黄土区不同尺度深层土壤水分研究

发布时间：2018-05-19 03:25

本文选题：样带 + 小流域　；参考：《中国科学院大学(中国科学院教育部水土保持与生态环境研究中心)》2017年硕士论文

【摘要】：黄土高原作为全球典型的半干旱、干旱区域,水分是限制该区植被生长的重要因子,黄土高原土壤经常处于水分亏缺状态。黄土高原天然降水具有降水量少、年际间变幅大、年内分布不均等特点,植物生长期内的降水常常不能满足植物生长的需求。因此,黄土高原地区土壤水分动态平衡是保证生态系统可持续、稳健恢复的关键。深入研究黄土高原不同尺度深层土壤水分的空间格局和分布特征是区域水资源评价、管理及植被科学布局过程中的一项重要任务。针对目前黄土高原现状,本论文分别在区域尺度的一条样带和三个典型的小流域为研究区域,对土壤水分的空间分布状态进行研究,并且进一步分析了土壤储水量和有效土壤储水量的分布特征及其相关因素的影响。小流域内揭示了沟道深层土壤的蓄水能力,主要取得的研究成果包括以下几个方面:(1)揭示了样带尺度土壤水分的分布规律及其两气候区土壤水分的分布特征。土壤储水量(SWS5m)从东南向西北逐渐递减,半湿润区5 m深的土壤储水量比半半旱区要高320 mm。半干旱区的SWS和土壤有效储水量(ASWS)在0-500 cm剖面比半湿润区表现较大的变异,半干旱区的SWS1m和ASWS1m随土层增加而增加,而在半湿润区,两者则表现出随土层而不断波动的状态。(2)土壤储水量垂直剖面的分布规律。旱季SWS5m和ASWS5m在100-500 cm的值比雨季小,说明土壤储水量在我们测量的这段时间内是相对稳定的。SWS1m和ASWS1m在0-100 cm土层表现出很大的波动,说明浅层土壤更容易受到环境因素(降雨、入渗、蒸发等)的影响。(3)分别在样带和两气候区探讨了土壤储水量与各个因子的关系。样带尺度上,SWS5m和ASWS5m在土地利用类型之间存在显著差异。半干旱区的SWS5m和ASWS5m主要受土壤性质的影响,半湿润区的SWS5m和ASWS5m则受土壤、海拔和纬度的综合制约。在大尺度上SWS5m和ASWS5m是由气候因素、地形要素、土壤性质共同决定的。(4)三个小流域土壤水分分布特征与相关因素分析。三个小流域土壤质量含水量在2.3%和46.6%之间变动,平均值为11.2%,变异系数为53%,属于中等程度变异。沟道土壤水分的平均值比坡面的要高11.6%。沟道水分的变异系数比坡面要高。四种土地利用类型下的坡面土壤水分的垂直分布表现出不同形式,三流域阴坡土壤水分均比阳坡的要高。(5)沟道新造耕地有很大的储蓄深层土壤水分的能力,南沟和顾屯治理流域增加的储蓄的水分分别占年均降水的19%和18.9%。
[Abstract]:As a typical semi-arid and arid region of the world, water is an important factor limiting vegetation growth in the Loess Plateau, and the soil in the Loess Plateau is often in a water deficit state. The natural precipitation in the Loess Plateau is characterized by less precipitation, large interannual variability and uneven distribution in the year. The precipitation in the plant growth period is often unable to meet the needs of plant growth. Therefore, the dynamic balance of soil moisture in the Loess Plateau is the key to the sustainable and steady restoration of the ecosystem. It is an important task for regional water resources evaluation, management and vegetation scientific distribution to study the spatial pattern and distribution characteristics of deep soil water in different scales on the Loess Plateau. According to the present situation of Loess Plateau, this paper studies the spatial distribution of soil water in a transect of regional scale and three typical small watersheds. The distribution characteristics of soil water storage and available soil water storage and the influence of relevant factors were also analyzed. The water storage capacity of the deep soil in the channel was revealed in the small watershed. The main research results included the following aspects: 1) revealing the distribution law of soil water in the transect scale and the distribution characteristics of soil water in the two climatic regions. Soil water storage (SWS5m) gradually decreased from southeast to northwest. The soil water storage at 5 m depth in semi-humid area was 320 mm higher than that in semi-arid area. The variation of SWS and soil available water storage in semi-arid area is larger than that in semi-humid area in 0-500cm profile. The SWS1m and ASWS1m in semi-arid area increase with the increase of soil layer, but in semi-humid area, the variation of SWS1m and ASWS1m in semi-arid area is higher than that in semi-humid area. The vertical profile distribution of soil water storage showed that the soil water content fluctuated continuously with the soil layer. The values of SWS5m and ASWS5m in dry season at 100-500 cm are smaller than those in rainy season, indicating that soil water storage is relatively stable in the period of time we measured. SWS1m and ASWS1m fluctuate greatly in 0-100cm soil layer, indicating that shallow soil is more vulnerable to environmental factors (rainfall). The effects of infiltration and evaporation) on the relationship between soil water storage and various factors were studied in the transect and in the two climatic regions, respectively. There were significant differences between SWS5m and ASWS5m in land use types on the scale of transect. SWS5m and ASWS5m in semi-arid areas are mainly affected by soil properties, while SWS5m and ASWS5m in semi-humid areas are restricted by soil, altitude and latitude. On a large scale, SWS5m and ASWS5m are determined by climatic factors, topographic factors and soil properties. The soil water content of the three small watersheds varied between 2.3% and 46.6%, the average value was 11.2, and the coefficient of variation was 53. The average value of soil moisture in the channel is 11.6m higher than that on the slope. The coefficient of variation of channel water is higher than that of slope. The vertical distribution of soil water on slope under four land use types shows different forms. The soil moisture of shady slope in three basins is higher than that of sunny slope. The water content increased in Nangou and Gutun watershed accounts for 19% and 18.9% of the average annual precipitation, respectively.
【学位授予单位】：中国科学院大学(中国科学院教育部水土保持与生态环境研究中心)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S152.7

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