【作者】 岳海英；

【导师】 李援农；

【作者基本信息】 西北农林科技大学 ， 农业水土工程， 2010， 硕士

【摘要】 滴灌条件下土壤水分运移规律的试验研究,是正确设计滴灌系统和对田间作物水分进行精准管理的前提和基础。为了探索滴灌条件下土壤水分的运动规律及分布状况,进行了单点源和双点源条件下的室内滴灌试验。本文主要研究了点源入渗条件下,滴头流量和灌水量等因素对湿润体内各点土壤含水量、湿润体形状和湿润范围的影响;双点源入渗条件下,滴头流量和交汇作用对土壤水分分布规律的影响。主要研究成果如下:1)通过室内滴灌单点源入渗试验,结果发现湿润体形状符合抛物线模型,并且水平湿润锋和垂直湿润锋之间存在显著的抛物线关系,湿润体内水平和垂直湿润距离均随着入渗时间的推移而逐渐增大;不同滴头流量入渗试验时发现,滴灌湿润体水平和垂直入渗距离与入渗时间之间存在显著的幂函数关系,并且滴头流量越大湿润锋运移速率越大。水平和垂直两个方向上的湿润锋运移速率具有相同的规律:入渗开始时湿润锋运移速率较大,随着入渗时间的推移,运移速率逐渐减小。2)滴灌自由入渗条件下,当滴头流量为4.6L/h时,粘壤土垂直湿润锋运移速度大于水平湿润锋运移速度所用的时间最短。3)滴灌自由入渗条件下,利用得到的湿润体形状的抛物线特征,推求土壤湿润体特征值的经验解模型,通过试验数据进行验证,实测值与计算值之间相对误差绝大部分在5%以内,模型精度较高。湿润体内含水率在水平或竖直方向,滴头附近含水率最大,随入渗距离的增加而逐渐减小;在湿润体内某一平面上,含水率值大致相等;在离滴头距离从近到远的位置上,含水率差别从大到小变化,等值线由疏到密分布。4)本文利用抛物线旋转体模型获得了湿润体体积与灌水量之间的关系,通过分析获得单点源入渗湿润体内平均含水率变化的转折点,对应的滴头流量为0.65L/h;双点源交汇入渗湿润体内平均含水率变化的转折点,对应的滴头流量为0.53L/h。5)双点源交汇入渗条件下,滴头下方的水平入渗距离和垂直入渗距离均随着入渗时间的延长而增大,并且与入渗时间存在显著的幂函数关系,而交汇界面处的水平和垂直入渗距离与入渗时间之间存在显著的线性关系。湿润锋交汇界面处的土壤含水率大于相同土壤深度处的含水率。6)双点源交汇入渗条件下,在相同灌水量和相同滴头间距情况下,滴头流量越大,湿润体发生交汇用时越短;相同滴头流量条件下,土壤交汇界面湿润体内含水率大于单点源入渗条件下相同位置处的含水率。湿润体发生交汇前后,水平和垂直两个方向上含水率分布规律:两者都随着入渗距离的增加,湿润体内含水率逐渐减小。更多还原

【Abstract】 Research on soil moisture movement of drip irrigation, is the right design system and the premise and basis of field crops to high water management. In order to understand the movement of soil moisture and water distribution under drip irrigation through the laboratory test on a single-point source drip irrigation and two-point source drip irrigation. Under the conditions of point source infiltration, this paper studied dripper discharge and dripper water on soil moisture content, shape and range of wetting; Under the conditions of two-point source infiltration, dripper discharge and the effect of soil moisture movement on interference effect of two-point source infiltration. The main results are as follows:1) Through indoor single point source drip irrigation experiments, the results showed that, generally, wetting front is similar to a parabola, and vertical wetting front and horizontal wetting front exist the significantly parabolic relationship. The body of horizontal and vertical sub-humid distance increases with the increase of infiltration time. Through infiltration experiments with different emitter flow, the results showed that, there is a significant power function relationship between horizontal and vertical infiltration distance of wetting drip and infiltration time, and emitter flow rate is the greater the wetting front migration rate the greater. The regular pattern of horizontal and vertical directions rate of wetting front migration is same. Infiltration wetting front movement rate of the beginning is larger. With the infiltration time, the migration rate decreases. What’s more, at the same time the vertical infiltration wetting front migration rate is greater than the horizontal migration rate of wetting front.2) Condition in the drip free infiltration and emitter flow is 4.6L/h, vertical wetting front migration speed of change is higher than the level change rate of wetting front movement velocity,which used the shortest time.3) Condition in the drip free infiltration, using the parabolic of moist body shape, wetting characteristic value of the experience of solution model can be calculated. Test data can verify model. The most of relative error is less than 5%. Model has high accuracy. Moist body water content in the horizontal or vertical direction, moisture content near emitter is maximum and with the increasing infiltration distance decreases. In a plane, moisture content close to the same. Distance from the emitter near to far, water content changes from big to small and contour distribution is from sparse to dense.4) In this paper, using the parabolic model of rotating obtained the relationship between wetted soil volume and irrigation water amount. Finally, through the analysis, the dripper discharges was 0.65L/h express the average soil moisture from content to increase. Under the conditions of two-point source infiltration, the dripper discharges was 0.53L/h express the average soil moisture from content to increase.5) In the conditions of point source interference infiltration, the horizontal and vertical movement distance of soil wetting front are increase with infiltration time, and the horizontal and vertical movement distance of soil wetting front accorded good power function relation with infiltration time underside of dripper; but the horizontal and vertical movement distance of soil wetting front accorded good linear relationship on the intersection side.6) In the conditions of point source interference infiltration, under the same irrigation water amount and the same emitter space, when in large dripper discharge, using shorter time when occurs intersection in wetting. In the same emitter flow, the soil moisture of wetting front on the intersection side is bigger than the soil moisture of same depth in single point source infiltration. In the before and after intersection, the discipline of moisture content distribution in horizontal and vertical direction: with the extension of infiltration distance, soil water content gradually decreases.更多还原