Water is an important resource on which life
depends for its existence.Based on the laws of hydrological cycle ,the limiting water resources
can cycle and cy-cle. Owing to an increasing demand for fresh water resources and fast
consumption byhuman beings,the blockage of fresh water cycle seriously threatens the
renewability ofwater resources on the earth.As a result,the arid areas continue to expand so
fast thatthe worsening of drought trends become more and...