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Humanitarian groundwater projects; notes on motivations from the academic world

Humanitarian groundwater projects; notes on motivations from the academic world

Post by Margaret Shanafield, ARC DECRA Senior Hydrogeology/Hydrology Researcher at Flinders University, in Australia. You can follow Margaret on Twitter at @shanagland.

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What led me down the slippery slope into a career in hydrology and then hydrogeology, was a desire to combine my love of traveling with a desire to have a deeper relationship with the places I was going, and be able to contribute something positive while there. I figured everyone needs water, and almost everyone has either too much (flooding) or too little of it.

But, from an academic point of view, aid/humanitarian/philanthropic projects can be frustrating and offer few of the traditional paybacks that universities and academia reward.  Last week, for example, I spent much of my time working on the annual report for an unpaid project, and I am soft money funded. And what’s worse, I couldn’t even get the report finished, because most of the project partners hadn’t given me their updates on time. When I went across the hall to complain to my colleague, he admitted that he, too, was in a similar situation.

So what is the incentive?

Globally, the need for regional hydrologic humanitarian efforts is obvious. Even today, 1,000 children die due to diarrhoeal diseases on a daily basis. Water scarcity affects 40% of global population, with 1.7 billion people dependent on groundwater basins where the water extraction is higher than the recharge.  And, the lack of water availability is only going to get worse into the future.

But being a researcher with pressure to “publish or perish” and find ways to fund myself and my research, what was/is my incentive to address these problems? From an academic point of view, water aid projects are often time-consuming, with expected timelines delayed by language and cultural barriers, difficulties in obtaining background data, expectations on each side of the project not matching up, and activities and communication not happening on the timescales academics are used to. And the results are typically hard to publish.

An online search revealed numerous articles discussing the pros and cons of pursuing a career in development work, including: having a job aligned with one’s morals and values, an exciting lifestyle full of change, motivated co-workers, the opportunity to see the world and different cultures, the opportunity to make a difference, and last but not least, because it is a challenge (in a good way).

As a scientist, I get elements of all these pros in my daily work. But, while much of what academics do fits under the umbrella of “intellectually challenging”, aid projects provide applied problems with real-world implications that can sometimes be lacking in the heavily research-focused academic realm, except for the creative “broader impacts” and outreach sections of grant proposals. They are therefore an opportunity for scientists to have an impact on the world by contributing to the collective understanding of water resources and hydrologic systems. And hey, many of us enjoy travelling and get to visit interesting places for work, too.

Pulling myself out of my philosophical waxings, I focused on these highlights and the benefits of working in an interdisciplinary project to address some of those global problems I mentioned earlier – and got back to report writing.

Training project partners in Vietnam to take shallow geophysical measurements (left). Sweaty days in the field are rewarded by cheap beers, magnificent sunrises, and relaxing evenings at the coast where the river meets the sea (right). Photos by M Shanafield.

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Margaret Shanafield‘s research is at the nexus between hydrology and hydrogeology. Her current research interests still focus on surface water-groundwater actions, although she work’s on a diverse set of projects from international development projects to ecohydrology. The use of multiple tracers to understand groundwater recharge patterns in streambeds and understanding the dynamics of intermittent and ephemeral streamflow are her main passions. Since 2015, she has been an ARC DECRA fellow, measuring and modelling what hydrologic factors lead to streamflow in arid regions. You can find out more about Margaret on her website.

Good groundwater management makes for good neighbors

Good groundwater management makes for good neighbors

Post by Samuel Zipper, postdoctoral fellow at both McGill University and the University of Victoria, in Canada. You can follow Sam on Twitter at @ZipperSam.

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Dedicated Water Underground readers know that this blog is not just about water science, but also some of the more cultural impacts of groundwater. Keeping in that tradition, today’s post begins with a joke*:

Knock, knock!

Who’s there?

Your neighbor

Your neighbor who?

Your neighbor’s groundwater, here to provide water for your plants!

Figure 1. Typical reaction to joke written by the author.

Ahem.

Perhaps this joke needs a little explanation. As we’ve covered before, groundwater is important not just as a supply of water for humans, rivers, and lakes, but also because it can increase the water available to plants, making ecosystems more drought resistant and productive. However, we also know that groundwater moves from place to place beneath the surface. This means that human actions which affect groundwater in one location, like increasing the amount of paved surface, might have an unexpected impact on ecosystems in nearby areas which depend on that groundwater.

Imagine, for example, two neighboring farmers. Farmer A decides retire and sells his land to a developer to put in a new, concrete-rich shopping center. Farmer B continues farming her land next door. How will the changes next door affect the groundwater beneath Farmer B’s land, and will this help or hurt crop production on her farm?

In a new study, my colleagues and I explored these questions using a series of computer simulations. We converted different percentages of a watershed from corn to concrete to see what would happen. Our results showed that the response of crops to urbanization depended on where the land use change occurred.

Figure 2. Conceptual diagram showing how urbanization might impact crop yield elsewhere in a watershed. From Zipper et al. (2017).

In upland areas where the water table was deep, replacing crops with concrete caused a reduction in groundwater recharge, lowering the water table everywhere in the watershed – not just beneath the places where urbanization occurred. This meant that places where the ecosystems used to be reliant on groundwater could no longer tap into this resources, making them more vulnerable to drought. However, places where the water table used to be too shallow saw boosts in productivity, as the lower water table was closer to the optimum water table depth.

In contrast, urbanization happening in lowland areas had a much more localized effect, with changes to the water table and yield occurring primarily only in the location where land use changed, because the changes in groundwater recharge were accounted for by increased inflows from the stream into the groundwater system.

So, what does this mean for the neighboring farmers we met earlier?

For Farmer A, it means the neighborly thing to do is work with the developers to minimize the effects of the land use change on groundwater recharge. This can include green infrastructure practices such as rain gardens or permeable pavement to try and mimic predevelopment groundwater recharge.

For Farmer B, the impacts depend on the groundwater depth beneath her farm. If the groundwater beneath her farm is shallow enough that her crops tap into that water supply, she should expect changes in the productivity of her crops, especially during dry periods, and plan accordingly.

*Joke written by scientist, rather than actual comedian.

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For More Information:

Zipper SC, ME Soylu, CJ Kucharik, SP Loheide II. Indirect groundwater-mediated effects of urbanization on agroecosystem productivity: Introducing MODFLOW-AgroIBIS (MAGI), a complete critical zone model. Ecological Modelling, 359: 201-219. DOI: 10.1016/j.ecolmodel.2017.06.002

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Sam Zipper is an ecohydrologist. His main research focuses broadly on interactions between vegetation and the water cycle, with a particular interest in unintended or indirect impacts of land use change on ecosystems resulting from altered surface and subsurface hydrological flowpaths. You can find out more about Sam by going to his webpage at: samzipper.weebly.com.

Of Karst! – short episodes about karst

Of Karst! – short episodes about karst

Episode 2: Dissolving rock? (or, how karst evolves).

Post by Andreas Hartmann, Lecturer in Hydrology at the University of Freiburg (Universität Freiburg), in Germany. You can follow Andreas on twitter at @sub_heterogenty.

Didn’t get to read Episode 1? Click this link here to do so!

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In the previous episode, I introduced karst by showing how it looks in different regions in the world. This episode will now deal with the processes that create such amazing surface and subsurface landforms. The widely used term “karstification” refers to the chemical weathering of easily soluble rock composed of carbonate rock or gypsum. Most typical is karstification of limestone (consisting of the mineral calcite, CaCO3) or dolostone (consisting of the mineral dolomite, CaMg(CO3)2). If exposed to CO2 rich water these rocks are dissolved to form aqueous calcium (Ca2+) or magnesium (Mg2+) and bicarbonate (HCO3 ) ions. For calcite, karstification is described by the following chemical equilibrium:

The dissolution of carbonate rock depends on various factors. Imagine a solid block of salt, which you pour water on. If completely solid, the water will flow down the salt surface slowly dissolving the block. If fractured, water will eventually enlarge the fractures in the salt block and dissolution will occur much faster. Now imagine smashing the salt block before pouring water on it. In such circumstances the salt will dissolve even faster as the surface area exposed to the water is much larger.

Karst and its evolution (educational video provided by Jennifer Calva on Youtube).

The same is true for karstification. If the carbonate rock is heavily fractured, it will dissolve faster than unfractured carbonate rock. Another factor is the availability of CO2, that depends on the relative amount of CO2 in the air, air temperature and soil microbiotic processes. Other factors are the purity of the carbonate rock, the availability of water, and the supply of CO2 from the surface. As soon as karstification takes place, more water will be able to pass the dissolution enlarged fractures providing more and more CO2, and creating a positive feedback between rock dissolution and water flow:

Positive feedback between carbonate rock dissolution and water flow (Hartmann et al., 2014, modified).

The hydrochemical processes described in this episode of the Of Karst! Series not only create beautiful karst landscapes but they also have a strong and particular impact on water flow paths in the subsurface, which will the topic of episode 4 that can be expected in early 2018. Before, I will present a special feature about karst in the movies as topic of episode 3 in autumn 2017.

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. Reviews of Geophysics, 52, 218–242, doi: 10.1002/2013rg000443.

Ford, D.C. & Williams, P.W. 2013. Karst Hydrogeology and Geomorphology. John Wiley & Sons, 576 pages.

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Andreas Hartmann is a lecturer in Hydrology 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.

 

Groundwater & Education – Part One

Groundwater & Education – Part One

Post by Viviana Re, postdoctoral researcher at the University of  Pavia (Università di Pavia), in Italy. You can follow Viviana on Twitter at @biralnas.

Part one of a two part series on groundwater and education by Viviana.

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Education /ɛdjʊˈkeɪʃ(ə)n
The process of receiving or giving systematic instruction, especially at a school or university.

  • from Latin educatio(n-), from the verb educare
  • Educare is a combination of the words e (out) and ducare (lead, drawing), or drawing out.

Based on this definition, I should change the title of this post to: Drawing out groundwater (from the well). This is actually the main occupation of groundwater scientists, isn’t it? Not only are we always withdrawing groundwater from a well or a borehole while sampling, but we also often have to “draw it out” when dealing with managers and policy makers, as sometimes they seem to forget about this hidden (but very important) component of the water cycle. Therefore, we are quite used to these forms of “drawing out” – but what about education? Are we really that effective in “drawing out” groundwater in explaining its peculiarities, issues, and connections within the whole water cycle and, more generally, with the environment?

Indeed, the effort of shedding light on something that is not so visible nor easily studied has the side effect of forcing us to focus solely on it, with a resulting tendency of developing sectorial approaches to water management.

In the preface of a UNESCO Technical paper, I found the following excerpt: “Water resources schemes are now increasingly considered as integrated systems and consequently, civil engineers, geologists, agricultural engineers and hydraulic engineers engaged in planning and design no longer work in isolation”. The document is dated 1974 but, still in 2017, we are somehow struggling to fitting groundwater into Integrated Water Resources Management (IWRM) and to connecting mental and structural “silos”. Quoting Daly (2017), the latter is particularly relevant (especially when education is at stake): if on the one hand, specialization can be the driver for a sound knowledge; on the other hand, this can encourage people to get stuck in their own individual disciplines (or said in other words, their “silos”). Indeed, “silos” exist in their structures, but can also exist as a state of mind that can go hand in hand with tunnel vision (Tett, 2015).

Therefore, in my opinion, the new generation of groundwater scientists (and teachers) should have a new mission: to work (and therefore, to teach) coherently with the integrated and complex nature of the water cycle. In fact, the role of hydrogeologists and groundwater scientists in times of increasing freshwater demand, exacerbated by population growth and climate change effects, requires a serious shift towards a more holistic approach targeting sound groundwater assessment and long-term management.

Arguably, if we are still discussing possible ways of practically implementing this integration, we should definitely start asking ourselves if the the “business as usual” way of working and teaching is effective.  If it is not, we must begin investigating how we can go beyond classical approaches to draw groundwater out of the well.

Playing with kids while sampling … can we call it capacity building?!

 

To be continued …

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What is the difference between ‘water withdrawal’ and ‘water consumption’, and why do we need to know?

What is the difference between ‘water withdrawal’ and ‘water consumption’, and why do we need to know?

Post by Inge de Graaf, University of Freiburg, Environmental Hydrological Systems group

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Last week I had to teach my first class in global hydrology. When I showed the global trend on increasing demands and withdrawals (see Figure) I needed to explain the different terms as sometimes the term “water use” gets, well, misused.

The term “water use” often fails to adequately describe what happens to the water. So I told the students; if you see or hear to term ‘water use’ always ask yourself what’s actually being said. The term is often used for water withdrawals or water consumption, and it’s important to understand the difference.

Water withdrawal describes the total amount of water withdrawn from a surface water or groundwater source. Measurements of this withdrawn water help evaluate demands from domestic, industrial and agricultural users.

Water consumption is the portion of the withdrawn water permanently lost from its source. This water is no longer available because it evaporated, got transpired or used by plants, or was consumed by people or livestock. Irrigation is by far the largest water consumer. Globally irrigated agriculture accounts for 70% of the total water used and almost 50% is lost either by evaporation or transpiration.

Understanding both water withdrawal and consumption is critical to properly evaluate water stress. Measurements of water withdrawal indicate the level of competition and dependence on water resources. Water consumption estimates help to quantify the impact of water withdrawals on downstream availabilities and are essential to evaluate water shortage and scarcity. For example, most water used by households is not consumed and flows back as return flow and can be reused further downstream. However, water is rarely returned to watershed after being used by households or industry without changing the water quality, increasing water stress levels.

Already more than 1.4 billion people live in areas where the withdrawal of water exceeds recharge rates. In the coming decades global population is expected to increase from 7.3 billion now, to 9.7 billion by 2050 (UN estimate). This growth, along with rising incomes in developing countries, is driving up global food demands. With food production estimated to increase by at least 60% (FAO estimate), predicting water withdrawal and consumption is critically important for identifying areas that are at risk of water scarcity and where water use is unsustainable and competition amongst users exist.

Global trend I showed in my class, published in Wada et al (2016).

Ref:

Wada, Y., I. E. M. de Graaf, and L. P. H. van Beek (2016), High-resolution modeling of human and climate impacts on global water resources, J. Adv. Model. Earth Syst., 8, 735–763, doi:10.1002/2015MS000618.

 

How prehistoric water pit stops may have driven human evolution

How prehistoric water pit stops may have driven human evolution

Post by Matthew Robert Bennett, Bournemouth University and Mark O Cuthbert, Cardiff University

Our ancient ancestors seem to have survived some pretty harsh arid spells in East Africa’s Rift Valley over five million years. Quite how they kept going has long been a mystery, given the lack of water to drink. Now, new research shows that they may have been able to survive on a small networks of springs.

The study from our inter-disciplinary research team, published in Nature Communications, illustrates that groundwater springs may have been far more important as a driver of human evolution in Africa than previously thought.

Great rift valley.Redgeographics, CC BY-SA

The study focuses on water in the Rift Valley. This area – a continuous geographic trench that runs from Ethiopia to Mozambique – is also known as the “cradle of humanity”.

Here, our ancestors evolved over a period of about five million years. Throughout this time, rainfall was affected by the African monsoon, which strengthened and weakened on a 23,000-year cycle. During intense periods of aridity, monsoon rains would have been light and drinking water in short supply. So how did our ancestors survive such extremes?

Previously, scientists had assumed that the evolution and dispersal of our ancestors in the region was solely dependent on climate shifts changing patterns of vegetation (food) and water (rivers and lakes). However, the details are blurry – especially when it comes to the role of groundwater (springs).

We decided to find out just how important springs were. Our starting point was to identify springs in the region to map how groundwater distribution varies with climate. We are not talking about small, babbling springs here, but large outflows of groundwater. These are buffered against climate change as their distribution is controlled by geology – the underlying rocks can store rainwater and transfer it slowly to the springs.

The lakes of the African Rift Valley.SeaWiFS Project, NASA/Goddard Space Flight Center, and ORBIMAGE

We figured that our ancestors could have stayed close to such groundwater in dry times – playing a greater part in their survival than previously thought. When the climate got increasingly wet, groundwater levels would have risen and made springs more plentiful – feeding smaller rivers and leading to lakes becoming less saline. At this point, our ancestors would have roamed across the landscape free of concerns about water.

Life and death decisions

To test this idea, we embarked on a computer experiment. If the springs and water bodies are thought of as the rest stops, or service stations, then the linkages between can be modelled by computers. Our model was based on what decisions individuals would have taken to survive – and what collective behaviours could have emerged from thousands of such decisions.

Individuals were give a simple task: to find a new source of water within three days of travel. Three days is the time that a modern human and, by inference, our ancestors could go without drinking water. The harder and rougher the terrain, the shorter the distance one can travel in those vital three days.

We used the present landscape and existing water springs to map potential routes. The detailed location of springs may have changed over time but the principles hold. If our agent failed to find water within three days, he or she would die. In this way we could map out the migration pathways between different water sources as they varied through 23,000-year climate cycles. The map shows that there were indeed small networks of springs available even during the driest of intervals. These would have been vital for the survival or our ancestors.

The model also reveals movement patterns that are somewhat counter-intuitive. One would assume that the easiest route would be along the north to south axis of the rift valley. In this way, hominins could stay at the bottom of the valley rather than crossing the high rift walls. But the model suggests that in intermediate states between wet and dry, groups of people may have preferred to go from east to west across the rift valley. This is because springs on the rift floor and sides link to large rivers on the rift flanks. This is important as it helps explain how our ancestors spread away from the rift valley. Indeed, what we are beginning to see is a network of walking highways that develop as our ancestors moved across Africa.

Mapping human migration.

Human movement allows the flow of gossip, know-how and genes. Even in modern times, the water-cooler is often the fount of all knowledge and the start of many budding friendships. The same may have been true in ancient Africa and the patterns of mobility and their variability through a climate cycle will have had a profound impact on breeding and technology.

This suggests that population growth, genetics, implications for survival and dispersal of human life across Africa can all potentially be predicted and modelled using water as the key – helping us to uncover human history. The next step will be to compare our model of human movement with real archaeological evidence of how humans actually moved when the climate changed.

So next time you complain about not finding your favourite brand of bottled spring water in the shop, spare a thought for our ancestors who may died in their quest to find a rare, secluded spring in the arid African landscape.

The ConversationThis research was carried out in partnership with our colleagues Tom Gleeson, Sally Reynolds, Adrian Newton, Cormac McCormack and Gail Ashley.

Matthew Robert Bennett, Professor of Environmental and Geographical Sciences, Bournemouth University and Mark O Cuthbert, Research Fellow in Groundwater Science, Cardiff University

This article was originally published on The Conversation. Read the original article.

Fire and groundwater

Fire and groundwater

Post by Andy Baker, University of New South Wales

The effects of fire on the surface environment are clear to see. Landscapes are coated in ash. Intense fires can destroy all vegetation and alter soil properties. Less intense fires destroy just the surface leaf litter, grasses and shrubs.  Grass fires can be fast moving, destroying buildings and threatening lives. Intense fires can even form their own local weather systems.

But what about the effects of fire on water underground? Let’s think about what happens on the surface, and translate that to what is likely to happen to the subsurface.

Firstly, ash is burnt vegetation. It is rich in carbon, nutrients and trace metals, and can be mobilised after heavy rainfall. Heavy rainfall events are most likely to cause groundwater recharge as some of the rainfall makes its way down to the replenish the water table. As this happens we should also expect nutrients and carbon to be moved downwards towards the water table, as well as horizontally to rivers.

Secondly, where a fire destroys tree cover, then the canopy shading will be lost. We would predict hotter surface temperatures. This could alter the water balance, changing evaporation and also the amount or timing of groundwater recharge.

Finally, we would expect increased sediment movement. This could block flow routes to the subsurface, such as fractures and sinkholes. This would change the routes by which water moves from the surface to the water table.

Of course, the problem with water underground is that it is hard to see and measure. So how can we observe the effects of fire in the subsurface? We have been using caves in karstified limestone as a way to sample the water as it moves from the surface to the groundwater.

In caves, you can monitor the water chemistry and hydrology after a wildfire. If you know when a fire will occur, you can make measurements before and after. And you can investigate the chemical record of past fires preserved in cave stalagmites.

What do we see from the cave? We see increased evaporation and decreased recharge in the years immediately after  an intense wildfire. We see nutrient flushes from the surface to the subsurface, moderated by vegetation uptake as regrowth occurs. And we have started to compare the stalagmite geochemical signals of fire, cyclones and global warming.

We are starting to understand a little bit about the effects of fire on water as it moves through the unsaturated zone of limestone. What about other rock types? What about the groundwater aquifer itself? We need to know more about the effect of wildfires on our subsurface water resource.  The fire season is getting longer. A greater extent of the earth’s surface is being burnt. Both will continue to increase with global warming, but how will this affect the water underground?

image source

Squeezed by gravity: how tides affect the groundwater under our feet

Squeezed by gravity: how tides affect the groundwater under our feet

Post from the Conversation, by Gabriel C Rau, Ian Acworth, Landon J.S. Halloran, Mark O Cuthbert

When returning from a swim in the ocean, sometimes it seems as though your towel has moved. Of course, it’s just that the water line has shifted.

The natural rise and fall of the ocean at the beach is an excellent demonstration of gravitational forces exerted by the Sun and the Moon. Although the tidal force is small, it is strong enough to pull regularly on the ocean, making an enormous volume of water rise and fall.

What you might not know is that tidal forces from the Sun and Moon also influence the air we breathe and the solid ground we stand on. These effects are referred to as atmospheric and Earth tides.

While we don’t tend to notice Earth and atmospheric tides, they do affect both the land and the world’s largest freshwater resource located underneath our feet: groundwater. This occupies the pores that exist in geological materials such as sand or soil, much like water in a kitchen sponge.

We have developed a method that incorporates tidal influences to monitor our precious groundwater resources without the need for pumping, drilling or coring.

Water beneath our feet

It has been estimated that groundwater makes up 99% of the usable freshwater on Earth. If all of Earth’s groundwater were extracted and pooled across the world’s land surface, it would be enough to create a lake 180 metres deep.

While this sounds like a lot of water, it is important to remember that not all groundwater is available for use. In fact, groundwater is currently mined on a global scale, especially in drier parts of the world, where groundwater underpins human activities during times of drought.

Groundwater extraction can lead to a downward shift in the land surface level (known as “subsidence”), particularly if groundwater is removed from underground zones that contain soft clays. This is a significant global problem, especially in coastal areas, due to urbanisation and associated water demand.

Alternatively, a long wet period with excess rainfall can cause the groundwater to rise up and cause flooding.

Effect of tides on groundwater

Deeper groundwater buried underneath layers of different types of sediments is under great pressure (in groundwater terminology this is called “confined”). The gravity change from Earth tides squeezes the sediment, and therefore changes the pressure of the water in the pores.

The atmospheric tides add to the weight that is sitting on top of the groundwater and cause a change in stress that results in a downward squeezing.

Groundwater at that depth responds to these stress changes, which can be measured as tiny water level fluctuations inside a groundwater borehole.

We have developed a new approach that exploits these tidal influences to calculate important subsurface properties. For example, this can predict how the pressure is lowered when groundwater is pumped, and by how much the land surface would sink as a result of shrinking subsurface material (just like squeezing a kitchen sponge).

The method basically allows accurate calculation of the compressible subsurface properties from the groundwater response to Earth and atmospheric tides.

This development is significant because it will allow analyses of a subsurface water reservoir (called an aquifer) without human-induced stresses such as pumping or taking physical samples of the material through drilling or coring in addition to constructing a borehole.

All that’s needed for this analysis is a roughly 16-day period of continuous measurements of groundwater levels and atmospheric pressure at hourly intervals.

Groundwater levels are routinely recorded as part of water monitoring programs around the world and in Australia, as funded by the Federal Government groundwater NCRIS scheme. Atmospheric pressure is a standard parameter measured by weather stations, such as operated by the Bureau of Meteorology.

The effects of tidal forces on groundwater might be less apparent to us than their effects on the ocean, but they’re just as important. Our new method of understanding the influence of tides on groundwater significantly reduces the effort to predict the response to groundwater pumping and the potential for land subsidence.

This technique can make passive use of existing boreholes and could be applied to the global archive of groundwater levels to inform more sustainable groundwater resource development in the future.

Monitoring groundwater drought without measuring it

Monitoring groundwater drought without measuring it

Post by Anne van Loon, University of Birmingham

You might remember that the summer of 2015 was extremely dry in large parts of Europe (Figure 1), leading to crop losses, wildfires, drinking water supply deficiencies, and reductions in energy production and navigation (Van Lanen et al., 2016), whether you experienced it yourself or read about it in the newspapers. Based on incomplete information the European Environment Agency already estimates the total economic losses of the event at more than 2 billion Euros (http://www.eea.europa.eu/data-and-maps/indicators/direct-losses-from-weather-disasters-3/assessment).

Figure 1: Media coverage of the 2015 drought in Europe (source: The Guardian)

Seventy-five percent of EU inhabitants depend on groundwater for their water supply, which makes groundwater management extremely important. To manage groundwater effectively during drought periods like 2015, data about groundwater levels are needed in (near-) real time. However, observations of groundwater levels are rarely available in real time, even in Europe, one of the most densely monitored areas of the world.

In a just published paper, we therefore tested two methods to estimate groundwater drought in near-real time (Van Loon et al., 2017). The first method is based on satellite data from the GRACE satellites (Gravity Recovery and Climate Experiment, grace.jpl.nasa.gov), a cool new pair of satellites that measure the Earth’s gravitational field to estimate changes in the amount of water on Earth. Previous research had suggested that the Total Water Storage (TWS) anomalies derived from GRACE could represent hydrological drought (e.g. Thomas et al., 2014). With models the TWS anomalies can be decomposed into their compartments, including groundwater storage. The second method uses a statistical relationship between rainfall and historic groundwater levels, which depends on aquifer properties and has previously been used to study past drought events (e.g. Bloomfield and Marchant, 2013).

To test both methods we looked at the benchmark 2003 drought for two regions in southern Germany and eastern Netherlands. First, we used observed groundwater level data from 2040 monitoring wells to calculate the Standardized Groundwater Index (SGI), which ranges from 0 (abnormally dry) to 1 (abnormally wet) (Figure 2a). Interestingly, the SGI reveals the patchiness of the 2003 groundwater drought caused by differences in aquifer characteristics. Quickly responding aquifer systems experienced drought in response to low rainfall in previous months and slowly responding aquifer systems experienced wetness in response to high rainfall in the preceding year (you might be aware of the 2002 summer floods in the same region). GRACE TWS showed dry anomalies in Germany and (to a lesser extent) in the Netherlands (Figure 2b), but the coarse resolution of GRACE prevents it from picking up the high spatial variability in groundwater levels we saw in the observations (Figure 2a). The groundwater storage derived from GRACE TWS by subtracting surface and soil storage gave abnormally wet conditions in most parts of the study regions (Figure 2c), with drier than normal values only in the eastern part of Germany which in the observations was mostly wetter than normal (Figure 2a). Finally, we calculated a form of the SGI based on the response of groundwater to precipitation (Figure 2d). The spatial pattern of this precipitation-based SGI closely resembles the observed SGI (Figure 2a), although it slightly overestimates the severity of the groundwater drought in Germany.

Figure 2: The 2003 groundwater drought in southern Germany and eastern Netherlands, derived from a) observed groundwater levels (standardised groundwater index, SGI), b) GRACE Total Water Storage (anomalies with regard to the long-term average), c) groundwater anomalies based on GRACE and model outputs (anomalies with regard to the long-term average), and d) observed precipitation and the relationship between precipitation and groundwater levels based on historic data (standardised groundwater index, SGI). Adapted from Van Loon et al. (2017).

We then used the precipitation-based SGI to estimate the 2015 groundwater drought in the same regions (Figure 3). This showed a completely different picture than the 2003 drought. Almost the whole region of southern Germany experienced an extreme drought, whereas the Netherlands was quite wet in August 2015. No patchiness in groundwater levels was observed in 2015, because both short- and long-term rainfall were below average. This means that the 2015 drought was more severe in terms of water resources for drinking water and irrigation because all groundwater wells had low levels, compared to about two thirds in 2003.

Figure 3: The 2015 groundwater drought in southern Germany and eastern Netherlands, derived from observed precipitation and the relationship between precipitation and groundwater levels based on historic data (standardised groundwater index, SGI). Adapted from Van Loon et al. (2017).

Based on our analysis, we think that using readily available rainfall data and the historic relationship between rainfall and groundwater is a cunning way to monitor groundwater drought at a high enough resolution for water management. However, this technique still has more uncertainties than using real-time groundwater observations directly. To prevent issues with drinking water supply for the EU’s 380 million people that depend on groundwater, there is a clear need to measure groundwater levels and make them freely available in real-time.

The scientific paper on which this blog is based can be found here (http://www.hydrol-earth-syst-sci.net/21/1947/2017/).

References

Bloomfield, J. P. and Marchant, B. P. (2013) Analysis of groundwater drought building on the standardised precipitation index approach, Hydrology and Earth System Sciences, 17, 4769–4787, doi: 10.5194/hess-17-4769-2013.

Thomas, A. C., Reager, J. T., Famiglietti, J. S., and Rodell, M. (2014) A GRACE-based water storage deficit approach for hydrological drought characterization, Geophysical Research Letters, 41, 1537–1545, doi: 10.1002/2014GL059323.

Van Lanen, H. A. et al (2016) Hydrology needed to manage droughts: the 2015 European case. Hydrological Processes, 30: 3097–3104. doi: 10.1002/hyp.10838.

Van Loon, A. F., Kumar, R., and Mishra, V. (2017) Testing the use of standardised indices and GRACE satellite data to estimate the European 2015 groundwater drought in near-real time, Hydrology and Earth System Sciences, 21, 1–25, doi: 10.5194/hess-21-1-2017.

 

Musical groundwater?

Musical groundwater?

Post by Kevin Befus, University of Wyoming

I don’t mean to get your hopes up, but keep them up there. I’m not talking about recording the sonorific excitement that is groundwater flow. And, I’m not talking about the squeak of a pump handle, the gurgling of a spring, the grumble of a generator, or the roar of a drill rig. Rather, I want to share with you some songs that reference groundwater in one capacity or another, though references to specific capacity have yet to be found. Groundwater might not be photogenic …more discussion to follow, but is it musical?

For the last couple of years, I have been amassing a playlist of songs that reference water (well, ever since I discovered how perfect “Once in a Lifetime” by the Talking Heads was for motivating me during graduate school…in my opinion, there is no better song to listen to before hitting submit on that manuscript or grant for good scientific mojo). Sifting through a couple hundred songs that sometimes only marginally use water to metaphorize the human condition, I have honed the list to an ordered version of what I consider “The best/only groundwater songs”:

1) Once in a lifetime – Talking Heads
See previous post for a thorough run down

2) Water of Love – Dire Straits
A yearning for water/love, deep underground and hard to find. Let’s hope for some recharge to elevate the water table and maybe even support the river’s running free.

3) Cold Water – Old Time Relijun
Warning, this song is different, but it is about groundwater and wonderfully so. “Cold water going down…through the roots, through the mud, through the rocks, through the ground, through the sand, through the Earth and all the land”. Talk about groundwater flow and potential recharge! It’s also cold, fitting the gross expectation that groundwater near recharge areas is cooler (in regional flow systems at least) than further along the flow system.

4) I am a River – Foo Fighters
They find a groundwater system that thinks it is a river beneath a subway floor…a classic case of mistaken identity.

5) Hallelujah Band – Eilen Jewell
“I climbed down underground
to listen for a new sound
found a river underneath our feet
dark and silent, deep”

Sounds like a quiet unconfined karst groundwater system to me.

6) You Don’t Miss Your Water – Otis Redding

7) Cool Water – Sons of the Pioneers (later sung by Johnny Cash, Joni Mitchell, and others)

8) Water in a Well – Sturgill Simpson

9) Water – Jack Garratt

10) Our Lady of the Well – Jackson Browne

11) Crow Jane – Skip James (also Derek Trucks Band)

12) Well Run Dry – Phat Phunktion

My musical explorations have taught me love is like water. Groundwater? Maybe, depends on its amount, depth, and quality. Wells can be the source of good and bad waters, and we can have some say on whether it’s one or the other. These songs and others (that don’t reference groundwater specifically) bemoan or extol love/water, which comes or goes and can be so uncontrollable.

Groundwater can also be a source of contemplation. Water underground is often interpreted as “silent” (in both “Hallelujah Band” and “Once in a Lifetime”), but springs are allowed to burble and gurgle. So long as we have saturated conditions in a simple single-porosity system, I would bet the groundwater flow is generally difficult to hear. But remember, groundwater is under pressure (atmospheric, hydrostatic, or otherwise) and “wants” to break free (Queen references…couldn’t help myself), especially when in confined aquifers.

There is at least one more way groundwater systems can invoke contemplation. Back before powered pumps, drawing water from a well took time, and that time could be used to think through the triumphs and trials of life. Maybe that’s one reason why groundwater hydrologists are often excited to get into the field.

Quick aside, San Diego has recently started a music festival called GROUNDWATER, where modern house music is the theme. I have not yet sifted through their performers’ lyrics in search of water references, but I would gladly take your help. Words may be in low concentrations.

Join my musical adventures in groundwater and share your finds with us in the comments below!

For your hydrogeological musical pleasure:

feature image: IAH Netherlands Chapter

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