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.