While water covers over 60 percent of the planet, the sweet water on earth comprises only 2.5 percent of the total. That is more like zakat of the oceans. This is provided in the form of rain, snow, glaciers, rivers, lakes and springs. Then, there are the water aquifers that are exploited by tube-wells. The 6.5 billion people of the world have to subsist on the 2.5 percent sweet water we have so it makes sense to use it economically to serve the agricultural, industrial usages as well as human and animal needs. Pakistan has 2.5 percent population of the world but is blessed with almost 8.5 percent of the total irrigated area of the globe. Our 170 million people subsist on it. This raises the natural question that if India persists in blocking our three western rivers, Indus. Jhelum and Chenab, with the ruse of generating power for itself, what would happen to Pakistan? As a country of the lower riparian, if we are unable to stop this, our water and power would be strangulated. -DR M. YAQOOB BHATTI, Lahore, via e-mail, August 10.