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Have you ever wondered if groundwater is connected to climate?

Have you ever wondered if groundwater is connected to climate?

Post by Tom Gleeson Assistant Professor in Civil Engineering at the University of Victoria.


‘Groundwater-surface water interactions’ has become standard hydrologic lexicon and a perennial favorite session title at various conferences… but how often do you hear the phrase ‘groundwater-climate interactions’?

A group of hydrologists, hydrogeologists, atmospheric scientists and geodesists that met in Taiwan this week would say ‘not enough!’ We met to discuss how groundwater, the slow-moving grandparent of the hydrologic cycle interacts with the atmosphere, the fast-moving toddler. The 2nd international workshop on Impacts of Groundwater in Earth system Models (IGEM), was a follow-up of a 2016 workshop in Paris in 2016 (and part of a the bilateral French-Taiwanese IGEM project).

Sessions were focused around a few themes:

  • Groundwater use and its impacts
  • Groundwater representation, assimilation and evaluation in climate models
  • Remote Sensing and in-situ observations on groundwater
  • Groundwater-climate interactions with a special focus on Nebraska

 

And in the afternoons we convened discussion groups focused on ‘groundwater representation in continental to global hydrologic models’ and ‘groundwater-climate interactions’ and arguably just as importantly we ate lots of great food including an awesome fusion dinner and dumplings at the famous Din Tai Fung.

I would love to say that we could provide you with a simple, robust answer to the leading question of how and where groundwater is connected to climate – a holy grail of Earth System science. But like all good questions, the answer at least right now is ‘a little bit in some places, and it depends how you look at it’. We discussed the first enticing but preliminary results of potential hotspots of groundwater-climate interactions, expounded on the importance to water sustainability and dissected vadose zone parameterizations in land surface models but the quest for this holy grail goes on… We plan to meet again in a few years in Saskatchewan and maybe have a few more answers. Do you want to join us on this holy grail quest, and maybe end up making ‘groundwater-climate interactions’ more standard lexicon?

P.S. Thanks to Min-Hui Lo and his group at National Taiwan University for the excellent hospitality and organization!

P.S.S. Just in case it goes viral, the term ‘baddest-ass model’ was first used by Jay Famiglietti (see below).

Celestial groundwater – the subsurface plumbing for extraterrestrial life support

Celestial groundwater – the subsurface plumbing for extraterrestrial life support

Post by Kevin Befus Assistant Professor in Civil and Architectural Engineering at the University of Wyoming.


Have you ever taken a walk on the beach during a lowering (ebbing) tide and see mini-rivers grow and create beautiful drainage patterns before your eyes? These short-lived groundwater seepage features (Fig. 1A) are tiny (and fast) analogs of how groundwater has shaped some parts of Mars! It appears that groundwater loosening sediments can lead to all sorts of scales of erosion on both Earth and Mars.

Figure 1. A) Beach drainage pattern on the order of 1 meter (Source: https://epod.usra.edu/blog/2017/01/beach-drainage.html), B) Martian “alcoves” suggesting groundwater seepage [1].

Mars is not currently a friendly place for water to exist at the surface or even the subsurface, but an abundance of photographic and topographic evidence point to there having been the right conditions for active groundwater flow on Mars.

But isn’t Mars too cold for liquid water? The answer is generally a strong yes for the past few billion years, but amazingly enough, there appears to have been some local places where groundwater discharged to the Martian surface and left behind telltale signs.

Because Mars is cold at its land surface (mean surface temperature of -50 C with daily swings from 0 C to -100 C) with a thinner atmosphere than Earth’s, water on the Martian surface can exist as ice (as in the polar ice cap), but sublimation and evaporation would quickly wick any water near the surface. So, liquid water on Mars needs both more pressure and a good bit of heat for mobile groundwater based on the phase diagram below (circle with M shows the present day Martian surface conditions).

Figure 2. Phase diagram showing average conditions at the planetary surface for Earth (E) near the triple point, and atmospheric conditions for the frozen Mars (M) and vapor-rich Venus (V). source: http://www1.lsbu.ac.uk/water/water_phase_diagram.html#intr2; License: https://creativecommons.org/licenses/by-nc-nd/2.0/uk/)

It turns out that the most expansive evidence of liquid groundwater on Mars comes from deep at the bottom of craters (…deeper than 5 km!), where the Martian geothermal gradient (~10 C/km [Michalski et al.2013]) heats up to the point where groundwater systems, probably made up of brines, can seep across the crater walls. Without the craters, the groundwater wouldn’t have anywhere to discharge, but extraterrestrial hydrogeologists (really based on the geomorphology, but using E.T. hydrogeology principles) have identified numerous craters with groundwater seepage erosional patterns (Figure 1). The question remains open on how connected the Martian “aquifers” could be, or if the craters represent only local flow systems.

With liquid groundwater transporting the chemical-rich waters from deeper geothermal areas, the conditions could be right for supporting a deep Martian biosphere. Buried in under the Martian ice, soil, and rock microbial life could have evolved in the subterranean shelter from cosmic radiation. Groundwater flow, potentially related to geothermal conditions, could then have served as the conveyor belt for energy-rich molecules to feed microbial life in the subsurface (and still could?).

So far, Earth is the only celestial body in our solar system with an active water-hydrologic cycle, making us the lucky green planet. But, there could be a methane-based hydrologic cycle on Titan with “methanifers” as methane aquifers! For more information on extraterrestrial hydrogeology, Baker et al. (2005) provides a great overview of the planetary, lunar, and exo-planetary potential for water and groundwater, loosely summarized in this table.

At the moment, Earthlings don’t know that much yet about the paleo-hydrologic processes on Mars. But with new boots…I mean wheels…on the ground in two water-focused locations, new clues could start rolling in on Martian groundwater. The recently-arrived InSight lander will probe the Martian subsurface by drilling 5 m deep and listen for acoustic signals for even more information on the interior of Mars. The next Mars Rover is scheduled to take flight in 2020 for the Jezero Crater, where a river delta could help unravel the water-life story of Mars. And could have some groundwater surprises! At only about 1 km deep, the focus in mainly on tracking down signs of life and unravelling surface hydrologic and erosional processes on Mars, but a long list of expected outcomes does show the mission will keep an eye out for evidence of groundwater activities. Keep your feet grounded, eyes in the sky, and visions of Martian groundwater flying high and drilling low!

References
[1] Malin, M. C., and K. S. Edgett (2000), Evidence for Recent Groundwater Seepage and Surface Runoff on Mars, Science, 288(5475), 2330–2335, doi:10.1126/science.288.5475.2330.
[2] Michalski, J. R., J. Cuadros, P. B. Niles, J. Parnell, A. Deanne Rogers, and S. P. Wright (2013), Groundwater activity on Mars and implications for a deep biosphere, Nat. Geosci., 6(2), 133–138, doi:10.1038/ngeo1706.
[3] Stofan, E. R. et al. (2007), The lakes of Titan, Nature, 445(7123), 61–64, doi:10.1038/nature05438.
[4] Baker, V. R., J. M. Dohm, A. G. Fairén, T. P. A. Ferré, J. C. Ferris, H. Miyamoto, and D. Schulze-Makuch (2005), Extraterrestrial hydrogeology, Hydrogeol. J., 13(1), 51–68, doi:10.1007/s10040-004-0433-2.
[5] Robinson, K. L., and G. J. Taylor (2014), Heterogeneous distribution of water in the Moon, Nat. Geosci., 7(6), 401–408, doi:10.1038/ngeo2173.
[6] Jurac, S., M. A. McGrath, R. E. Johnson, J. D. Richardson, V. M. Vasyliunas, and A. Eviatar (2002), Saturn: Search for a missing water source, Geophys. Res. Lett., 29(24), 25-1-25–4, doi:10.1029/2002GL015855.

Kevin Befus leads the groundwater hydrology group in the Civil and Architectural Engineering Department at the University of Wyoming. With his research group, he studies how groundwater systems respond to hydrologic conditions over glacial timescales and in mountainous and coastal environments.  You can follow along with Kevin’s research through any of the links below:

Personal Webpage | Twitter Research Group Page | UW Faculty Page

 

 

 

 

 


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Of Karst! – short episodes about karst

Of Karst! – short episodes about karst

Post by Andreas Hartmann Assistant Professor in Hydrological Modeling and Water Resources at the University of Freiburg.


Episode 4 – Karst Groundwater: quick and slow at the same time?

We often associate groundwater with large water storage and very slow water movement for instance compared to rivers. But is it possible that groundwater flow can be as quick as stream flow and, at the same aquifer, flow for several months or years before it is reaching the surface again? Of karst, it is possible! When chemical weathering is able dissolve carbonate rock, cracks and fissures may grow to a subsurface channel system that can take vast amounts of water flow (see Of Karst! – episode 2).

The schematic figure below shows how this affects water flow in a karst system. At the surface, water may flow for some distance (external runoff towards the recharge area or internal runoff within the recharge area), before it reaches a dissolution widened vertical crack or fissure. On its way, part of it may slowly infiltrate into the soil but the stronger the rainfall event, the more water will infiltrate quickly into cracks and fissures after being redistributed laterally. Consequently, slow and quick infiltration will be followed by slow and quick vertical flow through the vadose zone. The former through the carbonate rock matrix, the latter through the interconnected system of dissolution caves. Finally, recharge and groundwater flow take place, again quickly through the caves and slowly through the matrix.  When passing the system through the cave network, water can enter and leave the system within several hours. When taking the slow and diffuse path, the transit through the system may take months to years.

Because of this behavior, hydrogeologists often speak about the Duality of Karstic Groundwater Flow and storage, although it is known that there is a wide range of dynamics between quick flow through the caves and slow flow through the matrix and that lateral redistribution between the interconnected caves and the matrix takes place at almost every part of the system.

Figure 1: Schematic description of karstic groundwater flow and storage (Hartmann et al., 2014; modified)

A rather uncomfortable lesson on quick flow processes in karst was learned by a group of school students on a trip through a karstic cave in Thailand. Due to the quick recharge processes explained above, the groundwater tables could quickly rise blocking the return path of the group and resulting in a dramatic rescue mission:

In order to predict the impact of interplay of quick and slow karstic groundwater processes on cave water levels or water resources in general, karst-specific simulation models are necessary. If you are interested in those, follow the Water Underground blog’s postings and wait for Of Karst! Episode 5, which will introduce karstic groundwater modelling.


Andreas Hartmann is an Assistant Professor in Hydrological Modeling and Water Resources at the University of Freiburg. His primary field of interest is karst hydrology and hydrological modelling. Find out more at his personal webpage www.subsurface-heterogeneity.com  

Further reading: Hartmann, A., Goldscheider, N., Wagener, T., Lange, J., Weiler, M., 2014. Karst water resources in a changing world: Review of hydrological modeling approaches. Rev. Geophys. 52, 218–242. doi:10.1002/2013rg000443

 

 


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Water: underground source for billions could take more than a century to respond fully to climate change

Water: underground source for billions could take more than a century to respond fully to climate change

WaterUnderground post by Mark O. Cuthbert, Cardiff University; Kevin M. Befus, University of Wyoming, and Tom Gleeson, University of Victoria


Groundwater is the biggest store of accessible freshwater in the world, providing billions of people with water for drinking and crop irrigation. That’s all despite the fact that most will never see groundwater at its source – it’s stored naturally below ground within the Earth’s pores and cracks.

While climate change makes dramatic changes to weather and ecosystems on the surface, the impact on the world’s groundwater is likely to be delayed, representing a challenge for future generations.

Groundwater stores are replenished by rainfall at the surface in a process known as “recharge”. Unless intercepted by human-made pumps, this water eventually flows by gravity to “discharge” in streams, lakes, springs, wetlands and the ocean. A balance is naturally maintained between rates of groundwater recharge and discharge, and the amount of water stored underground.

Groundwater discharge provides consistent flows of freshwater to ecosystems, providing a reliable water source which helped early human societies survive and evolve.

When changes in climate or land use affect the rate of groundwater recharge, the depths of water tables and rates of groundwater discharge must also change to find a new balance.

Groundwater is critical to agriculture worldwide. Rungroj Youbang/Shutterstock

The time it takes for this new equilibrium to be found – known as the groundwater response time – ranges from months to tens of thousands of years, depending on the hydraulic properties of the subsurface and how connected groundwater is to changes at the land surface.

Estimates of response times for individual aquifers – the valuable stores of groundwater which humans exploit with pumps – have been made previously, but the global picture of how quickly or directly Earth’s groundwater will respond to climate change in the coming years and decades has been uncertain. To investigate this, we mapped the connection between groundwater and the land surface and how groundwater response time varies across the world.

The long memory of groundwater

We found that below approximately three quarters of the Earth’s surface, groundwater response times last over 100 years. Recharge happens unevenly around the world so this actually represents around half of the active groundwater flow on Earth.

This means that in these areas, any changes to recharge currently occurring due to climate change will only be fully realised in changes to groundwater levels and discharge to surface ecosystems more than 100 years in the future.

We also found that, in general, the driest places on Earth have longer groundwater response times than more humid areas, meaning that groundwater stores beneath deserts take longer to fully respond to changes in recharge.

Groundwater stores are ‘recharged’ by rainfall and ‘discharge’ into surface water bodies such as lakes. Studio BKK/Shutterstock. Edited by author.

In wetter areas where the water table is closer to the surface, groundwater tends to intersect the land surface more frequently, discharging to streams or lakes.

This means there are shorter distances between recharge and discharge areas helping groundwater stores come to equilibrium more quickly in wetter landscapes.

Hence, some groundwater systems in desert regions like the Sahara have response times of more than 10,000 years. Groundwater there is still responding to changes in the climate which occurred at the end of the last glacial period, when that region was much wetter.


Read MoreThe global race for groundwater speeds up to feed agriculture’s growing needs


In contrast, many low lying equatorial regions, such as the Amazon and Congo basins, have very short response times and will re-equilibrate on timescales of less than a decade, largely keeping pace with climate changes to the water cycle.

Geology also plays an important role in governing groundwater responses to climate variability. For example, the two most economically important aquifers in the UK are the limestone chalk and the Permo-Triassic sandstone.

Despite both being in the UK and existing in the same climate, they have distinctly different hydraulic properties and, therefore, groundwater response times. Chalk responds in months to years while the sandstone aquifers take years to centuries.

Global map of groundwater response times. Cuthbert et al. (2019)/Nature Climate Change, Author provided.

In comparison to surface water bodies such as rivers and lakes which respond very quickly and visibly to changes in climate, the hidden nature of groundwater means that these vast lag times are easily forgotten. Nevertheless, the slow pace of groundwater is very important for managing freshwater supplies.

The long response time of the UK’s Permo-Triassic sandstone aquifers means that they may provide excellent buffers during drought in the short term. Relying on groundwater from these aquifers may seem to have little impact on their associated streams and wetlands, but diminishing flows and less water could become more prevalent as time goes on.

This is important to remember when making decisions about what rates of groundwater abstraction are sustainable. Groundwater response times may be much longer than human lifetimes, let alone political and electoral cycles.The Conversation


Post written by:

Mark O. Cuthbert, Research Fellow & Lecturer in Groundwater Science, Cardiff University;

Mark Cuthbert is a Research Fellow and Lecturer in the School of Earth and Ocean Sciences, at Cardiff University in the United Kingdom. Mark’s work currently focuses on coupled hydrological-climate process dynamics in order to: understand groundwater sustainability; improve interpretations of terrestrial paleoclimate proxy archives;  and understand how Quaternary paleoenvironments influenced human evolution.

 

Kevin M. Befus, Assistant professor, University of Wyoming; 

Kevin Befus leads the groundwater hydrology group in the Civil and Architectural Engineering Department at the University of Wyoming. With his research group, he studies how groundwater systems respond to hydrologic conditions over glacial timescales and in mountainous and coastal environments.

 

 

Tom Gleeson, Associate professor, University of Victoria

Tom Gleeson leads the Groundwater Science and Sustainability group in the Civil Engineering Department at the University of Victoria.  His research interests include groundwater sustainability, mega-scale groundwater systems, groundwater recharge and discharge and fluid flow around geologic structures. Tom is also the founder of this blog, WaterUnderground.

 

 


This article is republished from The Conversation under a Creative Commons license. Read the original article.

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Data drought or data flood?

Data drought or data flood?

Post by Anne Van Loon, Lecturer in Physical Geography (Water sciences) at the University of Birmingham, in the United Kingdom.

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The basis for (almost) all scientific work, at least in the earth and environmental sciences, is DATA. We all need data to search for the answers to our questions. There are a number of options to get hold of data; we can measure stuff ourselves in the field or in the lab, generate model data, process data measured by satellites, or use data that other people collected. The last option has the advantage that you can cover much larger temporal and spatial scales than if you do all the measurements yourself, but it is not necessarily much easier or quicker. In this blog I do a quick and dirty tour of large-scale data collection initiatives in hydrology and introduce a new initiative focusing on groundwater drought.

“Hydrometeorological data…” (source: https://cloudtweaks.com/)

The classical way for hydrologists to use other people’s data (also called “secondary data”) is to use national-scale government-funded hydrometeorological databases such as the National River Flow Archive (NRFA, https://nrfa.ceh.ac.uk/) and National Groundwater Level Archive (NGLA, http://www.bgs.ac.uk/research/groundwater/datainfo/levels/ngla.html) in the UK and the US Geological Survey Water Data in the USA (https://water.usgs.gov/data/). This seems a good and reliable source for data, but there are worries, for example that the number of gauges worldwide is decreasing due to various reasons (Mishra & Coulibaly, 2009; https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2007RG000243; Hannah et al., 2011; https://onlinelibrary.wiley.com/doi/full/10.1002/hyp.7794) and that paper or microfilm archives are at risk (https://public.wmo.int/en/our-mandate/what-we-do/observations/data-rescue-and-archives). These national data are collated in global databases like the Global Runoff Data Centre (GRCD, http://www.bafg.de/GRDC/EN/Home/homepage_node.html) and the Global Groundwater Network (GGN, https://ggmn.un-igrac.org/), hosted by the International Groundwater Resources Assessment Centre (IGRAC). The problem there is that it is very dependent on the national hydrometeorological institutes to provide data, the records are not always up to date and quality checked, and important meta-data are not always available.

That is the reason that many researchers spend a lot of time combining and expanding these datasets. A few recent examples (NB: not at all an exhaustive list):

These are very helpful, but also quite time consuming for a single person (usually an early-career scientist) or a small group of people to compile and the dataset easily becomes outdated.

On the other side of the spectrum is crowd-sourced or citizen science data. This is already quite common in meteorology, both for weather observations (Weather Observations Website, WOW, http://wow.metoffice.gov.uk/), historic weather data (for example Weather Rescue, https://www.zooniverse.org/projects/edh/weather-rescue/) and climate model data (weather@home, https://www.climateprediction.net/, by Massey et al., 2014 https://rmets.onlinelibrary.wiley.com/doi/full/10.1002/qj.2455 ), but citizen science is starting to get used in hydrology as well. Some examples are (again not exhaustive):

Example of crowd-sourcing hydrological data via an App (source: http://www.crowdhydrology.com/)

Most of these are using citizens as passive data collectors with the scientists doing the analysis and interpretation. The nice thing is that it creates lots of data, but the downside is a lot of local knowledge is underused. There are, however, also initiatives that try to make use of this local knowledge, either from citizens themselves, from the experts in government agencies, or from local scientists who know much more about the local hydrological situation. Some of these are funded projects, such as:

Some of these are not funded, like the UNESCO NE-FRIEND Low flow and Drought group that produced an analysis of the 2015 streamflow drought in Europe after a community effort to collect streamflow data and drought characteristics from partners in countries around Europe (Laaha et al., 2017, https://www.hydrol-earth-syst-sci.net/21/3001/2017/hess-21-3001-2017.html). Or are only partly funded, for example by a COST action that only provides travel funding, as in the case of the FloodFreq initiative in which researchers collected a dataset of long streamflow records for Europe to study floods (Mediero et al. 2015, https://www.sciencedirect.com/science/article/pii/S0022169415004291) or the European Flood Database that could have been developed with support of an ERC Advanced Grant (Hall et al., 2015, https://www.proc-iahs.net/370/89/2015/piahs-370-89-2015.html).

The databases developed in funded projects are great because there is (researcher) time to develop something new. But it is also hard to maintain the database when the project funding stops and a permanent host then needs to be found. Unfunded projects can benefit from the enthusiasm and commitment of their collaborators, but have to rely on people spending time to provide data and be involved in the analysis and interpretation. These work best if they are rooted in active scientific communities or networks. I already mentioned the NE-FRIEND Low flow and Drought group (http://ne-friend.bafg.de/servlet/is/7402/), which developed into a nice group of scientific FRIENDs, but also organisations like the International Association of Hydrological Sciences (IAHS, https://iahs.info/) and the International Association of Hydrogeologists (IAH, https://iah.org/) play an important role (see Bonnell et al. 2006 – HELPing FRIENDs in PUBs; https://onlinelibrary.wiley.com/doi/full/10.1002/hyp.6196 ). IAHS for example drives the Panta Rhei decade on Change in Hydrology and Society (https://iahs.info/Commissions–W-Groups/Working-Groups/Panta-Rhei.do), which has a number of very active working groups that are driving data sharing initiatives. Another very successful example is HEPEX (https://hepex.irstea.fr/), which is a true bottom-up network with “friendly people who are full of energy” (https://hepex.irstea.fr/hepex-highlights-egu-2018/). These international networks can provide the framework for data sharing initiatives.

The value of international scientific networks for data sharing (source: https://hepex.irstea.fr/)

It also helps if there is one (funded) person driving the data collection and if there is a clear aim or research question that everyone involved is interested in. Also, a clear procedure and format for the data helps. With that in mind, portals have been developed specifically for data sharing in hydrology, for example:

– SWITCH-ON that focusses on open data and virtual laboratories where people can do collective experiments (http://www.water-switch-on.eu/project_pages/index.html).

– Hydroshare, which is a collaborative website where people can upload hydrological data and models (https://www.hydroshare.org/)

The most inclusive are the initiatives (either funded or unfunded) that manage to incorporate local knowledge, so those that do not only collect data, but also work with the data providers for the interpretation of the data. This synthesis aspect is the main strength of these initiatives and a lot can be learned by bringing data and knowledges together, even if no new data is created.

In a NEW initiative we are hoping to combine some of the advantages of the above-mentioned data collection efforts. The Groundwater Drought Initiative (GDI, http://www.bgs.ac.uk/research/groundwater/waterResources/groundwaterDroughtInitiative/home.html) is a three-year initiative starting in April 2018 that aims to develop and support a network of European researchers and stakeholders with an interest in regional- to continental-scale groundwater droughts. Through the GDI network we will collect groundwater level data and groundwater drought impact information for Europe. This is needed because most of the data collection initiatives mentioned above are focussed on floods, not on drought, and most collate data on streamflow, not on groundwater. Since around 65% of the Europe’s drinking water supply is obtained from groundwater and drought is (and will increasingly be) a threat to water security in Europe, it is essential to get a good understanding of groundwater drought and its impacts. Since groundwater drought is typically large-scale and transboundary, data on a pan-European scale is needed to increase this understanding.

The GDI initiative is embedded in the NE-FRIEND Low flow and Drought group and has obtained a bit of funding from the UK Research Council for workshops and some researcher time, but we hope to arouse the interest and the enthusiasm of even more scientists and government employees of various nationalities and regions to be involved in the initiative and to contribute with data, meta-data, local knowledge and interpretation of data. In return the GDI will provide tools to visualise and analyse groundwater droughts, a regional- to continental-scale context of the groundwater drought information, insights into the impacts of major groundwater droughts, access to a network of international groundwater drought researchers and managers, and the opportunity to participate in joint scientific publications. The long-term sustainability of the initiative will hopefully be developed through the network that we will establish and through the link with formal organisations like the European Drought Centre (EDC, http://europeandroughtcentre.com/) and IGRAC (https://www.un-igrac.org/ ), where the groundwater drought data will be stored after the end of the funded project.

If you are interested, please get in touch:

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Anne Van Loon is a catchment hydrologist and hydrogeologist working on drought. She studies the relationship between climate, landscape/ geology, and hydrological extremes and its variation around the world. She is especially interested in the influence of storage in groundwater, human activities, and cold conditions (snow and glaciers) on the development of drought.

Bio taken from Anne’s University of Birmingham page.

Happy birthday plate tectonics!

Happy birthday plate tectonics!

Post by Elco Luijendijk, a junior lecturer, and David Hindle, lecturer and head of geodynamic modelling, both at the Department of Structural Geology and Geodynamics at the University of Göttingen, in Germany.

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As we’ve firmly moved into 2018, we can say happy 50th birthday to one of the most revolutionary scientific theories of the last century: plate tectonics. Here we discuss the birth of plate tectonics and what it means for hydrogeology.

Plate tectonic theory explains the how the Earth’s surface is formed and how it consists of rigid plates on top of a layer that is called the asthenosphere and that behaves like a slow-moving liquid. The plates move around, collide and subduct beneath each other. Plate tectonics successfully explains many features of the surface of the Earth, such as mountain belts at the collision zones of plates, ocean basins at places where plates move apart and the concentration of earthquakes near plate boundaries. For instance it is quite easy to recognize the boundaries of tectonic plates if you look at the earthquake distribution in Figure 2.

Plate tectonics birthday cake, showing one tasty tectonic plate (left) subducting below another (right). Source: http://sara-geologicventures.blogspot.de/2012/05/cake-subduction-zone.html

Actually, depending on your definition either 2017 or 2018 is the 50th birthday of plate tectonics. The story why this is the case is a bit complex. Jason Morgan first presented the theory at meeting of the American Geophysical Union (AGU) in 1967. However, the first paper on the mathematical principle of the movement of tectonic plates was published in the same year by McKenzie and Parker (1967). Jason Morgan’s paper (Morgan 1968) is the first one to clearly demonstrate the global geometry of all the major tectonic plates, but had got delayed by peer-review for over a year. The development of plate tectonics involved many scientist and several earlier theories, such as seafloor spreading (which showed that ocean basins were split in two halves that were moving apart). There are surprisingly few books available on the history of plate tectonics, but one that is definitely an enjoyable read is “Plate Tectonics: An Insider’s History Of The Modern Theory Of The Earth” (Oreskes 2003). It is a fascinating collection of stories by most of the scientist that were involved in the development of the theory.

Figure 2 Plate boundaries on earth, with earthquakes > M6.5, since the year 2000, and with selected relative motion arrows for plate pairs – the motions shown are always those between adjacent plates. Double arrows imply spreading – moving apart of plates, mostly on oceanic ridges, while single arrows imply either strike slip motion (California and the San Andreas fault for instance) or convergence (either subduction of an oceanic plate under a continental one – under the Andes mountains in South America as an example, or collision of two continental plates as between India and Eurasia in the Himalayas for instance). Earthquakes are clearly concentrated on plate boundaries. This map was made using GMT (http://gmt.soest.hawaii.edu/).

Ok, that is all very interesting, but you could ask the question: what does plate tectonics have to do with Water Underground?

In some regards not much. We can often ignore plate tectonics when looking at groundwater flow. Hydrogeologists tend to study groundwater supply and pollution on human time and space scales. Because plates move very slowly (up to tens of mm per year), on short timescales the subsurface can be regarded as static layer of rocks that does not move or deform. However, most of the groundwater on our planet is old, and has infiltrated to the subsurface ten thousand years ago or earlier (Jasechko et al. 2017). The oldest groundwater that we know is 1.5 billion years old and was found at 2 km depth in a mine in near Timmins, Canada (Holland et al. 2013). Over its long history it was part of ancient and long disintegrated continents and the plate that holds this water moved from an area south of the equator to its present position.

Plate tectonics affect groundwater. Especially in deeper (several kilometers) parts of the crust, the groundwater pressure, salinity and composition that we encounter today are often the result of a long geological history. Over time, sediments were added and removed by erosion, layers were compacted, folded and/or faulted, which affected groundwater flow and its interaction with the rocks that contain it.

The reverse is also true: groundwater affects plate tectonics. This is perhaps most important near mid-ocean ridges, where two plates move apart, and new crust is being added to these plates all the time. There is abundant evidence for strong circulation of seawater through the subsurface, which cools the hot new crust, reacts with the rocks around it and changes the chemistry of the crust and the ocean. The most visible evidence are so-called black smokers (Figure 3), where hot (350 ˚C) water discharges into the ocean through fissures in the crust and carries along black plumes full of dissolved minerals. At the opposite end of the plates, the presence of water underground changes how easy or hard it is for one plate to subduct beneath another in a plate collision zone, as was discussed at a recent AGU conference (link to session), 50 years after the AGU conference where Jason Morgan presented his theory. On a smaller scale, faults that enable the stacking of rocks in plate collision zones (mountain belts) or the breaking apart of rocks in rift zones (where plates split up), are dependent on the presence of groundwater. Even before the advent of plate tectonics Hubbert and Rubey (1959), showed that water in fault zones can act as a kind of lubricant that enables two adjacent blocks of rocks to move past each other. Because this movement gives rise to earthquakes, groundwater may also play an important role in the earthquake cycle. This role is still heavily debated and is researched by drilling deep wells in faults at plate boundaries, such as at the San Andreas fault in California (Zoback et al. 2010) or the Nankai through (Hammerschmidt et al. 2013).

Without sufficient groundwater plate tectonics may not exist on our planet. The movement of tectonic plates depends on how easily the rocks below these plates can deform. At these depths, high pressures and temperatures promote the slow deformation of the crystals that make up the rocks at this depth. The mechanisms that cause the deformation of crystals are termed “creep”. Whether or not the rock contains water (in the form of -OH groups) affects creep: generally, “wet” minerals are up to a factor of 10 “softer” than “dry” ones. The actual physics and chemistry of how -OH affects and weakens different minerals is not entirely clear. Creep is also essential for the convection of the earth’s mantle, which controls the escape of heat from our planet’s interior and provides the energy to drive plate tectonics. Without convection, there would be no plate tectonics, so the presence of water throughout the earth’s crust, and its continued reintroduction to the earth’s mantle by the subduction of tectonic plates seems to be a key component driving the system, or at least, helping it to keep moving along.

There are many more links between groundwater and geologic processes, too many to cover in a short blog item like this. However, the current state of our understanding is summarized in a highly recommended book “Groundwater in geologic processes”. Many aspects of groundwater flow and its links with geological processes in newly formed, colliding or subducting plates are still uncertain and studied by hydrogeologists, which means that 50 years after the publication of the theory of plate tectonics, many discoveries still lie ahead.

Figure 3 A black smoker at the mid Atlantic ridge emitting hot groundwater into the ocean from newly formed oceanic crust. Copyright: MARUM – Center for Marine Environmental Sciences, University of Bremen.

Links:

1: McKenzie and Parker (1967) https://www.nature.com/articles/2161276a0

2: Morgan (1968): http://onlinelibrary.wiley.com/doi/10.1029/JB073i006p01959/full

3: Oreskes (2003): https://www.routledge.com/Plate-Tectonics-An-Insiders-History-Of-The-Modern-Theory-Of-The-Earth/Oreskes/p/book/9780813341323

4: Jassechko et al. (2017): https://www.nature.com/articles/ngeo2943

5: AGU fall meeting session (2017): http://agu.confex.com/agu/fm17/meetingapp.cgi/Session/31184

6: Hubbert and Rubery (1959): https://pubs.geoscienceworld.org/gsabulletin/article-lookup/70/2/115

7: Zoback et al. (2010): http://onlinelibrary.wiley.com/doi/10.1029/2010EO220001/full

8: Hammerschmidt et al. (2013): https://www.sciencedirect.com/science/article/pii/S004019511300098X

9: Ingebritsen et al. (2006) Groundwater in geologic processes. http://www.cambridge.org/de/academic/subjects/earth-and-environmental-science/hydrology-hydrogeology-and-water-resources/groundwater-geologic-processes-2nd-edition?format=PB&isbn=9780521603218#RcR6adP330ESbBPk.97

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David Hindle (L) is a lecturer and the head of geodynamic modelling in the Department of Structural Geology and Geodynamics at the University of Göttingen, and Elco Luijendijk (R) is a junior lecturer also in the Department of Structural Geology and Geodynamics at the University of Göttingen.

Crowdfunding Science: What worked and what didn’t, who pledged and how did we reach them?

Crowdfunding Science: What worked and what didn’t, who pledged and how did we reach them?

Post by Jared van Rooyen, MSc candidate in Earth Science at Stellenbosch University, in South Africa.

Part two of three in a Crowdfunding Science series by Jared.

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During March of 2017, myself and a group of students supervised by Dr. Jodie Miller of Stellenbosch University’s Earth Science department (South Africa) completed a 5-week long crowdfunding campaign. The Campaign raised R149 899.00 (€9800) from 120 backers that were both local and international. The campaign used several different mediums to attract potential backers. In this blog I will summarize what engagement methods we used and which ones worked the best.

Before I do this, I have also partitioned backers into three categories that describe to what degree they are separated from myself and the campaign team. Category 1 includes members of family, colleagues and close friends, that would likely contribute to your fundraising campaign regardless of how you marketed it or if they were confident you would succeed. Category 2 included people that myself or the campaign team either are acquainted with, have met before or have been suggested to us by a member of category 1. Category 3 backers are those that myself or my research team have no prior connection to and have been made aware of the campaign through 3rd party methods.

Half of backers fell into category 2 with the other half almost evenly distributed between categories 1 and 3. The distribution of funding received showed a similar distribution with a slightly skewed distribution toward category 3 backers contributing on average more than category 1 backers.

Engagement methods showed some interesting outcomes with direct contact contributing half of the backers as well as half of the funds raised, social media methods, which included Facebook, Instagram and Twitter, contributed the next largest portion of backers (a quarter) but was trumped by word of mouth backer’s average contribution amount. The remaining contributors were those who found out about the campaign through radio/newspaper interviews/articles, internet news and anonymous contributors for whom I have no data (Unknown).

Upon the completion of the campaign, backers were contacted to give feedback on what they believed was effective in the marketing strategy of the campaign. Although radio interviews did not produce a large amount of backers and funds, they produced the largest proportion of category 3 backers.

The data presented above only mentions the successful methods of engagement. In addition, there were several other attempts at fund raising that were somewhat less effective. These included: handing out flyers and putting up posters on campus and surround areas, approaching funding institutions as well as water related government and private entities for support and using mailing robots to send generic emails to large mailing lists.

Before the campaign had ended myself and two honours students had already left on our field sampling trip. In the final part of this blog series, I will break down, what we raised the funds for, what the groundwater sustainability project is trying to accomplish, and what has culminated as a direct result of postgraduate science crowdfunding.

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Jared van Rooyen is an MSc student at the University of Stellenbosch in South Africa. His primary field of interest is in isotope hydrology with major applications in groundwater vulnerability and sustainability. Other research interests include postgraduate research funding solutions and outreach as well as scientific engagement with the use of modern media techniques.

Check out Jared’s (and research group’s) thundafund  page here.

Bedrock: A hydrogeologist’s devotional

Bedrock: A hydrogeologist’s devotional

Post by Kevin Befus, Assistant Professor at the College of Engineering and Applied Science at the University of Wyoming, in the United States.

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I want to share a book with you that has encouraged me through initial academic mires (I was only in graduate school for 7 years…) and inspired me to expand my perception and appreciation of the natural world.

The book is Bedrock: Writers on the Wonders of Geology [Savoy et al., 2006]. It is a carefully curated collection of snippets and excerpts from international literary sources describing geologic processes and outcomes. Most of the writings come from the 20th century with several exceptions extending not quite as far back as the Pleistocene. Each chapter, or collection of writings, is oriented around a theme in the earth sciences, one of which is “Rivers to the Sea”…the creative views of hydrologic, mainly riverine, processes chapter. While the excerpts are the main event in each chapter, a quick introduction to each selection is given within the broader geologic context along with some reasoning in why each was chosen.

Bedrock is not a book about hydrogeology, and it really doesn’t directly talk about water underground. BUT, Earth is explored in the excerpts, and developing connections between groundwater and other geologic processes is our job, not the literary masters who “contributed” tidbits to the book. As you should have expected, John McPhee shows up a number of times, but not too much. Many of the early geologists (e.g., G.K. Gilbert, James Hutton, and John Wesley Powell) and environmentalists (e.g., Rachel Carson and John Muir) also share their reflections of geologic forces on nature.

As someone who reads blogs about groundwater, remember to extend the literary reflections to include how the topics interact with groundwater systems. For example, the cover image evokes excitement (or consternation) from a groundwater hydrologist, as it shows the coastline of Nullarbor Plain in southern Australia, home to the “world’s largest limestone karst area” (http://www.australiangeographic.com.au/travel/destinations/2016/04/hidden-nullarbor).

My suggestion for reading this book is to take it slow: one excerpt in the morning to kick-start the day, remembering why it is you do what you do. Be inspired, awed, and reminded of how geological processes have shaped our world over billions of years. Or, read an entry when the day has taken a turn to the slow or chaotic. Like any good devotional, Bedrock has great re-readability and also points you towards the original documents for more in-depth explorations of literary (hydro)geology.

Happy reading!

Savoy, L. E., E. M. Moores, and J. E. Moores (2006), Bedrock: Writers on the Wonders of Geology, Trinity University Press, San Antonio, TX.

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Kevin Befus leads the groundwater hydrology group in the Civil and Architectural Engineering Department at the University of Wyoming. With his research group, he studies how groundwater systems respond to hydrologic conditions over glacial timescales and in mountainous and coastal environments.  You can follow along with Kevin’s research through any of the links below:

Twitter | Research Group Page | UW Faculty Page

 

 

 

 

 

 

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Feature photo image source: 
http://tupress.org/img/upload/bedrock_front_cover_nl_copy.jpg

The new and exciting face of waterunderground.org

The new and exciting face of waterunderground.org

by Tom Gleeson

I started waterunderground.org a few years ago as my personal groundwater nerd blog with the odd guest post written by others. Since I love working with others, I thought it would be more fun, and more interesting for readers, to expand the number of voices regularly posting. So here is the new face of the blog…

http://www.fragilestates.org/wp-content/uploads/2012/10/collective-action.jpg

a kind of weird image of collective action

What is the new blog all about?

Written by a global collective of hydrogeologic researchers for water resource professionals, academics and anyone interested in groundwater, research, teaching and supervision. We share the following aspirations:

  • approachable groundwater science at the interface of other earth and human systems
  • encourage sustainable use of groundwater that reduces poverty, social injustice and food security while maintaining the highest environmental standards
  • compassionate, effective supervision
  • innovative, effective teaching
  • transparency of scientific methods, assumptions and data

Check out more details and how to be part of the blog on about.

Frequent contributors include:

  • Andy Baker (University of New South Wales, Australia) – caves and karst (I actually visit the water underground!), climate and past climate
  • Kevin Befus (University of Wyoming, United States) – groundwater-surface interactions, coastal groundwater, groundwater age
  • Mark Cuthbert (University of Birmingham, United Kingdom) – groundwater recharge & discharge processes, paleo-hydrogeology, dryland hydro(geo)logy, climate-groundwater interactions
  • Matt Currell (RMIT University, Australia) – isotope hydrology; groundwater quality; transient responses in aquifer systems
  • Inge de Graaf (Colorado School of Mines, United States) – global groundwater withdrawal, flow and sustainability
  • Grant Ferguson (University of Saskatchewan, Canada) – groundwater & energy, regional groundwater flow, sustainability
  • Tom Gleeson (University of Victoria, Canada) – mega-scale groundwater systems and sustainability
  • Scott Jasechko (University of Calgary, Canada) – global isotope hydrology; groundwater, precipitation, evapotranspiration
  • Elco Luijendijk (University of Gottingen, Germany) – paleo-hydrogeology,deep groundwater flow,large scale groundwater systems
  • Sam Zipper (University of Wisconsin – Madison, United States) – ecohydrology, agriculture, urbanization, land use change