盐渍化引黄灌区农田GSPAC系统对不同灌溉模式的响应机制及水肥热盐协同调控研究

The salinization Yellow River Irrigation District in Inner Mongolia was elected as a research object to study the movement of soil moisture, nutrient, heat as well salt,the chang of groundwater environment and the crop response mechanism under different irrigation patterns ( Yellow River surface irrigation , traditional irrigation combined with canal and wells , the drip irrigation with Yellow River Water direct, groundwater drip irrigation - Yellow River supplementary irrigation ),basing on field experiments and groundwater drip irrigation - Yellow River supplementary irrigation as the main pattern . The sduty aims at putting forward control technology of collaborating with water fertilizer heat salt,basing the effect of different irrigation patterns on the structure of the soil , water fertilizer salts migration mechanism,warming with drip irrigation under plastic,crop growth and groundwater quality as well level ,also on mechanisms of water -saving as well fertilizer-retaining and salt-washing as well water-storing in different patterns.The SWAP-GIS-MODFLOW model was built through coupling SWAP model , GIS and MODFLOW model,which will be used to simulate regional soil water -fertilizer-salt movement,the change of groundwater,agricultural non-point pollution,and water-saving potential analysis after well and canal - groundwater drip irrigation Yellow River supplemental irrigation carried out,combining with irrigated water resources assessment and planning achievements and existing research and basic data.The target of regional simulate is to reveal the feasibility of well and canal - groundwater drip irrigation Yellow River supplemental irrigation pattern in salinization Yellow River Irrigation District in Inner Mongolia ,and to provide a scientific basis for the planning of the water-saving irrigation and irrigation management decisions.

本课题以内蒙古盐渍化引黄灌区为研究对象，以井渠结合地下水膜下滴灌-引黄补灌模式为核心，以田间试验为基础，开展不同灌溉模式（引黄地面灌溉、传统井渠结合灌溉、黄河水直接滴灌、地下水滴灌-引黄补灌）农田土壤水肥热盐迁移规律-地下水环境变化与作物响应方面的对比试验研究，揭示不同灌溉、补水模式对土壤结构、水肥盐迁移、膜下滴灌增温、作物生长及地下水水质、水位的影响机制和不同滴灌补水模式的节水保肥和储水洗盐效应机理，提出不同滴灌补水模式下的水肥热盐协同调控技术。结合灌区水资源规划成果，将SWAP 模型、GIS 及MODFLOW模型进行耦合，构建SWAP-GIS-MODFLOW模型，结合已有研究成果和基础数据，开展河套灌区不同灌溉模式下区域土壤水盐迁移动态和面源污染模拟评价与节水潜力分析，揭示在引黄盐渍化灌区开展井渠结合膜下滴灌的可行性，为引黄灌区的农业水资源高效利用和灌区的可持续发展提供决策依据。

为了探明不同灌溉模式下农田GSPAC系统水热传输过程的盐分养分运移机理与响应机制，近而为农田土壤盐分调控提供理论支撑。本课题针对内蒙古河套灌区水资源短缺，干旱盐渍化严重的现状，根据农田尺度上节水控盐灌溉、区域尺度上井渠结合调控地下水位降蒸抑盐的思路，通过研究玉米膜下滴灌不同灌溉制度下的水盐分布运移规律，比较不同灌溉模式（黄河水畦灌、井水畦灌、井水滴灌）灌溉水－土壤水－地下水转化关系、土壤热量盐分状况及对玉米生长产量的影响等，分析井渠结合区渠灌、井灌区典型作物灌溉制度、水盐变化及井渠结合对地下水埋深的调控效果及对土壤盐分的影响，发现内蒙古河套灌区干旱少雨蒸发强烈，膜下滴灌土壤水分在强烈的蒸发作用下主要经不覆膜区蒸发和植株蒸腾散失，盐分随水分由膜内向膜外，由深层向地表定向迁移运动趋于膜外地表积累，剖面分布极不均匀。膜下滴灌土壤温度受气温、玉米覆盖度（LAI）、灌水及土壤含水率共同作用；不同灌溉模式土壤水分及盐分在灌水、降雨和蒸发作用下波动变化，灌溉水－土壤水－地下水交换强烈，建议膜下滴灌２年一洗盐。井渠结合区典型地块灌溉制度及水盐监测也表明，目前大的灌溉定额是井灌区生育期维持土壤盐分平衡而不用每年秋浇的主要因素。并且揭示了井渠结合对区域地下水及土壤盐分的调控机制。井渠结合区地下水埋深是降雨、灌溉、蒸发及井渠结合工程等人为因素与自然因素共同相互作用的结果。通过通径分析结果发现，降水及灌溉对地下水埋深的直接影响最大，是地下水下降的最主要因素；蒸发对地下水埋深的影响起到间接作用。同时发现井渠结合区地下水埋深与土壤盐分满足多项式关系，地下水埋深大子2m后，埋深越大，土壤盐渍化程度越轻，且盐分下降越快。通过不同灌溉方式与生物炭耦合研究发现，滴灌和生物炭耦合对提高土壤含水量具有积极效应，但同时加剧土壤盐分的积累，对土壤PH影响不显著。施加生物炭后，减缓土壤与大气热交换，对热量双向运动都有一定的阻碍作用，有效平抑土壤温度的波动幅度。.因此，调控地下水位是干旱半干旱地下水浅埋区土壤盐分控制的主要途径。建议，内蒙古河套灌区井渠结合膜下滴灌在生育期灌溉制度和非生育期引黄洗盐灌溉相结合。