Knowledge Resource Center for Ecological Environment in Arid Area
| 气候变化对中国天山雨雪冰产流过程的影响 | |
| 其他题名 | The Impact of Climate Change on Runoff Generation and Streamflow in the Tianshan Mountains, China |
| 张宜清 | |
| 出版年 | 2016 |
| 学位类型 | 博士 |
| 导师 | 罗毅 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 中国西北干旱区面积广阔，生态环境承载力弱，水资源问题突出。天山河源区产流保障了山前平原的水供给。近50年以来气候变化驱动了复杂的水循环过程，该区域温度和降雨的同步增加使山区径流呈增加趋势，但天山冰川面积的退缩导致冰储量持续减少，这可能会对未来水资源配置带来不利的影响。认清过去气候变化对天山流域水文过程产生的影响和预估未来潜在的水文过程变化对西北干旱区水资源的合理配置和利用具有重要意义。本文从区域水循环角度出发，以天山河源区冰川流域为研究对象，SWAT-RSG模型为工具，历史格点气象数据和GCM模式数据为驱动力，对过去(1961-2005年)和未来(2006-2100年) 多流域水文过程模拟，分析雨、雪、冰产流年内和年际变化特征，阐明产流过程机理，归纳冰川水文规律，探索流域、区域分异，归因径流变化主导因素，评估未来水资源变化。主要在方法论和冰川水文过程认识上取得以下进展。(1)依据统计分析理论，提出了冰川系统面积随高程分布的二阶高斯模型，可用于冰川面积分布偏态特征、集中程度和高程结构特征值的分析。基于中国第一次冰川编目，将全国冰川划分为27个冰川系统。结果表明，二阶高斯模型相比正态分布或经验公式能较好地描述冰川面积分布的偏态性和集中程度，易于计算高程特征值；采用第二次冰川编目检验了二阶高斯模型的适用性，发现气候变化导致冰川面积集中程度增加，但分布的偏态性没有发生显著变化。(2)改进了冰川水文响应单元(GHRU)方法中更新冰川分带高程面积的算法。在冰川单元尺度，模型能够对1号冰川面积及物质平衡进行有效模拟，识别出冰川融水对1号冰川小流域径流的贡献为72%，冰融水、冰上融雪产流和冰上降雨产流在冰川融水中的比重分别为54%、30%和16%。在流域尺度上，将径流(产流)划分为冰川融水、融雪产流、降雨产流和基流，模拟得出其在乌鲁木齐河流域径流中的比例分比为11.1%、10.6%、37.8%和40.5%。模型还可以识别不同尺寸冰川面积的变化。对比两个尺度的径流变化，发现1号冰川水文单元径流的增加是由冰融水和降水共同导致的。而在流域尺度为降水主导，冰融水表现为微减小趋势。说明冰川对径流的贡献在不同尺度是不同的。(3)通过采用SWAT-RSG模型模拟和分析1961-2005年天山河源区水文过程，发现流域的温度、降水和径流都呈显著性增加趋势(p < 0.05)，但冰川对产流贡献在流域间差异明显，贡献率为7.3-67.3%，均值为28.3%。在部分冰川面积覆盖率小的流域，冰川融水表现为减少趋势。基于多流域综合分析，归纳出冰川面积覆盖率是表征流域冰川水文效应的一个有效指标。其与冰川融水贡献率、冰融水贡献率、径流系数和径流变异系数呈幂指数关系(R2 > 0.58)。其中前三项随冰川面积覆盖率的增加而增大，后者随冰川面积覆盖率的增加而减小。当冰川面积覆盖率在10%以内时，冰川面积的微小变动可能会导致以上项的较大变化。冰川面积覆盖率这一指标能揭示同一区域冰川水文对气候变化响应的规律，可以用于分析和解释无资料区冰川水文过程。(4)利用气象数据分离方法，定量分析了1961-2005年天山河源区降水和温度变化对径流变化的相对贡献。结果表明，二者变化导致流域径流增加的比例为1.6-11.5%，均值为6.6%，但径流组成并没发生较大变化；对于增加的径流中，温度和降水的平均贡献率分别为42.9%和57.1%。多流域归因分析表明，温度和降水对冰川融水和径流变化的影响与冰川面积覆盖率有密切关系(R2 > 0.61)，温度的作用随冰川面积比例的增加而增大，而降水则为相反趋势，且在面积比例小于10%时，二者作用差异尤为明显。在空间分异上，在天山北坡降水为径流的主导因素，而在天山南坡为温度或二者共同主导。(5)采用GCM模式数据在RCP2.6、RCP4.5和RCP8.5三个情景下预估了2006-2100年各流域潜在的水文过程变化，并采用历史时期(1966-1995年)、近期(2016-2045年)和远期(2066-2095年)三个时段进行对比分析。结果表明，整个区域在RCP2.6、RCP4.5和RCP8.5情景近期温度平均上升1.76℃、1.46℃和1.80℃，降水平均增加3.8%、5.8%和5.7%；在远期温度上升2.15℃、2.99℃和5.40℃，降水平均增加4.7%、8.6%和8.4%。区域产流量近期平均增加13.4%、17.3%和17.9%，在远期分别为6.6%、16.0%和20.4%，增加最显著的是天山南坡冰川面积覆盖率较高的河流。大多数流域冰川融水和径流呈先增加后减少的趋势。对出现拐点的河流，发现径流的拐点要相对滞后于冰融水，冰融水滞后于冰川融水。基于水量平衡方法，归因分析了径流变化的主导因素。在近期降水和冰融水是整个天山径流变化的主要贡献者，而在远期天山北坡的流域将依赖于降水，而天山南坡流域为冰融水和降水共同主导。不确定性分析表明，干和冷、干和暖、湿和冷、湿和暖四个极端组合模式将会导致差异显著的径流过程。预估不同情景下冰川和水资源潜在的变化为该区域未来水资源的管理和利用提供了参考。 |
| 英文摘要 | The arid region of Northwest China is a large area with a weak ecological carrying capacity and severe water resources issues. Runoff from the headwaters of the Tianshan Mountains has significant implications for water supply in the piedmont plains. In the last five decades, climate-driven changes have complicated normal water cycle in the region. Simultaneous increase in temperature and precipitation has increased river runoff. However, glacier area in the region continues to shrink while glacier storage decreases, significantly affecting future water allocations. A clear understanding of the impact of climate change on hydrological processes and estimated potential changes in runoff in glacierized Tianshan basins is crucial for water resources allocation and utilization in the arid region of Northwest China.Based on regional water cycle, hydrological processes of glacierized headwaters of Tianshan Mountains were simulated using the Soil and Water Assessment tool-Rain-Snow-Glacier (SWAT-RSG) forced by historical grid data for 1961?2005 and the General Circulation Models (GCMs) for 2006-2100. This study analyzed the intra- and inter-annual processes of rainfall runoff, snow melt and glacier melt, clarified runoff generation mechanism, explored differentiation of hydrological processes at the basin and regional scales, attributed the dominant factors for the variations in runoff, and projected future changes in water resources. The main research results and achievements were as follows.(1) Based on statistical analysis, the second Gaussian regression model was built to describe the glacier area-elevation distribution of glacier systems, which was in turn used to analyze the skewed glacier distribution and the degree of glacier area concentration and elevation structure characteristics. The glaciers from the First Glacier Inventory of China were divided into twenty-seven sub-glacier systems. Compared with the normal distribution or empirical equations, the second Gaussian regression model better described the skew in glacier distributions with elevation. It also effectively computed the values of elevation structure in the study area. Furthermore, the model was tested using the Second Glacier Inventory of China and was found that while the degrees of glacier area concentration strengthened, the skewed glacier distributions did not significantly change.(2) The algorithm for the change in glacier area in each elevation band in the Glacier Hydrologic Response Unit (GHRU) was improved. At GHRU scale, the improved GHRU effectively estimated glacier area and mass balance of Urumqi Glacier No.1. The model was used to quantify the ratio of glacier melt to total runoff from Glacier No.1 GHRU, which was 72%. Then the ratios of ice melt, supraglacial snowmelt and rainfall-induced runoff on ice to glacier melt were 54%, 30% and 16%, respectively. At basin scale, runoff consisted of glacier melt, snow melt, rainfall runoff and baseflow, respectively contributed 11.1%, 10.6%, 37.8% and 40.5% to total runoff in the Urumqi River Basin. The model also quantified the changes in different glacier area sizes and the corresponding melt waters. Runoff increase from Glacier No.1 GHRU was attributed to the increase in ice melt and precipitation. However, the basin-wide runoff was dominated by an apparent increase in precipitation. It suggested that the regulation of runoff by glaciers varied in time and space. (3) Hydrological processes in glacierized basins were simulated for 1961-2005 using the SWAT-RSG model. The results showed that temperature, precipitation and total runoff significantly increased (p < 0.05) in the Tianshan Mountains. Glacier melt contribution to runoff was 7.3-67.3%, with a mean of 28.3% and the melt water apparently decreased in some little glacierized basins. Based on multi-catchment synthesis, it was found that glacier area ratio was an important and effective index which explained the effect of glaciers on basin hydrology. The relationship among ice/glacier melt contribution to runoff, runoff coefficient, runoff coefficient of variation and glacier area ratio was best expressed by power function (R2 > 0.58). While the first three factors increased with increasing glacier area ratio, the last one decreased with increasing glacier area ratio. When glacier area ratio was less than 10%, a small variation in ratio resulted in a significant variation in hydrological processes. This indicator approximated the response of glacio-hydrological processes to climate change, which was suitable for analyzing and exploring glacio-hydrological processes in ungauged glacierized basins.(4) Using the detrended approach, the relative contribution of the changes in temperature and precipitation to change in runoff were differentiated. The increase in runoff due to climate change was 1.6-11.5% (mean of 6.6%), of which temperature and precipitation contributed 42.9% and 57.1%, respectively. However, the ratios of inner runoff components did not significantly change. Based on multi-catchment synthesis, the effects of temperature and precipitation on glacier melt and runoff were closely related with glacier area ratios (R2 > 0.61). While the effect of temperature on runoff strengthened, that of precipitation apparently weakened with increasing glacier area ratio. When glacier area ratio was less than 10%, the effect of temperature and precipitation significantly differed. At regional scale, precipitation dominated runoff in the northern slopes of Tianshan Mountains. But in the southern slopes, runoff was mainly influenced by temperature or both the two factors. (5) The estimation of the hydrological processes in 2006-2100 was driven by GCMs under RCP2.6, RCP4.5 and RCP8.5 scenarios. The near future (2016-2045) and far future (2066-2095) projections were compared for change in runoff with that for baseline period (1966-1995). The results showed that regional mean temperature in the near future increased by 1.76℃, 1.46℃ and 1.80℃ under the RCP2.6, RCP4.5 and RCP8.5, respectively. Then the far future temperature increased by 2.15℃, 2.99℃ and 5.40℃ under the three RCPs, respectively. Mean precipitation in the near future increased by 3.8%, 5.8% and 5.7% and by 4.7%, 8.6% and 8.4% in the far future respectively under the three RCPs. Mean runoff in the near future respectively increased by 13.4%, 17.3% and 17.9%, and by 6.6%, 16.0% and 20.4% in the far future under the three RCPs. The most significant increase in runoff was in the heavily glacierized basins in the southern slopes of Tianshan Mountains. The glacier melt and runoff apparently increased initially and then decreased in most basins. The tripping point of runoff lagged behind that of ice melt, and that of ice melt behind that of glacier melt. Based on water balance, precipitation and ice melt dominated the changes in regional runoff in the near future. However, water resources in the far future depended on precipitation in the northern slopes. Both ice melt and precipitation were the dominant factors of runoff in the southern slopes. The four models combined with dry, wet, warm and cold conditions induced significant differences in runoff. The estimation of potential changes in glaciers and runoff in different scenarios provided a reference base for future management and utilization of water resources in the Tianshan Mountains. |
| 中文关键词 | 天山 ; SWAT ; 冰川融水 ; 气候变化 ; 水资源 |
| 英文关键词 | Tianshan Mountains SWAT glacier melt climate change water resources |
| 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/2XILL650/287663 |
| 推荐引用方式 GB/T 7714 | 张宜清. 气候变化对中国天山雨雪冰产流过程的影响[D]. 中国科学院大学,2016. |
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