Knowledge Resource Center for Ecological Environment in Arid Area
| 科尔沁沙丘-丘间低地生态水文过程观测与模拟研究 | |
| 其他题名 | Eco-hydrological processes of the dune–interdune landscape in the Horqin Sandy Land, Northeastern China—measurements and model simulations |
| 周学雅 | |
| 出版年 | 2017 |
| 学位类型 | 博士 |
| 导师 | 关德新 ; 吴家兵 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 沙丘–丘间低地景观单元是沙漠化区域的主要地貌类型，土壤水分是将固沙植被对水分循环过程的影响与水分循环对植被动态的影响联系起来的关键因子。本文以科尔沁沙丘–丘间低地景观单元为研究对象，调查观测9种不同类型固沙条件下沙丘–丘间低地景观单元的植被、地势地貌、土壤含水量等数据，初步探讨了土壤含水量与沙丘–丘间低地景观单元、微地形以及降雨量的关系。利用土壤含水量实测数据对SWMS-2D模型进行校准和验证，并采用校准和验证了的SWMS–2D模型模拟了沙丘-丘间低地景观单元在不同雨量年（2013和2015年）的水分运移过程，分析了不同微地形（即沙丘顶部、沙丘上部、沙丘下部、沙丘底部和丘间低地）的土壤水分对降雨的响应并量化了水量平衡组分，从而加强了对当地气候、土壤、植被和地势条件下沙丘–丘间低地景观单元土壤水分运移过程的认识。研究结果如下： 1. 沙丘–丘间低地景观单元各微地形的平均土壤含水量与降雨量同步，但不同固沙条件下沙丘-丘间低地景观单元土壤含水量间有显著差异，且这种差异因降雨、土壤深度和微地形的不同而不同。表现为以下特点：（1）在干旱期间，沙丘顶部、上部和底部位置的土壤水分含量较低，其中沙丘顶部和上部位置在60cm深度以下土壤含水量的变化幅度略大于上层，150cm以下其变化范围有限。沙丘底部位置从120cm深度开始，土壤含水量及其变化幅度显著增大。在丘间低地位置，从30–60cm深度开始，土壤含水量显著增大，以及不同丘间低地位置间土壤含水量的变幅也增大且大于其他微地形。（2）雨后湿润期间，在0–60cm深度范围内，土壤含水量及其变化范围随深度的增加而减小；在60cm深度以下，在干旱和雨后湿润条件下的土壤含水量间无显著差异，但其土壤含水量间的变化范围增大。丘间低地位置在150–200 cm处达饱和含水量。2. 利用沙丘–丘间低地景观单元土壤含水量实测数据对SWMS–2D模型进行校准和验证，结果表明：模拟值和测量值的吻合度较好，其RMSE小于0.04cm3·cm?3，R2大于0.81。3. 土壤水分动态及其对降雨响应的模拟研究表明，降雨对土壤水分的影响与次降雨量、土壤深度等因素有关，表现出如下特点：（1）表层（0–20cm深度）土壤含水量密切响应降雨模式，20–80cm深度的土壤含水量除在较大降雨影响下波动变化外，总体上呈略微的下降趋势。沙丘底部130–150cm深度和丘间低地80–110cm深度有较高且稳定的土壤水分含量（>0.4cm3·cm-3）。（2）降雨对土壤水分的影响随雨量的增加而增大，小于5mm的次降雨对土壤水分几乎无影响；5–10mm的次降雨对10cm深度的土壤含水量有显著影响；10-20mm的次降雨使40cm土壤深度的水分含量显著增加；仅大于20mm的次降雨使深层土壤（>40cm）的水分含量增加。（3）当次降雨小于20mm时，沙丘顶部、上部、下部和底部位置的最大入渗深度一致，然而次降雨大于20mm时，沙丘底部位置的入渗深度较大。此外，土壤水分对降雨的响应时间随深度发生滞后，响应程度随深度被削弱。4. 水量平衡组分季节变异的模拟研究表明，不同季节、微地形影响水量平衡组分的变化，（1）70%以上的蒸散发集中在6到8月份，最大日蒸散发值是6.56mm·d-1。在月尺度上，蒸散发与降雨量不同步，总体上蒸散发滞后于降雨的发生。（2）在湿润年（2013）5–10月份，蒸散发与降雨量的比值分别是1.84、0.39、2.49、0.93、2.26和1.14；在干旱年（2015），该比值分别是2.40、1.11、0.69、2.14、1.07和1.11。（3）不同微地形的水量平衡组分有显著差异。丘间低地位置的蒸散发显著大于其他微地形，且在湿润年（2013）的值显著大于干旱年（2015）；在湿润年（2013），沙丘顶部、上部、下部和底部位置，蒸散发分别占降雨量的96、97、86和96%；而在干旱年（2015），这个比是103、103、88和104%，表明降雨的所有补给均通过蒸散发消耗掉。（4）在生长季，从沙丘顶部到底部位置的根区侧流量占水分收支的比例很小（小于3%）。 |
| 英文摘要 | Dune–interdune is the main landscape pattern of desert areas such as Horqin Sandy Land, Northeastern China. Soil moisture plays a critical role in the interactive effects of vegetation and water cycle process. In this study, vegetation, topography, and soil water content were investigated in nine different types of dune–interdunes, and the correlations of soil water content with dune types, topography and rainfall were preliminarily explored. The measured values of soil water content were used to calibrate and validate the SWMS–2D model. Based on the calibrated and validated SWMS–2D model, soil water movement in the dune–interdune landscape was simulated during the growing season in 2013 and 2015 with different rainfall. Based on the simulation results, the response of soil water to rainfall and seasonal variations of water balance components were quantified and compared during the growing seasons at different micro-landforms (i.e., the top, upper, down and bottom positions of the dune slope, and the interdune lowland area). These improved our general understanding of water balance variations under the local topography, climate, soil, and vegetation conditions. The results were showed as follows:1. The observational results showed that during the growing seasons of 2013 and 2015, soil water content was synchronous with rainfall at different micro-landforms of dune–interdune landscape. Soil water contents among different dune–interdunes were significantly different, and the differences were mainly attributed to rainfall, soil depths, and micro-landforms. (1) Under dry conditions, soil water content was generally less at the top, upper, and bottom positions of the dune slope. At the top and upper positions of the dune slope, soil water ranges below 60 cm depth were slightly larger than that at upper soil layer, and below 150 cm depth, soil water content and its ranges decreased. At the bottom position of the dune slope, soil water content below 120 cm depth and its ranges among different dune–interdunes increased. In the lowland area, soil water content within 30–60 cm depths significantly increased, and its ranges among different lowland areas also increased, which was larger than other micro-landforms. (2) In relatively humid conditions (after rainfall), within 0–60 cm depths, soil water content in diferent dune–interdunes and its ranges decreased with increased depth; below 60 cm depth, soil water content was almost similar with time, but soil water content among different dune–interdunes showed the large change.2. The measured values of soil water content were used to calibrate and validate the SWMS-2D model. The results showed good agreement, with RMSE values of<0.04 3="" cm3="" and="" r2="" values="" of="">0.81.3. The simulation results from the SWMS-2D model showed that the influence of rainfall on soil moisture was related to rainfall and soil depths. (1) Soil water content dynamics in 0–20 cm depths were closely linked to rainfall patterns, whereas soil water content in 20–80 cm depths illustrated a declining trend during the growing season in addition to fluctuations caused by heavier rainfall. Dune bottom soil water content in 130–150 cm depth and lowland soil water content in 80–110 cm depth were stable during the growing season (>0.4 cm3·cm-3), prominently higher than that at top, upslope and downslope positions. (2) The influence of rainfall on soil water content increased with increase of rainfall amount. The larger the rainfall event, the deeper the infiltration. Rainfall of<5 10="" 20="" 40="" mm="" had="" almost="" no="" influence="" on="" soil="" water="" rainfall="" of="" only="" exerted="" to="" an="" content="" in="" cm="" made="" depths="">20 mm increased soil water content in deeper soil layers (>40 cm). (3) Maximum infiltration depths at the top, upslope, downslope, and bottom positions of the dune slope were almost unanimous except for deeper infiltration occurring at the bottom position under rainfall of >20 mm. The response time of soil water to rainfall lagged with depth, and the response degree also weakened.4. Based on the simulation results from the SWMS-2D model, the seasonal variations of water balance components including evapotranspiration, soil water storage change, drainage and lateral flow were compared in different micro-landforms during the growing seasons. Results showed that (1) over 70% evapotranspiration occurred between June and August, with a maximum daily value of 6.56 mm·d-1. At a monthly scale, evapotranspiration was not synchronous with precipitation. (2) The ratio of evapotranspiration to precipitation was 1.84, 0.39, 2.49, 0.93, 2.26 and 1.14 from May to October 2013 (a wet year), and 2.40, 1.11, 0.69, 2.14, 1.07 and 1.11 in 2015 (a dry year). (3) The water balance components at different micro-landforms were significantly different. For example, evapotranspiration of a lowland area was greater than that in other micro-landforms, and the value in the wet year (2013) was significantly greater than that in the dry year (2015). At the top, upper, down, and bottom positions of the dune slope, the ratio of evapotranspiration to precipitation in the wet year (2013) was 96, 97, 86, and 96%, respectively; while in the dry year (2015), the ratio was 103, 103, 88, and 104%. Therefore, in the dry year, evapotranspiration was mostly larger than precipitation, indicating that almost all water from precipitation was evaporated. (4) Moreover, the lateral flow of root zone from top to bottom positions of the dune slope accounted for only a small part of water budgets at a growing season scale (<3%). |
| 中文关键词 | 科尔沁沙地沙丘–丘间低地 ; SWMS–2D模型 ; 微地形 ; 土壤水分对降雨的响应 ; 水量平衡 ; 生态水文过程 |
| 英文关键词 | Dune–interdune landscape in the Horqin Sandy Land SWMS–2D model Micro-landforms Response of soil water to rainfall Water balance Eco-hydrological processes |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 生态学 |
| 来源机构 | 中国科学院沈阳应用生态研究所 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/287905 |
| 推荐引用方式 GB/T 7714 | 周学雅. 科尔沁沙丘-丘间低地生态水文过程观测与模拟研究[D]. 中国科学院大学,2017. |
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