In what parts of the world and to what degree have groundwater reservoirs been depleted over the past 50 years?
The Frankfurt hydrologist Prof. Petra Döll has been researching this using the global water model WaterGAP. Her conclusion: The rate at which groundwater reservoirs are being depleted is increasing, but that the rate is not as high as previously estimated.
In what parts of the world and to what degree have groundwater reservoirs been depleted over the past 50 years? The Frankfurt hydrologist Prof. Petra Döll has been researching this using the global water model WaterGAP. She has arrived at the most reliable estimate to date by taking into consideration processes which are important in dry regions of the world.
The values calculated were compared with monitoring data from many different wells and data from the GRACE satellites. These satellites measure changes in the Earth's gravity field. Döll has come to the conclusion that the rate at which groundwater reservoirs are being depleted is increasing, but that the rate is not as high as previously estimated.
90 percent of water consumption is due to irrigation for farming purposes. Only the comparatively small remainder is used for potable water and industrial production. As an example, 40 percent of the cereals produced around the world is irrigated. However, in many cases this results in increased scarcity of water resources and puts a burden on ecosystems. In dry regions, the amount taken from groundwater reservoirs can easily exceed the amount being replenished, so that the groundwater reservoir is overused and depleted.
"By comparing the modelled and measured values of groundwater depletion, we were able for the first time to show on a global scale that farmers irrigate more sparingly in regions where groundwater reservoirs are being depleted. They only use about 70 percent of the optimal irrigation amounts", explains Petra Döll from the Institute of Physical Geography at the Goethe University.
The rate at which the Earth's groundwater reservoirs are being depleted is constantly increasing. Annual groundwater depletion during the first decade of this century was twice as high as it was between 1960 and 2000. India, the USA, Iran, Saudi Arabia and China are the countries with the highest rates of groundwater depletion.
About 15 percent of global groundwater consumption is not sustainable, meaning that it comes from non-renewable groundwater resources. On the Arabian Peninsula, in Libya, Egypt, Mali, Mozambique and Mongolia, over 30 percent of groundwater consumption is from non-renewable groundwater.
The new estimate of global groundwater depletion is 113,000 million cubic meters per year for the period from 2000 to 2009, which is lower than previous, widely varying estimates. This can be considered to be the most reliable value to date, since it is based on improved groundwater consumption data which takes the likely deficit irrigation into account, and since the model results correlate well with independent comparative data.
The increased use of groundwater for irrigation also results in a rise in sea levels: According to Döll's calculations, sea level rise due to groundwater depletion was 0.31 millimetres per year during the period from 2000 to 2009. This corresponds to roughly one tenth of the total sea level rise.
The work was funded by the Deutsche Forschungsgemeinschaft through the priority program "Mass transport and Mass distribution in the System Earth".
Publication Döll, P., Müller Schmied, H., Schuh, C., Portmann, F.T., Eicker, A., (2014): Global-scale assessment of groundwater depletion and related groundwater abstractions: Combining hydrological modelling with information from well observations and GRACE satellites. Water Resour. Res. 50, doi: 10.1002/2014WR015595.
Online publication: http://dx.doi.org/10.1002/2014WR015595
Information Prof. Petra Döll, Institute of Physical Geography, Riedberg Campus, Phone: (069)798-40219: email@example.com.
The Goethe University is an institution with particularly strong research capabilities based in the European financial metropolis of Frankfurt. It celebrates its 100th year of existence in 2014. The university was founded in 1914 through private means from liberally-orientated citizens of Frankfurt and has devoted itself to fulfilling its motto "Science for the Society" in its research and teaching activity right up to the present day. Many of the founding donors were of Jewish origin. During the last 100 years, the pioneering services offered by the Goethe University have impacted the fields of social, societal and economic sciences, chemistry, quantum physics, neurological research and labour law. On January 1st, 2008, it achieved an exceptional degree of independence as it returned to its historical roots as a privately funded university. Today it is one of the ten universities that are most successful in obtaining external research funding and one of the three largest universities in Germany with centres of excellence in medicine, life sciences and humanities.
Publisher: The president of the Goethe University Frankfurt am Main. Editorial department: Dr. Anne Hardy, Public Relations Officer for Scientific Communication. Abteilung Marketing und Kommunikation, Grüneburgplatz 1, 60629 Frankfurt am Main, Phone: (069) 798-12498.
Dr. Anke Sauter | idw - Informationsdienst Wissenschaft
Devils Hole: Ancient Traces of Climate History
24.05.2017 | Universität Innsbruck
Supercomputing helps researchers understand Earth's interior
23.05.2017 | University of Illinois College of Liberal Arts & Sciences
Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.
The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....
An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.
We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...
Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.
Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...
An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...
In the race to produce a quantum computer, a number of projects are seeking a way to create quantum bits -- or qubits -- that are stable, meaning they are not much affected by changes in their environment. This normally needs highly nonlinear non-dissipative elements capable of functioning at very low temperatures.
In pursuit of this goal, researchers at EPFL's Laboratory of Photonics and Quantum Measurements LPQM (STI/SB), have investigated a nonlinear graphene-based...
24.05.2017 | Event News
23.05.2017 | Event News
22.05.2017 | Event News
24.05.2017 | Physics and Astronomy
24.05.2017 | Physics and Astronomy
24.05.2017 | Event News