Lost Water

Apologies for the total lack of posts in the last month. I will soon be finally posting the final part of my commentary on the Californian drought, but in the meantime I'd like to draw attention to this news story, based on the research presented in this article.

This new research suggests that human water use is up to 20% bigger than we previously thought. It is an interesting study, as most in this field have been based on national statistics and global scales models, whereas this research actually used real data from 100 river basins around the world. The reason for this increase is suggested to be human water management practices leading to greater evapotranspiration of water. Irrigation increases evapotranspiration, dams and reservoirs have the same effect as a result of increasing the surface area of water. Dams and reservoirs also raise groundwater levels, which means water is available to more plants compared to an unmanaged state, leading to more evapotranspiration.

Clearly, there is still a large lack of specific knowledge on this subject, but this synthesis of data is clearly an important piece of work. Understanding the size of the fluxes of water within the hydrological system are key for planning sustainable water usage.

California is Nuts

Last week, we looked at the fact that California has been in serious drought for the last few years, and touched on the implications this has for groundwater in the region. We also saw that the drought in California has been caused by a simple lack of rainfall. This week, we going to examine the drought a bit more detail, and focus on a key issue - farming.

I mentioned last time that water is important in California, because it has a lot of people and big urban areas like Los Angeles and San Francisco. However, in general, farming is the biggest water user in California. California is the breadbasket of the USA for fruits, vegetables and nuts. For some things, California pretty much single-handedly supplies the whole USA:

Credit: MotherJones

The drought map in this figure is out of date, and things are worse now (see last weeks post for the full picture), but it does aptly make the point that drought is a big issue for the USAs consumption of of some food products. Broccoli and walnuts are the worst offenders (this is some kind of culinary crimewatch) in terms of the water needed per 'unit' - 5.4 gallons are needed for one head of broccoli, and 4.9 gallons for one walnut.

Nuts are the most water draining, as so much water is needed for so little (one head of broccoli is a lot more than one walnut!).  Interestingly, almonds are the worst offender.

Credit: MotherJones

Almonds have become huge business - they are one of the lowest risk investments in the world, as their are so expensive and the price is unlikely to fall. As a result, more and more farmers in California are shifting to almonds and other tree nuts, simply because of their value and investment potential, and increasing demand from China. So, all the almonds produced in California need three times more water than all Los Angeles homes and business'. This really isn't just a theoretical idea - the Central Valley of California (the area that produce almonds) is the driest part of California, and has had the largest changes in well groundwater levels:

Credit: MotherJones

Again, a slightly outdated figure, but the picture it paints still applies. The Central Valley has been massively over-pumped, as nut orchards just keep expanding. Californian law is currently pretty lax on groundwater usages, to the extent that farmers can just drill into the ground and claim the groundwater as there. California is trying to change this, by managing access to all aquifers, but these rules wont come into effect for six years, and there is no way they will be an 'instant fix' - they are still weaker laws than many other Western states, and groundwater works on long, long timescales. Unsurprisingly, farm groups (and likely, the investors that back them) have not been too pleased to say the least, but their vested interests seem to be far less important than California's groundwater problem. 

So - California has got a bit of a problem on it's hands. Next week, we'll look at whether the drought is related to climate change, and if it is ever going to end.

Californication

There are approximately 196 countries in the world (political differences mean that not everyone recognises the same amount). California, just one state of 50 in the United States of America, has a population greater than all but the 34 most populated countries in the world - a population greater that 132 countries in the world.  Such a population requires a lot of water, particularly a resource hungry 'western' population, with huge urban areas like Los Angeles and San Francisco that have big water requirements. Unfortunately, that water simply hasn't been there - for the last four years, California has been gripped by drought. In April 2014, 100% of California was classed as being in drought, for the first time in at least 15 years:

It is notable that central southern USA were also in drought at the time. However, as the most recent picture shows, this area of the USA has recovered well.  However, for the Pacific Coast, there has been no recovery. In California, things have gone from bad to worse, with the majority of the state classed as being in exceptional or extreme drought:

Clearly, this is a difficult situation. The severity of the drought has necessitated implementation of the first mandatory water restrictions in the history of the state in April 2015, cities and towns being told to reduce consumption by 25%. Encouragingly, it was reported that Californian cities cut their water usage by 31.3% in July 2015, exceeding the mandatory water restrictions, rising steadily per month since the implementation in April 2015.

This is all very well and good - but why has California been in drought? Unsurprisingly, it is the simple matter that there has been a lack of rainfall. This has been caused by a persistent high pressure area over the Northeast Pacific Ocean, which has deflected winter storms and prevented them from depositing precipitation on California.

As a result of this lack of rainfall, California's reservoirs are nearly empty - in March 2015 it was estimated that there was one year of surface reservoir water left. This has lead to the use of an alternative source of water, particularly by agriculture: groundwater. Groundwater is a useful resource to have in dry times, but it takes a long time to be replenished once used. Nearly 75% of freshwater is now coming from groundwater in California, as there simply isn't enough surface water. This is a problem - if too much groundwater is used, and it runs out, it will take a very long time to replenish again. California needs to avoid using too much groundwater, but that is not easy when there is little rainfall - both surface water and groundwater stores are not being replenished.

Back in the Cycle

I haven't posted anything on this blog since January this year (I was busy finishing a degree), but I am going to be restarting the blog. Previously, the content had been very focused on climate change and river discharge, but it is my aim to expand the blog to cover the whole topic of climate change and water management.

With climate change ready to be debated by the world at the 2015 UN Climate Change Conference in Paris (also known as COP21), we are moving into an crucial period of potential political action on climate change. The conference aims to achieve a binding and universal agreement on climate change from all nations of the world, something which has proved impossible in the previous 20 years of UN negotiations - such an achievement would represent a defining moment in the 'fight' against climate change. I personally find it unlikely such an agreement will be reached, as there are some nations that still do not wish to engage with climate change (due to self interests, not doubt in the science), but I would be very happy to be proven wrong. The global political climate (pun not intended) appears to be far more suitable for such negotiations than the tense failure that was Copenhagen 2009, but nobody has entered the debating chamber yet. However, there are already concerns that anything agreed is likely to keep us below the 2C 'danger' threshold.

 

Water is a part of the hydrological cycle (see Fig 1), which hopefully is hopefully familiar. In simple terms, it is a big circle of water - water evaporates from the sea into the atmosphere, condenses and falls as precipitation, and makes its way back to the sea both on and within the ground. This is of course a gross simplification, but it is enough to make the point that all of these different parts of the cycle will be affected by climate change. This could lead to a variety of impacts, including droughts, floods, pollution, erosion, changes in water availability, just to name a few. Clearly, these are important impacts that could have a significant impacts on both humans and the environment. I hope to explore the different impacts in detail over time in this blog.

Hoping to aim for weekly posts, but obviously this will vary - sometimes more posts than once a week, sometimes less! 

Fig 1 - The Hydrological Cycle. | Credit - USGS.

Mouth

I’d like to use this final post to reflect on my blogging experience, and draw up a few conclusions. Over the last 3 and a half months, I’ve thrown a huge amount of information at this blog, on a subject I am extremely passionate about. While all of the posts have all come under a blanket of the effect of climate change on discharge and runoff, some have had a very individual theme – as such, it would be nice to conclude the messages I’ve been trying to get across, in a simple form.

1. Anthropogenic forcing of climate is altering the hydrological cycle as a whole. Patterns of rainfall and evaporation will change in differing way around the world. As such, there also are changes in discharge and runoff around the world.

2. While they are not perfect, environmental models have a lot of value. They allow us to attempt to predict the future, and in this case model how discharge may change around the world. It is not an exact science, and there is much uncertainty, but these models certainly have great scientific value, and will only improve.

3. Management of rivers and their surrounding areas has to change in the face of these expected changes in discharge and run-off, whether an increase or decrease. We must stop altering channels from their natural state, constructing hard engineering projects and the urbanisation of floodplains. Riverine environments have a certain natural capacity to adapt, but we are not allowing them the chance.

4. These changes are not just a matter of a bit more or a bit less water. Resultant floods and droughts could have serious consequences for both humans and ecosystems around the world.

5. This is not a problem to leave to consider into the future. We have to act now if we want to be able to adapt to possible changes in the future. Ideally, we need to reduce emissions to reduce the anthropogenic forcing of climate, but we also must start to put management strategies in place for the most at risk places.

6. Hydrology and environmental modelling are incredibly exciting areas of research that are essential for understanding the future of our earth.

I hope that the blog has been somewhat informative, and has presented a fair discussion of the science I have discussed. Writing this blog has been an enjoyable experience, and something that I have really grown to love doing over the last few months, and it is certainly something I intend to continue doing in my own time. Initially writing these posts was difficult and uncomfortable – I’ve never blogged or written in a ‘popular science’ style before. I am all the better for doing so as a person though; dense academic prose has its place, but it is writing in a clear, engaging and concise manner that matters most – science exists to be communicated freely.  As I’ve progressed, I’ve very much enjoyed putting these posts together and writing about something I have a passion for.  My own opinions on the subject have also developed over the last few months, from middle of the road to more impassioned about the importance of changes to discharge and the hydrological cycle of a whole.

I might be taking a break from blogging for a while, but rivers are still flowing, and our climate is still changing. We as humans have the chance to put right and prepare for the mistakes we have made. I just hope we end up doing so, or else risk getting caught in the flow.

La La Land

There has been a lot of academic content in this blog, so I’d like to take the opportunity here to write a post that is more based on my own opinion. Just before Christmas last year the BBC published an article talking about the Los Angeles River.  The LA River is a huge artificial concrete river channel that is designed to stop LA from flooding during high flows by moving water away from the city quickly, and discharging it into the Pacific Ocean. The arguments to return parts of the river to a more natural setting, but these have been countered by hydrological worries, suggesting that changes in rainfall extremes forced by climate change could cause large scale flooding of LA.

I should make it clear from the outset that I am not a fan of brutal hard engineering strategies to control river systems. They are a relic of an unfortunate period of history where many rivers were managed by over-zealous engineers with buckets of concrete in hands and calculators in their pockets. It is unsurprising to see that the voices singing the praises of the LA River in this article are from the Nasa's Jet Propulsion Laboratory, lording over ‘the particular design, the angle, the slickness of concrete’. The flood prevention characteristics of the channel are important - but this brutalist design is certainly not the only method of preventing flooding, and does nothing to address the large water shortages in LA, a city that is piping in water from as a far away as the Colorado River (which is drying up)! It will cost money, but some naturalisation of the channel has to occur to restore LA’s parched aquifers, even if this just involves diverting some water from the channel. This would also help reduce flood risk, as there will be less water in the channel. Unfortunately this is a difficult proposition; LA is now so built up around the river, some displacement of people would have to occur. 

I am not saying there is an easy solution, because there isn’t. The main problem here is that we need to learn from past mistakes – building huge concrete channels is a naïve and short term approach to river management. Because there is so much new river run-off from increased urbanisation there is no guarantee the current concrete channel would be able to withstand rainfall totals similar to the LA flood of 1938 (the flood that lead to building of the channel). Brutalist hard engineering strategies like these are almost always doomed to fail – there is always an upper limit on capacity, even if you think you are building something to be future proof.  Add to this that once you have built up a city next to a concrete channel that you have little room to expand if you reach capacity, and you can see how silly the hard engineering fetishism of the 1940s-1970s was. Thankfully we now realise that a mixture of hard and soft engineering strategies are the best way to manage rivers in the face of changing future discharge, but it is very hard to undo mistakes like the LA River.

I hope a suitable resolution to the problem is found, but I fear Nasa will win and things will just stay as they are, one day doomed to fail. At least we have to chance to act if we act now.

Help

I’ve talked a lot about changes in discharge associated with climate change. In fact, I’ve been talking about it for the last three and a half months, like a demonic hydrological record stuck on repeat. For the most part, it’s also been very sciency: numbers, figures, theories, possible impacts, models. This is all well and good, but all these numbers and theories are not an abstract nothingness. The changes in discharge they suggest may occur will have an impact on us fleshy things: humans. We cause the changes, and we also have to bear the brunt of them.

Natural river flow regimes define ecosystems found in rivers, the movement of water and the sediment within it shaping the physical structure of the environment and thus habitat (LeRoy Poff, et al. 1997). These ecosystems are incredibly important for a variety of human functions including food production (e.g. irrigation), power production, waste management and flood control (LeRoy Poff et al., 1997). We must acknowledge that a change in the regime of a river (i.e. changes in discharge) will change ecosystems found in rivers, and then may affect our ability to use them in the same way. Changes in food production could be particularly important in areas where irrigation fed agriculture is key for producing staple foods in local diets (e.g. rice growing). The loss of natural flood control functions could be a considerable problem for communities that rely on river ecosystems for protection during high flows.

In regions of the world where discharge may increase in the future, the frequency of flooding may also increase. Floods can have significant health consequences for humans, ranging from short term (e.g. injuries, communicable disease, exposure to toxicants) to the more long term (e.g. malnutrition, mental health disorders, water-borne disease) (McMichael, et al. 2006). Reductions in discharge may cause droughts, which have the greatest global effects because of the large areas that are often affected, the main problems being famine and disease (Sari Kovats, et al. 2003).

I am just scratching the surface here in this short blog post with regards to the possible effects changes in discharge could have upon humans. But my point is that all the complex hydrological science that has come before does not exist purely for the sake of hydrological interest, but is of real importance for the future of millions of people around the world; their livelihoods, health and property. This is really happening, and we need to think about what are going to do about it, before it is too late.

Divination

Throughout this blog, I’ve been talking about models. Not ones that go down the catwalk, nor ones made out of paper and glue. I’m talking about computer models that attempt to represent the natural environment in some logical way and predict what is going to happen in the future. Predicting the future is an extremely difficult task, with huge uncertainties. It’s time to talk about the art of modelling to provide some context for the variety of studies I have examined.

Most of the models in studies I’ve been talking about are extremely complex, using a huge amount of data and making a lot of calculations to make predictions about the future. Other types of environmental model can be much simpler (less data and making less calculations), but sometimes are not suited to the complex nature of future climate change research. However, there are examples of these models being used to discuss the general direction of change.

Just getting the data alone to run large environmental models can be a considerable issue – the requirements can be very hard to meet, particularly in a scientific climate in which a lot of meteorological and hydrological data is not free to access and hidden behind barriers (Alliance for Permeant Access, 2011). The high data requirements also may increase uncertainty in predictions – more data means more parameters (changeable values that alter the results of a model), and so more uncertainty in the predictions the model makes as the range of possibilities is higher (Beven 1993). This uncertainty is exacerbated by the fact often only the bare minimum of data needed to run models is available – there would be less uncertainty if there were fuller data sets, but these are rarely available.

Complex models used require huge amounts of computing power, expertise and most of all time to construct and run.  I would personally argue that the massive uncertainties associated in complex climate and hydrological modelling mean we certainly need to take results with a huge pinch of salt – in most cases all we can tell is the direction and general magnitude of change, and even this can be unclear in some models due to huge uncertainties. I hope this does not put everything that has come before in doubt, but the modelling studies I have talked about really do only represent our best guesses, and by no means prescribe with accuracy what will happen in the future. This is not to deride modelling work though – it is our best guess, and a necessary guess. It is with some urgency that we need to attempt to quantify future changes to runoff and discharge – I will explore why in the next post.

Surprise, surprise, it’s extremely hard to predict the future. But we are doing the best we can.