Actually the idea would be to do it in the poorest areas rather than in a centralized fashion. The reason there are so many hungry children in Africa is because they go to the river with big bowls to get their water. In Ethiopia they eat Injera a type of flat bread(delicious...i love Ethiopian food) anyhow apparently making the bread the traditional way is a tremendous waste of resources.
What needs to be done in Africa/other poor places
1 build Several large pan continental canals
-how to do it
-get several thousand shovels, and several thousand workers
-buy lots of bulldozers
- do not canal off of rivers or lakes, canal off the ocean only
-build an estuary to naturally clean the water
-no dams
2 build large desalination plants
-have companies/governments invest
3 build large water towers in every town or near every town
-in the old west when the united states was being settled, they either had to canal to a major water source, there is no need to waste good time going to the river with jugs or bowls to fetch water, this time can be used to be building other infrastructures
4 build greehouses
-alot of the problem with famine in africa is because they let the weater dictate their food, bad idea, nature is harsh and unpredictable, to protect the food supply is to protect the people. Locust can't get inside a greenhouse.
5 community centers
-the average African is poor, and cannot afford to buy fluff or non-necessities, by communally owning certain things, money can be saved and not wasted. The community center could double as a school.
6 new housing.
-with populations booming, housing has to boom as well. Apartment style buildings can house hunndreds of people.
This all requires a great deal of money im sure your all aware, however an initial investment may yield greater results.
The first fold is the water distribution plan, the second is the food, the third is the community improvement.