Global assessment of current water resources using total runoff integrating pathways

Abstract

The anticipated water scarcity in the first half of this century is one of the international issues of most concern, which needs to be adequately addressed. However, even though the issue has an international impact and worldwide monitoring is critical, there are limited global estimates at present. In this study, annual water availability has been derived from annual runoff estimated by land surface models using total runoff integrating pathways (TRIP) with 0.5° by 0.5° longitude/latitude resolution globally. The global distribution of abstraction was estimated for each sector at the same spatial resolution based on country-based statistics of municipal water use, industrial water use, and agricultural intakes, using a global geographical information system with global distribution of population and irrigated crop land area. The total population under water stress estimated for 1995 corresponded very well with earlier estimates. However, the number is highly dependent on how one assumes the volume of water from upstream of a region, which can be considered as "available" water resources within the region. Therefore it is important, even for global scale analysis, to evaluate the regional water quality deterioration and the real consumption of water resources in the upper part of the stream, as well as the accessibility of water. Further studies should be promoted by an integrated approach to improve the accuracy of future projections on both the natural and social aspects of water resources.

Water availability in +2°C and +4°C worlds

“…However, MacPDM is used in this investigation owing to its relative simplicity and therefore amenability for running large ensembles. The spatial resolution used in this study is also not as fine as those used by others [5][6][7][8][9][10][11] but does compare well with recently published work [27][28][29]. Despite infrastructure and flow routing not being included in the model, the compromise in the spatial resolution should not hinder our analysis of impacts on a larger, more synoptic scale.…”

Resistance and Resilience of A Stream Salamander To Supraseasonal Drought

“…Global estimates of the number of people living in areas with water stress differ significantly between studies (Vörösmarty et al, 2000;Alcamo et al, 2003aAlcamo et al, , b, 2007Oki et al, 2003;Arnell, 2004). Nevertheless, climate change is only one of many factors that influence future water stress; demographic, socio-economic and technological changes possibly play more important roles at most time horizons and in most regions.…”

“…Such water-stressed basins are located in northern Africa, the Mediterranean region, the Middle East, the Near East, southern Asia, northern China, Australia, the USA, Mexico, north-eastern Brazil and the west coast of South America (Figure 1.1). The estimates for the population living in such water-stressed basins range between 1.4 billion and 2.1 billion (Vörösmarty et al, 2000;Alcamo et al, 2003a, b;Oki et al, 2003;Arnell, 2004). [WGII 3.2] Water use, in particular that for irrigation, generally increases with temperature and decreases with precipitation; however, there is no evidence for a climate-related long-term trend of water use in the past.…”

Enhanced fixed-size parallel speedup with the Muskingum method using a trans-boundary approach and a large subbasins approximation

“…River gauges are of essence to terrestrial hydrology despite their declining availability [The Ad Hoc Group et al, 2001], and the expected Surface Water and Ocean Topography (SWOT) mission [Alsdorf et al, 2007a[Alsdorf et al, , 2007bDurand et al, 2010] promises to further enhance the study of the global terrestrial water cycle. While the combination of in situ and remotely sensed observations will remain key to research in water resources, continental-to-global scale river network models [e.g., Miller et al, 1994;Olivera et al, 2000;Oki et al, 2001;Lohmann et al, 2004;Yamazaki et al, 2011Yamazaki et al, , 2012 will still be required to interpolate between space-time acquisitions of observations, to better understand process interactions, to support water management decisions, for climate simulations, and for prediction. However, the development of river transport models having the ability to simulate the past, present, and future states of surface water bodies at continental-to-global scales is progressing slowly compared to the advances in the oceanic and atmospheric sciences [Arrigo, 2011;Famiglietti et al, 2011].…”