【作者】 李天霄；

【导师】 付强；

【作者基本信息】 东北农业大学 ， 农业水土工程， 2010， 硕士

【摘要】 水是人类赖以生存和社会发展不可缺少的物质基础,而我国是一个严重缺水的国家,水资源短缺严重制约了我国工农业的发展。与工业相比,农业用水面临的形势更为严峻。由于我国的国情特点,农业资源利用中水资源短缺与水资源浪费并存的情况比较严重。因此,提高农业水资源利用效率显得越来越重要,农业节水灌溉和高效用水已经成为全社会所关注和重视的重大问题之一。本论文立足于北方寒区,以冬季冻融土壤大田观测试验为依据,结合现代数据处理方法,对冻融条件下的土壤水分相变、入渗和蒸发规律进行了系统的研究,主要研究内容和成果如下：(1)将土壤冻融过程划分为单项冻结和双向融化阶段,采用粒子群优化的偏最小二乘回归模型对土壤冻融过程进行了模拟；分析了得出了试验周期内,地表温度的变化不会立刻对深层土壤温度场产生影响,而是要滞后一段时间,且滞后时间随深度增大而增大；深层土壤温度在整个冻融期基本保持不变。而且冻结初期,表层土壤相变特性在水平方向变异较小,垂直方向随着深度的增大相变逐渐变弱,直至冻层以下不存在相变,而冻结中后期,冻层范围内的土壤水分相变无论在水平方向还是在垂直方向,其变异特性均大于冻结初期。(2)对冻结土壤与非冻结土壤的区别进行了阐述,得出：寒区冻结土壤入渗过程在不同冻深条件下达到相对稳定入渗时间与非冻结土壤存在较大差异；在相同冻深条件下,冻结土壤入渗能力随着冻深的发展有减小的趋势,且冻深对冻结土壤的早期入渗能力影响较大,后期相对减弱；采用多元回归的方法,建立了冻结土壤入渗能力模拟方程,通过精度检验,模型满足要求,可以将其应用在冻结土壤入渗能力的模拟和预报中。(3)对冻结土壤蒸发特性进行了总结和概括,得出冻结条件下的土壤蒸发在各个阶段持续的时间要远远小于非冻结土壤,同时各阶段的的蒸发速率也要小于非冻结土壤：采用定性和定量相结合的手段,对土壤蒸发的影响因子进行了详细的分析与评价,得出：哈尔滨地区冬季土壤蒸发量的变化是众多影响因子综合作用下相协调的结果。其中地温、气温、相对湿度、风向、气压和水汽压是主要影响因子。采用BP人工神经网络技术对冻结土壤蒸发过程进行了模拟,取得较好的效果。综上所述,研究冻融土壤水分相变和蒸发入渗规律,探索科学、合理、可行的土壤水资源高效利用措施,不仅为北方干旱、半干旱寒区解决水资源供需矛盾、促进农业可持续发展提供了科技支撑,而且对于充分发挥冻土储水保墒作用和合理高效利用有限的土壤水资源具有重大意义。更多还原

【Abstract】 Water is the indispensable material basis for human survival and social development, and China is seriously shortage of water, which has seriously hampered the development of industrial and agricultural. Compared with the industrial, Agricultural water faces more serious situation. Because of China’s national conditions, Water resources shortage and waste are all serious in using agricultural resources. Therefore, it is very important to improve agricultural water resources use efficiency, agricultural water-saving irrigation and efficient water use has been one of the major concern and attention issues.This paper adopts the modern data processing methods and combines with frozen soil observation test in winter to systemically study phase-change law, infiltration law and evaporation on the condition of seasonal frozen soil in northern cold area. The main research contents and production are presented as follows:(1) Surface temperature will not immediately affect the deep soil temperature, but lag some time, which increases with the depth in test cycle. Deep soil temperature basically unchanged throughout the thaw period. At the same time, in initial frozen period, the variation of surface soil phase-change is small in the horizontal direction and in the vertical direction it gradually changes weak as the depth increases, and there is no phase-change under the frozen layer. However, in frozen middle and later periods, the variation is bigger than that in initial frozen period not only in the horizontal direction but also in the vertical direction.(2) The difference between frozen soil and unfrozen soil is elaborated respectively. The results show that:compared with unfrozen soil, frozen soil infiltration process in different frozen depth conditions to achieve the relative stable time is quite different. The frozen soil infiltration capacity tends to decrease as the development of frozen depth in the same frozen depth, which has great influence on the infiltration capacity in early stage and relative weakening in later stage. At the same time, multiple regression method is used to set up frozen soil infiltration capacity simulation equation. Through accuracy testing, the model meet the requirements and can be used to simulate and forecast frozen soil infiltration capacity.(3) The characteristics of frozen soil evaporation is summarized, the time and rate for frozen soil evaporating at various phase is smaller than that of unfrozen soil. The methods of qualitative and quantitative are used to analyze and evaluate the factors of soil evaporation, and the result show that soil evaporation change in winter is induced by the action of multi factors. The main factors are ground temperature, air temperature, relative humidity, wind direction, air pressure and vapor pressure. BP artificial neutral network technology is used to fit the evaporation course and the results is effective.To sum up, it is very significant to study on the phase-change law, evaporation law and infiltration law of frozen-thawed soil and explorer scientific, reasonable and feasible measures for efficient utilization of soil water resources. It can not only provide technology support for solving water supply contradiction in northern arid and semi-arid cold region and promoting sustainable agricultural development, but also is of great significant to fully play the role of frozen storage moisture and rationally and efficiently use limited soil water resources.更多还原