An integrated model for the assessment of global water resources ? Part 1: Input meteorological forcing and natural hydrological cycle modules

N. Hanasaki (1) , S. Kanae (2) , T. Oki (2) , K. Masuda (3) , K. Motoya (4) , Y. Shen (5) , K. Tanaka (6)

1 NIES - National Institute for Environmental Studies
2 Institute of Industrial Science
3 FRCGC - Frontier Research Center for Global Change
4 Faculty of Education and Human Studies
5 Center for Agricultural Resources Research
6 DPRI - Disaster Prevention Research Institute

An integrated global water resources model was developed consisting of six modules: land surface hydrology, river routing, crop growth, reservoir operation, environmental flow requirement estimation, and anthropogenic water withdrawal. It simulates both natural and anthropogenic water flow globally (excluding Antarctica) on a daily basis at a spatial resolution of 1°×1° (longitude and latitude). The simulation period is 10 years, from 1986 to 1995. This first part of the two-feature report describes the input meteorological forcing and natural hydrological cycle modules of the integrated model, namely the land surface hydrology module and the river routing module. The input meteorological forcing was provided by the second Global Soil Wetness Project (GSWP2), an international land surface modeling project. Several reported shortcomings of the forcing component were improved. The land surface hydrology module was developed based on a bucket type model that simulates energy and water balance on land surfaces. Simulated runoff was compared and validated with observation-based global runoff data sets and observed streamflow records at 32 major river gauging stations around the world. Mean annual runoff agreed well with earlier studies at global, continental, and continental zonal mean scales, indicating the validity of the input meteorological data and land surface hydrology module. In individual basins, the mean bias was less than ±20% in 14 of the 32 river basins and less than ±50% in 24 of the basins. The performance was similar to the best available precedent studies with closure of energy and water. The timing of the peak in streamflow and the shape of monthly hydrographs were well simulated in most of the river basins when large lakes or reservoirs did not affect them. The results indicate that the input meteorological forcing component and the land surface hydrology module provide a framework with which to assess global water resources, with the potential application to investigate the subannual variability in water resources. GSWP2 participants are encouraged to re-run their model using this newly developed meteorological forcing input, which is in identical format to the original GSWP2 forcing input.

Domaines: Interfaces continentales, environnement; Océan, Atmosphère; Sciences de la Terre

N. Hanasaki, S. Kanae, T. Oki, K. Masuda, K. Motoya, et al.. An integrated model for the assessment of global water resources ? Part 1: Input meteorological forcing and natural hydrological cycle modules. Hydrology and Earth System Sciences Discussions, 2007, 4 (5), pp.3535-3582. ⟨hal-00298898⟩