Sự khan hiếm HOẶC AN OLD ERROR NƯỚC Chất thải? Việc phát hiện ra từ những vân gỗ của chu kỳ hạn hán cổ đại, xuất hiện của thế kỷ đắm tàu cũ trên lòng sông khô, và các dự báo về biến đổi khí hậu phóng túng và biến đổi có thể dễ dàng khuấy động nỗi sợ hãi cho tương lai nước của chúng tôi trong cả hai nhà khoa học và công dân như nhau. Tuy nhiên, điều kiện như vậy không cần phải dự báo của nước của chúng tôi số phận. Chính xác như thế nào nhu cầu nước của thế kỷ 21 ngày. | 7 Managing Demand Water Conservation as a Drought Mitigation Tool AMY VICKERS CONTENTS I. Introduction A New Era of Water Scarcity or an Old Error of Water Waste . 173 II. Water Conservation The Great Untapped Water Supply. 178 III. Conclusions. 187 References. 187 I. INTRODUCTION A NEW ERA OF WATER SCARCITY OR AN OLD ERROR OF WATER WASTE The discovery from tree rings of ancient drought cycles the emergence of centuries-old shipwrecks on drying riverbeds and the forecasts of unruly climate change and variability can easily 173 Copyright 2005 by Taylor Francis Group 174 Vickers stir fear for our water future in both scientist and citizen alike. Yet such conditions need not be predictors of our water fate. Exactly how the water demands of the 21st century s growing population will be met is indeed a formidable challenge. Half of the world s 6 billion people now live in urban environments projected to increase to 60 by 2030 and the majority of the globe s 16 mega-cities 10 million or more residents reside in regions confronting mild to severe water stress according to the United Nations 2003 . Between 1950 and 2000 the world s population more than doubled United Nations 2002 and its water demands roughly tripled Postel and Vickers 2004 . From 2000 to 2050 global population is projected to grow 45 reaching nearly 9 billion people United Nations 2002 . Clearly the world s water demands are increasing but nature s present and future water budget remains largely fixed at the limits of its primordial creation. From where and at what cost future water supplies will be derived remains an unanswered and troubling question for many public officials and water managers. With falling groundwater tables and approximately 800 000 dams now altering natural river flows worldwide more than 75 of the river systems in the United States Canada Europe and the former Soviet Union are already diverted by dams much of the developed world s freshwater sources have already been tapped Postel .
