Although dams can be built to store water for agricultural use in dry areas and dry seasons, the costs of water redistribution(重新分配) are very high. Not only is there the cost of he engineering itself ,but there is also an environmental cost to be considered .Where valleys(山谷) are flooded to create dams, houses are lost and wildlife homes destroyed . Besides , water may flow easily through pipes to filds, but it cannot be transported from one side of the world to the other. Each country must therefore rely on the management of its own water to supply its farming requirements.

　　This is particularly troubling for countries with agricultural industries in areas dependent on irrigation(灌溉). In Texas, farmers’ overuse of irrigation water has resulted in a 25% reduction of the water stores , In the Central Valley area of southwestern USA ,a huge water engineering project provided water for farming in dry valleys , but much of the water use has been poorly managed.

　　Saudi Arabia’s attempts to grow wheat in desert areas have seen the pumping of huge quantities of irrigation（灌溉） water from underground reserves . Because there is no rainfall in these areas ,such reserves can only decrease, and it is believed that fifty years of pumping will see them run dry.

　　72. From the first two paragraphs we learn that

　　.

　　A. much of the world’s water is available for use

【2017届高考英语二轮复习考点讲义：阅读理解-地理】相关文章：

★ 2017届高考英语二轮复习书面表达限时测验：5（含解析）

★ （全国通用）2014届高考英语一轮单元复习 限时强化训练五

★ 【课堂新坐标】2017届高考英语（通用版）二轮复习书面表达专题训练：技法3 丰富充实的细节信息（含解析）

★ 2017届高考英语二轮复习考点讲义：阅读理解-职业

★ 湖南省汝城二中2014届高考英语一轮复习阅读训练 (59)

★ 英语2016高考二轮复习语法必须注重训练

★ 湖南省汝城二中2014届高考英语一轮复习阅读训练 (82)

★ 2017届高考英语二轮复习考点讲义：阅读理解-购物、饮食与健康

★ 总结2016年有效进行高考英语复习的方法

★ 2017届高考英语二轮复习考点讲义：阅读理解-兴趣爱好与语言学习