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Global Groundwater Sustainability – A Call to Action… do you want to sign?

Global Groundwater Sustainability – A Call to Action… do you want to sign?

I am excited about a new initiative called “Global Groundwater Sustainability: A call to action” that was first drafted at the recent Chapman conference in Valencia, Spain.  Overall, we are a global group of scientists calling for action to ensure groundwater benefits society now and into the future, and hope that you would like to join us by signing.

You can see the statement, list of signatories and and sign on groundwaterstatement.org. We already have over 80 signatures from ~20 countries with representatives from the major international groundwater organizations (IAH, NGWA, IGRAC, IWMI etc.) and leading academics and practitioners. As a global group of scientists, practitioners and experts in groundwater and related fields, we call for action to international and national governmental and non-governmental agencies, development organizations, corporations, decision-makers and scientists on three action items:

  • Action Item 1: Put the spotlight on global groundwater sustainability
  • Action item 2: Manage and govern groundwater sustainability from local to global scales
  • Action item 3: Invest in groundwater governance and management

Please sign and distribute in a timely fashion since we are preparing for press releases likely in December. We humbly recognize that many of you, influential actors in the science and policy of groundwater sustainability, were not able to be present for the drafting of the above statement but we hope that you will support this initiative since we recognize the importance of needing to act as a group of groundwater scientists and practitioners including diverse voices from across the world.

Please share widely by email to your personal networks as well as via blogs and social media using #groundwaterstatement. If you have any questions, concerns or ideas on how to spread the word, please contact Tom Gleeson tgleeson@uvic.ca .

We apologize for cross-posting but hope you are interested in joining this important initiative.

Groundwater pumping poses worldwide threat to riverine ecosystems

Groundwater pumping poses worldwide threat to riverine ecosystems

Post by Inge de Graaf, Assistant Professor of Hydrological Environmental Systems at the University of Freiburg.


With the climate strikes happening all over the world, I sometimes wish I had a crystal ball that would allow me to look into the future. Or even better, a crystal ball that could show me different scenarios of what will happen if we change, or not.

Well, I do not have a crystal ball, but I do have a global scale hydrological model. I use this model to glimpse into the future and see what will happen to our rivers and streams if we keep pumping groundwater like we do now. Me and my co-authors recently published a paper on this in Nature.

Over the last 50-years strong population growth and economic development have led to a large increase in freshwater demand, especially for the irrigation of food crops. About half of the water used for irrigation is pumped from groundwater. In many dry regions around the world, more groundwater is pumped than recharged from rain, causing water levels to drop. When the water levels drop, the flow of groundwater to rivers and streams will reduce. As a consequence, river flows will decline (or even completely dry up) and water temperatures will rise, forming a major threat to fish and water plants.

In our study, we used a new global-scale hydrological model to investigate how freshwater ecosystems have been, and will be, affected by groundwater pumping. Using the model, I am able to calculate the flow of groundwater to rivers all over the world. This allows me to study how a reduction of this groundwater flow, when it is pumped, impacts river flow.

Our calculations show that almost 20% of the regions where groundwater is pumped currently suffer from a reduction of river flow, putting ecosystems at risk. We expect that by 2050 more than half of the regions with groundwater abstractions will not be able to maintain healthy ecosystems. Our estimates of when and where critical river flows are first reached are presented in Figure 1.

Figure 1. First year critical river flow is reached and aquatic ecosystems are threatened due to groundwater pumping.

The most striking insight is that only a small drop of groundwater level will already cause these critical river flows (Figure 2). Moreover, the impact of groundwater pumping will often become noticeable after years, or decades. This means that we cannot detect the future impact of groundwater pumping on rivers from the current levels of groundwater decline. It really behaves like a ticking time bomb.

Figure 2. Groundwater level drop that causes critical river flows to be reached.

We already see the negative impact of groundwater pumping on river flows in Central and Western United States and in the Indus river basin in Asia. If groundwater pumping continues as it is now, we expect negative impacts to occur in Southern and Eastern Europe, North Africa, and Australia in the coming decades. Climate change will accelerate this process.

Although seeing the consequences of groundwater pumping on the environment globally is rather shocking, I am still optimistic about the future. I hope we can raise awareness on a slowly evolving crisis. A reduction of groundwater pumping will be the only way to prevent negative impacts, while at the same time, global food security should be maintained. Groundwater should be used more sustainably. It is important to develop more efficient irrigation techniques worldwide and experiment with crops that use less freshwater or can live in salty water.

If you would like to read about this research of mine in more detail, read my publication Environmental flow limits to global groundwater pumping.

I conducted this work with my co-authors Tom Gleeson (University of Victoria), L.P.H. (Rens) van Beek, Edwin H. Sutanudjaja, and Marc F.P. Bierkens (all form Utrecht University).

de Graaf, I. E. M., Gleeson, T., (Rens) van Beek, L. P. H., Sutanudjaja, E. H. & Bierkens, M. F. P. Environmental flow limits to global groundwater pumping. Nature 574, 90–94 (2019).

Groundwater and a ‘green drought’

Groundwater and a ‘green drought’

Post by Andy Baker, professor in the Connected Waters Initiative Centre at UNSW Sydney, Andreas Hartmann, assistant professor in Hydrological Modeling and Water Resources at the University of Freiburg, and Romane BerthelinPhD student in Hydrological Modeling and Water Resources at the University of Freiburg.


Here in New South Wales (NSW) in southeastern Australia, a long-running drought continues. The government’s water minister Melinda Pavey noted recently that “This drought is more severe than NSW has ever experienced” and some of the worst in living memory. Almost all the state of NSW is suffering from drought, according the NSW Dept of Primary Industries, with some regions predicted to run out of water by November.

Almost a year ago, one of us (AB) wrote about the relationship between groundwater and drought, concluding that a groundwater drought had commenced across much of New South Wales. We noted that flooding rains were needed to generate some river recharge, to replenish our groundwater resource. It hasn’t happened. But, in many places, the landscape is green, and the term ‘green drought’ is now being used. What is it?

Wellington, NSW. August 2019. This is the UNSW Research Station, normally stocked and cropped, but not in 2018 or 2019.

Before answering that, we will quickly explain some groundwater terminology. Firstly, recharge is the process by which water reaches, or ‘tops up’, an aquifer. The two main types of recharge are ‘river recharge’, where water leaks from the base of a river, lake or reservoir and into the groundwater system. The other is ‘rainfall recharge’ which occurs when the water holding capacity of a soil is exceeded, allowing the downward flux of water. Quantifying the relative contributions of river recharge and rainfall recharge is not easy. For example, groundwater levels measured in bores or wells would be determined by one or both of these processes, plus of course any other non-climate factors such as groundwater abstraction.

So how does this relate to a ‘green drought’? Well, the term is being used because in some regions there has been enough rainfall for some shallow rooted vegetation to grow. In farming regions, a ‘green drought’ can specifically refer to the fact that fields look green, but the colour comes from weeds and other undesirable plants. When you see extensive green weeds across the landscape they reflect that there is another environmental problem – a paucity of recharge heading towards the aquifer. This rainfall can penetrate the soil profile, but only to a limited extent before the water is taken up by plants or evaporates back into the atmosphere (both process together are called evapotranspiration). In a ‘green drought’, none of this water penetrates deeper parts of the soil profile; there is not enough rain to saturate the soil and generate either a downward flux of water from the soil profile (often called deep drainage) or surface runoff to rivers. The groundwater recharge drought continues.

Here in the Central West NSW we have some excellent data to show exactly what is going on. At a karstified limestone site we have been simultaneously measuring rainfall, soil water storage and recharge events expressed by cave drip waters since April 2018. All part of an international network to characterize karstic recharge and evapotranspiration.

On the surface, Andreas Hartmann downloads data from the network of soil moisture probes at Wellington, New South Wales. 25 meters underground, loggers record when water reaches the cave.

Since April 2018 we have had only one recharge event recorded in the cave. This occurred in October 2018 and was after 50 mm of rainfall on one day (5 October 2018). No other rainfall events have generated recharge at the monitoring site since April 2018, despite many rain days with much lower rainfall amounts. The frequency histogram of daily rainfall shows this:

Since the start of 2018, there have been just over 100 days where 10 mm or less of rain has fallen. Some of this rain will have contributed to vegetation growth and the greening of the landscape. But only one day had enough rain to generate rainfall recharge.

What about the soil moisture? The probe network shows that the highest water content of the soil occurred after the October 2018 rainfall event, the same one that led to the only recharge event. However, there are also many other rainfall events that increased the soil water content, but did not lead to recharge. This increased soil water can be utilized by vegetation, leading to a greening of the landscape.

Hence the term ‘green drought’. However, as our monitoring network shows, this green drought is also a groundwater drought. The date when water will run out, or ‘Day 0’, is approaching for some towns. The drilling of new ‘emergency bores’ to tap groundwater are planned to help maintain water supplies in drought affected regions. Let’s hope for groundwater recharging rainfall events soon. Our monitoring at Wellington, NSW, shows how much rain is needed and how rarely such events occur.


Andy Baker is a Professor in the Connected Waters Initiative Research Centre at UNSW Sydney. His research interests include the study of unsaturated zone hydrological and geochemical processes in karst. Find out more at his personal webpage www.bakerlabgroup.org
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
Romane Berthelin is a PhD student in the Hydrological Modeling and Water Resources at the University of Freiburg. Her primary field of interest is karst hydrogeology. In her PhD, Romane is collecting soil moisture data and soil water isotopic profiles at five representative sites across the globe.

Shedding light on the invisible: addressing potential groundwater contamination by plastic microfibers

Shedding light on the invisible: addressing potential groundwater contamination by plastic microfibers

Post by Viviana Re, researcher at the University of Pisa in Italy. You can follow Viviana on Twitter at @biralnas.


Until recently, the topic of plastic pollution was relatively unknown to the general public, although the problem was already under everyone’s very eyes.

Indeed, plastic pollution has become one of the most debated issues over the last few years, in some cases even overshadowing the concerns about climate change, and with particular concern about the effects of microplastic (i.e. plastic particles smaller than 5 mm in length) in the natural environment.

First reported in the early 1970s in the Sargasso Sea of the North Atlantic, microplastics have since become a ubiquitous pollutant found in fish and marine animals, table salt, beer, and even drinking water.

Screenshot of LITTERBASE’s Online Portal of Marine Litter (https://litterbase.awi.de/litter).

In parallel with raising awareness (and concern), this emerging issue prompted the scientific community to advance the understanding of the presence and potential effects of microplastics on natural ecosystems and human health.

As a result, the number of studies addressing microplastic pollution in surface water is rapidly increasing, ranging from case studies assessing the presence of these particles in a specific surface water body, to investigations on their possible toxicity, to proposed methodology regarding qualitative and quantitative assessment of their occurrence.

However, despite this growing body of literature, there is a component of the water cycle that remains less considered: groundwater. In fact, so far, only a few studies targeting microplastic occurrence in groundwater have been published (e.g. Bouwman et al. 2018; Mintenig et al. 2019; Panno et al. 2019). Further, only recently was the presence of microscopic plastic fibers in tap water from underground sources revealed. Thus, a great challenge for the international hydrogeological community lies in addressing the potential for groundwater contamination by plastic microfibers. In particular, the key challenges to be addressed are:

  1. The determination of microplastic occurrence in groundwater and, if present, to assess transport mechanisms in different aquifers.
  2. An assessment of the role of microplastics as carriers of contaminants within aquifers.
  3. To define a standardized procedure for microfiber sampling and monitoring in groundwater.

 

In order to complement the existing knowledge on microplastic contamination of aquatic environments, all issues should be tackled in collaboration with surface hydrologists, biologists and scientists already active in the filed.

Additionally, while doing so, we should also engage firsthand and be part of the solution, hence reducing as much as we can the production and release of plastic and microplastic. Don’t know how to start? Consider joining the recently concluded (but annually run) Plastic Free July challenge!

This post is based on a recently published paper:

Re (2019). Shedding light on the invisible: addressing the potential for groundwater contamination by plastic microfibers. Hydrogeology Journal. Open access

A do-it-yourself Jupyter notebook to constrain sediment permeability

A do-it-yourself Jupyter notebook to constrain sediment permeability

Post by Elco Luijendijk, Junior lecturer in the Department of Structural Geology and Geodynamics at Georg-August-Universität Göttingen and WaterUnderground founder Tom Gleeson (@water_undergrnd), Associate Professor in the Department of Civil Engineering at the University of Victoria.


Most of the groundwater on our planet is located in sedimentary rocks. This is why it is important to know how easy or hard it is for water to flow through pores in sediments, which is governed by permeability. Unfortunately, permeability is extremely variable. Wouldn’t it be great if we could estimate permeability based on sediment types (for which a decent amount of data exist)?

Enter the 150+ year challenge to estimate the permeability of sediments with universal equations. Most of the equations work well for one sediment type, such as pure sands or clay. For instance, the Kozeny-Carman equation from the 1920s tends to work well for most granular materials such as sand or silt. However, pure sands or clays are rare, and most of what’s out there are mixtures.

Evaluating how well existing and new equations work for mixed sediments is tricky business. Searching high and wide only three datasets with 78 samples were found that contained all the required information (grain size distribution, clay mineralogy). Needless to say, more data are needed to improve the predictive equations. In a paper published a few years ago we found that in most cases, the permeability of the sediments could be estimated in a two-step process:

  • calculate the permeability of clay and granular (sand/silt) components, and
  • calculate the permeability of the mixed sediment by taking the geometric mean of the two components weighed by the clay content of the sediment.

The resulting workflow was published as a series of equations that are not particularly easy to work with. That is why we recently decided to take advantage of the general awesomeness of Jupyter notebooks to publish a do-it-yourself notebook to calculate permeability on GitHub (https://github.com/ElcoLuijendijk/permeability_notebooks). For those of you new to Jupyter notebooks: these are documents that contain a readable mix of text, code, data and figures and can be used to publish studies in such a way that you can reproduce the analysis and make the figures yourself (much like R Markdown).

The Jupyter notebooks to calculate permeability consist of a main notebook and additional notebooks to calculate the specific surface area of sediments. Also included are all the calibration datasets Jthat were compiled for the publication. You can use the data to evaluate how well the permeability equations match these datasets, or you can set up a new spreadsheet with data from your own study area which can then be used by the notebook to calculate permeability. The notebook automatically generates several figures like the one below (Figure 1).

There is also an additional notebook that calculates first-order estimates of permeability from well log data collected by geophysical tools that map the density or water content of sediments. Such well log data can be more widely available than detailed sediment records and may help estimate permeability for the deeper subsurface (>100s of m), where permeability data are generally scarcer than at the surface.

Comparing these datasets and equations with the Jupyter notebooks highlight the gaps in quantifying permeability. These notebooks and datasets are out there for the world, so join the effort to make more accurate predictions of permeability (and groundwater flow) in sediments!

Figure 1: Figure produced by the Jupyter notebook showing measured vs calculated permeability using an example dataset of mixed natural sediments.

 

Urban water underground: How green infrastructure makes it visible

Urban water underground: How green infrastructure makes it visible

Post by Theodore Lim, assistant professor of Urban Affairs and Planning at Virginia Tech. He researches the socio-hydrology of green infrastructure planning and implementation.


In order for people to care about something, to value it, they have to be able to see it and experience it. This point should not be taken lightly. So much about decision-making and policy-making depends on how much public support can be organized around any given issue. So, when it comes to protecting the water resources that sustain society and the natural environment, it is perhaps unsurprising that groundwater is the part of water cycle that most folks tend to ignore.

Historically, urbanization has made it difficult for residents to experience key parts of the water cycle. In Philadelphia, for example, in order to improve sanitation, reduce flooding, and make way for the regular street grid, dozens of streams were channeled into brick sewers that were then buried under roads to make transportation routes more efficient and the city easier to navigate. Today, these historical streams are literally buried underground, and still carry a mix of raw sewage and stormwater runoff, that overflows into neighboring creeks and streams when it rains.

Sewering Mill Creek in West Philadelphia, 1883. Image Source: http://www.phillyh2o.org.

Green infrastructure is an approach to urban water management that reintroduces key parts of the hydrological cycle to the visible urban environment. Green infrastructure can involve surface water, through daylighting streams, but it can also means removing concrete and asphalt, to allow water to trickle slowly into the ground, be soaked up by plant roots, and evaporated back into the air, or to recharge deeper groundwater tables. An example of this is a rain garden, or bioinfiltration facility, which intercepts rainfall with vegetated land, as an aesthetic and low-maintenance alternative to conventional drainage systems.

Bioinfiltration facility installed in a residential neighborhood in Washington, D.C. (Photo by author)

How do urban residents “see” these important elements of the hydrological cycle? One answer is: by their recognizing them as “infrastructures” for modern cities — elements that provide critical services, in addition to environmental amenities. Plants and restored soils are not just “nice to have,” they help moderate surface temperatures, protect water quality, and support biological function. Public investment in street tree planting has been shown to increase pedestrian activity, public health, and property values. Green infrastructure programs in cities can also be integrated with climate action plans, sustainability initiatives, and parks and recreation programs; such programs often attract businesses and residents with their progressive attitudes.

Urban residents can learn about the “ecosystem services” associated with hydrological cycle improvements thanks to scientific signage, infographics, partnerships between  environmental non-profits and community outreach, programs run by municipal water managers (water/wastewater utilities, departments of environmental protection, or stormwater districts). Most of all, residents learn from each other and are more likely to adopt environmentally friendly behaviors when they are surrounded to neighbors who do the same.

Stormdrain art in Philadelphia, designed by children in Philadelphia public schools (Photo by author)

Green infrastructure monitoring and signage in Chicago. Image: https://nextcity.org/daily/entry/chicago-sensors-green-infrastructure-study

Restoring hydrological function within urban areas can be seen as a microcosm of larger-scale environmental policy-making. On the regional scale, “green infrastructure” can refer to the large swaths of undeveloped land in a natural state, or to working lands, such as those used for timber production or agriculture, which all provide critical ecosystem services to society. Environmental planners who work at the state or regional level or with land trust organizations, might use policies, economic incentives, and land regulations to protect these landscapes from low density suburban sprawl or urbanization. However, on both urban and regional scales, the decision-making about land use, management, and development is heavily dependent on co-operation between diverse stakeholders, and relies on a mutual understanding of the value of natural environments for various communities..

Urban and environmental planners tell stories that bring together multiple voices in collaboration.  These stories also give the historical and social context to decision-making around environmental systems, which is vital to ensure equitable outcomes. Unfortunately, despite advances in integrated modeling and the scientific knowledge of complex interrelations between water and society, decision-making still falls back on heuristics and rules-of-thumb. A highly relevant question therefore is: how can we integrate groundwater science into more robust city and regional-scale participatory planning, that is equitable and implementable? The answer will hopefully lead us to a strategy where urban and environmental infrastructures visibly advance the well-being of communities.

Quest for Sustainability of Heavily Stressed Aquifers at Regional to Global Scales: Upcoming Chapman Conference

Quest for Sustainability of Heavily Stressed Aquifers at Regional to Global Scales: Upcoming Chapman Conference

Abstracts are due soon (July 10th) for the upcoming Chapman conference on groundwater sustainability on Oct 21-24, 2019 in Valencia, Spain. Hopefully this will be a rare opportunity where many of the leading people on groundwater sustainability will gather with a shared intention to share, discuss and debate scientific advances and encourage a pivot towards groundwater sustainability.

A range of prestigious invited speakers will provide diverse perspectives on groundwater sustainability. We have limited travel funding from the NSF – priority will be given to US-based students and early career researchers (pre-tenure faculty and postdoctoral fellows). Please pencil this in the conference date and submit an abstract here, and pass this along to anyone who might be interested!

WaterUnderground founder Tom Gleeson is part of the Chapman conference organizing committee and is leading an effort to draft ‘The Valencia Statement and Action Agenda on Global Groundwater Sustainability’. Please get in touch with Tom  if you are interested in contributing!

 

Doing Hydrogeology in R

Doing Hydrogeology in R

Post by Sam Zipper (@ZipperSam), current Postdoctoral Fellow at the University of Victoria and soon-to-be research scientist with the Kansas Geological Survey at the University of Kansas.


Using programming languages to interact with, analyze, and visualize data is an increasingly important skill for hydrogeologists to have. Coding-based science makes it easier to process and visualize large amounts of data and increase the reproducibility of your work, both for yourself and others. 

There are many programming languages out there; anecdotally, the most commonly used languages in the hydrogeology community are Python, MATLAB, and R. Kevin previously wrote a post highlighting Python’s role in the hydrogeology toolbox, in particular the excellent FloPy package for creating and interacting with MODFLOW models. 

In this post, we’ll focus on R to explore some of the tools that can be used for hydrogeology. R uses ‘packages’, which are collections of functions related to a similar task. There are thousands of R packages; recently, two colleagues and I compiled a ‘Hydrology Task View’ which compiles and describes a large number of water-related packages. We found that water-related R packages can be broadly categorized into data retrieval, data analysis, and modelling applications. Though packages related to surface water and meteorological data constitute the bulk of the package, there are many groundwater-relevant packages for each step of a typical workflow.

Here, I’ll focus on some of the packages I use most frequently. 

Data Retrieval:

Instead of downloading data as a CSV file and reading it into R, many packages exist to directly interface with online water data portals. For instance, dataRetrieval and waterData connect to the US Geological Survey water information service, tidyhydat to the Canadian streamflow monitoring network, and rnrfa for the UK National River Flow Archive.

Data Analysis:

Many common data analysis tasks are contained in various R packages. hydroTSM and zoo are excellent for working with timeseries data, and lfstat calculates various low-flow statistics. The EcoHydRology package contains an automated digital filter for baseflow separation from streamflow data.

Modelling:

While R does not have an interface to MODFLOW, there are many other models that can be run within R. The boussinesq package, unsurprisingly, contains functions to solve the 1D Boussinesq equation, and the kwb.hantush package models groundwater mounding beneath an infiltration basin. The first and only package I’ve ever made, streamDepletr, contains analytical models for estimating streamflow depletion due to groundwater pumping. To evaluate your model, check out the hydroGOF package which calculated many common goodness-of-fit metrics.

How do I get and learn R?

R is an open-source software program, available here. RStudio is a user-friendly interface for working with R. RStudio has also compiled a number of tutorials to help you get started!

Other Useful Resources

Louise Slater and many co-authors currently have a paper under discussion about ‘Using R in Hydrology’ which has many excellent resources.

While not hydrogeology-specific, there are many packages for generic data analysis and visualization that will be of use to hydrogeologists. In particular, the Tidyverse has a number of packages for reading, tidying, and visualizing data such as dplyr and ggplot2.

Claus Wilke’s Fundamentals of Data Visualization book (free online) was written entirely within R and shows examples of the many ways that R can be used to make beautiful graphs.

Update on the groundwater situation in Cape Town

Update on the groundwater situation in Cape Town

Post by Jared van Rooyen, PhD student in Earth Science at Stellenbosch University, in South Africa.


When the Cape Town water crisis first emerged it took almost a year before active contingencies were put in place. Four major ideas were proposed: (1) Intense water restrictions for municipal water users, (2) greywater recycling facilities, (3) groundwater augmentation of water supplies, and (4) desalination.

Although not all the proposed ideas came to fruition, there was a significant increase in the installation of well points and boreholes for municipal and private use. The national and provincial governments began the investigation and development of three major aquifers in the Western Cape. Unfortunately (or fortunately), the initial estimates for extraction were never realized as a result of poor water quality in the Cape Flats aquifer, power struggles between government parties and typical delays in service delivery in South Africa. In contrast, private groundwater consultants are benefiting from the high demand for groundwater use by residents installing private wells to alleviate the pressures of stringent water restrictions.

There are now two plausible scenarios for the groundwater use situation in the Western Cape: either we have not yet begun to abstract any significant amounts of groundwater, or we lack the data to show if we have. It is difficult to provide empirical evidence on whether groundwater levels are indeed declining and if it is a result of the drought (or abstraction or both). The trouble is that, unlike surface water storage where we can see the direct evidence of the drought, how much water is in an aquifer cannot be directly observed and must be estimated via an indirect method.

Estimating changes in groundwater availability usually requires detailed baseline data to be available, meaning that the state of a resource is relative to the baseline data available and can be over/underestimated as a result. One example of this was the subject of a controversial string of news articles released in the first months of 2019.

The Department of Water Affairs (DWS) released an interactive map of monitoring boreholes across South Africa which includes a record of normalized water levels (0% being the lowest measured water level in meters above sea level (masl) and 100% the highest measured water level) averaged over a province (Figure 1) . The graph shows a decline in average water levels in the last three years, but the record only goes back to 2009 and it is difficult to say if this a drought signal, a result of abstraction, or simply a natural fluctuation over a longer timescale.

Figure 1: Plot showing the severity of groundwater levels in the Western Cape of South Africa, averaged groundwater levels are plotted as a normalized percentage of the lowest and highest recorded levels in the borehole history. Credit: NIWIS DWA South Africa

Respected researcher and geochemist Dr. Meris Mills investigated historical data from the national groundwater archive and found that much of the data before 2015 were too sparse to be considered representative of the groundwater level. Data density and availability still is a major limiting factor in groundwater studies in South Africa.

Dr. Mills found that 55% of boreholes show statistically significant declining water levels and 63% of boreholes recorded an all time low water level after 2015 to late 2018 (since 1978). She concluded that fractured rock aquifers were the least affected and that 37% of boreholes with falling water levels were, in fact, not related to the recent drought. The cause for these declines in water levels are still unknown.

It is still difficult to quantify how much groundwater contributed to the recovery of Cape Town’s dam levels, if at all, but the resultant interest in long term groundwater supply has sparked debate surrounding local groundwater resources.

It is also clear that the effects of the drought on groundwater resources remain to be fully realized, however our groundwater, in general, is more resilient to change than we may think. Depending on the angle you look at it, initial findings may either indicate that groundwater is potentially a lifeline to cities crippled by a water supply crisis, or a time bomb with a delayed fuse.

Data sharing: an update on new and existing initiatives

Data sharing: an update on new and existing initiatives

Post by Anne Van Loon, Gemma Coxon, and Bentje Brauns.


Last year, Anne Van Loon wrote about data sharing initiatives in hydrology (“Data drought or data flood? 28 May 2018). This post gives an update on existing and new initiatives.

CAMELS (Catchment Attributes and MEteorology for Large-sample Studies) 

The CAMELS datasets are expanding: from the United States and Chile to Great Britain and Australia.  The CAMELS-GB dataset will consist of hydro-meteorological timeseries and catchment attributes for 671 catchments across Great Britain and is expected to be released on the Environmental Information Data Centre later this year.

The Groundwater Drought Initiative

The Groundwater Drought Initiative is collecting more and more groundwater level data and groundwater drought impacts. The Initiative is very happy to welcome new partners and supporters from as far East as Ukraine and as far South as Albania, increasing the number of participating countries and countries currently considering to participate to 23 (see map). Additionally, a first getting-to-know-each-other & info meeting was held at EGU19 with participants from Austria, Belgium, Canada, Estonia, Germany, Latvia, Luxembourg, Netherlands, Norway, UK, Ukraine, and Switzerland. If you are from Bulgaria, Greece, Hungary, Italy, Romania, Slovakia or any of the other yellow countries on the map below and you have groundwater data (or contacts in organisations who could help) or you are interested in groundwater drought, please contact Bentje Brauns (benaun@bgs.ac.uk).

The IAHS Panta Rhei Working Group on Large Sample Hydrology

The IAHS Panta Rhei focus on efforts to facilitate the production and exchange of datasets worldwide.  This year at EGU, the group organised a splinter meeting to discuss the generation of large sample catchment datasets in the cloud and a session (HS2.5.2 Large-sample hydrology: characterising and understanding hydrological diversity) that showcased several recent data- and model-based efforts on large-sample hydrology from new global datasets to large multi-model ensembles.  If you are interested in being updated on the activities of the group then please contact Gemma Coxon (gemma.coxon@bristol.ac.uk) to be added to the mailing list.

There seems to be a lot going on in the world of hydrological data sharing! To share your own story or initiative, please leave a reply below.



Anne Van Loon (website | @AnneVanLoon) is a Senior Lecturer in Physical Geography  in the School of Geography, Earth and Environmental Sciences at the University of Birmingham.

Gemma Coxon (website) is a Postdoctoral Research Associate and Lecturer in Hydrology in the School of Geographical Sciences at the University of Bristol.

Bentje Brauns (website) is a Hydrogeologist at the British Geological Survey.