It would probably help to think of Africa as something other than a monolithic block.
Exactly.
I think the OP just took his first freshman "world politics" course and he's ready to delve in and solve problems.
It's nice, you're treating this like its "Africa the country," where all people in all areas live like aboriginal hunters and gatherers. In several areas people do not live in tribal areas, they live in homes, with streets and cars and plumbing, they speak English and French. Now, you want to start studying real problems in Africa?
HIV/AIDS epidemic in Sub-Saharan Africa:. The continent has 60% of the worlds HIV/AIDS infected population. There are vast social stigmas with the disease as well, so many people refuse to be tested. In some places people are ostracized for having the disease. It is a leading cause of death.
Malaria: Deadly illness caused by parasites who attach themselves to female mosquitoes. Unlike HIV/AIDS, this disease takes complete control causing every flu symptom imaginable. Malaria kills and destroys, it is endemic (meaning it belongs to a specific geography).
Neglected Diseases: These effect the populations you would consider ideal candidates for your small, self-contained cities. They attach themselves to the lining and insides and you can actually feel them under the belly of the people they infect (which is a rather unbelievable number of people). Your idea of having readily farmed food in the area is great, except for these parasites are known to suck the nutrients from the host no matter how much they eat. Luckily, these can be treated for 50 cents a person per year with a simple pill... but it is still a very serious problem.
Tuberculosis: TB is a pulmonary disorder. It is a very common cause of death in HIV infected patients and it can attack the lungs, central nervous system, lymphatic system, and more. It's very deadly, and the people contracting it are often too weak to fight it off.
That is just a fraction of the public health issues covered
very broadly. Your water systems are often plagued with cholera epidemics (check recent news in Zimbabwe). There is ethic violence and genocide to consider, also. It's a nice thought to think that your circular villages could just "live in peace," but that's more difficult when political borders were drawn haphazardly as a result of colonization, and leaders profit immensely from corruption. What do you think a local military would do with these newfound resources? Spread them about the people?
I'm not trying to harass you here, I just want you to take what seems to be an open mind and understand that there are many, many people in dozens of fields working in unison to solve these problems. The water pumps you mentioned have done wonders some areas where they are installed. Those low cost homes are nice, too-- and they ARE being built. The United States, in particular, under George W. Bush sent
unprecedented resources in the country with PEPFAR (the President's Emergency Plan to Fight Aids, TB and Malaria). We are distributing medications for neglected diseases. The Gates Foundation is funding programs all of the world to find cures for these disaseses. The Faith Based organizations are sending thousands of people abroad. People are working hard, but it is a daunting task.
If you are committed to helping, there are so many ways. Just look into it.