DepletionofOgallalaAquifer.ppt

Depletion of the Ogallala Aquifer End of Depletion of the Ogallala Aquifer * * * * * to reduce the amount of something Target 1. words 2. exercises 3. structure analysis of the text semiarid [,s?m??r?d] adi rancher [rɑ:nt??] n. Ogallala Sioux Indians negligible [n?ɡl?d??bl] adj incentive [?ns?nt?v] adj words and expressions: somewhat arid, a semiarid region with little annual rainfall. a person who owns or operates a ranch,which is a large farm used for raising animals, especially cattle, horses, or sheep. a member of a group of North American Indian peoples who spoke a Siouan language so small as to be meaningless; insignificant a positive motivational influence 1．According to paragraph 1, which of the following statements about the High Plains is true? ○Until farmers and ranchers settled there in the 1880s, the High Plains had never been inhabited. ○The climate of the High Plains is characterized by higher-than-average temperatures. ○The large aquifer that lies underneath the High Plains was discovered by the Ogallala Sioux Indians. ○Before the early 1900s there was only a small amount of farming and ranching in the High Plains. Paragraph 1: The vast grasslands of the High Plains in the central United States were settled by farmers and ranchers in the 1880s. This region has a semiarid climate, and for 50 years after its settlement, it supported a low-intensity agricultural economy of cattle ranching and wheat farming. In the early twentieth century, however, it was discovered that much of the High Plains was underlain by a huge aquifer (a rock layer containing large quantities of groundwater). This aquifer was named the Ogallala aquifer after the Ogallala Sioux Indians, who once inhabited the region. 2. According to paragraph 2, all of the following statements about the Ogallala aquifer are true EXCEPT: ○The aquifer stretches from South Dakota to Texas. ○The aquifer’s water comes from underground springs. ○Water has