Wonders of Water
More than 97% of the Earth�s water is salty ocean, which we can�t drink or use to grow crops. Less than 3% is fresh water on which all human life hangs. Twelve thousand years ago, every human on the planet was a hunter-gatherer. But once farming took hold, it had a profound impact on our relationship with water. No longer could we simply follow the rains. People needed regular reliable sources of water to make sure their crops grew. The need for water began to define where the first civilizations could flourish.
- Rivers and rain are the paths of the water cycle that we depend on. And yet they�re only a tiny proportion of the world�s fresh water, a measly 2% of all fresh water on the planet.
- The rest of the Earth�s fresh water is locked away in the ground. The vast majority of it is stored as ice. Most of the rest seeps deep into the earth where it�s known as groundwater. More than 30% of all the fresh water on Earth is under our feet.
- Our struggle to control water has been behind the rise and fall of some of the greatest civilizations on Earth.
- Six thousand years ago, the Sahara was not a desert. About five and a half thousand years ago, the Sahara began to dry. The rains failed, the rivers shrank, and the lakes dried out. Little is known about the early Saharans who lived there then, but we do know that they depended entirely on water.
- The power of rivers to shape history is graphically illustrated by perhaps the greatest of all early civilizations: Ancient Egypt.
- Every year the seasonal flood of the Nile covered the fields and left behind nutrient-rich silt that fertilized the crops.
- Other great civilizations also formed by rivers. In Mesopotamia, the Sumerian civilization flourished between the Tigris and the Euphrates. Further east, the Harappan civilization formed by the Indus, and early Chinese civilizations emerged along the Yellow River.
- Today we control water on a massive scale. The world�s reservoirs now hold over ten thousand cubic kilometres of water. That�s five times as much as water as in all the rivers on Earth.
Air menjadi sesuatu kebutuhan yang amat penting di bumi ini,siapa yang menyangka air bisa dijual.....
6000 tahun yang lalu sahara bukanlah gurun,lalu 500 tahun mulai mengering dan sekarang sudah menjadi gurun..
sungai2 di beberapa negara seperti negara pecahan rusia mulai surut dan menjadi daratan..
sungguh mengenaskan apabila nanti air akan menjadi sesuatu yang amat langka di bumi ini
20th June 2010
Wonders of Water
