塔克拉玛干沙漠公路防护林棵间土壤蒸发及蒸发量估算

Characterizing and Estimating Soil Evaporation in Taklimakan Desert Highway Shelterbelt

棵间土壤蒸发是塔克拉玛干沙漠公路防护林耗水的重要组成部分。应用Micro-Lysimeters测定了1个灌溉周期内咸水滴灌下距林木不同位置处的土壤蒸发量。分析了土壤蒸发与水面蒸发的关系,通过一维平差处理对防护林土壤蒸发量进行了估算。结果表明,塔里木沙漠公路防护林棵间土壤蒸发具有明显的季节变化特征。试验初期棵间土壤蒸发量:根基部>距根基50cm处>距根基100cm处;第5d以后,根基50cm处>根基部>距根基100cm处。林地土壤蒸发随土壤含水量的减低呈整体下降趋势。通过估算,咸水滴灌下整个防护林年土壤蒸发总量为2.63×106 m3,占总灌水量的21.43%,生长季蒸发量占全年蒸发量的92.28%。

Soil evaporation is an important component of water consumption of the Taklimakan Desert Highway Shelterbelt.Micro-Lysimeters were used to measure soil evaporation within an irrigation cycle at different distances from the trees drip-irrigated with saline water.Meanwhile,the relationship between soil evaporation and water surface evaporation was analyzed,and soil moisture evaporation was estimated through one-dimensional adjustment processing.The results show that a spatial-temporal variation pattern of soil evaporation can be clearly identified in the shelterbelt： at the starting stage,the order of soil evaporation was tree base 50 cm from tree base 100 cm from tree base;and after the 5th day,the order was 50 cm from tree base tree base 100 cm from tree base.Soil evaporation in the shelterbelt decreased with soil water contents.The estimation shows that annual total soil evaporation of the shelterbelt will be approximately 2.63×106 m3 with drip-irrigation using saline water,accounting for 21.43% of total irrigation volume,and soil evaporation in a growing season accounts for 92.28% of annual soil evaporation.As soil evaporation results in such a high amount of water loss,appropriate measures may be required for reducing soil evaporation and improving water use efficiency.