Stormwater is also a resource and important as the world's human population demand exceeds the availability of readily available water. Techniques of storm water harvesting with point source water management and purification can potentially make urban environments self-sustaining in terms of water.
Rivers flow downhill to sea level (generally speaking; some end in other bodies of water or join another rver). They flow with gravity from a higher elevation to a lower. The Nile rises on the western flank of the Great Rift Valley (many people consider Lake Victoria to be the source) and the Blue Nile joins the White Nile at Khartoum. The land falls away towards the north, thus the river flows north until it reaches the Mediterranean Sea at the Nile Delta. Direction of flow of a river is determined by elevation of the drainage basin, not geographical (North, South etc.) direction. http://en.wikipedia.org/wiki/Nile#Course.
The River Nile - Main Facts The River Nile is the second longest river in the world, after the Amazon River, and it is the longest river in the continent of Africa with a length of approximately 6695 kilometres. It flows through the following countries: Kenya, Eritrea, Congo, Burundi, Uganda, Tanzania, Rwanda, Egypt, Sudan and Ethiopia. The Nile is called this after the Greek word 'Nelios', meaning River Valley. The Nile used to flood once every year during the inundation season, what the Egyptians called Akhet, between June and September.