| The lan-xin railway is an important railroad in our country which passes through the ancient Silk Road.Its length is 1892km and the line of 1050kin is located in Gobi desert and sandy desert area.The railroad windbreak system which mixed with trees and shrubs were built up in mid 1960s. However,the natural conditions are very harsh in the area,the most part of the area surface is covered by gravels,and grit stones,also some tree and shrub species were not selected appropriately in the afforestation design and procedure in that time and flood irrigation was not properly in the area.The result is the most of man-made and natural plants were died by drought because the moisture in sandy soil is too low for a long time and water leaching is serious, encroachment and disaster have been formed frequently to the railroad circulation.Based on this kind of situation,the sustainable development of railway system is one of the key factors for our country's economic development.The development of water-saving techniques has been become into an important meaning for the reforming traditional windbreak system in the Gobi and sandy desert areas at Heshanhu section in Lan-xin railway.This paper describes water-saving technology on railroad windbreak system at the Heishanhu section in Lan-xin line,Israel subsurface drip inigation system has been introduced and applied in the project.According to the water requirement and the regulation of water consuming of the windbreak system at the railway on the basis of the subsurface drip irrigation principle to establish the scientific water-saving irrigation system,build up the irrigation mode for the drought Gobi and sandy desert area in railroad protection system.The research result indicates the stubble's willow bush under the subsurface drip irrigation system grows better,the average height growth is 1.753m yearly,crown is 1.536×1.619m, however,the contrast to ditch irrigation,height growth is only 1.032m per year,the crown is 0.777×0.691 m;under the subsurface drip irrigation system,the height growth of popular trees is 0.435m per year,the chest diameter at the height position of 1.3m to the ground increases 0.4 cm,however, the contrast to ditch irrigation,height growth of the trees is -0.24 m,the chest diameter increases 0.015 cm.Under the subsurface drip irrigation system,the rational water capacity per hectare per year is 6135 m~3;the water requirement is 306.75 m~3/hm~2 per time.April to September is the period for subsurface drip irrigation in whole year,three time irrigation monthly and 10 hours each time, the final irrigation should be given for 20 hours in the end of October in a year.Comparing the subsurface drip irrigation to the traditional ditch irrigation,the subsurface drip irrigation system can save water capacity of 9883.28 m~3/hm~2 annually,the water-saving rate is 61.7%.After the subsurface drip irrigation system has been arranged(6.3hm~2)at the section,the water-saving capacity in the windbreak system is 186793.98m~3 for three years.If each cubic meter water on the basis of 0.2 Chinese Yuan is calculated,the water-saving charge is 37358.80 Chinese Yuan,the electricity-saving charge is 86952.85 Chinese Yuan,the resource charge of water-saving is 28019.06 Chinese Yuan,labor force-saving is about 120000 Chinese Yuan.The total amount brings the economic benefit 272330.71 Chinese Yuan directly in three years.Moreover,protection function has been improved remarkably,the wind-sand encroachment and disaster was reduced,the circulation speed of the railway line was increased,the railway circulation ability was improved obviously.In addition,through the sustainable improvement of railway transport ability through the railway reforming and strengthening,the circuit devotion of the railroad public work section has been reduced about 59,400,000 Chinese Yuan in three years. Under the subsurface drip irrigation system,the wind speed inside of the windbreak system and outside at the height of 1.5m reduced 36.7%and 39.2%respectively compare to the wild land in the same area.The humidity inside of the windbreak system increased 9.5%compare to the wildness,the temperature increases 1.0℃.After the railroad windbreak system has been renewed, the artificial windbreak and the natural plants grow much better than that in the past,it has also improved the natural landscape along railroad in a certain degree,and also made the travelers relax and pleasure when they pass through the Gobi desert and sandy desert.
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