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China-BWS Map - WRI's New China Map

BWS-China: WRI’s New Water Stress Map

The World Resources Institute (WRI)’s Aqueduct Baseline Water Stress (“BWS-Global”) indicator, a central component of Aqueduct’s Water Risk Atlas, provides an overview of the total demand for surface water across sectors and the available annual renewable surface water supply in a given place.

BWS-Global has attracted a large group of users including companies and investors, researchers, NGOs, consultants, international organizations, and governments.

BWS-Global uses water withdrawal data at country level

Mapping the entire globe, BWS-Global uses water withdrawal data at country level, as reported to the Food and Agriculture Organization of the United Nations (FAO), which are then spatially disaggregated across use sectors by catchment area.

While more detailed water withdrawal or demand data (e.g. higher spatial resolution, more temporally frequent) data are available in some countries, they are often not universally available or use different units of analysis or inconsistent methodologies.

But in China, data is available at the prefecture level for a total of 345 administrative subdivisions …

For example, in the US, water withdrawal data is available at county level, while in China, they are available at the prefecture level for a total of 345 administrative subdivisions nationally. Some spatial patterns can be lost when an aggregated number is used at the country level, especially when the regions within a country have distinct water withdrawal characteristics due to their economic and social development differences.

To reduce or avoid the loss of spatial pattern information which is important for estimating water risk accurately, it is important to use more detailed data for a country-specific purpose when they are available. WRI did just this with BWS-China.

BWS-China: WRI’s next level of water mapping in China

In an effort to respond to this need, WRI has developed BWS-China, a mapping tool that provides spatial analyses on baseline water stress in China.

The main distinction is that BWS-Global uses FAO AQUASTAT country-aggregated data, while BWS-China uses more spatially detailed data from govt sources

Developed based on the BWS-Global with some modifications, BWS-China and the BWS-Global have both similarities and distinctions. The primary similarity is that both BWS-China and BWS-Global use the same method for calculating water supply, or “total available blue water,” or, the total annual renewable surface water supply available at that point (for details see here).

The primary distinction is that BWS-Global uses FAO AQUASTAT country-aggregated water withdrawal data and spatially disaggregates it to sub-national level; while BWS-China uses more spatially detailed water withdrawal data from official government sources.

To construct BWS-China, two measures of water withdrawals (water withdrawal and consumptive use) are required:

  • Water withdrawal: is the total amount of water abstracted from freshwater sources for human use. Water withdrawals data by sector (domestic, industrial, and agricultural) in China were derived from the Chinese Water Resources Bulletin (WRB) published by each Chinese province. In China, the Water Resources Department in each province is responsible for collecting water resources data within that province and publishing the WRB every year on the department’s website. Water withdrawal data are collected from surveys reported by source and representative sampling, and compiled for each prefecture as a whole. In total, there are 369 prefectures in China, excluding Hong Kong, Macau, and Taiwan. As a contrast, the BWS-Global used sectoral water withdrawal data at the country level.
  • Consumptive use: is the portion of water evaporating or being incorporated into a product, and no longer available for downstream use. Consumptive use is derived from total withdrawals based on ratios of consumptive use to withdrawals developed by Shiklomanov and Rodda.1

Calculating water withdrawal

Following the same analytical methodology in BWS-Global, water withdrawals for the year 2010 were spatially disaggregated by sector based on spatial datasets. All spatial datasets had a resolution of 1 square kilometre.

  • Agricultural water withdrawals were disaggregated using irrigated areas data
  • Industrial water withdrawals using factory gross output
  • Domestic water withdrawals using population density data (click on image to enlarge)

 Water Withdrawal Intensity By Type 2010

The BWS Map also calculates Total withdrawal, which is the total amount of water removed from fresh water sources for human use. The total withdrawal is the sum of agricultural, industrial and domestic water withdrawals (so the three maps above) at total catchment level. . Figures 1, 2, 3 displays total catchment level water withdrawal intensity by agricultural, industrial, domestic sector, respectively. The map below displays total water withdrawal intensity (all sectors) at the catchment level.

Total withdrawal is the total amount of water removed from fresh water sources for human use

Total Water Withdrawal Intensity (all sectors) 2010

Calculating water consumptive use

Consumptive use is the proportion of all water withdrawn that is consumed through evaporation, incorporation into a product, or pollution, and therefore no longer available for reuse. Consumptive use by sector is estimated from total withdrawal using consumptive use ratios by Shiklomanov and Rodda.1  The map below displays consumptive use intensity at the catchment level.

Consumptive use is the proportion of all water withdrawn that is consumed and therefore no longer available for reuse

Consumptive Use Intensity 2010

Calculating China’s Freshwater Baseline Water Stress

Baseline Water Stress (BWS) is the annual water withdrawals (domestic, industrial, and agricultural) divided by the mean of available blue water (surface). So, before can calculate China’s new BWS we need to calculate its available blue water.

Available blue water (Ba) is the total amount of water available to a catchment before any uses are satisfied. It is calculated as all runoff water from upstream catchments minus upstream consumptive use plus runoff in the catchment. Ba is calculated as  where R is runoff, Qout is the volume of water exiting a catchment to its downstream neighbour: Qout(i) = max(0, Ba(i)-Uc(i)), Uc(i) are the consumptive uses. Negative values of Qout are set to zero.2

China’s available blue water intensity at the catchment level is displayed in the map below.

Available blue water is the total amount of water available to a catchment before any uses are satisfied

Available Blue Water Intensity 2010

Now to move onto BWS. It is a chronic measurement of the level of competition and depletion of available water, and is a good proxy for measuring water risks more broadly.3

BWS is a chronic measurement of the level of competition & depletion of available water

A higher value = more competition for water & depletion of water resources

A higher value indicates more competition for water among users and depletion of water resources. These ratio values were then grouped into Baseline Water Stress classifications based on the methodology used in BWS-Global: low (<10%), low to medium (10 – 20%), medium to high (20 – 40%), high (40 – 80%), and extremely high (>80%).

In BWS-China, BWS was calculated for the year 2010 as the total water withdrawals from year 2010 divided by mean available blue water. A long time series of runoff data from 1950 to 2010 was used to reduce the effect of multi-year climate cycles and the complexities of short term water storage (e.g., dams, floodplains).4

Being consistent with the BWS-Global classification, areas with available blue water and water withdrawal less than 0.03 and 0.012 m/m2 respectively were classified as “arid and low water use.”2 The map below displays BWS at the catchment level. The white patches located within grey areas (i.e. arid and low water use) are lakes and ponds which are not delineated as a catchment in the GDBD dataset.

Freshwater Baseline Water Stress China 2010

Data accuracy & important caveats about available blue water in BWS calculations

As we have previously described, many data used in BWS-China were from surveys (e.g. CIED) and public records (e.g. WRB) published by the Chinese government. To the best of our knowledge, these scientific and official government datasets provide the best spatial and water withdrawal data available at high resolution for China nationally. We are unable to independently verify or validate each dataset and we assume they are trustworthy and accurate.
 
It is important to underscore that water supply data in BWS-China includes only surface water but likely does not include human activities (e.g. inter-basin water transfers) that may augment or remove naturally available water to other catchments. Further, BWS-China does not include groundwater, though in many places groundwater may be an important source of water supply. Therefore, BWS-China does not reflect the complete water supply that may be available for human use in a given catchment, and thus, some catchments may have lower BWS in reality than presently indicated by BWS-China. Major inter-basin water transfers and available groundwater resources will be taken into consideration in the next version of BWS-China.

 

Comparing results: BWS-Global vs. BWS-China

As noted in the box above, a major difference between the BWS-Global and BWS-China is the industrial water withdrawals disaggregation methodology: BWS-Global used night-time lights, while BWS-China used industrial factory locations and their gross output.

BWS-Global used night-time lights … while BWS-China used industrial factory locations & gross output

BWS-China and BWS-Global are compared side by side below (click on image to enlarge).

Compared with nighttime lights, industry factory locations provide more detailed and accurate information on the likely location of industrial water withdrawals. For example, although nighttime lights are used as a proxy for industrial water use, the dataset also captures streets and roads with lights where industrial water withdrawals do not occur.

Overall results show BWS-Global and BWS-China share similar spatial patterns, and, as expected, both show that the relatively arid northern region of China experiences more stress than China’s wetter southern regions.

BWS-China & BWS-Global comparison 2010

However, a closer look at the catchment level reveals differences. For example, BWS-China shows less stress than BWS-Global in the downstream areas of the Yellow River.  This reflects BWS-Global’s overestimation of water withdrawals, particularly the industrial sector.

BWS-China shows less stress than BWS-Global in downstream areas of the Yellow River

And higher stress in the river mouth areas of the Yangtze River

BWS-China shows higher stress than BWS-Global in the river mouth areas of the Yangtze River. In this case, BWS-Global significantly underestimated domestic withdrawal.  These differences are attributed to the more detailed water withdrawal data and higher resolution used to develop BWS-China.

We will compare the BWS-Global map and BWS-China map in more detail in a future publication.

For the first time more detailed, country-specific data having been substituted into the BWS-Global indicator. BWS-China provides a useful model for other stakeholders wishing to develop BWS assessments using locally relevant datasets in their countries. Users are encouraged to: use BWS-Global for a global understanding of water stress and comparison across countries and larger regions; and use BWS-China for more detailed, geographically specific information on water stress in China.

BWS-China is useful for investors, companies, govt agencies & more

Investors, companies, government agencies and others whose interest is mainly focused within China can use BWS-China to evaluate investment opportunities and/or dig deeper into understanding potential water risks and begin to address these challenges.

For the full paper, click here.


1 I.A. Shiklomanov and J. C. Rodda, eds. 2004. World Water Resources at the Beginning of the Twenty-First Century, International Hydrology Series, Cambridge University Press.
2 Gassert, F., M. Landis, M. Luck, P. Reig, and T. Shiao. 2013. “Aqueduct Global Maps 2.0.” Working Paper. Washington, DC: World Resources Institute. Available online at http://www.wri.org/sites/default/files/pdf/aqueduct_metadata_global.pdf
3 The CEO Water Mandate. 2014. “Driving Harmonization of Water Stress, Scarcity, and Risk Terminology.” Discussion Paper. Available online at http://ceowatermandate.org/files/Driving_Harmonization_of_Water_Terminology_draft.pdf
4 Gassert, F., M. Luck, M. Landis, P. Reig, and T. Shiao. 2015. “Aqueduct Global Maps 2.1: Constructing Decision-Relevant Global Water Risk Indicators.” Working Paper. Washington, DC: World Resources Institute. Available online at http://www.wri.org/sites/default/files/Aqueduct_Global_Maps_2.1-Constructing_Decicion-Relevant_Global_Water_Risk_Indicators_final_0.pdf

WRI Disclaimer: The boundaries, colours, and other information shown on these maps do not imply on the part of the WRI any judgment on the legal status of any territory or the endorsement or acceptance of such boundaries.


Further Reading

Water flows & stresses + pollution:

  • Can We Build A Clean & Smart Future On Toxic Rare Earths? - Almost all smart, green & clean tech need rare earths to work, but mining & processing these are highly polluting. Lead author Liu of China Water Risk’s new report:  “Rare Earths: Shades Of Grey” explores this paradox. It is time to rethink our clean & smart future
  • Rare Earth Black Market: An Open Dirty Secret – The black market exacerbates environmental pollution from rare earth mining in China. With low prices, depleted reserves and contaminated drinking water, find out if your smartphone, tablet or electric car is party to this. Hongqiao Liu expands
  • Wind & Sun: Relief For China’s Dry North – China’s North is parched but is home to a significant amount of coal reserves & arable land. Can wind & solar power help bring relief? CWR’s Thieriot on how but be warned, challenges remain
  • E-Waste: Downside to the Tech Revolution – China is one of the largest producers of e-waste globally. Faced with mountains of toxic e-waste, Green Initiatives launched the [WE] Project in Shanghai. Co-founder, Nitin Dani on this easy, safe & scalable way to recycle phones, home appliances & more
  • Quantifying Water Risk: What’s My Number? – Industries are exposed to water risks but financial valuation of such risks remain elusive. China Water Risk’s Thieriot reviews existing quantification tools & methods and highlights gaps that need to be filled to put a number on water risks
  • Water Stewardship: Actions Must Match Risk – Despite acknowledgement of water risks, 58% of companies in CDP’s 2014 Global Water report do not have a public commitment to water. We expand on actions needed in China & globally to match the risk
  • Water Permits: How to Get Water in China – How are water total water quotas set? How can you access water in China? China Water Risk gives an overview on these and the risks associated when China’s water permit system is reformed
  • China’s Hidden Water Flows – Prof Hubacek & Dr. Feng contributing authors of ”Virtual Scarce Water in China” share key findings. Find out why developed but water-scarce regions like Beijing, Tianjin and Shanghai are contributing to the country’s water depletion

Aqueduct Water Risk Mapping

  • Mapping Water with Aqueduct - With a water supply crisis as a top five risks facing the world, WRI’s Tien Shiao walks us through how Aqueduct can help companies and investors gain perspective
  • Aqueduct Global Water Stress Rankings - Aqueduct’s first-ever water stressed rankings of 100 river basins & 181 nations found that 37 countries face national & economic security threats from exposure to extremely high baseline water stress levels
  • Conflicting Reporting Hinders Water Risk Strategies – World Resource Institute’s Tien Shiao & Paul Reig discuss how inconsistent definitions of water stress & scarcity, and risk mean that not only do companies end up with inadequate mitigation strategies, but investors too are unable to form comparable benchmarks
  • Shale Gas & Water: A Tale of 3 Countries - Governments & energy companies are grappling with balancing large shale gas reserves & limited water resources. Can countries unlock these reserves? WRI’s Maddocks & Reig share three shale tales from China, Argentina & the UK
Dr. Jiao Wang

About Dr. Jiao Wang

Dr. Jiao Wang is a Research Associate with WRI’s China Water Team, where she works with the Global Aqueduct Team and external partners to establish in-house hydrological modeling capacity and develop China water atlas by applying the WRI Aqueduct Global Water Risks Framework. Jiao previously worked as a junior researcher at University of Hawaii at Manoa. She has more than 10 years’ experience in environmental modeling using remote sensing and Geographic Information Systems (GIS) techniques. She has worked on various projects including evapotranspiration estimation, domestic water use distribution, precipitation down-scaling, land cover and land use change, as well as vegetation phenology monitoring. Jiao holds a PhD in Geographic Information Science from Texas State University, USA. Her PhD work focused on scaling effects of remotely sensed evapotranspiration. She has a MS in GIS from Chinese Academy of Sciences and a BS from Northwest University, China. Jiao lives in Beijing. She is an avid hiker. Her other passions include pottery, karate, and volunteering with local NGOs.

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Dr. Lijin Zhong

About Dr. Lijin Zhong

Dr. Lijin Zhong as Senior Associate leading the water team in WRI’s China office. Prior to coming to WRI, Dr. Lijin Zhong served as the Deputy Director of the Tsinghua University Water Policy Research Center in the Department of Environmental Science and Engineering. She has nine years of experiences in the fields of environmental engineering, environmental planning and management, environmental impact assessment, and environmental policy and institutional reform. During that time she focused on the water sector and provided environmental policy consulting services to various Chinese ministries including the Ministries of Construction and Environmental Protection, the National Development and Reform Commission, and international organizations such as the World Bank and the Asian Development Bank. With this expertise and experience, she is intimately familiar with China’s water policies and institutional systems. Dr. Lijin Zhong has B.S. and M.S. degrees in environmental engineering from Tsinghua University and a Ph.D. in environmental policy from Wageningen University in the Netherlands.

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Dr. Ying Long

About Dr. Ying Long

Ying Long, Ph.D., an associate professor in School of Architecture, Tsinghua University, China, is an inter-disciplinary scholar with a global vision and substantive planning experiences in China. His research focuses on urban planning, quantitative urban studies, and applied urban modeling. Familiar with planning practices in China and versed in the international literature, Dr. Long’s academic studies creatively integrates international methods and experiences with local planning practices. Dr. Long is also the founder of Beijing City Lab (BCL), an open research network for quantitative urban studies.

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