Knowledge Resource Center for Ecological Environment in Arid Area
| 干旱区重度和轻度盐碱地包气带水分运移对比研究 -以克拉玛依农业开发区为例 | |
| 其他题名 | Comparison of Soil Water Movement through Unsaturated Zone in Severe and Mild Saline-alkali Fields - Case Study in Karamay Agricultural Development Area |
| 周田田 | |
| 出版年 | 2018 |
| 学位类型 | 硕士 |
| 导师 | 韩冬梅 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 在干旱区，由于气候、水文地质条件和无排水系统的影响，不合理的灌溉洗盐方式致使灌区内潜水位普遍上升，存在土壤次生盐渍化的风险，威胁当地的水土环境安全。包气带作为地表灌溉与地下含水层之间的缓冲带，研究包气带水分运移规律能够为制定高效节水的灌溉洗盐措施提供重要的理论依据，对于促进区域农业以及经济社会的可持续发展和保障水土环境安全具有重要意义。本文以克拉玛依农业开发区的重度和轻度盐碱化棉田为例，综合原位观测、同位素示踪和数值模拟方法，分析棉花生育期地表灌溉、降水，土壤水，地下水相关物理化学指标的时空分布特征，阐明干旱区基质势调控下滴灌棉田的包气带水分运移规律。得到的主要结论如下：（1）土壤含水量和土水势的时空分布特征：受灌溉（降水）入渗和棉花蒸散发的影响，重度和轻度盐碱地表层0~150 cm土壤含水量和土水势随时间的变化较为明显，在灌溉期增大，非灌溉期减小。深层（重度盐碱地150~260 cm、轻度盐碱地250~350 cm）受地下水毛细作用补给，土壤含水量和土水势随地下水位的抬升而增大。轻度盐碱地存在中间层（150~250 cm），几乎不受灌溉（降水）入渗和地下水毛细作用的影响，土壤含水量和土水势处于动态平衡。（2）降水（灌溉水）-土壤水-地下水同位素组成的时空分布特征：重度和轻度盐碱地表层0~150 cm土壤水同位素组成为前期土壤水与本次灌溉入渗水的混合特征。其中重度盐碱地120 cm、150 cm体现本次试验期间入渗水的同位素组成特征，降水和灌溉水的贡献比例分别为22%和78%。深层（重度盐碱地150~260 cm、轻度盐碱地250~350 cm）土壤水同位素组成为前期土壤水与地下水混合特征。轻度盐碱地中间层150~250 cm以前期土壤水为主，且土壤水同位素组成没有明显的分层性。（3）土壤水流动系统概念模型和基于零通量面法的包气带水量平衡结果：在基于基质势调控的滴灌模式下，灌溉影响深度主要集中在表层（0~150 cm）。轻度盐碱地中层（150~250 cm）不受灌溉水（降水）入渗和地下水毛细作用的影响。深层（重度盐碱地150~260 cm；轻度盐碱地250~350 cm）受地下水毛细作用的补给。对于重度盐碱地，从花期后期（8月4日-8月18日）和铃期前期和中期（8月18日-9月11日），到铃期后期（9月11日-9月18日），表层0-150 cm土壤水储存量对于轻度盐碱地分别减小1.9 mm、减小59.0 mm和增加0.7 mm；深层150~220 cm土壤水储存量分别增加7.7 mm、55.4 mm、7.1 mm。对于轻度盐碱地，从花期后期、铃期前期和中期（8月3日-9月11日），到铃期后期（9月11日-9月18日），0~150 cm土壤水储存量分别减小50.0和17.7 mm；中层150~250 cm土壤水储存量分别增加10.8 mm和减小2.6 mm；深层250~350 cm土壤水储存量分别增加13.1 mm和17.9 mm。总体而言，表层土壤水储存量基本都在减小；深层土壤水储存量增加；中层土壤水储存量变化较小。（4）基于数值模拟的包气带水量平衡和棉花的耗水规律：在模拟期间，重度盐碱地灌溉水（降水）、地下水对土壤水的补给比例分别为92.1%和7.9%；灌溉水主要以蒸散发的形式排泄（64.3%），土壤水储存量的增量较小（35.7%）。轻度盐碱地灌溉水（降水）、地下水对土壤水的补给比例分别为85.0%和15.0%；灌溉水主要以蒸散发的形式排泄（92.4%），土壤水储存量的增量较小（7.6%）。总体而言，模拟期间地下水通过毛细作用对土壤水以补给作用为主，灌溉水主要以蒸散发的形式排泄，土壤水储存量的增量较小。重度和轻度盐碱地在各个时期的蒸散强度相差不大，但高于前人研究。（5）灌溉水对地下水的影响及地下水补给来源：在此灌溉模式下，灌溉水难以补给到地下水。试验期间重度和轻度盐碱地地下水位分别抬升了60 cm和50 cm，主要由地下水侧向径流引起。轻度盐碱地的中间层增加了作物根区与地下水位之间的距离，使得轻度盐碱地相比于重度盐碱地更难发生土壤次生盐渍化。为了抑制开发区地下水位抬升，可以采取如下措施：（a）进一步优化灌溉方式；（b）建立排水系统；（c）修建水处理厂，对咸水加以利用；（d）盐碱地的生物改良。 |
| 英文摘要 | In arid areas, due to the dry climate, special hydrological geological conditions and lack of the drainage system, unreasonable irrigation desalting often causes sharp water table rise, and potential soil secondary salinization, which poses great threat to the local water and soil environment. Water movement through the unsaturated zone, a buffer zone between the surface irrigation and aquifers, can provide important theoretical basis to formulate efficient and water-saving irrigation desalting measures, to promote the sustainable development of regional agriculture and economy, and is of great significance to guarantee the safety of water and soil environment.In this study, taking the severe (Plot 1) and mild (Plot 2) saline-alkali cotton fields in Karamay agricultural development zone as an example, we applied in-situ monitoring, stable isotopes tracer and numerical simulation, and analyzed spatial and temporal distribution of physical and chemical indicators in surface water (irrigation water and precipitation), soil water, and groundwater, to clarify the water movement characteristics in mulched drip irrigation mode with soil matric potential control. The main conclusions are as follows:(1) Spatio-temporal distribution of soil water content (SWC) and soil water potential (SWP): Affected by irrigation water (precipitation) infiltration and cotton evapotranspiration, the SWC and SWP at surface layer (0~150 cm) for both plots changes obviously over time, showing increasing trend during irrigation period and decreasing trend during non-irrigation period. Affected by groundwater capillary rise, SWC and SWP at deep layer (150~260 cm for Plot 1 and 250~350 cm for Plot 2) are comparatively stable, increasing with water table rise. Middle layer (150~250 cm at Plot 2) is almost not affected by infiltration and groundwater capillary rise, and SWC and SWP of this layer show dynamic balance.(2) Spatio-temporal distribution of isotopic compositions in waters: Isotopic compositions of soil water at 0~150 cm for both plots are the mixture of antecedent soil water and infiltration water during this experiment. Among which, isotopic compositions of soil water at 120~150 cm for Plot 1 is representative of infiltration water during this experiment, with precipitation and irrigation water accounting for 22% and 78%, respectively. Isotopic compositions of soil water at deep layer (150~260 cm for Plot 1 and 250~300 cm for Plot 2) is close to that of groundwater, affected by groundwater capillary rise. Isotopic compositions of soil water at middle layer, i.e. 150~250 cm for Plot 2 is dominated by antecedent soil water, and has no obvious stratification compared with Plot 1. (3) Water balance calculation based on the zero flux plane method: For Plot 1, from the late flowering (August 4-August 18), the early and middle boll (August 18-September 11), to the late boll (September 11-September 18) periods, Soil water storage (SWS) at surface layer (0~150 cm) decreased by 1.9 mm, decreased by 59.0 mm and increased by 0.7 mm, respectively, while SWS at deep layer (150~220 cm) increased by 7.7 mm, 55.4 mm and 7.1 mm. For Plot 2, from the late flowering and the early and middle boll (August 3-September 11), to the late boll (September 11-September 18), SWS at surface layer (0~150 cm) decreased by 50.0 mm and 0.7 mm, respectively; SWS at the middle (150~250 cm) increased 10.8 mm and decreased by 2.6 mm respectively; while SWS at deep layer (250~350 cm) increased by 13.1 mm and 17.9 mm, respectively. In general, SWS decreases at surface layer, increases at deep layer, and changes little at middle layer.(4) Water balance and cotton water consumption calculation based on the numerical simulation: For Plot 1, water (precipitation) and groundwater account for about 92.1% and 7.9% of all sources of the unsaturated zone, respectively; evapotranspiration is the main sink (64.3%), and the increment of SWS is relatively small (35.7%). For Plot 2, water (precipitation) and groundwater account for about 85.% and 15.0% of all sources of the unsaturated zone, respectively; evapotranspiration is the main sink (92.4%), and the increment of SWS is relatively small (7.6%). In general, groundwater recharges into soil water through capillary rise during simulation period, evapotranspiration is the main sink, and the increment of SWS is relatively small. Evapotranspiration intensity is similar in these two plots during different cotton growth periods, but higher than that of previous studies, because of the large amount of the total irrigation and high irrigation frequency in our experiment. (5) Impacts of irrigation water on groundwater and groundwater recharge source: The irrigation water has no significant recharge into groundwater under this irrigation mode. Lateral groundwater flow is the main reason for the water table rise (about 60 cm at Plot 1 and 50 cm at Plot 2) during experiment period. The middle layer at Plot 2 extends the distance between crop root zone and water table, and thus Plot 2 is less prone to secondary soil salinization compared with Plot 1. To retard the water table rise, the following measures can be taken: (a) to further optimize irrigation methods; (b) to build drainage system; (c) to build a water treatment plant to use the salty water; and (d) to conduct biological improvement of saline-alkali soils. |
| 中文关键词 | 干旱区 ; 盐碱地 ; 滴灌棉田 ; 包气带 ; 地下水补给 |
| 英文关键词 | Arid zone Saline-alkali soils Drip irrigated cotton fields Unsaturated zone Groundwater recharge |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 自然地理学 |
| 来源机构 | 中国科学院地理科学与资源研究所 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/288071 |
| 推荐引用方式 GB/T 7714 | 周田田. 干旱区重度和轻度盐碱地包气带水分运移对比研究 -以克拉玛依农业开发区为例[D]. 中国科学院大学,2018. |
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