基于暗管排水的冻融期盐碱地水盐运移规律与改良调控模式

In recent years, Hetao Irrigation District of Inner Mongolia is facing a series complicated variations, such as the irrigation water from Yellow River being limited down seriously, micro drip irrigation being greatly promoted, subsurface drainage being applied gradually, saline soil improvement being varied in so much ways, autumn or spring leaching irrigation being confused for choose and etc,. From these factors, autumn irrigation, subsurface drainage and soil freezing-thawing are found outstanding elements which interfere saline soil improvement and irrigation-drainage scheduling. In this research, indoor soil column experiments on soil infiltration is to be performed to reveal the different irrigation-drainage mode effects on soil water retention characteristics, seepage characteristics and groundwater level variation. Indoor soil freezing-thawing experiment is also to be performed as well as to find unfrozen water content measurement and estimation methods. The in-situ monitoring of soil water and salt dynamic movements under subsurface drainage coupled with freezing and thawing is to be carried to specify quantitatively the transformation of soil free water - bound water, irrigation water-soil water-underground water- atmosphere water. According to "salts come and go with water", the movement of salts can be analyzed quantitatively after understanding the traces of water. Finally, the optimum irrigation-drainage mode during non farming period will be determined with the goal of salinization improvement and water saving and efficiency increasing. This research will fill the blank of the new scientific problems formed by the combination of subsurface drainage technology and the freeze-thaw process, and improve the theoretical basis for the adjustment of the agricultural development strategy in specific regions.

本研究针对内蒙古河套灌区近年来面临的引黄灌溉水量骤减、膜下滴灌大幅推广、暗管排水方兴未艾、盐碱地改良多管齐下、秋浇春汇各行其道等一系列错综复杂的动态发展过程，围绕困扰盐碱地改良和灌排制度制定的秋浇、暗管排水和土壤冻融三大要素，通过室内土柱的渗透实验，揭示不同灌排模式对土壤渗水性、持水性和地下水位的影响；通过土壤的室内冻融实验，明确适用于灌区盐碱土的未冻含水率的计测和估算方法；通过野外原位暗管排水与冻融作用叠加后的水盐动态监测，定量剖析土壤自由水-束缚水、灌溉水-土壤水-地下水-大气水的转化关系；凭借明晰的水分运移规律，根据“盐随水来，盐随水去”的基本原理，定量分析盐分的运移过程。最终以盐渍化改良和节水增效结果为目标导向，逆向确定最适宜的非耕种期灌溉排水模式。本课题内容将填补干旱寒冷灌区暗管排水技术与冻融过程叠加作用下形成的新科学问题的研究空白，完善特定地区调整农业发展战略的理论基础。

本研究针对内蒙古河套灌区近年来面临的引黄灌溉水量骤减、膜下滴灌大幅推广、暗管排水方兴未艾、盐碱地改良多管齐下、秋浇春汇各行其道等一系列错综复杂的动态发展过程，围绕困扰盐碱地改良和灌排制度制定的秋浇、暗管排水和土壤冻融三大要素，通过不同埋深、间距的暗管对地块尺度土壤盐分、水分、管道排水排盐量的持续观测研究，研究不同暗管埋深、间距等参数对土壤盐分分布、地下水埋深、矿化度以及水盐平衡的影响，建立盐碱地加速土壤脱盐的暗管高效控排盐技术并制定相应的技术规范；通过野外原位暗管排水与冻融作用叠加后的水盐动态监测，定量剖析土壤水热盐协同耦合作用关系；凭借明晰的水分运移规律，根据“盐随水来，盐随水去”的基本原理，定量分析盐分的运移过程。最终以盐渍化改良和节水增效结果为目标导向，逆向确定最适宜的非耕种期灌溉排水模式。整个项目实施过程中收集了研究区土壤调查、地下水调查、气象数据与多年灌排水量资料；完成了暗管埋设与冻融作用双重条件下的灌溉水-土壤自由水-土壤束缚水-地下水-大气水转化关系与模拟计算等成果；制定了以盐碱地改良为目的、适用于暗管排水和冻融作用的非耕种期灌排模式；撰写了年度报告、中期考核与结题报告；培养硕士研究生2名、当地技术人员3名；因疫情，未能参加国际学术会议；项目组6人次参加了3次国内学术会议；发表相关学术论文3篇，其中EI收录1篇，预期项目结束后1年内，完成1篇SCI论文。本项目所得成果已在内蒙古五原县2万亩盐碱地改良项目中进行了小规模应用。本研究内容将填补干旱寒冷灌区暗管排水技术与冻融过程叠加作用下形成的新科学问题的研究空白，完善特定地区调整农业发展战略的理论基础。