雨养玉米农田水热交换的环境控制机理研究     

李祎君 《气候与环境研究》2015,20(1):71-79

基于连续3年的涡相关观测数据分析了雨养玉米农田水热交换的环境控制机理.结果表明:热量(辐射与温度)与水分(土壤含水量与大气水汽压亏缺)因子是控制农田水热交换的关键因子,但随着研究时间尺度变化,其作用强度显著不同.当研究时间尺度由小时—日—月—季—年逐渐增大时,热量因子对玉米农田水热交换的影响逐渐减弱,而水分因子的影响却逐渐增强.因而,模拟玉米农田水热交换,以小时时间分辨率模拟时,能量输入应以辐射为主;以月为时间分辨率时,能量输入应以温度为主,可以提高模拟精度.另外,不同水文年型控制雨养农田水热交换的主要因子也有显著差异.湿润年,土壤水分充足,决定蒸发强度的可用能量是限制水分交换的关键因子;偏干年,农田水热交换受制于水分与能量的双重制约.因此,在估算半干旱地区水热交换时,同时还应关注不同水文年型的迥异环境控制机理,以提高不同时间尺度模型模拟精度.  相似文献   

Water availability in almond orchards on marl soils in southeast Spain: The role of evaporation and runoff   总被引：1，自引：0，他引：1  

A. Meerkerk  B. van Wesemael  E. Cammeraat 《Journal of Arid Environments》2008,72(12):2168-2178

Clean sweeping (i.e., frequent and shallow tillage in orchards) is a common practice in semi-arid areas. A potential drawback in dry areas is that the tree roots cannot access the water in the plough layer. Our objective was to quantify the loss of water by evaporation and the loss or gain by overland flow in almond (Prunus dulcis Mill.) orchards on loamy soils in southeast Spain. The evaporation from a 15 cm plough layer equals 70–104% of annual precipitation, taking into account losses or gains by overland flow. The large evaporation explains the low canopy cover observed, which averaged 3.2%. The runoff coefficient of the test sites is 1–6%. There is no drainage below 15 cm during dry years, except for an area that receives a net influx of overland flow. The trunk basal area in this depression is 12% larger compared to the rest of the field. The options for increasing the water intake of the trees are to reduce the tillage depth or to switch from clean sweeping to no-tillage combined with chemical weeding.  相似文献