Review: Humble Pi

I got this book after hearing the author (Matt Parker) a few times on various podcasts. Its perspective is captured in the subtitle: “when math goes wrong in the real world.”

The book is a page turner, moving crisply (and humorously*) from one disaster to another.

In most cases, problems arise from conversion errors (metric to imperial), mistakes in formulas (dividing by zero), disagreements on starting points (you’re “zero years old” until you’ve been alive 365 days?), misusing software (Excel is nota. database!), or things going on for longer than expected (the clock runs off a cliff). The resulting problems are sometimes funny but sometimes deadly.


This is a common theme in human progress. We make things beyond what we understand, as we always have done. Steam engines worked before we had a theory of thermodynamics; vaccines were developed before we knew how the immune system works; aircraft continue to fly to this day, despite the many gaps in our understanding of aerodynamics. When theory lags behind application, there will always be mathematical surprises lying in wait. The important thing is that we learn from these inevitable mistakes and don’t repeat them.

And then we can turn from making mistakes and learning from them to the situations where marketers are deceptive (“McDonalds: We have 6,000 meal combos!), where the “average person” doesn’t actually exist (just like the average height of a point between Mt Everest and sealevel is not 4424m high), where what we see now is not what was once there (survivor bias), or where scammers or attention seekers claim big significance in spurious correlations. For example:

If you love numbers and hate the people that abuse them, then read this book. FIVE STARS.

*This was in the end notes: “Charlie Turner fact-checked the crap out of the book and all remaining errors are hilarious jokes I’ve demanded be left in”

Here are all my reviews.

How Annecy’s Lake got so pure

Leo writes*

Annecy is a city in eastern France whose lake and vibrant colours attract tourists from all around the country. Boasting a modest population of around 120 000 people, Annecy is a small city with seemingly not many problems in regard to water (Wikipedia). The main attraction is its lake “Lac d’ Annecy.” Often called the blue lung of the region, Lac d’ Annecy helps with droughts and other water issues (Annecy Lake saves local ski station from drought).

This has not always been the case, as the lake’s water was not always so clean. In the last century, the lake was overwhelmed with water demand from growth in development and population (Barraqué, 1986).

When the lake’s water was initially used in 1908, water quality was good enough to forego treatment (Barraqué, 1986). But quality started to deteriorate in the “entre-deux-guerres” (interbellum) period (Barraqué, 1986), as waste waters were discharged into the lake (Le Dauphine). Numerous carnivorous fish species started to disappear — notably the famous Omble chevalier.

After the liberation of France in 1945, growing industry and tourism increased water demand as well as pollution (Barraqué, 1986).

It was only ten years later that the alarm was rung in face of the dire situation. Charles Bosson the maire of Annecy at the time, expedited the complete renovations of sewer systems and water treatment for all municipalities around the lake (Barraqué, 1986). A new syndicate was created in order to address water quality, the SILA (Intercommunal Syndicate of Annecy Lake) which still exists to this day (Le Dauphine).

A completely new system was designed: a collection belt around the lake brought waste water to Annecy for treatment. This solution, although more costly for Annecy spread the costs and benefits of the new system between the communes of the lake. For the scale of the town at the time, this construction was massive: 47km of collection pipes, 190 km of new sewer pipes and a new purification facility (Barraqué, 1986). All for 2,275 billion French francs or the equivalent of 350 million euros today (Le Dauphine). With the system’s completion in 1976, water quality improved (Le Dauphine). Today, Lake Annecy has a reputation as the purest and cleanest lake in Europe.

Bottom Line: The modernisation of Annecy’s water management systems permitted its transition from a polluted body of water to one of Europe’s purest lakes.

* Please help my Water Scarcity students by commenting on unclear analysis, alternative perspectives, better data sources, or maybe just saying something nice 🙂

Valencia’s flood escape?

Bodil writes*

Valencia is known for its recurrent floods, with the first documented one occurring in October 1321. Since then, the city has experienced nearly 80 devastating floods over the years, caused by excess rainfall overwhelming the soil’s capacity to absorb the water fast enough. The river Turia, which runs through the city, brings death and destruction. The most impactful flood occurred in October 1957, when hundreds of people died, and three quarters of buildings were destroyed by waters rising five meters over their normal level. Something needed to be done to prevent such disasters from happening again (Valencia International).

Spain’s dictator Franco promised funding to reconstruct the city. Plan Sur proposed to divert the river around the city, and 16 years after the disaster, the Turia River was running 3 km south of Valencia for 12 km over a 175m-wide river bed (Caroline Angus).  The old river bed, now one of the biggest city parks in Europe (the Turia Gardens), is full of life and activities.

Map of the re-routing of the Turia

To regulate their waters, Valencia created reservoirs in case of drought and water escape routes in case of floods. Although the project might seem extreme and expensive, it is a necessary precaution to save lives and prevent the need for constant rebuilding. However, there are still very big quantities of water falling into this region, leading to a high risk of flooding. The 2022 record saw 260 mm of rain falling in 24 hours, with 2023’s record being about 150 mm in 24 hours. Considering that it rains on average 45 days a year and the annual rainfall is a bit less than 500 mm, this is a huge amount of water in just a few days.

In comparison, London receives approximately 600 mm of rainfall annually, yet it is known for experiencing a lot of rain as it rains approximately 112 days a year.  We would expect a bigger difference in mm, this shows just how immense the quantity of water that falls on the Valencia region in a day is. Even though the infrastructure has improved with the creation of immense storm drains, there are still many incidents of people getting trapped in their vehicles and houses getting flooded every year. In September 2023, there were already 30 severe incidents of flooding reported. Valencia’s greatest challenge is fighting drought for most of the year and then dealing with immense bodies of water that fall all at once.

Bottom Line: Valencia, a city going to extreme measures to keep the rare and great quantities of water out of the city.

* Please help my Water Scarcity students by commenting on unclear analysis, alternative perspectives, better data sources, or maybe just saying something nice 🙂

Crisis in the Caribbean

Melle writes*

St. Maarten is a beautiful holiday destination for many. With its alluring beaches, fantastic nightlife, many attractions and of course the crystal-clear ocean surrounding the island, it seems like a surreal place to a lot of visitors.  Unfortunately, its true nature does not match its promise of paradise. It faces many challenges, such as hurricanes, political instability, economic hardships, and infrastructural failures. And at the moment, it also faces an unforeseen challenge, namely a billing error within the one and only drinking water company.

GEBE is the sole supplier of drinking water on St. Maarten. They buy water from the three desalination plants (owned by Seven Seas Water) and transport it to their storage tanks.  From there, the water is brought to households through pipes that criss-cross the island.

GEBE’s pricing is progressive, meaning the more you use the more you pay: “If a household uses 3 cubic meters of water, they are charged NAF 2.50 per cubic meter, an additional 7 cubic meters will then cost them NAF 5.50 per cubic meter while anything over that amount will cost the customer NAF 6.00 per cubic meter.”  To put this into perspective, NAF 6.00 is equal to approximately 3 euros. This might not seem a lot, but 3 euros is a lot for most of the population, and it is in general a lot for a cubic meter of water.

Besides this “choice” from the drinking water monopolist GEBE, customers can get water from rain (not readily available), discharges (not drinkable), or bottled water (crazy expensive).

Since March 2022, GEBE has been issuing correct bills to only 50% of its customers due to a “cyber event that disrupted its computer systems”. To the other 50%, they have sent nothing or incorrect bills. GEBE has given limited explanations and has decided to “solve” the problem by sending all bills since March 2022 at once. Customers who have not paid anything for 18 months now face massive charges.

To make matters worse, the different water pricing mechanisms are not taken into account when merging the bills. Normally, if customers use 3 cubic meters of water, they will pay less per cubic meter than if they used 10. But this concept is completely ignored with merging.  Instead, GEBE’s customers pay the top price for every cubic meter of water they used over the past 20 months. For the 19% of locals living below the poverty line, this is simply not possible.

Bottom Line: Many of St. Maarten’s residents face a billing (or payment) crisis due to GEBE’s mistake and a “solution” that is causing financial pain for everyone, but especially the poorest.

* Please help my Water Scarcity students by commenting on unclear analysis, alternative perspectives, better data sources, or maybe just saying something nice 🙂

Toulon’s flood alert: erosion risk

Ness writes*

Le Gapeau is both the name of a river and a watershed in the south of France, Toulon, dominated by forests around its slopes, and urbanization and agriculture at the bottom of the watershed towards Hyeres (Rollet et al, 2022).

There is currently a sedimentary deficit in le Gapeau mainly due to extractions of granulates and sand that has been taking place since the 19th century. These “massive extractions” do not consider the dynamic nature of the rivers (SAGE, 2022). Between 1859 and 1986, measures were taken to reduce extractions, but illegal and “authorized” extractions continued. In 1966, the construction of the Hyeres airport used so much sediments that the river’s banks destabilized, reducing water quality and water retention. The government did not acknowledge those impacts, and information on them can only be found by talking with those who live by the river (riverains); there is no information on the internet (Capanni, 2022).

Nowadays, in the Golfe de Giens, a strong deficit in sediment is observed now of around 1 to 3 meters in 73 years, and in the rade d’Hyàeres, a natural zone classifies as a “Special zone of conservation,” erosion is important especially in the seasonal periods due to tourism (SAGE, 2022). Despite all of the above, it must be noted however that climate change exacerbated these issues regardless of human management, since increases in temperature increase the likelihood of storms, leading to even more erosion (Capanni, 2022). This affects the capacity of the water body to store water, leading to potentially water scarcity issues.

Extractions are not the only reason for sedimentary deficits. The presence of dams and weirs is argued to influence fluvial morphology. For instance, a definite issue causing presence was an anti-salt dam constructed in the 1970’s. This dam caused contamination of groundwater as well as siltation, which is the deposition of fine sediments, which now and in the future decreases the storage capacity of the river (Capanni, 2022).

Erosion has a direct impact on an already existing issue; the value of riparian areas. They are essential for the correct workings of the watercourse, they filter pollution, and habitat many species (SAGE, 2022). Farmers and riverains rely on these forests yet they do not care enough for them, which exacerbates issues of sedimentary changes as erosion degrades the health of these areas.

Flooding is especially exacerbated by this issue of deficits in sediment. The flood plain of Cuers drains le Gapeau and le Réal Martin, which are both main rivers of Le Gapeau watershed. There are sedimentary repositories in these plains, and during rain periods, flood plains are more likely to overflow (see image below) since they have a lower water holding capacity due to less sediment, which can also lead to erosion.

The floodplain of Cuers at the intersection between le Gapeau and Réal Martin. Source: Capanni (2022)

Bottom Line: Humans have taken too much sediment and erected too many barriers on Le Gapeau, thereby increasing flooding, lowering water quality, and harming ecosystems. Climate change will only worsen these impacts.

* Please help my Water Scarcity students by commenting on unclear analysis, alternative perspectives, better data sources, or maybe just saying something nice 🙂

Interesting stuff

  1. Watch how amazing octopuses are!
  2. Watch “South Park The Streaming Wars” for an excellent farce on water rights (and mismanagement) in Colorado.
  3. Analyze the changing energy sources of our electricity. (The Dutch are probably the worst in Europe, and NL is certainly worse than the US!)
  4. Read: Gonzo right-wingers may destroy the US government’s administrative capacity (if the Supreme Court agrees). Wow.
  5. Read How the Feds bounced Binance
  6. Read “What happened after my wife and I removed Wi-Fi from our home” (their lives got better — and a marriage was saved!)
  7. Read how the natural gas industry keeps expanding its market share (and thus GHG emissions) with “bridge to sustainability” promises lies.
  8. Rhinos for sale? Good. Profit incentives can beat poachers.
  9. Holy fuck. The World Coal Association has rebranded itself as “FutureCoal: The Global Alliance for Sustainable Coal.” Matt Levine is hilarious on this (while also highlighting ongoing ESG fraud laziness):
    We talked a few months ago about a company called GreenSaif Pipelines Bidco, which is Saudi Aramco. I mean, it isn’t really; it’s a special purpose vehicle that owns some Saudi Aramco pipeline joint ventures and that sold some bonds to finance them. The bonds found their way into an index of environmental, social and governance investments, because technically they were not bonds issued by an oil or pipeline company (bad ESG) but by an investment company (good ESG, or at least neutral). Even though “Pipelines” is right in the name. But “Green” is in the name first. If you were an extremely careless ESG investor — and it is arguably rational to be an extremely careless ESG investor? — you might look at that name, see the word “Green,” stop reading before you got to “Pipelines,” and buy the bonds. I guess.
    Anyway here’s coal:

    The World Coal Association has rebranded itself as “FutureCoal: The Global Alliance for Sustainable Coal,” Chief Executive Officer Michelle Manook said at a press conference in Delhi.

    “For too long our global coal value chain has allowed anti-coal sentiment to dominate and fragment us,” Manook said in a statement. That’s “resulted in a lowering of the global coal IQ,” which the group defines as an understanding of coal’s contribution to society.

    “Lowering of the global coal IQ” is a magnificent bit of marketing and I lost several points of (regular) IQ just by reading it. But presumably the point here is that some investors, activists, governments, etc., are going to see that name and read “The Global Alliance for Sustainable” and figure “ah well that’s good then” without getting to the word “Coal.” I suppose starting with “FutureCoal:” is a mistake? Really they should put that off as long as possible. Call it “FutureGreen: The Global Alliance for Responsible, Sustainable and Clean Energy Derived From Natural Resources Such As Our Favorite Resource, One You Might Have Heard of, It’s a Really Good One, You’re Not Going to Believe This, Get Ready, It’s Coal.” No one’s gonna read that far.

H/Ts to MM and TB

Infrastructure Incapacity: Caracas

Isabella writes*

One would not expect to see a country ranked in the top 15 worldwide with the most freshwater resources (WorldAtlas, 2018) to also be one where 82% of the population does not continuously receive water (Reporte Nacional, Octubre 2018). Yet this is the case with Venezuela, and many of its issues manifest in the capital: Caracas. Though not the only aspect to blame, the capital’s ailing water infrastructure clearly explains this shocking statistic.

The Tuy System and its subsystems–Tuy I, Tuy II, and Tuy III–bring water to Caracas (“Trasvases en América,” 2023), which is then distributed by the public utility Hidrocapital (McMillan, 2020). Tuy I and Tuy II are both operating at half of their functional capacity (“Dealing with a Water Crisis and a Pandemic in Venezuela – Interactions between Water Security and COVID-19,” 2020), and this lack in productivity is exacerbated by the frequent blackouts the entire country experiences (McMillan, 2020). As Caracas is in a valley, it lacks its own local water sources, hence the Tuy System must pump water from sea level to approximately 2000m in altitude. Caracas is highly dependent on this electric pumping system which requires maintenance to function — and maintenance is lacking.

This absence can be attributed to a lack of institutional capacity (Rendon et al., 2019), which encapsulates corruption, brain drain, and a lack of funding. There is no way for procedures to be effectively monitored, enabling corrupt practices and the deterioration of the water system (Rendon et al., 2019). It is estimated that this malpractice causes losses of around 5400 litres of treated water per second in the distribution systems–this is not only negative for the residents who are unable to receive water, but the water sector themselves, who are losing money in the process (Reporte Nacional, Octubre 2018).

Regarding the actual approaches to improving maintenance, we run into another issue: brain drain. About 15% of the country’s population has fled since 2015, including many of the specialists needed to operate, maintain, and improve the water system (Rendon et al., 2019).

How can the systems be rebuilt without the necessary knowledge? Short answer: they can’t.

To further add complexity to addressing these issues, it must be noted that sanctions make it hard for Caracas to import replacement parts for repairs. Running an inefficient system functioning at half its capacity puts a larger strain on the parts, thus damaging the system more rapidly and therefore requiring even more maintenance–it is a never-ending cycle (McMillan, 2020).

There have been several initiatives to rationalize infrastructure and improve operations, but these have been delayed by budget shortfalls and project design changes. Some infrastructure investment agreements were even made with strategic partner countries, however decreased public oversight has fostered an environment fit for corruption and rushed decisions, ultimately leading to “white elephant infrastructure projects” (McMillan, 2020).

These issues with the water system are indubitably cause for concern, as they ultimately result in further problems: increased waterborne diseases (“Urban Water in Venezuela“), exacerbated effects on the already crippled public health system, and further social disparities, as barrios receive less water than urbanised areas (“Dealing with a Water Crisis and a Pandemic in Venezuela – Interactions between Water Security and COVID-19,” 2020). Therefore it is pertinent that the water systems be corrected–but that is much easier said than done.

Bottom Line: Caracas’s water system is consistently and rapidly depleting due to a lack of institutional capacity. Brain drain, corruption, and failing government systems have led to a near impossible situation to address in the water sector, yet it is most important that it be addressed quickly. More and more citizens lack access to safe, clean water — and there is no solution in sight.

* Please help my Water Scarcity students by commenting on unclear analysis, alternative perspectives, better data sources, or maybe just saying something nice 🙂

Where did all the water go?

Celine writes*

Dublin, the vibrant capital of Ireland, is facing a pressing issue that often goes unnoticed by its residents: water scarcity caused by an alarming leakage rate in its aging water supply infrastructure. Every day, a staggering 37% of treated water is lost through leaks before it reaches the taps of Dubliners (Uisce Éireann, formerly Irish Water). The labyrinthine network of pipes beneath the city poses a challenge in identifying and addressing these leaks, as many of the pipes are old and damaged (The Irish Times 2020).

In 2018, the national leakage rate was 46%, but there is hope on the horizon. By the end of 2022, Dublin had managed to reduce the leakage rate to 37%, and ambitious plans are underway to achieve a national leakage rate of 25% by the end of 2030 (Uisce Éireann 2023). Despite this progress, the city’s water supply system faces intense pressure due to factors such as population growth, construction activities in the city center, and the natural deterioration of aging pipes (Kelly-Quinn, Mary, et al. 2014)

The roots of Dublin’s water infrastructure issues trace back to the Victorian era, particularly in the city center (Kelly-Quinn, Mary, et al. 2014). Many of these pipes, constructed in an age when leaking was an afterthought, now stand as potential hazards, especially lead pipes compromising the quality of drinking water (Kaur, Jasmine, and Aoife Gowen 2020). The recent surge in demand exacerbates the strain on an already beleaguered system, and while some improvements have been made in leakage management and water conservation, the system lacks the redundancy needed to weather increasing demands.

Some of the structural fragility of these pipes finds its roots in the history of Irish water charges. In a bid to provide equal service to all citizens, water in Ireland used to be free (Kelly-Quinn, Mary, et al. 2014). However, this seemingly noble policy led to unintended consequences. The absence of charges during cold spells prompted homeowners to let taps run continuously, resulting in short-term demand spikes and a significant decrease in water supply (Kelly-Quinn, Mary, et al. 2014). Additionally, the lack of a profitable business model hindered funds for maintaining water infrastructure, explaining why many aging pipes remain untouched.

Although water charges are now in place, the task of replacing old pipes remains a challenge (The Irish Times 2020). Dublin is currently grappling with the repercussions of severe winter cold spells that expose buried pipes to frost, causing numerous bursts and for example leaving around 40,000 consumers without water (The Journal 2023). Once again this crisis is exacerbated by the prevalence of deteriorating pipes, emphasizing the urgent need for infrastructural upgrades and heightened water conservation awareness.

This extreme water loss is becoming a larger issue due to climate change, as more frequent droughts challenge water supplies (The Irish Times 2020). Additionally the city’s growing population exacerbates the strain on the water system, demanding sustainable solutions to ensure a resilient and reliable water supply for the future (The Irish Times 2022). With these challenges in both supply and demand, it appears that Dublin is aimlessly losing vital water in its pipes.

Bottom Line: Dublin’s journey to overcome water scarcity and leakage requires a combination of infrastructure upgrades, water conservation efforts, and a collective commitment from its residents to use water more responsibly. The pursuit of a sustainable water future for Dublin is not just a necessity; it is a shared responsibility for the well-being of the city and its inhabitants.

* Please help my Water Scarcity students by commenting on unclear analysis, alternative perspectives, better data sources, or maybe just saying something nice 🙂

Can Brussels rely on imported water?

Solène writes*

Belgium is ranked 23rd out of 164 countries with water stress exposure by the World Research Institute, meaning that it is the third country in Europe facing the most important water scarcity []. Knowing that it rains between 150 and 200 days per year, it is difficult to imagine that the country faces water issues. However, the water is not allocated equally throughout the country.

Indeed, the natural environment has an important role in the way people have access to water. First, Brussels lies at a lower elevation than the surrounding region of Wallonia. Moreover, it also rains more in the south of the country than in the north. Finally, the ground composition is different depending on the North or the South as Wallonia’s ground tends to collect and keep the water. In addition to those natural environment dispositions, as Brussels is the biggest city in Belgium, its area is superpopulated and urbanised, and its most of its surface is impermeable — compared to 15% in  Wallonia []. Furthemore, Brussels doesn’t have a river big enough to sustain its water consumption. That’s why the capital is dependant on Wallonia concerning its water supply [].

In order to satisfy the water needs of the country, a collaboration between Vivaqua, the company in charge of conveying the water in Brussels and the Société Wallone de Eaux (Company of the Wallonian water) has been set up in order to extract enough water from the Meuse as well as from Wallon aquifers. Wallonia provides 97.4% of Brussels’ water.

With the summers becoming drier because of climate change, stress about water becomes more important in the North, impacting the South because it depletes aquifers at a rate that is not sustainable.

Moreover, in order to limit its economic dependence on Wallonia, Flanders decided to take more water from the Albert Canal, which links Liege and Antwerp and is a major economic axis. In drought periods, this action could involve a decrease in the water level which could impact negatively economic activities that depends on it[].

In the years to come, as scarcity will become a bigger issue, we can then expect more tension between the two regions. However, as Belgium lies in the heart of different international basins and has to find means to cooperate with different countries. We can hope that the different regions will be able to work together [].

Bottom Line: In Belgium, water management is stressed by climate change as it becomes scarce. The question is: are the different regions going to help each other and share the resources or is it going to create more tensions?

* Please help my Water Scarcity students by commenting on unclear analysis, alternative perspectives, better data sources, or maybe just saying something nice 🙂

Water scarcity AND abundance

Ezra writes*

One might think: what is a Dutch city like Dordrecht doing on a blog about water scarcity? The city sits on an island in the Rhine Delta and is literally surrounded by water!

Dordrecht’s long history is inevitably connected with water, which has given it prosperity and sorrow. Now, the next stage in its history will be marked by a lurking crisis: water scarcity in its abundance. This blogpost will provide a short overview of the recent developments surrounding the drinking water problems in the Netherlands with a particular interest in Dordrecht’s paradoxical situation.

In 2021, the Dutch Waterschappen (Water Boards) and drinking water companies (DWC) called for a renewed view on water: water policies were reaching their limits and water quality and quantity already were under pressure. The Waterschappen appealed to the newly forming government to create a climate-robust water-system plan. The Netherlands is renowned for its water drainage strategy but must change this into a water retaining strategy because of reoccurring droughts. Up until then, the government had not paid attention to this developing crisis, since its priorities were elsewhere.

The year after, multiple concerning reports were published. One report, published by Deltares, warned the water sector about the degrading quality of the Meuse and the decreasing water availability. Deltares found that “in all researched climate scenarios […] longer periods of low discharge” will eventually occur, endangering the drinking water supply. In these periods of low discharge, the river is also extra vulnerable to heavy pollution, therefore raising risks for 7 million people — including the inhabitants of Dordrecht. According to the drinking water company Evides, outdated pollution permits have to be updated and the enforcement has to become more strict. The low discharge does not only affect drinking water, it also affects local agriculture, shipping, and industry. It, furthermore, causes salination of the soil and the rivers, according to Geert Slijkhuis (via personal interview) of Waterschap Hollandse Delta. The Waterschap has to keep the groundwater level high to avoid subsidence in the city. Preferably, they use fresh water since agrarians also use the land. However, it occurs more and more that they have to use salt and polluted water, thereby affecting the soil quality.

Another report, published by Vewin (Vereniging van Waterbedrijven) and later backed up by the RIVM (Rijksinstituut voor Volksgezondheid en Milieu), proved that if changes were not made quickly in the DWC drinking water shortage would occur before 2030. This has to do with several things: degrading water quality, decreased water supply, and steady increases in population, economic growth, and urban areas. Both also emphasised the dangers of multiple bottlenecks in the purification process and storage. To solve these problems the DWCs need to find alternative water sources, regulations and permits have to be expanded, and investments need to be secured for new production, purification and distribution possibilities.

Bottom Line: Scarcity does not only occur when there is an absence of a particular commodity, it also occurs when the commodity, in this case water, is made or becomes more unsuitable for its purposes. In the case of Dordrecht, water is abundant, but a scarcity of usable water is starting to develop, due to a decrease in the quantity and quality of the Meuse’s water, bottlenecks in the purification process, and an increase in, among others, population. If future governance is not changed, this process will only be accelerated.

* Please help my Water Scarcity students by commenting on unclear analysis, alternative perspectives, better data sources, or maybe just saying something nice 🙂