دانلود کتاب The Science of Water: Concepts and Applications

Water is a limited resource. The average person might ask how this can be? We are literally shrouded in water-water covers most of the earth-water, water, water, everywhere you look there is water. Obviously, this person does not live in or is not familiar with arid and semi-arid parts of the globe. Maybe our viewer is referring to the hydrologic cycle-that natural process of rainfall-runoff-evaporation, which repeats itself continuously (we can only hope that it continues to do so). Our viewer is not alone in his/her assessment of water-the state of water-the fact is most people do not give water a second thought. A belief prevails that the earth's finite water resources can be increased constantly to meet growing demands. At the present time, the supply of water is constantly made to respond to demand. Modern technology has allowed us to tap potable water supplies and to design and construct elaborate water distribution systems. We have developed technology to treat water we foul, soil, pollute, discard, and flush away. History has demonstrated that consumption and waste increase in response to rising supply. But the fact remains: fresh waters are a finite source-one that can be increased only slightly through desalinization or some other practice-all at tremendous cost. If water is so precious, so necessary for sustaining life, then two questions arise:1.Why do we ignore water? 2.Why do we abuse it (pollute or waste it)?We ignore water because it is so common, so accessible, so available, so unexceptional (unless you are lost in the desert without a supply of it) that we don't have to think about it. Why do we pollute and waste water? Several reasons are discussed in this text. This text deals with the essence of water: what water is, and what water is all about. While this text points out that water is one of the simplest and most common chemical compounds on earth, it is also one of the most mysterious and awe-inspiring substances we know. Essential to this discussion of water and its critical importance on earth is man-man and his use, misuse, and reuse of fresh water and wastewater. Since water is the essence of all life on earth, it is precious-too precious to abuse, misuse and ignore. The common thread woven through the fabric of this presentation is water resource utilization and its protection.