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Assessing Water Scarcity with Explicit Incorporation of Green Water and Environmental Flow Requirement

English title Assessing Water Scarcity with Explicit Incorporation of Green Water and Environmental Flow Requirement
Applicant Yang Hong
Number 188686
Funding scheme Project funding (Div. I-III)
Research institution EAWAG Systems Analysis, Integrated Ass. & modeling
Institution of higher education Swiss Federal Institute of Aquatic Science and Technology - EAWAG
Main discipline Other disciplines of Environmental Sciences
Start/End 01.04.2020 - 31.03.2021
Approved amount 83'654.00
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All Disciplines (2)

Other disciplines of Environmental Sciences
Hydrology, Limnology, Glaciology

Keywords (6)

water scarcity; green water; EFR; climate change; water and food security; virtual water trade

Lay Summary (German)

Wasserknappheit ist zu einem großen Hindernis für die sozioökonomische Entwicklung und zu einer Bedrohung der Lebensgrundlage der Menschen in immer grösseren Teilen der Welt geworden. Eine Reihe von Indikatoren wurde entwickelt, um den regionalen und globalen Status der Wasserknappheit zu bewerten. Es bleibt jedoch eine wissenschaftliche Herausforderung, die Bodenfeuchtigkeit (grünes Wasser) und die Anforderungen an den Umweltfluss(EFR) angemessen in die Bewertung einzubeziehen
Lay summary

Ziele des Forschungsprojekts zu Beginn der Forschung

In diesem Projekt werden Möglichkeiten untersucht, wie grünes Wasser und EFR [SN1] angemessen in den Wasserknappheitsindikator einbezogen werden können. Anhand des entwickelten Indikators wird eine Bewertung der Wasserknappheit. Die konkreten Aufgaben umfassen: 1) Erstellung eines physikalisch robusten Indikators für Wasserknappheit unter Einbeziehung von Grünwasser [SN2] und EFR-Komponenten; 2) Bewertung der Wasserknappheit und ihrer Entwicklung in den letzten vier Jahrzehnten; 3) Bereitstellung einer integrierten globalen Bewertung der Wasserknappheit im Kontext zukünftiger Klima- und Wasserressourcen- / Nachfrageänderungen unter verschiedenen Szenarien; 4) Prognose möglicher Auswirkungen künftiger Veränderungen und Wasserknappheit auf die Lebensmittelproduktion und den internationalen Handel sowie Ermittlung von Regionen mit hohem Risiko für Wasser- und Ernährungsunsicherheit. Es werden Maßnahmen zur Risikominderung vorgeschlagen und Trade-offs diskutiert.

Wissenschaftlicher und gesellschaftlicher Kontext des Forschungspro-jekts

Das Verständnis der Wasserknappheit ist wichtig für die Formulierung von Strategien auf globaler, regionaler, nationaler und lokaler Ebene. „Die Zahl der Menschen, die unter Wasserknappheit leiden, erheblich reduzieren“ ist eines der von den Vereinten Nationen verabschiedeten Ziele für nachhaltige Entwicklung (SDGs). Die Ergebnisse des Projekts werden dazu beitragen, die Entwicklung in der Vergangenheit und die künftige Entwicklung der Wasserknappheit zu verstehen und Maßnahmen zur Minderung der Risiken im Kontext globaler Veränderungen zu unterstützen.

Direct link to Lay Summary Last update: 14.02.2020

Responsible applicant and co-applicants


Name Institute


Water scarcity has become a major constraint to socio-economic development and a threat to livelihood of people in increasing parts of the world. As the largest user of water, agricultural production has been facing unprecedented challenges. Compounding the situation is the future climate change that adds large uncertainties in water availability and demand in time and space. Addressing water scarcity has been set as a primary task in many international programs and initiatives, including the Sustainable Development Goals (SDGs) adopted by the United Nations (UN, 2015). Since the late 1980s, water scarcity assessment has drawn much attention in scientific communities. A number of indicators have been developed to assess water scarcity. Population, water availability and water use are the key elements of these indicators. Most of the progress made in the past decades has been on refining the quantification of water availability and use by applying spatially explicit models. Despite the recognition of importance of green water (soil moisture) for agricultural production, most of the indicators developed so far have ignored it. There is a lack of appropriate approaches to incorporate green water, partly due to its different existence status compared to blue water: the former is in storage and the latter is in flow. Ignoring green water underestimates water availability and use, misleading the assessment results in many places. In addition, water scarcity assessment so far has not explicitly taken into account the environmental flow requirement (EFR) across rivers/regions in the world. Few considered EFR have merely used a pre-fixed percentage for all rivers. The two shortcomings specified here have greatly affected the robustness of the existing indicators in representing the real status of water scarcity across the regions of the world. Furthermore, existing water scarcity assessments have generally been conducted in a static way. No study has addressed historical evolvement as well as future development of water scarcity associated with global changes.With the clear need to improve the water scarcity assessment, the aim of this project is to explore ways to appropriately incorporate green water and EFR in its indicator. In view of the dynamic nature of water scarcity, the assessment will be conducted for the past decades and projected to the future. The concrete tasks include: 1) Building a physically robust water scarcity indicator with incorporation of green water and EFR components; 2) Assessing the existing water availability and water use data from the multi-model simulations and using an ensemble data to assess historical changes in water scarcity with explicit incorporation of green water (from the 1970s to current); 3) Determining EFRs for different river regimes considering ecological status of the systems; 4) Providing integrated global water scarcity assessment incorporating green water and EFR for the present and projecting to the future in the context of climate and water resources/demand changes and associated uncertainties (up to 2050). The whole project is designed for 4 years. A PhD student has been carrying out the work since the late 2017 with the funding secured for 2 years. This project proposal is for applying for the funding to fill in the budget gap during the period Oct. 2019 - Sept. 2021. The conduction of the project has been in consultation and collaboration with experts in the relevant disciplines from Eawag and the network built by the applicant over the years, particularly through the ISI-MIP project ( At the time this proposal is submitted, Task 1) has been more or less completed and Task 2) is ongoing. A journal paper will be submitted based on the results of the first two tasks in late 2019. The SNF funding applied in this proposal is primarily for fulfilling Tasks 3) and 4). The output of the project will provide a robust way for water scarify assessment and will be useful for supporting water resources (scarcity) management.