Land Use and Land Cover Changes and Their Impacts on Hydroclimate, Ecosystems and Society

This chapter presents recent advances in the understanding of the effect of land cover/land use changes on the hydrologic cycle, and identifies current gaps in the knowledge needed for useful decision-making and water resource management. Research achievements within a framework of Earth System Models (ESM) are introduced, and research needs and future challenges are identified. Land surface provides the lower boundary condition to the atmosphere over continents by controlling the fluxes of momentum, heat, water, and materials such as carbon. In turn, land surface conditions are substantially influenced by atmospheric conditions on various temporal scales. As such, a land-atmosphere coupled system is established through biogeochemical feedbacks. Current land surface models exhibit a wide variety of responses to the same forcings, suggesting the need for increased research at the land-atmosphere interface. Indeed, all Earth System Models require the inclusion and validation of the processes that pertain to the biogeochemical feedbacks. Anthropogenic activities that result in land use and land cover changes affect the land surface characteristics and consequently the land-atmosphere feedbacks and coupling strength. Therefore, human activities play a role in the land-atmosphere coupling system, and thus, in the climate system. Water is essential to societal needs that require the construction of reservoirs, extraction of ground water, irrigation, changes in land use, urbanization among many other influences. The extent and sustainability of those interferences in the natural system remains to be assessed at global scales.