tailieunhanh - ENVIRONMENTAL ENGINEER’S MATHEMATICS HANDBOOK - CHAPTER 12

Hãy xem xét một hồ bơi sông, bị cô lập bởi các quá trình sông ngòi và thời gian dòng chảy chính. Chúng tôi ngay lập tức bị ấn tượng quá: nó xuất hiện vẫn còn . rất yên . vẫn còn đủ để làm dịu chúng tôi. Các hồ bơi sông cung cấp một loại của đại lễ thơ, nếu chỉ ở bề mặt của hồ bơi. Không có từ nào của hòa bình, không có mô tả của sự im lặng hoặc motionlessness có thể truyền đạt sự hoàn hảo của nơi này, trong thời điểm này bị. | Chapter 12 Still Waters introduction Consider a river pool isolated by fluvial processes and time from the main stream flow. We are immediately struck by one overwhelming impression it appears so still . so very still . still enough to soothe us. The river pool provides a kind of poetic solemnity if only at the pool s surface. No words of peace no description of silence or motionlessness can convey the perfection of this place in this moment stolen out of time. We ask ourselves The water is still but does the term still correctly describe what we are viewing Is there any other term we can use besides that Is there any other kind of still Yes of course we know many ways to characterize still. For sound or noise still can mean inaudible noiseless quiet or silent. With movement or lack of movement still can mean immobile inert motionless or stationary. At least this is how the pool appears at its surface to the casual visitor. The visitor sees no more than water and rocks. The rest of the pool We know very well that a river pool is more than just a surface. How does the rest of the pool the subsurface for example fit the descriptors we tried to use to characterize its surface Maybe they fit maybe they do not. In time we will go beneath the surface through the liquid mass to the very bottom of the pool to find out. For now remember that images retained from first glances are almost always incorrectly perceived incorrectly discerned and never fully understood. On second look we see that the fundamental characterization of this particular pool s surface is correct enough. Wedged in a lonely riparian corridor formed by river bank on one side and sand bar on the other it is between a youthful vigorous river system on its lower end and a glacier- and artesian-fed lake on its headwater end. The surface of the large pool almost entirely overhung by mossy old Sitka spruce at least at this particular location is indeed still. In the proverbial sense the pool s surface is .