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塔里木沙漠公路防护林带土壤水热盐动态及模型模拟
刘海东
学位类型硕士
导师赵英 ; 李生宇
2017-05-01
学位授予单位中国科学院大学
学位授予地点新疆乌鲁木齐
学位专业农学硕士
关键词塔克拉玛干沙漠 咸水滴灌 土壤水热盐动态 数值模拟 Taklimakan Desert Dynamics of soil water and salt Saline water drip-irrigation Numerical simulation
摘要In the desert area of Xinjiang, it has a potential to irrigate the shelterbelt using theunderground saline water, however, drought and salt stress could influence the plantgrowth and development. Therefore, understanding of soil water and salt dynamics, as wellas the plant response to the stress is a basis to design the reasonable irrigation schedule.With the field investigation, control experiment and model work together, to analyze thespatial and temporal dynamics of soil heat and salt and the tolerant mechanism of typicaldesert plants under different soil types and water salinities in Taklimakan Desert artificialshelterbelt, HYDRUS-1D is used to simulated soil moisture movement and salt. Mainresults for this study are as follows:The difference of soil water characteristic curve of each soil layer in the test areacorresponds to the difference of physical properties, that is, the features of curve of the soillayer with less content of the slits and clays and the bulk density larger is lower, theopposite is higher. Soil water retention capacity was stronger, which were related to thehigher content of clay particles and the smaller soil bulk density. Two models can be usedto test the soil water characteristic curve fitted, Van Genuchten model has more parameters,the fitting accuracy is higher in low suction less than 1.0×105 Pa, the fitted precision ofGardner model in the suction from 1.0×105 Pa to 15.0×105 Pa is slightly higher, on thewhole, Van Genuchten model fitted effect is better than that of Gardner model.Mean monthly soil temperature under the conditions of different depth of theTaklimakan desert shelterbelt approximate sine curve, and the seasonal alternation effecton temperature in the deeper soil layer is smaller than that of the shallow. The soiltemperature diurnal variation curve of 10~50 cm significantly dynamic than the others, thehighest temperature and the minimum temperature are gradually decline at the beginningof September. The soil temperature was affected by precipitation, 10 cm soil layer has mostsignificant response to rainfall. Compared with the sunny day, there is a significantdifference with change process, but the other layer features of the soil temperature is not obvious difference with sunny days, rainfall directly influenced the daily variationcharacteristics of shallow soil temperature.the soil temperature was basically consistent under different plant types, and the airtemperature was significantly correlated with soil temperature (p<0.01). Meanwhile, thecorrelation of soil temperatures in different soil layers decreased as the soil depth increased.In the soil of artificial shelterbelt, the dynamics of soil water and salt displayed an obviousperiodic rule. With respect to Haloxylon ammodendron, the distribution of soil water andsalt displayed a single-peak curve with the peak appeared at 30 cm in soil depth, while thedistribution of soil water and salt to Calligonum mongolicum showed a single-peak curvewith the peak occurred at 10 cm in soil depth. In the 0~200 cm soil profiles, the soilmoisture is divided into active layer, weak layer, and stable layer in Haloxylonammodendron, but active layer and weak layer in Calligonum mongolicum. The soilwetting front was a semi-ellipsoid shape after drip irrigation. The affected depth ofirrigation water was 0.6 m in Haloxylon ammodendron, while 1.5 m in Calligonummongolicum. The soil salt was concentrated in the upper layer. However, soil salinizationdid not exist due to less than 1.0 mS/cm. The growing season of soil pondage is 116.34 mmin Haloxylon ammodendron, but 100.99 mm in Calligonum mongolicum. All the soil waterdeficit ullage reached more than 270 mm. The plant types had few influences on soiltemperature. The irrigation of Calligonum mongolicum should be properly increased formaintaining the health of shelterbelt system.Hydrus-1D model was used to simulate the dynamics of soil water, heat and salt, thesimulated values of soil water, heat and salt transport were obtained, which can basicallyreflect the time variation law of growing season soil water heat salt. Among them, thewhole simulation of soil temperature in the process of simulation effect is better, the soilmoisture is the second, and the soil salt movement simulation effect is relatively poor. ingeneral, the simulated values can reflect the dynamic changes of soil water and salt indifferent soil layers. Our study is beneficial to provide a suitable irrigation system andapproach, which can ensure the sustainable development of shelterbelt system in Taklimakan Desert.
其他摘要新疆沙漠区可以利用地下咸水灌溉进行生态恢复,但是也会出现土壤次生盐渍化。因此,理清沙漠土壤水、热、盐的动态变化规律,是制定合理的灌溉制度的前提和基础。本研究针对塔克拉玛干沙漠公路防护林带滴灌条件下土壤水盐平衡问题,通过试验研究(室内测定、野外监测)与模型模拟相结合的方法,利用土壤水热盐原位动态观测等技术手段,分析不同区段、不同矿化度水灌溉下植物生育期土壤水热盐的时空分布及其运移规律,并应用 HYDRUS-1D 模拟试验地土壤水热盐动态变化。主要结果如下: 试验地各土层土壤水分特征曲线之间的差异与各自土层的物理性质差异相对应,即土壤黏粉粒含量较少、容重较大的土层,对应土层曲线的位置较低,反之则较高。各土层持水能力主要与土壤容重和颗粒组成等因素有关,土壤容重越小、黏粉粒含量越多,土壤含水量越高。VG 和 Gardner 模型均可用于拟合试验地土壤水分特征曲线,其中从拟合精度考虑,VG 模型本身参数较多,在 0~1.0×105Pa 吸力范围内的拟合精度较高,Gardner 模型在 1.0×105~15.0×105Pa 吸力范围的拟合精度稍高,但整体 VG模型的拟合效果优于 Gardner 模型。塔克拉玛干沙漠防护林较深土层范围内土壤温度变化受季节交替气温回升作用影响比浅层土壤温度小。10cm、30cm 和 50cm 土层土壤月均最高温和最低温均变化剧烈,在 9 月初月均最高温和最低温均逐渐下降。降雨发生的天气下,土壤温度受降水的影响,较浅土层(10cm)温度从凌晨至 23:00 时,总体变化趋势持续下降,与晴天时先降后升的变化过程差异显著,与晴天相比日变化幅度大,但其他土层温度变化特征与晴天相比差异不明显,降雨直接影响了较浅土层温度日变化特征。梭梭和沙拐枣根区土壤温度基本一致,气温与土壤温度呈极显著相关(P<0.01),各土层间土壤温度相关性随深度的增加逐渐减弱。受灌溉制度影响,防护林土壤水盐呈现明显的周期性变化规律,梭梭和沙拐枣根区土壤水盐动态变化趋势相似;在垂直方向上呈单峰曲线,其峰值分别位于 30cm 和 10cm 土层处。其中,梭梭植株下可分为水分速变层、弱变层和稳定层 3 个土壤层次,而沙拐枣可分为水分速变层和弱变层2 个土壤层次。灌溉后土壤湿润体均呈“半椭球形”分布,梭梭和沙拐枣根区土壤灌溉水影响深度分别为 60cm 和 150cm;而土壤盐分呈“表聚型”分布,但尚未造成土壤盐渍化(<1.0mS/cm)。 6~9 月份梭梭根区 0~200cm 土层平均贮水量(116.34mm)略大于沙拐枣(100.99mm),土壤水分亏缺明显,都大于 270mm。防护林各试验地土壤盐分含量随着灌溉水矿化度的增高而增加,且土壤盐分表聚性强,较浅土层含盐量最高。土壤水分和盐分的动态变化紧密相关,土壤水分表现出较浅土层水分波动幅度大于深层,且周期性变化规律明显。应用 Hydrus-1D 模型对防护林土壤水热盐动态进行了数值模拟,模型可以反映梭梭生长季土壤水热盐的时间变化规律。其中,整个模拟过程中土壤温度的模拟效果整体较好,土壤水分运移的模拟效果次之,而土壤盐分运动的模拟效果相对较差。整体来看,该模型可以用来进行区域土壤水热盐动态的预报。
学科领域水土保持与荒漠化防治
语种中文
文献类型学位论文
条目标识符http://ir.xjlas.org/handle/365004/14886
专题研究系统_荒漠环境研究室
作者单位中国科学院新疆生态与地理研究所
第一作者单位中国科学院新疆生态与地理研究所
推荐引用方式
GB/T 7714
刘海东. 塔里木沙漠公路防护林带土壤水热盐动态及模型模拟[D]. 新疆乌鲁木齐. 中国科学院大学,2017.
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