【作者】 张新；

【导师】 崔远来；

【作者基本信息】 武汉大学 ， 水利水电工程， 2005， 硕士

【摘要】 水稻田由于长期淹水并且将灌溉余水或田间径流量由渠道排入其他水体,造成灌溉用水给外界有浪费的印象,但是大范围来看,被排出的水大部分均得到了重复利用。国内外有不少关于回归水的研究,但大都通过实测资料估计。如何采用数值模拟技术量化水稻田回归水,充分掌握并且运用回归水以减少灌溉用水量,目前越来越受到农业水管理及区域水管理研究领域的重视。本研究在国内外众多研究成果的基础上,以水量平衡原理为基础,运用系统动力学方法,并以目前国际上流行的系统动力学分析软件Vensim为工具,在稻田田间尺度建立了上中下游三种典型田的水平衡转化过程的模拟模型,然后将模型用于田间尺度的模拟分析。在田间尺度模型的基础上,根据土地的不同类型构建中等尺度的稻田水平衡模拟模型。方法为:将中等尺度的土地使用分为水稻、旱田和其它三类,同时假定同一类型的土地是集中在一起的。根据三种土壤使用类型,分别采用相应的模拟方法进行灌、排水的连续计算,以逐日灌溉水量、降雨量和参考作物蒸发蒸腾量为输入,计算可得到不同土地使用类型的逐日排水过程,然后将逐日排水量相加,得到整个中等试区的逐日排水量。最后将此模型应用于中等尺度稻田回归水量的模拟分析。通过对漳河灌区稻田田间尺度和中等尺度水量平衡转化过程的模拟表明,模拟的地表出流过程与实测值吻合,模型能反映稻田水量平衡转化过程。对田间尺度回归水量的动态模拟表明:地表回归水量与来水量的变化趋势一致,地下回归水变化比较平稳,逐日回归水量动态变化随着来水量的增加表现出增加的趋势,同样累积回归水量随累积来水量的增加而增加。地下回归水量主要取决于当地的自然条件,如地形,土地情况,其中坡度对地下回归水的影响最大。对回归水量的敏感性分析表明,地表回归水量随着田埂有效高度的增加,表现出线性减少的趋势,但是田埂有效高度对田间回归水的影响可以忽略;田埂回归水量随着田块长度的增加表现出线性增加的趋势,随着田埂宽度的增加表现出明显减少的趋势;田埂回归水和田间回归水均随着水力传导度的增加而增加;田间回归水随着水平水力传导度的增加,表现出线性增加的趋势;地下回归水随坡度的变陡而增大;地表更多还原

【Abstract】 Because there is standing water in the paddy field and irrigation return flow or other runoff enter other water bodies via channel, it is thought that irrigation water is wasted. However, at a larger scale, most discharged water has been reused. Although there are many studies on return flow, but most of them are based on measured data to estimate return flow. How to quantify return flow from paddy rice field using numerical simulation to better understanding and use it more efficiently has been one of the focuses of agricultural water management and regional water management.Previous related studies have been reviewed. A Vensim based system dynamics water balance model for three typical fields (upper, middle and lower) was developed to simulate return flow, and then use the model to simulate the return flow of the paddy rice field at field scale. On the basis of model of field, according to different kinds of the land use the model at the medium scale. We divided land uses into three kinds: rice, upper land and others; meanwhile assumed that the different land use is concentrated. Using the data of the three kinds of soil, daily input irrigation, rainfall and ETo,we simulate the irrigated, drained off water in succession. Summarizing the daily discharge of different land uses we got the daily whole medium-sized discharge. Finally we applied the model to simulate the return flow of middle scale in the paddy rice field.We applied the model to Zhanghe irrigation scheme. The results show the simulated variation trend of the surface flow is consistent with the observed and the model can reflect the transform processing of water balance at the field scale. The dynamic simulated results of the field scale indicates surface return flow changing with inflow but subsurface return flow changing little; the daily return flow increases with the increasing of inflow and the cumulated return flow also increased with the cumulated inflow. The amount underground of return flow depends mainly on local natural conditions, such as the topography, land situation, while the slope has great impact influence on it.The sensitive analysis of the return flow proves the surface return flow decreased with the increasing of effective height of the border, but can neglect the influence of the subsurface return flow; the return flow of the border increased with the length of the terrain and obviously decreased with the increasing of the width of the terrain; the return flow of the border and farm increased with the increasing of hydraulic conductivity; the subsurface return flow increased with increasing of the slope; the surface return flow and the returnflow of the border and the farm decreased with the percentage of the upper land increasing; the effective return flow of the long and narrow combination is larger than the wide and narrow one .while the recycling factor is less than the other one.After calculating evaluation indicator of return flow, it indicates return flow factor of irrigation can reflect the runoff of the field and the use of water better than return flow factor of irrigation and rainfall; the return flow factor of irrigation and return flow factor of irrigation and rainfall of middle scale is about twice of the factors of the field; the recycling factor of the middle scale is low, while the effective return flow factor is high, which proves that can offer so much return flow for the lower fields; the recycling factor of the droughty year is bigger than the median flow year.更多还原