Water for Thought...

While writing my next post I came across this article for Eva-Lotta Jannson's new book An Acid River Runs Through It which shows the effect of mining on South Africa's rivers.

The blue and yellow-green colour of this pond is where acid mine drainage has created such a low pH. This low pH value means fish and birds cannot survive here.  Source: www.theguardian.com

Untreated water from mining has been allowed to mix with local rivers, making the water highly toxic and devastating local wildlife and communities. As well as affecting surface waters, polluted water will have entered groundwater aquifers. Much like dryland salinity but with perhaps more deadly effects, I think we are going to see the land and local communities experience the consequences of this for a while. 

This is Robinson Lake in Randfontein. It was once rich with wildlife but is now a 'no-go' area as it is filled with dried uranium oxide sediment. Source www.theguardian.com

Sea Under the Land

Unlike river discharge or snow cover groundwater is harder to quantify and monitor, precisely because it is under the ground. Yet it is our largest accessible store of freshwater. therefore, we need to understand how agricultural practices are affecting it.

Bumpiness shows variation in gravity.
GRACE satellites are those in the top right hand corner
 Image source: CEOS EO handbook

We can retrieve information about groundwater levels using piezometers, which will provide information concerning one aquifer or part of an aquifer. Alternatively, to obtain a wider picture we can use the satellites of GRACE (NASA's Gravity Recovery and Climate Experiment mission). From GRACE we get an estimate of terrestrial water storage (TWS) which consists of snow, ice, permafrost, surface water, soil water and groundwater. In order to obtain an estimate of groundwater we first calculate the quantities of the other components using remote sensing, models, and ground based measurements THEN subtract these from the TWS. Here is a really clear document to read explaining more about how GRACE satellites work and how groundwater data can be retrieved.

So how can agriculture impact globally upon groundwater? This will be a bit longer than my average post so have a cup of tea and a mince pie handy!

Thirsty Crops:

Roughly 70% of groundwater abstracted is used for irrigation. When abstraction exceeds recharge then groundwater depletion, the permanent loss of groundwater, can occur. 

The risk of groundwater depletion occurring is especially high during periods of drought. Castle et al., (2014) studied the changes in surface water storage and groundwater storage in the Colorado Basin during drought from December 2004 to November 2013 using GRACE data for TWS, Land Surface Models for soil moisture estimates, SNOWDAS data for snow water equivalent, and reservoir storage data from U.S. Bureau of Reclamation. This period was one of the driest that the area has seen. 

Monthly volume anomalies (changes in volume) for groundwater storage (black line) and surface water storage (green line) with errors (shading) for A) the whole basin and Lake Powell and Lake Mead combined  B)  the upper basin and Lake Powell C) the lower basin and Lake Mead. Source: Castle et al., 2014

The results show that the groundwater store of the Colorado basin risks becoming depleted. Groundwater levels have been decreasing as a consequence of successive droughts reducing recharge and driving higher levels of groundwater abstraction due to drought surfacewater allocations not meeting water demands. The Colorado basin the world's most over allocated catchment and with potential increases in drought severity and occurrence due to climate change we are going to see higher levels of groundwater abstraction in the Colorado basin. Joodaki et al., (2014) using the same method highlighted a similar groundwater situation occurring in the Middle East, which indicates this is a situation we are likely to see happening across the globe as climate becomes more variable.

Land Change:  

Source: http://www.sciencemag.org/site/feature/misc/
webfeat/soilmap/soil_austral_links.html

One of the most dramatic situations illustrating the complex relationship between land use and groundwater can be seen in Australia. In parts of Australia groundwater is very saline and the original vegetation, which was deep rooted trees, kept groundwater levels low and in equilibrium. Deforestation of the land and replacement with agricultural crops (that are shallow rooted) led to a huge rise in the level of the water table, bringing all the dissolved salts to the surface, the consequence of which was the salinisation of large swathes of land rendering it unusable. No vegetation can tolerate the salinity; this situation is known as dryland salinity and is still a major problem for Australia.

Another example is the type of crop grown on the land as different crops have different water requirements. Esnault et al., (2014) have undertaken detailed study to determine which groundwater irrigated crops could 'stress' an aquifer system further by looking at the 'groundwater footprint'. The groundwater footprint is the area needed to sustain groundwater use.

The results for the Central Valley and High Plains aquifer systems in the USA are:

The contribution of each crop type to the regions to groundwater footprint.
The colours for the High Plains aquifers (f, g, and h) are different. Source: Esnault et al., 2014

The pie charts shows each crop type's contribution to the region's groundwater footprint to area ratio. For the Central Valley system hay has the largest ratio and for the High Plains system it is corn gain and cotton. Such information can be highly useful in terms of managing groundwater resources by understanding the consequences of growing a particular crop in a certain region. 
Another point worth noting is that the corn grain and hay grown in the regions of study are mainly for the meat industry.... which makes me think more on the issue of whether you can reconcile being an environmentalist and eating meat brought up in the blog Sown on Stony Ground.

With modelling I don't want to present the results without showing a bit of what's going on 'behind the scenes'. 

Esnault et al., (2014) 's study is complex  requiring data on:

•  irrigated and harvested crop areas
• proportion of crop irrigated by groundwater
• efficiency of irrigation system
• management of surface and groundwater
• groundwater abstraction rates

as well as using global and local hydrological models to:

• obtain recharge estimates
• obtain environmental flow requirements 
• obtain net surface water (called blue water) requirements 

The margin for error grows with each parameter added in, however, to certain extents this cannot be avoided as all the information and processes listed above are needed to calculate groundwater footprint. To be aware of the uncertainty in their approach the authors quantified the amount of uncertainty that each parameter contributed:

The actual value and relative contribution to total uncertainty for each parameter for (a) Central Valley and (b) High Plains aquifer systems. Source: Esnault et al., 2014

By doing this the authors clarified where the largest proportion of uncertainty in their estimates of groundwater footprint lay. For this study it is concerning the quantification of irrigation system efficiency and in estimating groundwater recharge using models. 

This leads me onto my next post which will be about groundwater modelling and what we mean by uncertainty.  

Before I go i'll leave you with this interesting conversational tidbit for Christmas dinner:  in the tropics it is not the duration of rainfall but the intensity that is important for groundwater recharge. As such, we might see groundwater playing an important role in human adaption to climate change. 

With that food for thought have a very MERRY CHRISTMAS! 

Source: https://bongous.com/merry-christmas/

Water, water, everywhere .... ?

As my next post is on agriculture and groundwater, before we get started I thought I'd share this map from Taylor et al., (2012) showing locations of aquifer systems:

As well as Aqueduct's Water Risk Atlas; a really cool interactive map showing inter-annual variability, drought severity, flood occurrence etc across the globe.

Two maps I have picked out for you from the site are: 

Drought severity, red areas are those that have the most extreme droughts:

Groundwater stress, which is the ratio of consumption to withdrawal, red areas indicate potentially unsustainable use of groundwater.

BUT we still need a bit of caution: when studying these maps it is important to take note of the source of the data. These maps are based on data from 1901 - 2008  and 1958 - 2000 respectively. Another two important things to be aware of when looking at groundwater stress is recharge was modelled, and we don't have the full picture concerning groundwater withdrawals and rates. We don't actually know how many wells there are and how much water is being abstracted, especially in developing countries.This point is illustrated in this news article from 2010 (also an interesting tidbit for all those Christmas dinners you are going to) about groundwater withdrawals in Siem Reap, Cambodia which are endangering the future of Angkor Wat.


On another groundwater note ....

I love the history and culture of past civilisations like the Maya, Incas and Khmer Empire. Why such societies 'disappeared' is intriguing; usually attributed to conflict and/or the introduction of disease from explorers - access to water during drought could have played a part. For the Maya, settlements in the north of Yucatá who had natural and easier access to groundwater stores were the ones that appear to have been abandoned last.... interesting eh..... but could drought be the main cause for the disappearance of the Maya.....hmmmmm...... what do you think?

Part 2: Food + Carbon + COP 21 + YOU!

The question– how do we go about implementing better expansion policies and encouraging less deforestation while allowing countries to grow economically?

With COP 21 currently in process this issue has never been more important. On Friday 4th I took part in a COP 21 workshop where by representing different country groups we tried to reach the 2^OC threshold by committing to certain timescales and rates regarding reductions in CO₂ emissions, specifying levels of deforestation and afforestation, pledging certain financial help / requests, and accepting growth of regions. To hold global temperatures at 2^OC above pre-industrial levels is pretty much impossible! I didn't realise just how difficult it is to meet this target. We managed to reach 2.7 ^OC , which would still see a lot of adverse effects, but to even hold it at this temperature requires a lot of commitment and action now.

REDD+

One international method for trying to preserve carbon stocks is REDD+ : Reducing Emissions from Deforestation and Forest Degradation which offers developing countries a financial incentive encouraging:

1) Reductions in emissions from deforestation
2) Reductions in emissions from forest degradation
3) Conservation of forest carbon stocks
4) Sustainable management of forests
5) Enhancement of forest carbon stocks

This is in theory could work as large amounts of deforestation that we see occurring in developing countries for agriculture is done for the short-term gains in poverty alleviation, but lead to longer term environmental problems for the local people. Offering financial incentives means local populations benefit when they preserve carbon stocks. However, the question is whether these financial incentives are enough.

Cambodia. Source: Alice Fitch

In Cambodia, the profitably of REDD+ management can be larger that other land uses depending on carbon prices.

Whereas in Sumatra Indonesia, it would be more profitable to convert 10,000 hectares to palm oil production (which would emit 5.46 millions tons of CO2), than leave it undisturbed making it eligible for carbon credits from the REDD+ program

A worry that springs to my mind as soon as I heard financial incentives was corruption, and this is an issue but as long as it is recognised there are way to deal with it. Arwida et al., (2015) reviewed the effectiveness of a number anti-corruption methods for REDD+ schemes in Indonesia, and it provides an interesting read covering the impact of different methods. 

It seems that REDD+ schemes have the potential to be good but still have a long way to go. In my opinion schemes like this are needed as many people in developing countries can't afford not view forests in terms of monetray value....

Moratoriums

Voluntary moratoriums are something that can have a big impact, by voluntary I really mean agreeing due to pressure from NGOs and retailers. One such example is the soy moratorium in Brazil where soya-bean traders agreed not to purchase soy grown in the Amazon on land deforested after July 2006, creating a zero-deforestation supply chain. And look at the results:

Source Gibbs et al., 2015. Green bars show percentage of soy expansion into rainforest, peach bars percentage of soy expansion into previously cleared areas and the blue line is the soy expansion in hectares; each grid line is 100 hectares. 

Deforestation for soy planting has dramatically reduced! The reasons why this moratorium has been so effective over plain law enforcement and management methods is due to :

- there being only a small number of soy buyers which tightens the market control

- the requirements for compliance are very simple: basically no deforestation

- the Soy Moratorium had clear monitoring and enforcement systems in place

- combined efforts of government in wanted to reduce deforestation and NGO participation.

From this we can see how public pressure can drive the implementation of moratoriums! Yet they are not always this effective; the 2011 moratorium on palm-oil in Indonesia is one such case. The reasons for it not working in Indonesia are:

- conversion through deforestation is still occurring on already licensed land 

- there appear to be loopholes in the moratorium that can be exploited

- planting on already degraded land is not being consider

- clearing of forests by fire is being financed by palm-oil investors

- not enough enforcement.

You

REDD+ and moratoriums are two ways in which better expansion policies and less deforestation can be implemented while still allowing economic growth.

But one thing I got thinking about during the workshop was that we were stating percentages about reducing a regions carbon emissions but how can we in the UK on an individual level achieve this when we can't avoid aspects like needing to use a car.

I was a bit disheartened but then after some research can see how we can have a difference, especially as a consumer! Some of the things we can do regarding food and carbon are:

- Buy products that are made with certified Roundtable on Sustainable Palm Oil (RSPO) lets try and improve this problem!

Source: https://www.flickr.com/photos/karlaquintanilla
/6936591258

- When you can afford it, buy organic. In certain situations it is difficult to buy everything organic, being a student I can't afford to, so just focus on one thing. Ranking first is meat – if you can buy organic meat do so for ethical and carbon reasons!

- Buy local produce and food in season– the longer food has had to travel the larger the carbon footprint. Food from the EU will have a lower carbon footprint that food from Brazil.

- Eat less meat - Chloe has done a great couple posts on the impact of meat production in her blog. Well worth a read.

- Don't waste food and pop uneaten / old food in food recycle bin! When food is placed in landfills it produces a heck of a lot of methane. See the video on this page about what happens to waste chicken in landfill!

- Take a re-usable coffee mug with you - you can even get money off your coffee/tea!

- Plant trees in your garden, or even grow in pots! Lets take some of that CO2 out of the atmosphere

Lastly if you are interested in more about what each country has said for COP 21 that they intend to do to stop the rise in global temperatures, Climate Action Tracker is really good: