Water Security

The engineering is the easy half

A large water transfer looks like a problem of tunnels and dam walls, and the tunnels are the part that gets built on time. The Lesotho Highlands Water Project is the standard example and shows why the hard part is elsewhere. A treaty signed on 24 October 1986 allows water to be gathered in the mountains of Lesotho, a small and poor country, and sent by tunnel into the Vaal river system that supplies Gauteng, the industrial and financial heart of South Africa. Katse Dam was completed in 1997, standing 185 m high, among the tallest in Africa, and Mohale Dam followed in 2002. Every engineering question there has an answer. The questions that decide whether the scheme is a good one do not appear on any drawing: who decides, who pays, who is paid, and who has to move. Lesotho receives royalty payments for the water and generates its own electricity at Muela, which made it largely self-sufficient in power. It also lost valley floors that people farmed and grazed, and households had to be resettled so the reservoirs could fill. South Africa gained a secure supply for a region its economy depends on. That is why the specification wants this weighed politically as well as technically. Water crossing an international border is not the same as water moved within one country: it depends on a treaty holding, on two governments staying on terms, and on the smaller partner being paid fairly for something it cannot easily take back. Phase II was agreed in 2011 and the Polihali Dam followed, so the scheme is still growing, and the same questions apply again.

Six terms, and the third is the one with the politics in it

The third and fourth are the pair that separates a top answer from a description of a dam.

Building a cross-border transfer

Six stages take a mountain river to a distant city under a treaty. Put them in order.

• A growing industrial region runs short of water while a neighbouring highland country has more than it uses
• The two governments sign a treaty setting out volumes, payments and how disputes will be settled
• Households in the valleys to be flooded are resettled and compensation is agreed
• Dams are built across the highland rivers and the reservoirs behind them fill
• Tunnels carry the water under the mountains and into the receiving country's river system
• Royalties flow back to the supplying country, and both sides are now dependent on the other keeping to the agreement

What makes a cross-border scheme different?

A water transfer within one country and a transfer across an international border use the same engineering. Which difference matters most in an answer?

• That the arrangement rests on a treaty rather than on a domestic decision, so it has to survive changes of government, disputes over price and any wider quarrel between the two states. Each side becomes dependent on the other, the receiving country for a supply it does not control and the supplying country for income it cannot easily replace, and that mutual exposure is the thing to weigh.
• That the water has to travel a greater distance.
• That building across a border costs more.
• That water quality is harder to guarantee across a border.

Big, small, and using less

Three routes to water security, each with its own cost. Read the third column as seriously as the first two, because it is usually the cheapest per litre and almost always the one candidates leave out.

Match each feature to what it decides

Weigh the treaty, not just the tunnel

The content map is explicit about what this node wants from a large transfer answer: the cross-border and political tension weighed alongside the engineering and economic case, using the scheme's actual context. Most answers describe the dam and stop, which leaves the interesting half unwritten. Use four questions and you will not miss it. Who decides? Two governments, under an agreement that has to survive whatever else happens between them. Who pays? The receiving country, in royalties, and international lenders for the construction. Who is paid? The supplying country, which gains an income and electricity it did not have. Who is moved? The households whose valleys are now under water, and that cost is local, permanent and rarely fully compensated, because land of the same quality generally cannot be offered in exchange. Then remember that scale is a choice about control rather than only about volume. A scheme of that size can supply a conurbation and needs a treaty, foreign finance and resettlement to do it. A village earth bank needs none of those and will never supply a city. They answer different questions, so a comparison should say which question is being answered rather than declaring one better. And do not forget the unglamorous option. The cheapest new water is usually the water you stop losing, through repairing pipes, metering and recycling, which is why a serious answer weighs demand management against new supply rather than treating it as an afterthought.

Complete the water scheme record

The treaty behind the Lesotho Highlands Water Project was signed in _____, and the first of its great dams was completed in 1997 standing _____ metres high, with a second following in 2002. The water travels by tunnel into the river system serving _____, the industrial heartland of the receiving country, while royalties and hydroelectricity flow the other way. At the opposite end of the scale, work with villagers in Alwar district began in _____ and restored wells and river flow without a treaty, a tunnel or an international loan, and it was recognised with a major international prize in 2015. In the UK, meanwhile, close to a _____ of treated water is lost to leaks before it reaches a tap.

Spot the three sound water strategy statements

Select the THREE statements that could stand as they are in an answer.

• Because the supply crosses an international boundary it rests on an agreement that must outlast disputes and changes of government, so each country becomes dependent on the other in a way no domestic transfer requires.
• A scheme needing a treaty, foreign finance and resettlement can supply a conurbation, while village earth banks need none of those and never will, so the two answer different questions.
• Repairing mains that lose close to a fifth of treated water yields supply at a lower cost per litre than building a new source, so demand management belongs in the comparison.
• A water transfer increases the total amount of water available to the two countries involved.
• Local rainwater harvesting is always preferable to large schemes because it is cheaper and harms nobody.
• Desalination solves water shortage anywhere, since seawater is unlimited.

A 9-mark evaluation, marked

Using a named example, evaluate the advantages and disadvantages of a large-scale water transfer scheme. [9 marks] The Lesotho Highlands Water Project moves water from the mountains of Lesotho into the Vaal system that supplies Gauteng in South Africa, under a treaty signed on 24 October 1986. Its engineering advantages are substantial and measurable. Katse Dam, finished in 1997 at 185 m, and Mohale Dam in 2002 store the wet season and release it through tunnels that run under the mountains, giving South Africa a secure supply for the region that carries much of its economy. Lesotho gains a royalty income it had no other way of earning and, through the Muela station on the same works, became largely self-sufficient in electricity. Phase II was agreed in 2011 and the Polihali Dam followed, which is a reasonable indicator that both governments judge it to have worked. The disadvantages are just as real and fall in different places. The reservoirs flooded valley floors that were the best farmland and grazing for miles, so households had to be resettled, and compensation cannot readily supply land of equal quality in a mountain country. That cost is local and permanent, while the benefit is national and distant, which is the pattern to notice. The point the question is really testing is that this is not only an engineering scheme. Because the water crosses an international boundary, the arrangement rests on a treaty rather than on a domestic decision, and it has to hold through changes of government, arguments about price and any wider quarrel between the two states. South Africa depends for part of its supply on a country it does not govern, and Lesotho depends on a customer it cannot replace. That mutual dependence can be read either way: it gives both sides a strong reason to keep the agreement working, and it exposes each of them to the other. My judgement is that the scheme succeeds on the terms it was built for and that its costs were concentrated on the people least able to refuse them. Compared with the alternatives, it does something a local scheme cannot, since rainwater harvesting recharges village wells and could never supply a conurbation, while demand management in the receiving country would have been cheaper per litre and would not have reached the same volume. The transfer was therefore the right kind of answer for the demand, and the resettlement remains the strongest argument against the way it was done. What earned the marks: a named scheme with dates and dimensions; advantages and disadvantages weighed rather than listed; the political dependence treated as a finding in its own right; who gains and who pays identified separately; and a judgement that compares the scheme with the realistic alternatives instead of praising or condemning it alone.

Find the two that would cost marks

Five sentences from answers about water supply strategies. Two would lose credit for the argument they make rather than for being factually wrong. Tap those TWO.

• The transfer scheme increases the amount of water available overall, so both countries end up with more than before.
• Because the supply depends on a treaty rather than a domestic decision, it has to survive disputes between the two governments.
• Small local schemes are always the better option because they are cheap and nobody is harmed by them.
• The flooded valleys were the best farmland for miles, so the cost fell locally and permanently while the benefit was national.
• Repairing mains that lose close to a fifth of treated water produces supply more cheaply per litre than building a new source.

Build the political sentence

Assemble the sentence that weighs the agreement rather than the engineering.

Four water decisions

Each is a real choice. Ask what kind of question is being answered before choosing the technology.

• A conurbation of several million people faces a shortfall within a decade, and a mountain region across the border has more water than it uses.
• A town draws its water from boreholes, pumps more from them every year, and the water table beneath it is falling steadily.
• A reservoir is proposed on a forecast of industrial demand that assumes current growth continues for thirty years.
• A water company must add supply and is weighing a new reservoir against a mains replacement programme.

Evaluate the scheme

Using named examples, evaluate the strategies available for increasing water supply. [9 marks]

• The demand the large-scale scheme was built to meet
• Cross-border agreements: who decides, who pays, who is paid and who is moved
• Which question each scheme answers, rather than a ranking
• Recovered losses can cost less per litre than new supply
• The scheme compared against its realistic alternatives