Changes

Brikke和Bredero, 在著作Brikke和Bredero在著作''[http://www.washdoc.info/docsearch/title/117705 Linking technology choice with operation and maintenance in the context of community water supply and sanitation: A reference document for planners and project staff]''中，推荐如下图表中的运行与维护工作：

====Estimated Lifespan预计使用寿命====The lifespan depends on the materials used and expertise with which it is constructed and maintained. The dams in Kitui Kenya were built at a cost of US$7,500 and have a minimum lifespan of 50 years.沙坝的使用寿命由两方面来决定：第一，使用的建材；第二，建坝和维护时使用的专业知识。肯尼亚基图伊的水坝耗资7500美元，最短使用寿命为50年。

===Costs成本===