Agricultural green and blue water consumption and its influence on the global water system

Abstract

[1] This study quantifies, spatially explicitly and in a consistent modeling framework (Lund-Potsdam-Jena managed Land), the global consumption of both ''blue'' water (withdrawn for irrigation from rivers, lakes and aquifers) and ''green'' water (precipitation) by rainfed and irrigated agriculture and by nonagricultural terrestrial ecosystems. In addition, the individual effects of human-induced land cover change and irrigation were quantified to assess the overall hydrological impact of global agriculture in the past century. The contributions to irrigation of nonrenewable (fossil groundwater) and nonlocal blue water (e.g., from diverted rivers) were derived from the difference between a simulation in which these resources were implicitly considered (IPOT) and a simulation in which they were neglected (ILIM ), whereas irrigation increased evapotranspiration by up to 1.9% and decreased discharge by 0.5% at least (IPOT, 1971(IPOT, -2000. The diverse water fluxes displayed considerable interannual and interdecadal variability due to climatic variations and the progressive increase of the global area under cultivation and irrigation.Citation: Rost, S., D. Gerten, A. Bondeau, W. Luncht, J. Rohwer, and S. Schaphoff (2008), Agricultural green and blue water consumption and its influence on the global water system, Water Resour. Res., 44, W09405,

Potential effects of climate change on inundation patterns in the Amazon Basin

“…We apply the Dynamic Global Vegetation and Hydrology Model LPJmL (Sitch et al, 2003;Gerten et al, 2004;Bondeau et al, 2007;Rost et al, 2008) to understand and to assess the effect of climate change on current Amazonian inundation patterns. LPJmL computes establishment, abundance, vegetation dynamics, growth and productivity of the world's major plant functional types, as well as the associated carbon and water fluxes.…”

“…In the model, the routing velocity is used to calculate the distance that runoff water can move within a time step (see also Rost et al, 2008). We also estimate the extent of potential floodable area and monthly flooded area.…”

“…A disadvantage of these models is that they do not incorporate explicit simulation of vegetation dynamics which are an essential part of the water cycle. We use the dynamic global vegetation and hydrology model LPJmL (Bondeau et al, 2007;Gerten et al, 2004;Rost et al, 2008;Sitch et al, 2003), which has been improved for regional application to the Amazon Basin and includes the dynamic and spatially explicit reproduction of the specific hydrological patterns of the main river stem and its tributaries. These patterns consist of seasonal discharge, time and duration of low/high water periods and the changing extent of the flooded area during those periods.…”

Modeling water requirements of major crops and their responses to climate change in the North China Plain

“…Accordingly, CWR can be partitioned into crop blue water requirements (CBWR) and crop green water requirements (CGWR). Recently, a much large amount of global green water and blue water assessments have been reported with different hydrological models (Rost et al 2008;Hoff et al 2010;Fader et al 2011;Liu et al 2009;Liu and Yang 2010;Zang et al 2012;Zhang et al 2014). In addition, many studies have investigated global change impacts on crop yield and consumptive blue and green water use by establishing different scenarios Zang et al 2013;Chen et al 2014), but the impact of climate factors on CBWR and CGWR remains a rarely studied issue.…”

Modelling Freshwater Resources at the Global Scale: Challenges and Prospects

“…Consumptive irrigation water use in a grid cell is modelled as a function of irrigated area, crops and climate (e.g., Döll and Siebert 2002;Rost et al 2008). Estimation of areas equipped for irrigation and even more estimation of areas actually irrigated are prone to large uncertainties as quality of statistical information is very heterogeneous (comp.…”