Completed Research

Project No.C-02
Project NameGlobal Water Cycle Variation and the Current World Water Resources Issues and Their Perspectives


○Research Subject and Objectives

Research Objectives and Topics

 It is alleged that the 21st century is the "century of water." Wars over water might happen like over oil that occurred in the last century. The rapid increase in population and the coming global climate change could be cause of water scarcity. This project attempts to develop global perspectives of such water resource issues by integrating field observations, predicting natural water cycles and human's water usage in the future, and by establishing guidelines for

sustainability development from the viewpoint of water resource issues.

 The population increase, expected mainly in developing countries, increases water demand, resulting in more intense use of water resources in the world. For Japan or European countries, water resources issues will also be serious; for example, decreased water resources due to global climatic change, inappropriate water management and deteriorated water quality. Therefore, water issues are currently considered to be one of the most critical problems in

the world.

 Although much information about water issues is now available, it seems there is no academic conclusion of the information. And it is also a problem that only a little information is dispatched by Asian countries including Japan;most information is actually dispatched by the U.S. and European countries.

 This project aims at clarifying the true nature of world water issues mentioned above and showing perspectives of the current situation of global water cycles and resources, and making projections of future global water resources and stress". Also it aims "to pursue an integrated approach between social and natural sciences to deal with some specific water issues considered as a part of world water crisis.

○Progress and Results in 2018

Progress of the Project

 Regarding the primary goal, we have succeeded in positing our research as cutting-edge in the world with the finest estimation and projection of global water cycles and resources. As a result, Dr. Taikan Oki, the former leader and a currently core member, was chosen as a lead author of the IPCC AR4 and the Millennium Assessment. Also our paper in Science has promoted effectively the achievement of this project (Oki and Kanae 2006).

 We, hereafter, describe the details. First, regarding the global water circulation, we successfully reproduced the daily fluctuation of land hydrological cycles through the past 100 years for the first time in the world (Hirabayashi et al., 2005). Second, we made a projection of land hydrological cycles for the next 100 years. Third, current and future water demands were estimated. In making projections, we mostly apply the grid scale of 1 degree or 0.5 degree as horizontal resolution at a global scale. Then we calculate the current and future water stress in a global scale through an integration of all the estimations above (Oki and Kanae, 2006).

 As a result, the following three points are shown: (i) over 2 billion people are under physically high water stress; (ii) the number of people under the stress will increase in the future. What is more important, however, is that we can control the rate of increase; and (iii) as long as water stress, the current or the near future in the next several decades is more critical than the distant fixture.

 Conventional water resources assessment did not include the trade in virtual water, i.e. the amount of water that is embedded in food or other products needed for its production. We successfully estimated the amount of virtual water trade of the world for the previous several decades. Here, two main findings are addressed (Oki and Kanae, 2004): (i) the amount of virtual water trade accounts for no less than 10% of the total direct water intake; and (ii) Japan imports the largest amount of the virtual water in the world. The implication of findings is so influential in Japan that it has taken a sort of leading role through several mass media and trade books in the enlightenment about global water problem in its public sphere. Perhaps, the projection of virtual water would be expected. At this moment, however, we skip the projection to avoid an infeasible projection.

 And moreover, we conducted specific case studies on Asia and California. Particularly it should be noted that the latter case provides us a fruitful outcome, which tend to be overlooked in global scale analysis. California is one of the water-deficient areas that we estimate "the hot spot". We paid attention to water management policy in California to look for a countermeasure for global water crisis. Among others, we put focus on a system of water transaction named "water bank" that had been introduced in 1991 to cope with severe drought, with special reference to the legal framework, effectiveness, and problems. As a result, we concluded that "soft-path" solution such as law and institution as well as "hard-path" solution such as dam can be effective tools against water deficit problem.

○Project Members

KANAE, Shinjiro ( RIHN )

ARAIVIAKI, Toshiya ( Research Center for Advanced Science and Technology, The Univ. of Tokyo,Demand analysis and modelization of urban water )

ENDO, Takahiro ( RIHN,A policy analysis of water resource management in California )

HIRAKAWA, Yukiko ( (Graduate School for International Development and Cooperation, Hiroshima University,International political governance with respect to water )

HIRABAYASHI, Yukiko ( (Faculty of Engineering, Yamanashi University,The impact of global warming on hydro logical cycles )

KAWASHIMA, Hiroyuki ( Graduate School of Agricultural and Life Sciences, The Univ. of Tokyo,Agricultural water demand model considering an international grain price )

KIM, Wonsik ( National Institute for Agro-Environmental Science,Observation of water cycles in Asia )

KITSUREGAWA, Masaru ( Institute of Industrial Science, The Univ. of Tokyo,Development of global environ mental water information library )

KURAJI, Kooichiro ( Graduate School of Agricultural and Life Sciences, The Univ. of Tokyo,Water management in forest are and local community )

MATSUMOTO, Jun ( Graduate School of Science, The Univ. of Tokyo,Seasonal change of Asian monsoon and the relation with society )

MATSUMOTO, Mitsuo ( Faculty of Humanities and Economics, Kochi University,Water laws in Asia )

OKI, Taikan ( Institute of Industrial Science, The Univ. of Tokyo,Global water cycles and virtual water trade )

OHTE, Nobuhito ( (Graduate School of Agriculture, Kyoto Univ,Observation and modelization of water cycle process in forest area )

SATOMURA, Takehiko ( Graduate School of Science, Kyoto Univ.,Modelization of water cycle in mesoscale )

SHIBAZAKI, Ryosuke ( Center for Spatial Information Science, The Univ. of Tokyo,Land use change model considering water and provision demand )

SHIRAKAWA, Naoki ( College of Engineering System, Tsukuba University,Demand analysis and modelization of environmental water )

YASUOKA, Yoshifiuni ( Institute of Industrial Science, The Univ. of Tokyo,Remote sensing for hydrology and vegetation )

Hansa VATHANANUKIJ ( Kasetsart University,Analysis on water problems in Southeast Asia )

Thada SLTKHAPUNNAPHAN ( Royal Irrigation Department, Thailand,Flood management in Southeast Asia )

Yang DAWEN ( Tsinghua University,Analysis on water resources problems in China )

○Future Themes

 Relation with Research Program

 The "Conceptual Framework for Global Environmental Issues" is a relatively new axis which was changed from "Integration" in this institute. Since this project has been attempting to develop a new concept and new information related to global water issues, this change is very relevant for us. Quantification of "virtual water", one of the main outcomes of this project, needs to be investigated more in deep from the viewpoint of its concept. It will be a next subject in near future, and probably will be a good topic among the projects in the program.


【Original Articles】

M.S.Islam,T.Oki,S.Kanae,N.Hanasaki,Y.Agata,and K.Yoshimura 2007 A grid-based assessment of global water scarcity including virtual water trading. Water Resources Management 21:19-33.

Qiuhong T.,T.Oki,S.Kanae 2006 A distributed biosphere hydrological model (DBHM) for large river basin. Annual Journal of Hydraulic Engineering 50(7).

Yamada,T.,S.Kanae and T.Oki 2006 Seasonality of land surface influence on the variation of precipitation. Annual Journal of Hydraulic Engineerin 50:541-546. in Japanese

Hanasaki,N.,S.Kanae and T.Oki 2006 Development of global integrated water resource model based on Bucket-type land surface process model. Annual.Journal of Hydraulic Engineering 50:529-534. in Japanese

Komatsu H,.Y Kang,T. Kume,N.Yoshifuji and N.Hotta. 2006 Transpiration from a Cryptomeria japonica plantation,part1:aerodynamic control of transpiration. Hydrol. Process. 20:1309-1320.

Oki,T.,S.Kanae 2006 Global hydrological cycles and world water resources. Science 313:1068-1072.

Hanasaki,N.,S.Kanae,T.Oki 2006 A reservoir operation scheme for global river routing models. Journal of Hydrology 327(221).

Yoshimura,K.,S.Miyazaki,S.Kanae,T.Oki 2006 Iso-MATSIRO,a land surface model that incorporates stable water isotopes. Global Planetary Change 51:90-107.

Kanae,S.,Y Hirabayashi,T.Yamada and T.Oki 2006 Influence of"realistic"land-surface wetness on predictability of seasonal precipitation in boreal summer. J Climate 19:1450-1460.

P.A.Dirmeyer,X.Gao,M.Zhao,Z.Guo,T.Oki,and N.Hanasaki 2006 The Second global soil wetness project(GSWP-2):Multi-model analysis and implications for our perception of the land surface. Bull. Amer. Meteor. 87:1381-1397.

Murata,F.,M.D.Yamanaka,H.Hashiguchi,S.Mori,M.Kudsy,T.Sribimawati,B.Suhardi,and Emrizal 2006 Dry intrusions following eastward-propagating synoptic-scale cloud systems over Sumatera Island. J. Meteor. Soc.Japan 84:277-294.

Kodama Y.-M.,M.Tokuda,and F.Murata 2006 Convective activity over the Indonesian maritime continent during CPEA-I as evaluated by lightning activity and Q 1 and Q2 profiles. J. Meteor. Soc. Japan 84a:133-149.

Shibagaki Y,T.Kozu,T.Shimomai,S.Mori,F.Murata,Y Fujiyoshi,H.Hashiguchi,and S.Fukao 2006 Evolution of a super cloud cluster and the associated wind fields observed over the Indonesian maritime continent during the first CPEA campaign. J. Meteor Soc. Japan 84a:19-31.

Areki,R.,M.D.Yamanaka,F.Murata,H.Hashiguchi,Y.Oku,T.Sribimawati,M.Kudsy,and F.Renggono 2006 Seasonal and interannual variations of diurnal cycles of wind and cloud activity observed at Serpong, West Jawa,Indonesia. J. Meteor. Soc. Japan 84a:171-194.

Komatsu H.,Y Kang,T.Kume,N.Yoshifuji and N.Hotta 2006 Transpiration from a Cryptomeria japonica plantation,part2:responses of canopy conductance to meteorological factors. Hydrol. Process. 20:1321-1334.

Hirabayashi,Y.,S.Kanae,I.Struthers and T.Oki 2005 A 100-year(1901-2000)global retrospective estimation of the terrestrial water cycle. J. Geophys. Res. 110(D19). DOI:10.1029/2004JD005492

Kiguchi,Masashi,Matsumoto,Jun 2005 The rainfall phenomena during the pre-monsoon period over the Indochina Peninsula in the GAME-IOP year. J.Meteor.Soc.Japan 83:89-106.

Komatsu,H 2005 Forest categorization according to dry-canopy evaporation rates in a growing season:Comparison of the Priestley-Taylor coefficient values from various observation sites. Hydrological Processes 19:3873-3896.

Komatsu,H.,Kumagai,T.,Hotta,N. 2005 Is surface conductance theoretically independent of reference height?. Hydrological Processes 19(1):339-347.

Yang,D.,G.Ni,S.Kanae,C.Li and T.Kusuda 2005 Water resources variability from the past to future in the Yellow River,China. IAHS Publication 295:174-182.

Ichiyanagi,K.,K.Yoshimura and M.D.Yamanaka 2005 Validation of changing water origins over Indochina during the withdrawal of the Asian monsoon using stable isotopes. SOLA 1:113-116.

Kim,W.,S.Kanae,Y.Agata and T.Oki 2005 Simulation of potential impacts of land use/cover changes on surface water fluxes in the Chaophraya river basin, Thailand. J. Geophys. Res. 110(D8). DOI:10.1029/2004JD004825

Komatsu,H.,Hotta,N.,Kuraji,K.,Suzuki,M.and Oki,T. 2005 Classification of vertical wind speed profiles observed above a sloping forest at nighttime using the bulk Richardson number. Boundary-Layer Meteorology 115(2):205-221.

Oki,Taikan,Kanae,Shinjiro 2004 Virtual water trade and world water resources. Water Science & Technology 49(7):203-209.

Komatsu,H. 2004 A general method of parameterizing the big-leaf model to predict the dry-canopy evaporation rate of individual coniferous forest stands. Hydrological Processes 18(16):3019-3036.

Koster,R.D.,Dirmeyer,P.A.,Guo,Z.,Bonan,G.,Chan,E.,Cox,P.,Gordon,C.T.,Kanae,S.,Kowalczyk,E.,Lawrence,D.,Liu,P.,Lu,C.H.,Malyshev,S.,McAvaney,B.,Mitchell,K.,Mocko,D.,Oki,T.,Oleson,K.,Pitman,A.,Sud,Y.C.,Taylor,C.M.,Verseghy,D.,Vasic,R.,Xue,Y.,Yamada,T. 2004 Regions of strong coupling between soil moisture and precipitation. Science 305:1138-1140.

Yoshimura,Kei,Oki,Taikan,Ohte,Nobuhito,Kanae,Shinjiro 2004 Colored moisture analysis estimates of variations in 1998 Asian monsoon water sources. J Meteor.Soc.Japan 82:1315-1329.

Research Presentations

【Invited Lecture / Honorary Lecture / Panelist】

Lei, H., Yang, D., Sun, R, Kanae, S., Miyazaki, S. and Shen, Y Field experiment and analysis of the energy-water balances for the winter wheat in Weishan Irrigation District along the downstream of the Yellow River. Proceedings of the International Symposium on Sustainable Water Resources Management and Oasis-Hydroshperie-Desert Interaction in Arid Regions., , .

Shen,Y,C.Tang,J.Xiao,T.OKI and S.Kanae Effects of Urbanization on water resource development and its problems in Shijiazhuang, China. Proceedings of a symposium held during the Seventh IAHS Scientific Assembly IAHS Publ. 293: 280-288., , .