April 27, 2017
The Patterns, Causes and Consequences of Changes in Regional and Global Water Cycling
Water cycling is complicated by changing climate and intensifying human activities. While the impacts of climate on water have been extensively examined through the lens of diverse disciplines, the mechanisms of how human activities exert effects on water cycling remain less explored. I have been particularly interested in investigating the impacts of agricultural activities on the regional dry-out in Northern China – one of the regions experiencing the most intensive human activities and severe water shortage in the world. I found that, apart from the effect of global warming and precipitation declines, the intensification of agricultural activities had also aggravated drought conditions. To further examine how water interacts with other components (e.g., land, climate, energy, and socio-economics) of the intertwined Earth-human system, I developed a simple hydrological model that strikes a balance between predictability and computational efficiency, and coupled it with a widely-used integrated assessment model – Global Change Assessment Model. Using the coupled model, I investigated how land use and land cover change (LULCC) trajectories in different shared socioeconomic pathways (SSPs) may affect global water scarcity (i.e., the ratio of water demand to available renewable water supply). I found that the LULCC-induced changes in water scarcity are overall small at the global scale (<2%), but significant (5%-10%) in areas where LULCC is substantial (e.g., deforestation in South America and equatorial Africa). These studies highlight the role of human activities in determining the fate of water.