Nature Climate Change: Global drivers of future flood risk

Worldwide economic losses from river flooding could increase 20-fold by the end of the 21st century if no further actions on flood risk reduction are taken. Over 70% of this increase can be attributed to economic growth in flood prone areas

This follows from a recent study by a Dutch consortium that includes our research group.

See the study in Nature Climate Change!

Read more at: http://phys.org/news/2015-12-climate-main-prone-areas.html#jCp

 

A high-resolution global groundwater model

Inge de Graaf , PhD student in our group has published a paper about a global 6-arcminute one-layer groundwater model. The model is made in MODFLOW and is forced with recharge and surface water levels from our global hydrological model. In this publication a steady state global groundwater depth map has been made, but in subsequent work Inge will provide an updated 5-arcminute two-layer version and transient runs, including the effects of groundwater abstractions.

The reference:

De Graaf,  I.E.M., E.H. Sutanudjaja, L.P.H. van Beek, and M.F.P. Bierkens, 2015. high-resolution global-scale groundwater model. Hydrology Earth System Science, 19, 823-837.

The paper was highlighted at the EGU website:

Presentation1

A nice picture of the global groundwater table:

Long-term average groundwater depth (m below surface)

Long-term average groundwater depth (m below surface)

 

 

 

 

 

 

 

 

 

WRI Launches Global Flood Analyzer – based on model runs with PCR-GLOBWB

 

The World Resources Institute has launced the Aqueduct Global Flood Analyzer v1.0. It the first-ever public analysis of current and future river-flood risks worldwide.

The Analyzer estimates current and 2030 values for potential exposed GDP, affected population and urban damage from river floods for every state, country, and major river basin in the world.

The tool is based on a large number of runs with our global hydrological model PCR-GLOBWB  from 1070-2030 using bias-corrected global climate models as inputs. These runs have been downscaled by Deltares and turned into flood risk (people and GDP affected) by IVM-VU University of Amsterdam, Utrecht University and the  under different socio-economic scenarios made by PBL- Netherlands Environmental Assessment Agency.

See the blog post at WRI for more information.

The key findings are:

Key findings:

  • River flooding could affect more people and cause significantly more damage by 2030, as climate change and socio-economic development accelerate.
Floods_Global_Exposure

Increased flood expore by 2013

 

 

 

  • Today, river flooding affects 21 million people worldwide and exposes $96 billion in GDP on average each year. By 2030, those numbers could grow to 54 million people and $521 billion in GDP exposed every year.
Floods_GDP_Percentage

Today’s GDP exposed to river floods

  • Top 11 countries (ranked by affected population) are India, Bangladesh, China, Vietnam, Pakistan, Indonesia, Egypt, Myanmar, Afghanistan, Nigeria and Brazil.
Floods_Top_15

Top 15 countries with greatest percentage of population exposed to river floods

See the publications supporting this research: Winsemius et al (2013) and Ward et al. (2014).

 

Virtual water trade in the Roman world

oman aqueduct of Luynes (Credit: Daniel Jolivet)

oman aqueduct of Luynes (Credit: Daniel Jolivet)

The Roman World used trade of grain (actual virtual water trade) as a means to be more resilient against climate change. At the same time, as population grew as a result of a steady supply of food, it became more dependent on trade and thus more sensitive to political or climatological disturbances of the trade network. These are the main conclusions from a study by

The Roman World used trade of grain (actual virtual water trade) as a means to be more resilient against climate change. At the same time, as population grew as a result of a steady supply of food, it became more dependent on trade and thus more sensitive to political or climatological disturbances of the trade network. These are the main conclusions from a study by Brian Dermody and coworkers from the Netherlands and the US.

The paper appeared in Hydrology and Earth System Sciences:

Dermody, B. J., van Beek, R. P. H., Meeks, E., Klein Goldewijk, K., Scheidel, W., van der Velde, Y., Bierkens, M. F. P., Wassen, M. J., and Dekker, S. C.: A virtual water network of the Roman world, Hydrol. Earth Syst. Sci., 18, 5025-5040, doi:10.5194/hess-18-5025-2014, 2014.

See the press release of EGU!

It got quite some media attention. For instance in Smithsonian Magazine.

30% of global water use is non-sustainable

Using a newly developed index and our group’s global hydrological model PCR-GLOBWB Yoshi Wada and Marc Bierkens assessed the amount of groundwater consumption coming from non-renewable sources as well as the amount of surface water consumption exceeding environmental flow limits. They calculated that this non-sustainable blue water use exceeds 30% of the current water consumption and that this number will rise to 40% towards the end of the 21st century. When combined with virtual water use, the index, called the blue water sustainability index (BlWSI), can also be used to assess which part of individual products is from sustainable water.

Wada, Y.  and M.F.P.  Bierkens, 2014. Sustainability of global water use: past reconstruction and future projections. Environmental Research Letters 9, 104003 (17pp).

 

 

 

Modelling the saltwater intrusion throughout the Holocene

Joost Delsman of Deltares, with contributions from our group, modelled the Holocene development of the fresh-salt groundwater distribution along a coastal transect in the Netherlands.

To be able to understand and assess the current fresh-salt groundwater distribution and groundwater velocities one needs to go back a long time; this because of the large intertia of the system. Accurate predictions of the current  fresh-salt groundwater distribution is essential for meaningful projections of salt water intrusion under scenarios of future sea-level change, climate change and groundwater abstractions.

The reconstructed groundwater heads, chloride concentrations and groundwater origin matches very well with observations.

A movie showing the Holocene development can be found here!

The paper:

J.R. Delsman, K.R.M. Hu-a-ng, P.C. Vos, P.G.B. de Louw, G.H.P. Oude Essink, P.J. Stuyfzand, and M.F.P. Bierkens, 2014.Paleo-modeling of coastal saltwater intrusion during the Holocene: an application to the Netherlands. Hydrology and Earth System Science 18, 3891-3905.

 

Nature Geoscience commentary: Wedge approach to water stress

Yoshihide Wada of the Earth Surface Hydrology group co-authored a commentary in Nature Geoscience, arguing that the wedge approach proposed for evaluating carbon mitigation policies is also suitable to evaluate policies to avoid future water stress.

See the commentary at: Wada, T., T. Gleeson and L. Esnault, 2014. Wedge approach to water stress. Nature Geoscience 7, 615-617.

See also the article in Space Daily!

 

 

 

 

RS soil moisture helps to calibrate large-scale hydrological models

In addition to discharge observations, remotely sensed soil moisture estimates improve the calibration of large-scale hydrological models as shown by Niko Wanders  in a recent publication in Water Resources Research. In this paper a dual state-parameter Ensemble Kalman Filter is used to calibrate the hydrological model LISFLOOD for the Upper Danube. Calibration is done using discharge and remotely sensed soil moisture acquired by AMSR-E, SMOS, and ASCAT.

Wanders, N., M.F.P. Bierkens, S.M. Jong, A. Roo, and D. Karssenberg, 2014. The benefits of using remotely sensed soil moisture in parameter identification of large-scale hydrological models. Water Resources Research 50 (in press).