1. China’s Rising Hydropower Demand Challenges Water Sector? Beijing Forestry University 20 October 2015@ Beijing, China Junguo Liu, Dandan Zhao, Gerbens-Leenes P.W., Dabo Guan

2. G-science Academies Statements 2012 According to the G-science Academies Statement for the G8 Summit in 2012,“How to meet human’s water and energy demand”is one of the three largest global challenges

3. According to the “Global Risks 2014” of the World Economic Forum Report, water crisis has been identified as one of the top 10 global risks. Impact on World Economy Global Risks Landscape 2014 Water Crisis Likelihood

4. One third world people already lives in a country with moderate to high water stress By 2030 nearly half the global population could be facing water scarcity Oki and Kanae, 2006. Science; Vörösmarty et al., 2000. Science; Vörösmarty et al., 2010. Nature Global Water Scarcity Assessment

5. China’s Water Scarcity Liu et al., 2013. Global Environmental Change 23: 633-643 Water scarcity is a great challenge in China

6. Water-Food-Energy Nexus: what we have done 1. Food-induced water (and land) footprint in China 2. Biofuel-induced water (and land) footprint in China 3. Biofuel-induced water footprint in US 4. Hydropower-induced water footprint in China 5. Coal-induced water footprint in China

7. Per Capita Water Footprint in China Source: Liu and Savenije, 2008. HESS Animal Products Cereals & Roots Changing food-consumption patterns are the main cause of the worsening water scarcity in China (Liu et al., 2008. Nature)

8. Food losses from field to folk WF of Canada Arable area of Mexico Liu et al., 2013. Environmental Science & Technology

9. Average water and land footprint of biofuel produced with different feedstock crops Yang, Zhou and Liu, 2009. Energy Policy We were the very few scholars that first question the Sustainability of first-generation biofuel development.

10. Results Dominguez-Faus, Folberth, Liu, et al. 2013. Environmental Science & Technology Water footprint of corn-based biofuel in the USA

11. Large-scale hydro-engineering projects China’s Annual Hydropower Electricity Production  The Medium- and Long-term Plan of Renewable Energy Development proposed an installed capacity of hydropower of 300 million kW by 2020, more than double the size in 2007.  China’s 12th five-year plan (2011–2015) sets a goal for non-fossil fuel energy to account for 15% of total energy consumption by 2020, with more than half from hydropower  Hydropower energy in China has increased from 1.2 billion kWh in 1949 to 721 billion kWh in 2010 (600 times!!)  Since 2007, China’s gross installed hydropower capacity and hydropower energy generation have been ranked the highest in the world Liu et al., 2013. Global Environmental Change 23: 633-643

12. Large-scale hydro-engineering projects Environmental and Ecological Concerns of Dams and Hydropower  Reduce sediment flux and change temporal pattern of river discharge to downstream and ultimately the ocean  Affect biodiversity by inundation, flow manipulation, fragmentation of habitat  Impact emission of GHGs  Affect regional water supply and water use (water footprint of hydropower) Liu et al., 2013. Global Environmental Change 23: 633-643 Yangtze finless porpoise

13.  An increasing concern about water sustainability of hydropower leads to the need of an in-depth study on energy-water nexus of hydropower  As of 2013, few researchers had attempted to quantify the water footprint of hydropower production  When a reservoir provides multiple functions (e.g. hydropower, flood control, irrigation and navigation), its WF should be allocated among the different purposes  Most studies have attributed a hydroelectric reservoir’s water consumption entirely to power generation, overestimating the hydroelectric WF  Aim: we analyzed the reservoir WFs in China by determining the volume of freshwater that evaporates from reservoirs and the hydroelectric WF of reservoirs that generate power Background

14. Methodology Reservoir Water Footprint Reservoir WF at river basin and national levels Hydroelectric WF Product WF of hydropower F i, j = 10 × E i, j × A i, j H i,j = F i,j × η i,j η i,j = r i,j / R i,j f i,j = H i,j / G i,j ratio of annual revenue generated from hydroelectric power (r) to total annual revenue (R) generated by hydroelectric reservoirs

15. Results  The Chinese reservoir WF totaled 27.9×10 9 m 3 (Gm 3 ) in 2010, with values ranging from 0.7 Gm 3 for Northwest rivers basin to 8.0 Gm 3 for the Yangtze River basin  The reservoir WF accounted for 22% of the total blue water WF of China; this proportion ranged from 5% for Northwest rivers basin to 57% for Southeast rivers basin.  Neglecting reservoir WF seriously underestimates the blue water WF 875 reservoirs Liu* et al., 2015. Scientific Reports 5: 11446

16. Results When the reservoir WF is not considered, 3 river basins suffered from a moderate to severe annual water scarcity: Haihe (371%), Huaihe (154%),Liaohe (102%). When reservoir WF is considered, 4 river basins suffered from a moderate to severe annual water scarcity: Haihe (378%), Huaihe (182%), Liaohe (127%), Huanghe (104%). Water scarcity is significantly underestimated when the reservoir WF is not considered. Liu* et al., 2015. Scientific Reports 5: 11446

17. Results A moderate to severe water scarcity in six river basins for at least two months per year: Haihe (12 months), Huaihe (10 months), Liaohe (6 months), Yellow river (6 months), Northwest rivers (4 months),Songhuajiang (2 months) basins Monthly assessments can reveal critical seasons when measures should be taken to mitigate or adapt to water scarcity Liu* et al., 2015. Scientific Reports 5: 11446

18. Results China's hydroelectric WF totaled 6.6 Gm 3 yr -1 in 2010. This was about 24% of the reservoir WF Average hydroelectric product water footprint (PWF) of 3.6 m 3 GJ -1 PWF varied from 0.001 for Hongyi plant to 4234 m 3 GJ -1 for Zhanggang plant Hydropower resources are concentrated in western regions, where PWF is low; but energy demand is dominant in eastern regions with a high PWF. 209 hydropower plants Liu* et al., 2015. Scientific Reports 5: 11446

19. Discussion  The PWF of 3.6 m 3 GJ -1 is lower than several reported hydroelectric PWFs  Although many reservoirs are used for multiple purposes, WF was attributed only to hydropower in almost all studies before  Mekonnen and Hoekstra considered only 35 of the world’s 8689 plants, which accounted for 8% of global electricity generation  We are the first to analyze variances based on a large number of reservoirs (i.e. 875) and hydropower plants (i.e. 209) and to demonstrate the spatial distribution of WF of reservoirs and hydropower Liu* et al., 2015. Scientific Reports 5: 11446

20. Discussion  The Chinese national average hydroelectric PWF of 3.6 m 3 GJ -1 (3600 m 3 /10 12 J) is higher than that of most other technologies  PWF of wind energy and underground uranium mining is negligible  Water footprint of electricity from solar energy, coal-fired and nuclear thermal energy is generally far below 1.0 m 3 GJ -1  Hydropower is not an efficient solution to energy supply from a water consumption perspective Liu* et al., 2015. Scientific Reports 5: 11446

21.  Large variation of PWF was mainly determined by reservoir area per unit of installed hydroelectric capacity (  ).  A linear relationship between PWF and   Linear relationship was much stronger for plants with hydropower as their main purpose than those with power as secondary purpose Liu* et al., 2015. Scientific Reports 5: 11446

22. The procedure of determining allocation coefficient: 1. Assess the total economic value of all ecosystem services provided by the reservoir. 2. Calculate ratio of economic value of hydroelectricity to total economic value of all ecosystem services. This ratio is allocation coefficient  Three Gorges Reservoir is a multi-purpose reservoir with main ecosystem services of flood control, hydroelectricity, navigation, water supply, aquaculture, and recreation Zhao and Liu*, 2015. Physics and Chemistry of the Earth 79-82: 40-46

23.  Before 2009, hydroelectricity was main service provided by the reservoir, with η h > 0.6. The next-largest ecosystem service values were from navigation and aquaculture  Before 2009, reservoir provided little flood control, but thereafter, flood control service increased greatly, accounting for nearly half of total benefit  η h decreased gradually to 0.41 in 2012 Zhao and Liu*, 2015. Physics and Chemistry of the Earth 79-82: 40-46

24. Take-home Messages  We provided a spatially explicit assessment of reservoir and hydropower WFs by using 875 representative reservoirs and 209 hydropower plants in China  For multi-purpose reservoirs, it is more logical to “share the burden of water consumption” among the different beneficiaries  Hydropower development pose challenges on water sector; hence, WF should be assessed in any sustainability evaluation for reservoirs  From a water conservation point of view, eastern China should not further expand its capacity in hydropower  More holistic analysis should be further done for water-energy nexus of hydropower

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