城市化是一个人类社会活动及生产要素从农村地区向城市地区转移的过程。其结果,现代城市成为了人类社会的生活、生产、消费和污染集聚之地。淡水是城镇化发育的生命之源。根据生态系统法则的演绎,城镇发育的淡水资源消费或使用是通过直接、间接和诱发三种方式来实现的。更为重要的是,现代城镇发育的淡水资源消费或使用是按照直接〈间接〈诱发的格局排列,从而构成了与自然生态系统和农村生态系统完全相佐的倒"金字塔"型结构特征。在这种倒"金字塔"型消费或使用结构的作用下,现代城镇发育的淡水资源基础不仅在于城镇所在区域,而且也在于整个国家、乃至全球。
Urbanization can be referred to as a process by which human activities and productive factors are concentrated from rural areas to city areas. As a result, modern cities and towns play as the central places of wealth accumulation for human-being, not only in the ways of settlement and material consumption, but also in the ways of social production and environmental pollution. In terms of the law of ecological evolution, the behaviors of cities and towns in consumption of water resources are also composed of three types, namely, the direct one, the indirect one and the induced one. More importantly, however, such behaviors are proved in a general pattern formatted by the direct 〈 the indirect 〈 the induced according to the material and environmental input for city-ecological system, and it can be labeled as an inversed-Pyramid Structure compared with the Pyramid Structure for the natural eco-system. Under this circumstance, the water-resource base for the development of modern cities and towns is far beyond the boundaries of the cities themselves, and it covers, in the point view of city-ecology system, the region and the country where the cities and towns are located, and or even the whole world.