托福考试写作例文4
发布时间：2013/7/17 21:42:18 来源：城市网学院 编辑：admin
RESPONSE BY STUDENT 1 Word count:169
Irrigation, the artificial watering of land for agriculture, has a high use of water. Water for irrigation #es from several sources, such as direct rainfall, rivers, lakes, and reservoirs. Some irrigation methods use a lot of water, such as flooding large fields. According to the reading, flooding is widely used because of low cost and long tradition. However, the lecture casts doubt on this point by stating that surface methods are not efficient.
The water that is used for irrigation can’t be used for other purposes. With surface irrigation, some of the water goes to the plants; however, a lot of water evaporates or passes down into the ground. This wastes a lot of water because the water is not available for other purposes such as drinking.
The surface method of flooding large fields requires a lot of water. Some of the water evaporates when it collects into ponds on the field. Sprinkler systems are a more efficient type of surface irrigation, but they also lose water to evaporation.
