I say ’aquifer’ and she says ‘groundwater’ … Let’s call the whole thing off… (with apologies to Ella Fitzgerald & Satchmo)

The distinction between the aquifer and the groundwater it contains is helpful.
One purely “aquifer” issue is the soil compaction that can follow years of excessive abstraction, reducing the capacity of the aquifer to store groundwater. Parts of the high plains in the US have subsided by ten metres or more as a result.
Equally worrying (though I’m not sure if this is an “aquifer” or a “groundwater” issue, as water tables fall, more and more potential recharge is stuck in the expanding unsaturated zone, so that recharge rates are reduced.

And finally... it’s Ella, not Ela

Traditionally laws (both national and international) have focused on groundwater, albeit all too often inadequately. Influenced in part by Dr. Puri, the International Law Commission in drafting its "Draft Articles on the Law of Transboundary Aquifers," shifted the focus, as the title indicates, from groundwater to aquifers. As a result, the draft articles came up short. Despite repeated attempts to gain endorsement from the UN General Assembly, the Assembly has declined to embrace the draft articles. I would suggest that the major problem is that the focus on aquifer management to the exclusion of groundwater management is the major reason for this. While reminding us of the importance of aquifers in groundwater management, the draft articles simply fail to address adequately the need for integrated, conjunctive, and effective management of water. Aquifers, rock and soil that contains groundwater, is more or less stationary and leads to an emphasis on sovereignty as in the draft articles. Water is constantly in motion and is by its nature a shared resource over which notions of sovereignty don't go very far in developing appropriate policies. Compared to the international law applicable to transboundary watercourses, the draft articles could at best be termed retrogressive. We must simply not forget that what we are concerned about in managing groundwater/aquifers, and in the law governing that management, is the water.

Indeed a valuable observation that the interchangeable use of groundwater and aquifers has led to challenges in policies and regulation. The tone, however, tends to be moving towards an explanation that seems to highlight the environmental determinism when it comes to groundwater and aquifers. Aquifers and aquifer studies often rely on a set of assumptions without bringing in the context of human engagement with them. The only reference drawn is the water withdrawn from the aquifers. Beyond that, there are an array of engagements that can be termed of hydro-social character that shape the relationships between farmers, communities, groundwater users and aquifers.

For eg. In the peninsular region of India (mostly hard rock aquifer typologies), farmers often rely on certain practices, which have largely emerged locally than being a prescription from hydrogeology or cognate fields. They drill 'horizontal bores' in their large diameter dug-wells, trying to influence the 'geometry' of the aquifers and improving water flows into their dug-wells. This seemingly common sensical act of attempting to maximise one's water reserves sheds light on the complex human-aquifer relations. To elaborate, the aquifer properties (I guess Transmissivity and Storativity) often make water available for use a variable. To influence this and overcome the 'natural' limitations of the aquifers, farmers adopt the practice mentioned above.

Hence, when policy makers next time design governance norms for aquifer management or regulatory policies for utilising groundwater, there is a need to consider the hydrosocial aspect of such interactions that shape these relations as simultaneously social and natural phenomena. Else, we may start with the 'natural' (what do aquifers tell us) to shape the 'social' (how should people behave) and this linearity of policy making will lead us nowhere, at least in our pursuit of sustaining groundwater.

Would be most informative if WA Forum participants addressed the virtues and defects of IBTs as an alternative to groundwater overdraft and the ensuing urban enviro/infrastructure problems following sometimes-irreversible surface subsidence. Since Mr. Shaminder cited Bangkok, it would be useful to hear his views on the proposed Salween/Thanlwin-Chaophraya IBT now being put forward by Thailand's Royal Irrigation Department.

Further to my raising the Bangkok subsidence problem, see ***** showing the trajectory of surface subsidence in the Indonesian capital Jakarta (population >10 million). Much of the city has already subsided 5 meters, with most of northern Jakarta reaching that status by 2050. The solution now being seriously put forward is to construct an entirely new national capital in Kalimantan, the Indonesian sector of the island of Borneo. This would likely entail quite a problematic shift in Kalimantan's demographics, with the Javanese —the nationally dominant ethnic group— presently less than 9% of Kalimantan's population.

Thank you for your informative blog post! I wholeheartedly agree that the aquifer has been lost in the discussion of groundwater policies. I wrote extensively on this topic in my thesis: https://ir.library.oregonstate.edu/concern/graduate_projects/pn89dd30b.

I argue that we should pursue both a transition from "groundwater" and "management" to "aquifer" and "governance." The switch to aquifer governance means including other interconnected aquifer resources (like groundwater, temperature, biology, pressure, water quality, etc) into a single framework and inclusion of a bottom-up, inclusive governance system.

An example of something like aquifer governance has already been developed in another subterranean liquid resource: oil and gas. The international standard in reservoir governance is unitization, which was developed in the early 1900s in Texas. Unitization is flexible (voluntarily negotiated), includes multiple interconnected resources (oil, gas, brackish water, pressure, temperature, etc), respects existing rights (public and private rights to the resource), and can function in transboundary contexts (many international and offshore unitization contacts exist).

The key issue is unitization is centered on the reservoir's storage space as the "unit" and not the contents. The next step for groundwater, as you identified, is to re-center our focus on the aquifer.

Thank you Shammy and Karen for this interesting piece. I wholeheartedly agree that groundwater science is too distant from policy and decision-making, and that greater understanding of the potential and drawbacks of using groundwater is desirable. But it’s not all bad. For every regulatory failure there is probably an example of innovation in groundwater management, usually driven by wider awareness and experience of past depletion. Groundwater management is tied intimately to the wider political economy with all its competing interests and dynamics, of which groundwater specialists (alas!) are only a small part. In a perfect world "we" would anticipate aquifer depletion and stop it long before it happened - although ironically this would deprive us of one of the best arguments we have for groundwater management, which is being able to clearly demonstrate the consequences of its absence. In the meantime, I'm concerned that we groundwater specialists tend to emphasize the drawbacks of over-abstraction and underplay the world-changing benefits it can provide, and that this emphasis has led to policy-makers filing groundwater under "awkward and contentious" and avoiding it like the plague. Essentially, we can't complain that groundwater scientists are sidelined if we seem preoccupied with how difficult and dangerous groundwater is to use, how much potential conflict it can bring, how easily it is polluted, and how complicated it is to understand. It's also worth reflecting that without broad-based economic development and water infrastructure for all, environmental sustainability and conservation risk remaining largely a preoccupation of an economically advantaged sub-set who rely on the very infrastructure and resources that they caution against. Economic prosperity, enabled partly by water security, also appears to be at least a contributing factor to the development of systems and bureaucracies for environmental management. None of this justifies poor decision making about groundwater of course, nor invalidates problems with over-use and pollution in some parts of the world. But let’s keep the drawbacks of groundwater, and its complexity, in perspective – these tend to diminish when set against the benefits it can bring.

First of all, I would like to thank you for the discussion about the aquifer and groundwater resource. I have read and come to understand that groundwater is highly used when compared to aquifers. There are more difficulties in the management of aquifers over groundwater. This leads to over-exploitation of groundwater resource for agriculture and allied sector of the economy which in turn reduces the groundwater table/level. If it is sustainably happened in the economy, our future generation automatically get affected due to lack of groundwater resource. Some of the research studies recently proved that groundwater level is continuously reducing day by day due to over extraction of groundwater for agriculture and allied sectors of the economy. Thus, aquifers have also to be used efficiently like groundwater resource by the Government. Suitable policy measures have to be taken by Government for the effective management and accessibility of aquifers in order to provide sufficient groundwater resource for the future generation.

The power of terminology indeed becomes clear when one looks at their effects in groundwater governance, as social hydrologists (more precisely: hydrosocial researchers) have shown. In the context of the European Water Framework Directive for instance, the focus on ‘groundwater’ brings with it a definition of ‘good quality’ based on chemical and quantity indicators solely. The ecological functions of aquifers have largely been neglected until recently. ‘Aquifer governance’ may well draw attention to the complex interactions of groundwater and land use. To address these, policy makers need not only be able to refer to the differentiated knowledge on groundwater and aquifers provided by hydrogeologists. Distal effects (e.g. from virtual water flows) play a role. Land and water use practices that affect groundwater are embedded in longstanding traditions and economic framework conditions. Formulating and implementing governance instruments regulating resources and ecosystems that are largely ‘invisible’ and slow in showing effects of management strategies is counterintuitive to political interests and may involve conflicts. Knowledge for improved groundwater and aquifer governance therefore needs to integrate multiple perspectives, disciplines and knowledge exchange at the science-policy interface. Communicating clearly about what we mean by ‘groundwater’ and ‘aquifer’ is crucial; the same is true when we speak of ‘land use’ and ‘governance’ in this transdisciplinary endeavour.

Thank you for the comments and inputs so far. Some very good examples and thoughts are coming forward. To keep the dissensus going, let me try to sharpen and entice the discussion further. The challenge/dissensus we are putting forward relates to how to better contextualize the management and governance of the water-related underground resources. The resources in question (‘aquifer’ and ‘groundwater’) are so closely interlinked that non-specialists struggle to implement appropriate policies. Groundwater would not exist without an aquifer, and an aquifer would not exist without groundwater. So what is the big deal? Well, they are actually two distinct, but interconnected, resources. The aquifer is the storage container (solid porous media, filled or partially filled with groundwater). This ‘space’ is indirectly managed, such that it is optimized for its capacity to store and transmit water at a given time and place and for a given purpose, whether for subsequent abstraction or for some in-situ or downstream environmental purpose.
These targets could be e-flows (or other kind of groundwater-discharge like spring flow), phreatophytic/riparian vegetation, subsidence prevention, or some kind of human infrastructure underground, like tunnels or buildings, or even for mining activities. The indirect management may be through regulations on groundwater levels or pressure, and hence could dictate allowable pumping rates (i.e., managing groundwater utilization), but the main point here is that you implement policy to managing the available storage and transmission of the ‘container’, as the primary ‘objective function’, not the groundwater pumping per se.
A related example is managed aquifer recharge. In these approaches, the management strongly relates to aquifer storage (hence also the terms ‘aquifer storage and recovery’ and ‘water banking’) rather than the management of the groundwater. Here, the recharge is managed to optimize the storage volume, while the ‘water’ component of the exercise relates to the management of the source water for recharging and the use and rights to the stored (new) groundwater. Different, but interlinked, regulations may apply to regulating the aquifer and the (ground)water component of MAR (see e.g. Ward and Dillon (2011)).
The issue of aquifer compaction (subsidence) (given by Chris Perry) and the Draft Articles on transboundary aquifers (given by Joseph Dellapenna) are also items for further scrutinizing. Finally, acknowledging the ‘human factor’ (as mentioned by Dhaval and Fanny Frick-Trzebitzky) (including the interesting example of people manipulating the aquifer storage and conductance properties), as the central means to achieving management and governance goals is central and this cannot be overemphasized. But, this then immediately ties back to our key point that people in charge of regulating groundwater and the actors and stakeholders directly or indirectly involved in e.g. groundwater abstraction or affecting the land surface and land use, need to understand the pathways to sustainable underground resource use and the fingerprint of various actions and regulations – in essence understanding the 'aquifer' and the 'groundwater' components.
I am sure there is a lot to be discussed, and I am looking forward to further feedback. As ‘water security’ remains critical on the global agenda, policy makers and policy implementers should be explicit and clear about how to ensure that those who are so dependent on these resources are not left ‘high and dry’.

Ward and Dillon (2011): https://www.researchgate.net/publication/265271534_Robust_Design_of_Managed_Aquifer_Recharge_Policy_in_Australia

Under the original title of Ella Fitzerland’s well-known song, this discussion is very useful for making the distinction between “aquifer” and “groundwater” and understanding why this is very important. One can probably deduce from the forum’s title that the two terms can be used indifferently to indicate the same thing. Many scientists use the two as synonyms, while others prefer to avoid “aquifer”, focusing only on “groundwater”.
According to the Greek Athenian philosopher Klisthenes, “beginning of knowledge is visiting the word's etymology”.
Aquifer comes from aqui- in Latin aqua "water" and also in Latin –fer (carry). This means that an “aquifer” is a recipient or a water-bearing geological formation that can be unconsolidated sediments of sand or gravel or permeable or fissured rocks.
Groundwater from ground + water is water in the ground and groundwater flow is the water movement in an aquifer.

Most of the time people think that groundwater flows in a water continuum like an underground lake. In fact, groundwater moves within the porous space between solid grains of sand or gravel or in rock fissures or pores. The two-phase groundwater-solid matrix discontinuous medium becomes a hydro-geological continuum at a regional scale, where Darcy’s law is valid. At a local scale, groundwater movement follows the Navier-Stokes equations that have been resolved in a rough porous medium composed of a bundle of cylinders. Laser measurements and numerical simulations at a local scale were able to analyze non-linear groundwater flows when the pressure gradient is strong. See:
https://ascelibrary.org/doi/10.1061/%28ASCE%290733-9429%281989%29115%3A9%281223%29
https://www.witpress.com/Secure/elibrary/papers/HY94/HY94008FU2.pdf
https://click.endnote.com/viewer?doi=10.1002%2Fzamm.19940740808&token=WzMzMzMzNzQsIjEwLjEwMDIvemFtbS4xOTk0MDc0MDgwOCJd.QQr4x1ByMeyo47HxA_bjMDY3TUY
The distinction between aquifer and groundwater becomes vital in the case of multi-disciplinary approaches, such as those of hydro-geological, soil-mechanical, water economical, ecological and legal point of view. Aquifer Governance is different from Groundwater Governance, because in the case of managing an aquifer we should take into account not only groundwater flows in terms of quantity and quality, but also the land use, soil subsidence, vegetation, and other issues related to aquifer geological characteristics.
The distinction becomes crucial when law experts draft policy laws to be legally enforced. In this particular case, it is very important to agree on the correct definition of physical items, like aquifer and groundwater.
According to UNESCO international hydrological glossary:
https://unesdoc.unesco.org/ark:/48223/pf0000221862?locale=en
Aquifer
Geological formation capable of storing, transmitting, and yielding exploitable quantities of water.
Groundwater
Subsurface water occupying the saturated zone

In the 2008 draft articles on the Law of Transboundary Aquifers:
https://legal.un.org/ilc/texts/instruments/english/draft_articles/8_5_2008.pdf
we can read in Article 2:
For the purposes of the present draft articles:
“aquifer” means a permeable water-bearing geological formation underlain by a less permeable layer and the water contained in the saturated zone of the formation;

By adding the groundwater in the aquifer’s geological formation definition, countries should share not only transboundary groundwater but also the aquifer’s geological extend. In this case, national sovereignty issues may prevent neighboring countries to adopt such international law. In future international negotiations I think is necessary to correct the aquifer definition to make clear that managing internationally shared transboundary groundwater doesn’t include internationally shared transboundary aquifers.

As Prof Ganoulis quite rightly point out the principles of hydrogeology have been well set out over the last 70 years and no new discovery has been made that undermines the Darcy’s law under laminar aquifer flow conditions. And as he rightly point out, turbulent flow in fractured aquifers is understood, though not easy to mathematically simulate without a huge amount of field measurements. Having said that, Prof Ganoulis' summary of what our concerns are, as set out in blog above, have not readily been absorbed by policy makers, because, from the generally accessible literature, the distinction between the fluid, and the system that it moves about in, is too blurred. We hear the phrase “groundwater acts as a subsurface sponge for floods” (in https://www.nature.com/articles/d41586-019-03711-0 ). The question here to ask is, ‘does groundwater act as a sponge?’ The physics of groundwater acting as a sponge is unclear – what is clear, is that an aquifer contains pore spaces, into which flood water may be diverted (through sound managed aquifer recharge) – when the pore spaces are unsaturated they may indeed be understood to act as a sponge for any spare water. Imagine the consternation of a non specialist reading such a statement in a journal no less than Nature – and interpreting this to mean that ‘groundwater’ has some rare quality that allows it to behave as a sponge to soak up more water ?!
An equally baffling statement is “Groundwater is key to climate adaptation, serving as a manageable buffer to droughts and water stress.” [italics added] https://www.groundwaterstatement.org/ . In this statement, is groundwater a manageable buffer to drought?? Or is it the storage in the pore spaces of an aquifer that is the buffer? Again a non specialist would be excused for assume that groundwater has some odd value that does not appear in water also found in rivers / lakes and reservoirs.

Why is a need for such clarity essential?

Well, from two instances mentioned above, in the first instance, in order to fill up the sponge, a policy needs to reflect appropriate land use. In the second instance, a policy maker simply understands this to mean that when a drought occurs ‘lets suck up groundwater’ – as a result, what happens once its been sucked up, is not any one's business!

Prof Ganoulis make one other point in relation to sovereignty in transboundary aquifers – I think this has been an unnecessary distraction in the discourse and I will respond to this point more fully in my comments on the point made by Prof Joe Dellapenna's above shortly, and it will be a robust response!

My impression, if I may extrapolate some of the above arguments – hopefully without betraying them -, is that the main misunderstanding is a conception of an aquifer as an underground 'swimming pool' that is replenished and that you can tap as long as you don't 'exceed recharge' : the idea that everything is fine as long as you pump less than the recharge is the most ubiquitous and damaging misconception. And indeed the understanding of the fact that groundwater is (generally) a flow drained to the sea or back to the surface should replace this conception by one whereby any pumping is seen as deemed to have an impact on the appropriators of, or ecosystems dependent on, these outflows (leaving aside the particular case of coastal aquifers and other complexities of the aquifer such as subsidence, etc). Even if this impact may (often) be benign, imperceptible, dampened, delayed, depend on timing, etc. This squarely shifts the perspective. And takes us back to the vexatious groundwater discussion about the 'safe yield'…

This 'recharge fallacy' is extremely widespread, even in the writings of many (ground)water specialists… So the notion of a 'communication gap' should be enlarged to account for these misconceptions, and also for some of the political reasons behind them: the understanding of groundwater as a flow 'does not help'… it prevents you from doing the handy double-accounting that justifies overexploitation, whereby one looks at abstraction, and depletion of the stock, without considering what is lost on the outflow side. In many instances people in charge in the ministry, and sometimes experts, do not want to correct the simplified arithmetic on which their water balances are based because that would 'upset numbers' and reveal that no more water should be pumped, an inconvenient truth politicians obviously do not want to hear.

Thanks to all for the well drafted blog followed by very informative and thought provoking discussion. However, the discussions seems more literal than practical actions. The perception that policy makers have meager understanding of difference between source (aquifer) and resource (groundwater) is not that convincing. Whether called aquifer or groundwater, it is almost conjunctively managed. However management deficiencies and policy flaws deserve consideration.Usage of groundwater is inevitable and its implication would be there. The question is that whether prevailing policies, especially in the developing world, are conducive to mitigate the implications, or otherwise. One example is extensive campaign by the environmentalists against dams which are major source of groundwater recharge in the wake of unavoidable extensive abstraction. Horizontal proliferation of settlements and pavements are further hindering groundwater recharge. Floodwaters are not only huge source of recharge in the active flood plains but also crucial for rejuvenation of their fertility and revitalization of wetlands. Under the disaster risk reduction programs, flood protection bunds are constructed that deprive the otherwise active flood plains from that blessing. The flood dikes also increase flood peaks thereby posing more threat on the infrastructure, property and people downstream. Groundwater specialists are supposed to give their insight and input to counter the implications of such policies and measures.

What an interesting discussion! Thanks to Karen and Shammy for hosting this dissensus.
How comforting to read that we all agree that policymakers need to understand the difference between managing an aquifer and managing groundwater and that groundwater can no longer be viewed as a magic, inexhaustible solution to unsound management of surface water. I would like to add another wrinkle to the exchange of ideas -- how should offshore aquifers containing fresh groundwater be managed? Some of the same concerns exist -- subsidence, enviro damage from abstraction (drilling rigs), over-dependence -- and the transboundary governance issues are also similar, since nations have exclusive sovereign rights over natural resources in their continental shelves. If a nation possesses part of a TB aquifer, does it own the groundwater in proportion to the portion of the aquifer in its territory? I would argue yes in theory, but the practice may be problematic. When development of these vast resources finally arrives, nations with TB offshore aquifers will probably utilize unitization/joint development mechanisms that have been honed over decades by the offshore hydrocarbon industry. Is that better than the law of capture that applies to onshore aquifer development, where the one with the most wells in the aquifer gets to capture as much water as possible? I would argue that collaborative extraction reduces conflicts, but probably doesn't serve to preserve the resource for future generations.

We are now coming to the end of this Dissensus. We appreciate all the thoughts and contributions it has sparked, and we have been impressed by the extent of interest and commentary that has come in. We, as the initiators (Shammy and Karen) have collated, and would like to put forward some thoughts on what the discussion brought out.

There is a consensus that the terms aquifer and groundwater each express and define complementary, but not synonymous elements about the solid and the liquid phases of the subsurface environment. There is also some consensus that we need to work towards a clearer distinction in policymaking. Examples mentioned by commenters were interesting and refining our conceptualization An interesting observation is the hydro-social angle, exemplified by users (usually non-scientists) overriding the natural aquifer’s properties through radial horizontal shafts in a low yielding wells for maximizing the yields, thus creating an issue not explicitly addressed in current policies.

An astute observation made is that ‘science is too distant from policy and decision making’ that we wholeheartedly agree with, and add, that it is the ‘science in academia’ rather than the practical and applied science that might be the culprit. As noted in the discussion, at times the consequences are that policy makers place this 'business' into the “awkward and contentious” category, with a perfect excuse ‘lets do nothing for now’. In the same line of reasoning, the vexatious issue about ‘safe yield’ has been mentioned. As correctly pointed out, so often the arithmetic on the water balance is simply wrongly done - either due to double accounting, or due to discarding one of the variables, with the excuse that field measured data is not available. We have noted that in some very detailed ‘water resource systems’ models, with multiples of variables in them – the ‘groundwater term’ is just lumped in with the error term! Why? we ask. As also pointed out in the comments, there are (groundwater) specialists who unintentionally contribute to the confusion.

A very interesting point has been made in the statement…”The perception that policy makers have meager understanding of the difference between source (aquifer) and resource (groundwater) is not that convincing.” We believe that there is a very urgent need to run a semi-quantitative surveys of the world’s policy makers to test out the thesis we have put forward in the Dissensus, namely that misconceptions in the terminology have led to policy failures. Please look out for the next steps in this to be taken by us (Shammy & Karen), soon.

However, in the comments that all floodwaters, if dammed, provide groundwater recharge, reinforces the concern we expressed in the blog. Firstly, in arid and hyper-arid areas, too many dams just turn out to be no more than evaporation ponds! Secondly, accretion to groundwater storage can only occur if the dam chosen is on a permeable aquifer outcrop. If it is on tight bedrock, there is no likelihood of 'recharge'. Herein lies the problem – the unsuspecting policymaker believes: “flood water plus dams = groundwater recharge”. The policy maker has not been briefed instead, that “modified land use management of the aquifer outcrop, plus infiltration gullies, plus modest recharge ponds, plus targeted improvements in soil fertility WOULD improve aquifer recharge”, though over time. One can see why the policy maker would put this into the "think about this later" basket!

Important complementary lessons that seem to emerge from our Dissensus evolve around:

1. Groundwater is still not properly understood by decision makers, let alone the distinction between the terms groundwater and aquifer, and the importance of considering both explicitly in management. Also, the ignorance may extend to a convenient excuse for not addressing the sustainability issues of the groundwater resources in an evidence-based way, as it may entail difficult/political choices and regulation challenges, in particular with respect to less obvious ‘stakeholders’ like the often disregarded or misunderstood recipients of groundwater discharge, such as freshwater ecosystems (rivers, lakes) or coastal zones, often called groundwater-dependent ecosystems, on which biodiversity and poor people typically depend.
2. There are management questions around groundwater and aquifers that are tied very closely to each other, e.g. the problem of subsidence where groundwater pumping has an impact on the aquifer properties. A similar example is where costal saltwater intrusion degrades the aquifer to a point where it is very difficult to revert, due to the slow release of salt from double-porosity systems, The latter example is again linked to abstraction, and similarly affects the aquifer properties with respect to withholding/releasing freshwater. The extended temporal aspects of impacts on groundwater and aquifer systems is indeed of particular importance, as also highlighted. A third good example is the manipulation of the aquifer properties by humans (like the horizontal bores in an existing well), to increase yields. This is the opposite direction, i.e. users affecting the aquifer thereby affecting the abstraction levels. Getting these aspects into proper management requires good attention to integrated issues.
3. There were also links to wider physical interphases to consider, beyond the groundwater-aquifer dichotomy. Here the obvious ones were the link to surface water (e.g. how inter-basin transfers may alleviate groundwater depletion), the particular issue of transboundary aquifers, and even transboundary freshwater aquifers found in the continental shelf, and the link to other sub-surface resources, like fossil fuel, heat energy, etc.
4. There were a number of references to the importance of giving clear weight to the ‘management’ or involvement of stakeholders in groundwater and aquifer management, as disregarding this issue could lead to intractable solutions.
5. Another associated lesson may be that hydrogeologists need to bring evidence to the policy makers in the correct shape and form (hitting a balance between making groundwater/aquifer issues simple or complex enough to act upon), and in a timely and relevant fashion. Another point may be that stakeholder involvement increases the ‘evidence base’ for both hydrogeologists and policymakers.
6. Equity issues were brought forward as an argument for concerted development of groundwater for poverty alleviation, and for combatting economic water scarcity, even at the expense of some groundwater depletion, as the lack of groundwater development would entail continued disparity in the access to the resource. This would likely be correct, if the groundwater development agenda, where the resource is still available in good supply, like in parts of sub-Saharan Africa, was driven by these goals, and not primarily by larger-scale users, which may capture disproportionate shares of the benefits.
7. Finally, there was the distinction between groundwater management and aquifer governance. We may want to leave this hanging. There may be some drive towards this. However, if we look across the issues prevailing, in terms of achieving sustainable outcomes for the natural systems and resources tied to the sub-surface, and here in particular freshwater resources, it may be safe to argue that both the groundwater and the aquifers need governance, and approaches that integrates a vision on both.

In closing, we would like to thank the Editors (Francois and Doug) for facilitating this Dissensus, which has resulted in a fruitful debate. We acknowledge the likelihood of divergence in opinions, as is the point of a Dissensus. Hence, should you still want to reflect on or be part of an ongoing debate, feel free to contact Shammy or Karen.