竖管地下灌溉毛管水力特性及土壤水分布对土壤空间变异的动态响应

The subsurface vertical tube irrigation is a new type of water-saving irrigation technique. Because vertical tube emitters of subsurface vertical tube irrigation buried in the soil, soil spatial variability is one of the main factors that affect hydraulic characteristics. Because of vertical tube emitters with low-pressure head, the infiltration driving force is the pressure potential and matric potential, infiltration flow of emitter changes with time, so water flow in both vertical tube emitter and lateral is the unsteady flow. Scientifically understanding the effects of dynamic coupling process between lateral pressure flow and soil water movement under soil spatial variability , to create a mathematical model for describing the dynamic coupling process ,is become a key scientific problem to be solved for farther researching the system hydraulic characteristics , the soil water distribution and technology key element of subsurface vertical tube irrigation. The vertical tube emitters, lateral and surrounding soil will be studied as a system, based on soil water dynamics, unsteady flow theory, geostatistics, fractal theory, random theory, model simulation and optimization theory, support vector machine and advanced experiment testing technology :(1) The numerical simulation of soil water infiltration and movement of vertical tube emitters; (2) The stochastic simulation of laterals unsteady flow based on the soil spatial variability;(3) Effects of soil spatial variability and irrigation technique parameters of subsurface vertical tube irrigation on irrigation quality. The research objectives is to reveal the interrelationship of soil spatial variability, emitter and lateral dynamic hydraulic characteristics, temporal and spatial distribution characteristics of soil water and irrigation quality, Research results will provide the scientific basis for the planning, design, management, and equipment development of the subsurface vertical tube irrigation.

竖管地下灌溉是一种新型节水灌溉技术。竖管灌水器（简称灌水器）埋在土中，土壤空间变异影响竖管地下灌溉系统水力特性。在压力势和基质势作用下，灌水器入渗流量随时间变化，灌水器及毛管均为非恒定流。科学认识基于土壤空间变异性的毛管压力水流动与非饱和土壤水运动的动态互馈机制，创建描述这一互馈过程的数学模型，是进一步研究竖管地下灌溉系统水力特性、土壤水分布和灌溉技术要素亟待解决的科学问题。运用土壤水动力学、非恒定流理论、地统计学、分形理论、随机理论、优化理论、支持向量机、响应面分析和先进的测试技术，将灌水器、毛管和周围土壤作为一个系统研究：(1)灌水器入渗及土壤水运动数值模拟方法；(2)基于土壤空间变异的毛管非恒定流随机模拟方法；(3)土壤空间变异与有关技术参数对灌水质量的影响。旨在揭示土壤空间变异性、灌水器和毛管动态水力特性、土壤水时空分布特性和灌水质量的内在联系，为竖管地下灌溉技术应用提供科学依据。

竖管地下灌溉是一种新型节水灌溉技术。竖管灌水器埋在土中，果树生长的异质性和土壤空间变异影响竖管地下灌溉系统水力特性。在压力势、重力势和基质势的作用下，竖管灌水器入渗流量随时间变化，竖管灌水器及毛管均为非恒定流。将竖管灌水器、毛管和周围土壤作为一个系统研究。研究内容包括：(1)竖管灌水器入渗及土壤水运动数值模拟方法；(2)基于土壤空间变异的毛管非恒定流随机模拟方法；(3)土壤空间变异性、果树生长异质性与技术参数对灌水质量的影响。通过研究揭示土壤空间变异性、灌水器和毛管动态水力特性、土壤水时空分布特性、果树生长的异质性和灌水质量的内在联系，为竖管地下灌溉技术应用提供科学依据。项目重要成果为：（1）竖管灌水器入渗开始，周围土壤含水率低，基质势起主导作用，入渗流量大，随着入渗时间的延续，竖管灌水器周围土壤含水率增加，基质势作用降低，入渗流量逐渐降低，竖管灌水器可根据土壤含水率，自动调节入渗流量，当土壤含水率较低时，入渗流量大，当土壤含水率较高时，入渗流量小。竖管灌溉满足连续灌溉的条件，可实现自动和精准灌溉。竖管灌水器入渗流量为0.53～3.25 L/h，流量范围较大，表明竖管地下灌溉技术对不同作物需水要求的适应性更强。（2）与地表滴灌对比试验表明，新疆阿克苏灰枣树竖管灌溉的灌溉量约为地表滴灌的50%左右。竖管灌溉的产量与滴灌持平，并降低裂果率，提高了灰枣的品质。竖管灌溉为果树根系区持续供水，并维持适宜土壤含水量。当植物根系吸水时，土壤含水量减小，基质势增加，竖管灌水器流量增加；当气温过高，叶片气孔关闭，根系吸水减小，竖管灌水器的流量减小。竖管灌溉技术具有节水、节能、省肥、抗堵、优质高产、寿命长、自动灌溉和水肥一体化等技术优势，适用于果树灌溉，具有显著的经济效益、社会效益和生态环境效益。