World Water Resources: Assessment and Prediction

Terrestrial vegetation and water balance—hydrological evaluation of a dynamic global vegetation model

“…The terrestrial area is defined as the common denominator of the model-specific land masks from LPJ, WBM, WaterGAP, and Macro-PDM (,131 £ 10 6 km 2 ). The data of Baumgartner and Reichel (1975), Shiklomanov (1997) both are based on an area sized ,135 £ 10 6 km 2 . The time period is 1961-1990 for the model results, and varies among basins and regions for Baumgartner and Reichel (1975), Shiklomanov (1997), and Cogley (1998) .…”

“…Simulated runoff was compared with (i) global and zonal estimates from various sources (Baumgartner and Reichel, 1975;Shiklomanov, 1997;Cogley, 1998), (ii) long-term observed mean annual runoff from 663 basins with an area . 10 4 km 2 and an observation period .…”

Demand modulation of water scarcity sensitivities to secular climatic variation: theoretical insights from a computational maquette

“…RWD is a proxy for average water-related stress on both ecosystems and socioeconomic systems. In this wellestablished framework (e.g., Vörösmarty et al, 2000;Falkenmark and Lindh, 1976;Raskin et al, 1997;Shiklomanov, 1997;Alcamo et al, 2003;Rijsberman, 2006;Falkenmark, 1997;Oki and Kanae, 2006;Shen et al, 2014), values between 0.2 and 0.4 indicate medium to high stress, corresponding to conditions under which water stress can begin to be a limiting factor on economic development insofar as management costs start to be large in relation to the national economy; and RWD > 0.4 represents severe water limitation, indicating the onset of heavy competition between water users. Note that this critical value of RWD is less than unity, i.e., when many water uses and broader scarcity implications are taken into account, severe water stress can occur well before absolute demand exceeds absolute supply.…”

Observing the solid Earth, oceans and land waters from space

“…In many regions, data collection is restricted due to economic reasons, or the diffusion of collected data is restricted, being considered as sensitive national information. For example, more than 20% of the freshwater discharge into the Arctic Ocean is ungauged and surface water across much of Africa and portions of the Arctic is either not measured or has experienced the loss of over two thirds of the gauges [40]. Therefore, our ability to measure, monitor, and forecast global supplies of fresh water using in situ measurements is almost impossible because of the decline in the numbers of gauges worldwide and the complexity of the physics of water flow across vast lowlands.…”