modeling of surface water and groundwater in arid and semi-arid , but have rarely been used in this context, and especially when it comes to modeling of hydrological changes . In this research program , I will try to develop this methodology using a wide range of satellite and airborne instruments at various spatial and temporal scales for calibration and validation of model hydro (geo) logical for simulation the impact of environmental changes.

Three main types of hydrological changes were identified in semi-arid areas: the overexploitation of groundwater, the intensive use of surface water, and the impact of changing land use. Three major hydrological and hydrogeological basins were selected as study sites, each representing a major hydrological changes: the aquifer system in the plain of Marrakech, Iullemmeden basin and the basin of Senegal. The aquifer of the plain of Marrakech is one of the two main projects of this Chair of Excellence. The continuing decline of the water, large and widespread evidence of overexploitation of agricultural development in the region, no doubt much higher than indicated by the estimates currently available. In the Senegal River valley, I will help UMR G UAE mount a new unifying project to study the impact of large dams on wetlands and groundwater reserves that support the river. In parallel, but with less human and financial investment, I will continue to work in the basin Iullemmeden to quantify the hydrological impact of deforestation. Commonalities of these three areas are a part of owning water changing due to human pressures, and others from lack of field data to predict the future development of these resources and their responses to various management strategies. The study of these three semi-arid regions is therefore a coherent whole that will allow us to better understand the various mechanisms of hydrological changes and the complex interactions between humans, the environment and the water cycle.

NA

The scientific results of the research undertaken in this project will be widely disseminated to the international scientific community through publications in journals of high impact factors (eg Water Resources Research, Journal of Geophysical Research, Nature Climate Change, Journal of Hydrology, Global and Planetary Change) and presentations at international conferences (European Geophysical Union). If necessary, we also intend to communicate our results through radio and television interviews and articles in newspapers / magazines for the general public.
I will attend conferences as part of IAHS and IAH. I will also take this opportunity to provide specialized scientific sessions and workshops on the theme of our research program. It is with great interest that I am already for several years two scientific committees within the International Hydrological Programme (IHP) amino UNESCO GRAPHIC and G-WADI. The results of our research program will fit perfectly with the mission of these two international committees. Thanks to these working groups, we share our experience with colleagues facing similar scientific issues in other parts of the world. We will also use this platform to promote our findings to government agencies responsible for the management of water resources.

The current pace of global changes affecting the environment is unprecedented. The fate of water resources in arid and semi-arid regions is of particular concern. In addition to a natural scarcity and a high variability of water resources, these regions now face one of the highest rates of environmental change, and an explosion in demand to supply a growing population and agricultural sector. So far, most studies published in scientific literature on this subject are limited in their spatial and temporal coverage and often focus on a single compartment of the water cycle. Thus, the spatial and temporal dynamics of hydrological changes in arid regions remain largely unknown. Similarly, the mechanisms that control the joint response of surface water and groundwater to multiple stressors remain poorly understood. Much of the problem stems from the lack of in-situ data, particularly at large scale and on the long-term - a phenomenon that commonly encountered in semi-arid regions.

The aim of my research program within the G-EAU UMR is to gain a better understanding of the recent history of water in arid and semi-arid regions in order to predict the future evolution of these scarce resources and to adapt management policies. New observations from remote sensing will be analysed to overcome the lack of field data which represents a scientific bottleneck in these areas. These space observations will be assimilated into hydrological and hydrogeological models to quantify the evolution of resources in response to global environmental changes. The final phase of work will be the integration of our research results in more general models taking into account socio-economic dynamics. Results from this project will inform policy makers and managers of the hydrological and socio economic impacts of various management strategies.

This application to a Chair of Excellence is part of a permanent return to France. This Chair will enable me to be employed by the Institute of Development Research (IRD) to work on these scientific questions within the UMR G EAU, based in Montpellier.