外文翻译--节水灌溉(编辑修改稿)

外文翻译--节水灌溉(编辑修改稿)内容摘要：

ble. To irrigation groundwater table elevation to the water can enter the height of the root activity layers, the ground remains dry, so very provincial water, no irrigation, groundwater levels drop down. The limitations of this approach, only the root activity layers impermeable layer Caixing. 2. Select the factors that affect watersaving irrigation methods weather conditions China from the southeast coast to the inland northwest, generally divided into subhumid areas, semihumid areas, semiarid and arid regions, With dryness incremental, the dependence of crop irrigation is incremented accordingly. Humid regions for many years the average annual rainfall is greater than the cultivation of dry crops in the field water consumption, water resources total more than just a lack of precipitation in the dry season and drought years, supplemental irrigation is required。 semihumid areas average annual rainfall is basically in line with planting drought crop water demand, but due to the uneven distribution of precipitation, dry years and dry season water shortages more。 semiarid areas average annual rainfall can not meet the crop water requirements, if there is no irrigation, agricultural production is very unstable, such areas such as irrigation, wasteland farming, the destruction of natural vegetation, can easily cause desertification。 rainfall is scarce in arid regions, irrigation agriculture, water scarcity of such areas, river runoff from the alpine rain and snow melt water, industry and agriculture not only 3 depend on the development and survival of the natural vegetation along the river channel near river water for irrigation, and therefore reference, must take into account the natural ecological water. the topography and hydrogeological conditions Topography and hydrogeological conditions affecting the natural distribution of rainwater, will also affect the pattern of watersaving irrigation. Ground on steep mountain hilly area prone to soil erosion and drought, watersaving irrigation to adopt prehensive measures. Cultivation technology and terracing, field ridges through agricultural consumption, reduce the sloping soil erosion and soil evaporation。 gullies on the construction of embankments, or in suitable locations for the construction of water cellars, storing runoff solve drinking water and a small area irrigation water。 repair reservoirs in the gullies and tributaries, centralized control runoff diversion project isolated tangba munication, formation of Chodo Jieguairrigation systems, improve rain water utilization and irrigation water to en。