"africa is much larger than europe. why doesn't it have much more fresh water? "

For one thing, Africa has the large Sahara desert which has very little water and South Africa is at least in part quite arid so that is one reason why there is less water plus the temperatures get a lot higher in Africa than in most of Europe to create more evaporation and most of Europe is in the temperate zone so gets some snow in the winter which stores some waterl.

I'm pretty sure it's c. extremely gradual but not 100% sure though.