Relationship with Population Density

So far in my blog I haven't touched upon rainfall and it's relationship with population density. For populations to increase, water is necessary. In poorer regions, such as most of SSA, this water needs to be local. Le Blanc and Perez studied the relationship between rainfall and human density in conjunction 

Le Blanc and Perez found that a threshold of 900mm/year of rainfall existed when considered a relationship with population density. When rainfall is below 900mm/year, rainfall becomes a limiting factor on population densities. If above, then density and rainfall do not have any spatial correlation.

Then they apply future population change scenarios and climate change scenarios on rainfall. With projected population growth the areas limited by rainfall, and experiencing increasing water stress, are set to increase. Le Blanc and Perez concede that the impacts of rainfall are harder to predict as different climate models differ locally, especially intermediary areas fed by the ITCZ such as the Sahel and East Africa. Predictions expect Sahelian rainfall to increase, offsetting some demographic pressures but not all. Contrastingly, East African precipitation is projected to fall. Will population increase, this will increase water stress in the region. Regarding Southern Africa, le Blanc and Perez note that population stagnation will clearly help any water stress situations.

Changing rainfall and demographic concentration and spatial distribution will play a major role in dictating which areas experience relative water stress, and which relative water security.