Geology for Global Development


Heather Britton: China’s Water Diversion Project

Heather Britton: China’s Water Diversion Project

China has enjoyed economic growth over the past decades, bringing undoubted prosperity to the country. But exponential industrialisation and rapid growth comes at a significant environmental cost. The nation is heavily dependent on coal-fired power, making it one of the world’s largest emitters of greenhouse gases and it’s thirst for development is a drain on vital resources, including water. In today’s post, Heather explores how China’s geography accentuates an anthropogenic problem. 

When travelling from the North to the South of China there are number of trends that can be observed – dialects change, the dominance of noodles is replaced with a preference for rice and, crucially, the climate becomes more humid. The South typically receives excessive rainfall, often leading to devastating flooding, whilst the North dries due to the thirst of industry and a booming population. China’s water diversion project aims to solve both problems with one monumental feat of engineering – by diverting 44.8 billion cubic metres of water annually from South to North via a network of canals and tunnels. I’ll explore the impact that this is having on China and its people, and whether it is a sustainable solution to the disparity in water supply across the country.

Water shortage is a constant concern in the North, with the groundwater stores that support the region dwindling to a fraction of what is required to allow the cities and industries centred here to thrive. In addition, more than half of China’s 50,000 rivers have disappeared in the last 20 years. Having experienced unprecedented economic growth over the past few decades, Beijing is on the brink of a water crisis. In the South, flooding is the primary hydrological issue, exacerbated by the drainage of lakes and the damming of rivers for construction. It was commented in the 1950s by Chairman Mao that ‘The south has plenty of water, but the north is dry. If we could borrow some, that would be good’. This statement is heralded as the idea that has grown to become what is now ‘The world’s most ambitious water-transfer program’.

The project is not merely a fantasy – construction on a number of the pathways is already complete or nearing completion, and already over 70% of Beijing’s water is transferred from the South as a result of this project. Costing $62 billion, there is a clear driving force for the project – the thirsty North is running out of water fast, and although an extreme move, it is true that this project will provide some vestige of relief – but for how long, and at what cost?

Millions have benefitted from the water transfer and it certainly is a solution to the disparity in water supply between the North and the South of the country, but it is also arguably one of the worst. China’s demand for water is growing so quickly that even before the project’s completion in 2050 further solutions are likely to be required, and industrialisation along diversion routes poses a serious pollution threat. Salinization  of some waters heading North seems inevitable. An even larger concern is that the South may no longer have enough water to spare – the Han river, an important tributary to the Yangtze, is planned to have 40% of its water diverted to the North, but the towns and cities situated along its course are already experiencing water shortages. Furthermore, 345,000 villagers have been displaced from their homes to make way for the new water courses, often to lands and property far inferior to what they were promised and what they left behind. It is clear that the project is far from sustainable.

It would be wrong, however, to say that the Chinese government is doing nothing to reduce the impact of the scheme. Addressing environmental concerns in the Danjiangkou reservoir, a $3 billion ecological remediation package has been put together, and the water diversion project has allowed the groundwater reservoirs in Beijing to rebound by at least 0.52m. The environmental threat persists, however, and it seems unlikely that retrospective measures will be able to dissipate all of the environmental risk. By considering more sustainable solutions, the impact on the land and the people of China could have been drastically reduced. The Chinese vice minister of Housing and Urban-rural development has called the project unsustainable, acknowledging that, in the case of many cities, recycled water could replace diverted water. If efforts were focussed on water desalination technology and the collection of more rainwater, rather than the creation of multiple colossal aqueducts with unsavoury environmental consequences, then water resource management could be tackled in a far more sustainable manner.

Effective water conservation is something that is becoming a larger and larger problem for the Global South, particularly in the drier parts of the world. The water diversion project acts as an interesting case study, and shows the repercussions of dramatic engineering solutions to water resource problems. Although possible from an engineering perspective, forcing a change in the hydrological system of a country is rarely without its complications (and substantial expense). Lessons can be learned from the water diversion project, and future Global South nations should think twice before entering into any project of such scale without considering the full implications or other, more sustainable options. Doing this would help towards the achievement of UN Sustainable Development Goals 11 (sustainable cities and communities) and 6 (clean water and sanitation).

Saltwater intrusion: causes, impacts and mitigation

In many countries, access to clean and safe to drink water is often taken for granted: the simple act of turning a tap gives us access to a precious resource. In today’s post,Bárbara Zambelli Azevedo, discusses how over population of coastal areas and a changing climate is putting ready access to freshwater supplies under threat. 

Water is always moving downwards, finding its way until it gets to the sea. The same happens with groundwater. In coastal areas, where fresh groundwater from inland meets saline groundwater an interesting dynamic occurs. As salt water is slightly denser than freshwater, it intrudes into aquifers, forming a saline wedge below the freshwater. This boundary is not fixed, it shows seasonal variations and daily tidal fluctuations. It means that this interface of mixed salinity can shift inland during dry periods, when the freshwater supply decreases, or seaward during wetter months, when the contrary happens.

Freshwater and saltwater interaction. Credit: The National Environmental Education and Training Foundation (NEEF).

Once saline groundwater is found where fresh groundwater was previously, a process known as saltwater intrusion or saline intrusion happens. Even though it is a natural process, it can be influenced by human activities. Moreover, it can become an issue if saltwater gets far enough inland that it reaches freshwater resources, such as wells.

According to the UN report, about 40% of world’s population live within 100km from the coastline or in deltaic areas. A common source of drinking water for those coastal communities is pumped groundwater. If the demand for water is higher than its supply, as can often occur in densely populated coastal areas, the water pumped will have an increased salt content. As a result of overpumping, the groundwater source gets contaminated with too much saltwater, being improper for human consumption.

With climate change, according to the IPCC Assesment Reports, we can expect  sea-level to rise, more frequent extreme weather events, coastal erosion, changing precipitation patterns and warmer temperatures. All of these factors combined with the a increased demand for freshwater, as a result of global population growth, could boost the risk of saltwater intrusion.

Shanghai – an example of densely-populated coastal city. By Urashimataro (Own work) [CC BY-SA 3.0 ],via Wikimedia Commons.

Although small quantities of salt are important for regulating the fluid balance of the human body, WHO advises that consuming higher quantities of salt than recommended can be associated with adverse health effects, such as hypertension and stroke. In this manner, reducing salt consumption can have a positive effect in public health, helping to achieve SDG 3.

With the aim of preserving fresh groundwater resources for coastal communities at present and in the future, dealing with the threat of saline intrusion is becoming more and more important.

Therefore, to be able to mitigate the problem, first of all, it needs to be better understood. This can be done by characterising, modelling and monitoring aquifers, assessing the impact and then drawing solutions. Currently there are many mitigation strategies being designed worldwide. In Canada, for example, the adaptation options rely on monitoring and assessment, regulation and engineering. In the UK, on the other hand, the simpler solution adopted is reducing or rearranging the patterns of groundwater abstraction according to the season. In Lebanon, a fresh-keeper well was developed as an efficient, feasible, profitable and economically attractive way to provide localised solution for salination.

Every case should be analysed according to its own characteristics and key management strategies adopted to ensure that everyone has access to clean and safe water until 2030 – SDG6.