Rainwater Harvesting System Components
Rainwater harvesting systems mainly constitutes of following components:
...Surface Runoff | Water Management | Ground Water Recharge
Runoff is water running off the surface. When there is rainfall, a portion of it seeps into the ground and replenishes groundwater. However, most of it flows out or runs off. Surface runoff may also be due to the water from snowmelt, stormwater, snowfall etc. In runoff, soil is saturated by water and cannot absorb the water anymore.
...Water Distribution on Earth
It is estimated that the Earth has a total volume of 1.386 billion km³ (333 million cubic miles) of water. However, over 97% of the water on earth is saline or seawater, with an average salinity of 35‰ (or 4.5%, roughly equivalent to 34gm of salts in 1kg of seawater). Typically, fresh water is defined as water with a salinity of less than 1 percent that of the oceans – i.e. below around 0.35‰.
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