Estimating flow requirements of freshwater ecosystems in China with the global hydrology and water use model WaterGAP
Background
Freshwater scarcity has been recognized as a global issue of utmost importance. There is a growing awareness that increased water use by humans does not only reduce the amount of water available for future industrial and agricultural development but also has a profound effect on aquatic ecosystems and their dependent species. Balancing the needs of the aquatic environment and other uses is becoming critical in many of the world’s river basins as population and associated water demands increase.
Chinais characterized by an uneven distribution of water resources and a rapid economic development. In many regions, water scarcity is already severe. Increasing water consumption by the domestic, industrial and agricultural sectors, and a number of human activities such as deforestation, agricultural land expansion, wetland reclamation, construction of reservoirs, and water diversion significantly affect hydro-geomorphic processes and hence result in a series of environmental water problems such as increasingly frequent freshwater shortage, declining groundwater tables, dangerous levels of pollution, serious habitat degradation and disastrous flooding over the past decades in many areas throughout China.
On account of the already stressed situation of many freshwater ecosystems and the rapid socio-economic development inChina, it is necessary to introduce freshwater ecosystem requirements into water management in all Chinese water basins. However, only a few scattered assessments of environmental flows exist for a few river basins and cities. These assessments are not sufficient as a scientific basis for the allocation of water for environmental purposes throughoutChina.
Goal
The research goal is to develop a model-based, macro-scale assessment of flow requirements of freshwater ecosystems inChinausing an existing macro-scale hydrological model which covers all ofChina. In addition, new water stress indicators that include ecosystem water requirements will be quantified such that an improved characterization of water scarcity inChinawill be achieved.
Methodology
The global water modelWaterGAP(Döll et al. 2003; Alcamo et al. 2003) is employed in this research in order to simulate natural river discharges and environmental water requirements in all Chinese basins. It simulates the terrestrial part of the global water cycle, including river discharge and human water consumption. It consists of two main parts, theGlobal Hydrology Model WGHMand theGlobal Water Use Model.
The definition ofenvironmental flow requirementsin this research will be based on two methods. The simple method ofSmakhtin et al. 2004 relies on computed estimates of natural river discharge and has already been applied at the global scale, using WaterGAP. The more complexRange of Variability Approach (Richter et al. 1997)incorporatesthe concepts of hydrological variability and river ecosystem integrity.
Keywords:Freshwater ecosystem, environmental water requirements, natural flow, global hydrology, water use, hydrological variability
Participants:Jing Zhang, Petra Döll
Cooperating institutions:Bernhard Lehner, Wang Liming and Li Lifeng (World Wildlife Fund) and Li Peicheng (Environmental Science University of Montreal, Canada and Technology Institute of Chang’an University, China)
Duration: until July 2009
Funding entity: Hessian State Ministry for Science and Arts, Federal Ministry of Education and Research stipend program IPSWAT
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