If nations care about food security, their first concern should be sustainability of freshwater supplies. Here is the logic:
The world’s fresh water supply is largely inaccessible for water production: 70% is tied up in the polar ice caps, and much of the rest tied up in soil moisture or deep underground. Only 1% is available for fresh water production.
Saudia Arabia (admittedly an extreme example), has actively managed its water consumption down from 32 km3/yr in 1992 to about 17.2 km3/yr now , and yet even at that rate is using almost 15 km3/yr more than the country can naturally and renewably supply . This 15 km3/yr (85%) deficit is pumped from underground aquifers which do not replenish fast, if at all. Saudi Arabia has given up on food security altogether and is now practically importing all its food. The alternative of import more than 30bn metric tons of water is not an option: all the oil tankers in the world combined transport only about 2bn metric tons of oil per year, for example. So shipping it is not an option. Pipelines that would do the trick  would have to have a capcity 30x larger than The Great Manmade River of Libya (note: river (!), note pipeline(!)). Or for another comparison: you’d have to have 50x the capacity of both the Los Angeles aqueducts combined (which were subject to a lot of sabotage, so think twice about doing that in the Gulf, and they also aren’t pipelines), and yet carry this capacity over a much larger distance. Note that the Great Manmade River of Libya and the LA aqueducts use gravity alone to power the transport of water. This would also not be an option. It is a no-brainer that it is easier and more sustainable to import food directly, and safer when measured against sabotage and geopolitical risk.
Desalination is an alternative. Saudi Arabia does that already. I am not aware of what the costs of desalination are in Saudia Arabia, but in Israel it is apparently US$0.53 per m3. Another reference point for desalination is energy consumption, which can go as low as 3.2kWh/m3. To satisfy Saudi Arabia’s peak water demand of 1992, you could in theory do it with running costs of US$15bn p.a. and run the desalination process off a power plant with 11GW capacity (for a nuclear plant that would equate to approximately 10 reactors). Doable, if your country has a sea-coast, but still not easy: So far, Saudi Arabia produces about 1.2bn km3/yr through desalination, less than 10% of its (already drastically reduced) consumption, and less than 3% of its peak consumption in 1992.
But Saudi Arabia is a special case in many ways, because it has — at least in principle — the resources to attack the problem. India and many other countries also extensively use aquifers that don’t replenish fast enough. In north Gujarat, for example, undeground water levels are falling by a staggering 7m per year. And much of the demand that drives such over-reliance on an utterly unsustainable resource is caused by climate change: The monsoons, so important for agriculture, show signs of shifting in a way in which the biosphere cannot keep up. And if the biosphere cannot keep up, water gets lost for agriculture and plant growth and plant fertility are disturbed. But there are negative feedback effects on top, for example where the biosphere cannot absorb rain water that comes to soon, too late, or to fast, and the resulting floods then accelerate the demise of the very biosphere that we rely on to prevent these very floods in future years. We have all seen the statements that aggressive agricultural practices drive problems in water pollution (pesticides, antibiotics, fertilizers), but do we also see the bigger picture on how some agriculture undercuts its most important life-line by causing water shortages?
Lester Brown, president of the Earth Policy Institute, stated recently in a talk in London: “we have to grasp what climate change means in terms of food security”. We have seen peak water as a real phenomenon play itself out in the gulf states, but it may be coming to either a country near you, and if not that, it may certainly be coming to a very populous country like India or China.
To Lester Brown’s words I would add that we also have to see the reverse; We also have to grasp what agricultural practices do to climate change, so we can start to see where the dangerous feedback loops are (1) from depleting rivers (The Ganges and Indus rivers are so heavily used that they mostly don’t reach the sea any more), to (2) deforestation which creates new fertile agricultural fields but depletes the global CO2 absorption capacity and appears to disrupt rain cycles in South America, to (3) the wholesale destruction of lakes and the biodiversity they support (In western China’s Qinghai province, through which the Yellow River’s main stream flows, more than 2,000 lakes have disappeared over the last 20 years).
One big problem is that the world has plenty of experts in economics, climate change, development, agriculture, disaster risk and other fields, but few people able to understand the larger picture of how all those aspects combine to produce – or alleviate – hunger.
“A big problem is fragmentation and specialization of knowledge,” Brown says. “We’ve been so narrowly focused, looking at our own little piece, that very few people see the big picture.”
With worsening hunger looming, change needs to happen soon, he said. “Of all the resources we have, time is the scarcest.”
 Please don’t argue whether these numbers are exact: they don’t have to be, to see the larger issue.
 Aqueducts won’t work because of evaporation and pollution issues over that distance