Panta Rhei Library

Are you interested in learning about any of the topics highlighted by Panta Rhei? This "Panta Rhei Library" resource promotes collaboration and knowledge sharing between Panta Rhei working groups. Each working group is invited to list up to 6 key papers that summarize the field for someone new to the topic. This includes up to 3 key papers in the field, and up to 3 papers written by group members (including a summary paper written by the group if that exists). Each paper is provided together with a very short explanation of why it is useful and relevant.

Click on the name of any working group below to go to their Panta Rhei Library collection:

Hydrologic Services and Hazards in Multiple Ungauged Basins
Water scarcity assessment: methodology and application
Understanding flood changes
Drought in the Anthropocene

Panta Rhei Library Collections

Hydrologic Services and Hazards in Multiple Ungauged Basins

Key papers in the field:

1. Vörösmarty, C.J., Pahl-Wostl, C., Bunn, S.E. and Lawford, R., 2013. Global water, the anthropocene and the transformation of a science. Current Opinion in Environmental Sustainability, 5(6), pp.539-550.
This paper discusses the transformation of hydrological research towards the global scale, including the merging of biogeophysical and human dimension perspectives. It summarizes research themes that have encouraged a global view of water systems, such as “peak water”, and the “impair then repair” approach to water management. The paper highlights the role of international science consortia, and looks to the future of globally-focused water governance.
2. Wood, E.F., Roundy, J.K., Troy, T.J., Van Beek, L.P.H., Bierkens, M.F., Blyth, E., de Roo, A., Döll, P., Ek, M., Famiglietti, J. and Gochis, D., 2011. Hyperresolution global land surface modeling: Meeting a grand challenge for monitoring Earth's terrestrial water. Water Resources Research, 47(5).
This paper outlines the steps necessary to create a global hydrological model at spatial resolution of 100m – 1km, which is deemed necessary for hydrologic process representation. The paper outlines 6 research challenges towards creating such a model: (1) Representation of surface-subsurface interactions (2) Representation of land-atmospheric interactions (3) Inclusion of water quality (4) Representation of human impacts from water management (5) Using massively parallel computer systems (6) Developing global data sets.

3. Poff, N.L., Richter, B.D., Arthington, A.H., Bunn, S.E., Naiman, R.J., Kendy, E., Acreman, M., Apse, C., Bledsoe, B.P., Freeman, M.C. and Henriksen, J., 2010. The ecological limits of hydrologic alteration (ELOHA): a new framework for developing regional environmental flow standards. Freshwater Biology, 55(1), pp.147-170.
This highly-cited paper describes a new framework for assessing environmental flow needs at large regional scales, across multiple river types and gauged and ungauged catchments - something that had previously only been achieved at local scales. Environmental flows specify the river flow regime characteristics necessary to provide the ecosystem and hydrologic services required of the river. This framework therefore demonstrates a possible method for quantifying hydrologic services across multiple, human-impacted catchments.

Key papers from our group:

1. Archfield, S.A., Clark, M., Arheimer, B., Hay, L.E., McMillan, H., Kiang, J.E., Seibert, J., Hakala, K., Bock, A., Wagener, T. and Farmer, W.H., 2015. Accelerating advances in continental domain hydrologic modeling. Water Resources Research, 51(12), pp.10078-10091.
This paper, written by our working group, discusses how research from the catchment modeling, global water security, and land surface modeling communities is converging towards the aim of continental domain hydrologic modeling. We describe the progress to date by each community, and then consider remaining challenges common to all communities. We review the availability of open data from global or continental databases, and discuss the need for data quality assurance and model performance benchmarks.

2. Blöschl, G., Sivapalan, M., Wagener, T., Viglione, A. and Savenije, H. eds., 2013. Runoff Prediction in Ungauged Basins: Synthesis across Processes, Places and Scales. Cambridge University Press. ISBN: 9781107028180.
This paper, with members of our working group among its editors, synthesises statistical and process-based methods for predicting runoff, low flows and floods in ungauged basins. It draws substantially from research conducted under the Prediction in Ungauged Basins (PUB) initiative, the predecessor to Panta Rhei.

Water scarcity assessment: methodology and application

Key papers in the field:

(1)    Oki T., & Kanae S. 2006. Global Hydrological Cycles and World Water Resources. Science, 313 (5790): 1068-1072.
This highly-cited paper reviewed the global hydrological cycles and water scarcity situations in a changing world. It showed that more than two billion people live in highly water-stressed areas because of the uneven distribution of freshwater resources in time and space. Climate change is expected to accelerate water cycles and thereby increase the available water resources. This would slow down the increase of people living under water stress; however, changes in seasonal patterns and increasing probability of extreme events may offset this effect. Reducing current vulnerability will be the first step to prepare for such anticipated changes.

(2)    Schewe J., Heinke J., Gerten D., Haddeland I., Arnell N.W., Clark D.B., Dankers R., Eisner S., Fekete B.M., Colón-González F.J., Gosling S.N., Kim H., Liu X., Masaki Y., Portmann F.T., Satoh Y., Stacke T., Tang Q., Wada Y., Wisser D., Albrecht T., Frieler K., Piontek F., Warszawski L., & Kabat P. 2014. Multimodel assessment of water scarcity under climate change. Proceedings of the National Academy of Sciences of the United States of America, 111(9): 3245-3250.
This paper uses a large ensemble of global hydrological models (GHMs) forced by five global climate models and the latest greenhouse-gas concentration scenarios (Representative Concentration Pathways) to synthesize the current knowledge about climate change impacts on water resources. It shows that climate change is likely to exacerbate regional and global water scarcity considerably. This study also highlights large uncertainties associated with these estimates, with both global climate models and GHMs contributing to the spread. GHM uncertainty is particularly dominant in many regions affected by declining water resources, suggesting a high potential for improved water resource projections through hydrological model development.

(3)    Vörösmarty C.J., McIntyre P.B., Gessner M.O., Dudgeon D., Prusevich A., Green P., Glidden S., Bunn S.E., Sullivan C.A., Reidy Liermann C., & Davies P.M. 2010. Global threats to human water security and river biodiversity. Nature, 467:555-561.
This paper presents the first worldwide synthesis to jointly consider human and biodiversity perspectives on water security using a spatial framework that quantifies multiple stressors and accounts for downstream impacts. It shows that nearly 80% of the world’s population is exposed to high levels of threat to water security. Massive investment in water technology enables rich nations to offset high stressor levels without remedying their underlying causes, whereas less wealthy nations remain vulnerable. The cumulative threat framework offers a tool for prioritizing policy and management responses to this crisis, and underscores the necessity of limiting threats at their source instead of through costly remediation of symptoms in order to assure global water security for both humans and freshwater biodiversity.

Key papers from our group:

(1)    Zhao X., Liu J., Liu Q., Tillotson M.R., Guan D., & Hubacek K. 2015. Physical and virtual water transfers for regional water stress alleviation in China. Proceedings of the National Academy of Sciences of the United States of America, 112(4): 1031-1035.
This highly-cited article integrates the economic approach, the input-output table, with water use and water resources to explore the roles of physical water flows and virtual water flows in mitigating water scarcity. For the first time, a study compiles a full inventory for physical water transfers at a provincial level and maps virtual water flows between Chinese provinces. The analysis shows that both physical and virtual water flows do not play a major role in mitigating water stress in the water-receiving regions but exacerbate water stress for the water-exporting regions. The authors point out that Improving water use efficiency is key to mitigating water stress, but the efficiency gains will be largely offset by the water demand increase caused by continued economic development. They conclude that much greater attention needs to be paid to water demand management rather than the current focus on supply-oriented management.

(2)    Liu J., Liu Q., & Yang H. 2016. Assessing water scarcity by simultaneously considering environmental flow requirements, water quantity, and water quality. Ecological Indicators, 60: 434-441.
Most previous methods of water scarcity assessment only considered water quantity, and ignored water quality. In addition, the environ-mental flow requirement (EFR) was commonly not explicitly considered in the assessment. In this study, the authors developed an approach to assess water scarcity by considering both water quantity and quality, while at the same time explicitly considering EFR. This new method was called quantity–quality-EFR (QQE) approach. The authors found that to keep the river ecosystem health at a “good” level (i.e., suitable for swimming, fishing, and aquaculture), 26% of the total blue water resources should be allocated to meet the EFR. When such a “good” level is maintained, the quantity- and quality-based water scarcity indicators were 1.3 and 14.2, respectively; both were above the threshold of 1.0. The QQE water scarcity indicator thus can be expressed as 1.3(26%)|14.2, indicating that the basin was suffering from scarcity problems related to both water quantity and water quality for a given rate of EFR.

(3)    Zhao X., Liu J., Yang H., Duarte R., Tillotson M. R., & Hubacek K. 2016. Burden shifting of water quantity and quality stress from megacity Shanghai. Water Resources Research, 52(9): 6916–6927.
This is a featured article in Water Resources Research. It revealed an interesting phenomenon that megacities shift their burden of water quantity and quality stress to less wealthy regions through commodity trade. In this study, the authors investigate how Shanghai, the largest megacity in China, draws water resources from all over China and outsources its pollution through virtual quantity and quality water flows associated with trade. The results show that Shanghai's consumption of goods and services in 2007 led to 11.6 billion m3 of freshwater consumption, 796 thousand tons of COD, and 16.2 thousand tons of NH3-N in discharged wastewater. Of this, 79% of freshwater consumption, 82.9% of COD and 82.5% of NH3-N occurred in other Chinese Provinces which provide goods and services to Shanghai. Thirteen Provinces with severe and extreme water quantity stress accounted for 60% of net virtual water import to Shanghai, while 19 Provinces experiencing water quality stress endured 79% of net COD outsourcing and 75.5% of net NH3-N outsourcing from Shanghai. The authors suggest that megacities should share their responsibility for reducing water quantity and quality stress in its trading partners through taking measures at provincial, industrial, and consumer levels.

Understanding flood changes

One summary paper from our working group

Hall, J. et al., (2014), Understanding flood regime changes in Europe: a state-of-the-art assessment, Hydrology and Earth System Sciences, 18, 2735-2772, doi:10.5194/hess-18-2735-2014.

The paper, written by our working group together with other hydrologists, reviews the current knowledge on flood regime changes in European rivers. Two alternative research approaches are discussed: (1) data-based detection of changes in observed flood events; (2) modelled scenarios of future floods. Challenges and opportunities associated with both methods are discussed as well as future opportunities to be gained by making a synthesis of these two approaches.

Two key papers written by group members

(1) Blöschl, G., L. Gaál, J. Hall, A. Kiss, J. Komma, T. Nester, J. Parajka, R. Perdigão, L. Plavcová, M. Rogger, J.L. Salinas and A. Viglione (2015), Increasing river floods: fiction or reality?, WIREs Water, 2(4), 329-344, doi:10.1002/wat2.1079.
This overview paper examines whether floods have changed in the past and explores the driving processes of such changes in the atmosphere, the catchments and the river system based on examples from Europe. Methods are reviewed for assessing whether floods may increase in the future. It is argued that accounting for feedbacks within the human-water system is important when assessing flood changes over lead times of decades or centuries.

(2) Merz, B., Vorogushyn, S., Uhlemann, S., Delgado, J., Hundecha, Y. (2012), HESS Opinions ' More efforts and scientific rigour are needed to attribute trends in flood time series'. - Hydrology and Earth System Sciences, 16, 5, p. 1379-1387.
This opinion paper suggests that a change in perspective and more scientific rigour is needed in respect to flood trend attribution: detection should be seen as an integral part of the more challenging attribution problem, and detection and attribution should be placed in a sound hypothesis testing framework. The paper proposes a hypothesis testing framework for trend attribution which consists of the following essential ingredients for a sound attribution: evidence of consistency, evidence of inconsistency, and provision of confidence statement.

Three key papers from the field

(1) Vogel, R.M., C. Yaindl, and M. Walter (2011) Nonstationarity: Flood Magnification and Recurrence Reduction Factors in the United States. Journal of the American Water Resources Association (JAWRA) 47(3):464-474. DOI: 10.1111/j.1752-1688.2011.00541.x
This paper explores trends in floods in watersheds which are subject to a very broad range of anthropogenic influences, including changes in land use and water use, and not limited to climate change. Indicators are developed to quantify changes in magnitude and frequency of floods.

(2) Kiem, A. S., S. W. Franks, and G. Kuczera (2003) Multi-decadal variability of flood risk, Geophys. Res. Lett., 30(2), 1035, doi:10.1029/2002GL015992, 2003.
This paper relates the temporal variability of flood frequency and magnitude to the observed modulation of El Niño/Southern Oscillation (ENSO) for New South Wales (NSW), Australia. The paper shows how strongly natural climate variability affects flood risk at the multi-decadal timescale.

(3) Brázdil, R., Z.W. Kundzewicz and G. Benito (2006) Historical hydrology for studying flood risk in Europe, Hydrological Sciences Journal, 51:5, 739-764.
This paper describes what the interdisciplinary field of ‘historical hydrology’ is and what is its potential in providing information for flood hydrology. The paper reviews existing European historical hydrology studies and discusses future research needs.


Key papers from our working group

(1)      Van Loon, A. F., et al. (2016), Drought in a human-modified world: Reframing drought definitions, understanding, and analysis approaches, Hydrology and Earth System Sciences, 20(9), 3631–3650
This paper, written by many members of our working group, proposes a new framework for drought definitions and research in the Anthropocene. It provides an extensive overview of previous studies related to drought in the Anthropocene and gives recommendations for robust drought definitions.  The paper proposes frameworks for analysing drought and identifies research gaps on (1) drivers, (2) modifiers, (3) impacts, (4) feedbacks, and (5) changing the baseline of drought in the Anthropocene.

(2)     Van Dijk, A. I. J. M., Beck, H. E., Crosbie, R. S., Jeu, R. A., Liu, Y. Y., Podger, G. M., and Viney, N. R.: (2013), The Millennium Drought in southeast Australia (2001–2009): Natural and human causes and implications for water resources, ecosystems, economy, and society, Water Resources Research, 49, 1040–1057
This paper presents a real-world case study of complex interactions between natural and human drivers and impacts for the Millennium Drought in southeast Australia.  It analyses the causes and impacts of drought holistically, illustrating the complex nature of multi-year droughts. 

(3)     Blauhut, V., Stahl, K., Stagge, J.H., Tallaksen, L.M., De Stefano, L. and Vogt, J., (2016). Estimating drought risk across Europe from reported drought impacts, hazard indicators and vulnerability factors. Hydrology & Earth System Sciences
This paper introduces a paradigm shift in drought risk analysis. Defining drought by its impacts, this work introduces an approach to analyse drought risk based on the combination of reported drought impacts, drought hazard information and vulnerability factors. Drought risk is mapped for three different hazard severities and fifteen different impact sectors. Furthermore, it introduces a simple approach to test the usability of commonly applied drought indices and vulnerability factors in order to predict drought impacts for a variety of different impact sectors.

Key papers in the field

(1)      Mishra, A., K., Singh, V. P., (2010), A review of drought concepts, Journal of Hydrology, 391(1), 93 – 98
This paper provides a broad overview of drought concepts from both practical and analytical perspectives. After a thorough review of the available drought definitions, this paper provides a review of fundamental concepts of drought, classification of droughts, drought indices, historical droughts using paleoclimatic studies, and the relation between droughts and large-scale climate indices. The paper also highlights the current gaps in the field and offers ideas for future research.

(2)     Lloyd-Hughes, B., (2014), The impracticality of a universal drought definition, Theoretical and Applied Climatology, 117, 607 – 611,
This paper discusses the impracticality of a universal drought definition.  The paper highlights how the influence of human intervention is intrinsic to the definition of drought and shows that a universal description of drought requires reference to water supply, demand and management. 

(3)     Castle, S. L., B. F. Thomas, J. T. Reager, M. Rodell, S. C. Swenson, and J. S. Famiglietti (2014), Groundwater depletion during drought threatens future water security of the Colorado River Basin, Geophysical Research Letters, 41, 5904–5911,
This paper shows the high pressure on groundwater during recent drought years in the Colorado River Basin.  Groundwater declined whereas actively managed surface water in reservoirs remained stable. The paper shows the importance of considering the impact of human activities on different domains of the hydrological cycle and the way they are connected, both for drought research and management.

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