Development of human impact modeling in global hydrology

Abstract:

During the late 1980s and early 1990s, awareness of the shortage of global water resources lead to the first detailed global water resources assessments comparing water availability with water use. These first efforts mostly relied on statistics of water use and observations of meteorological and hydrological variables. Shortly thereafter, the first macroscale hydrological models (MHM) appeared. In these models, blue water (i.e., surface water and renewable groundwater) availability was calculated by proxy by accumulating runoff over a stream network and comparing it with population densities or with estimated water demand. In this talk we review the evolution of human impact modelling in global hydrology, e.g.: confronting yearly water demand with water availability using a water scarcity index; calculating a water scarcity index at monthly time scale; adding groundwater depletion; adding dams and reservoirs; fully integrating water use (abstraction, application, consumption, return flow) in the hydrology; simulating the effects of land use change. A number of challenges are identified that hamper the further development of current water use modelling as well as prohibit realistic modelling of future water use. We also speculate on pathways to overcome these challenges.