Knowledge Resource Center for Ecological Environment in Arid Area
| 祁连山北大河流域冰川变化及其对河流径流的影响 | |
| 其他题名 | Glacier Mass Variation and its Effect on Surface Runoff in the Beida River Catchment, Qilian Mountain |
| 王盛 | |
| 出版年 | 2018 |
| 学位类型 | 博士 |
| 导师 | 姚檀栋 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 青藏高原东北部河西走廊地区是丝绸之路通道上的关键区域和支撑点，对“丝绸之路经济带”的整体发展起到不可缺失的作用。然而，水资源匮乏问题严重制约着该区域经济和环境的可持续发展，同时也是“一带一路”战略中亟需解决的重大课题。近年来，在气候变暖的影响下，区内冰川持续退缩且消融强烈，物质亏损严重，冰川融水径流量普遍增加。冰川作为重要的淡水资源及径流组分，其过去和未来的变化对区域水循环影响显著，同时关系着流域中下游的绿洲农业发展、区域水供应以及水文生态系统的可持续性。因此，研究该地区过去和未来的冰川变化及其对河流径流的潜在影响具有重要的理论和现实意义。鉴于此，本论文选取青藏高原东北部的北大河流域作为研究区，在流域内七一冰川开展气象-物质平衡观测的基础上，综合利用气象、水文和遥感数据，基于度日和能量平衡的分布式冰川模型，从历史和未来两个时期对七一冰川和北大河流域的冰川开展变化规律、影响因素和未来预估三个方面的研究。此外，基于改进的SWAT水文模型(耦合了冰川能量-物质平衡方案)，对北大河流域水文过程和径流的未来变化进行了模拟预测，重点分析了冰川融水组分变化对河流径流的潜在影响。本论文的主要结论如下：(1) 七一冰川变化及其对气候变化的响应 2011~2016年，七一冰川的平均物质平衡为-476 mm w.e.，平均ELA为4941 m a.s.l.，物质平衡梯度为2.9 mm/m。受气候变暖和风吹雪的影响，11月~翌年3月冰川消融加剧，呈现负平衡；4月和9月物质平衡受降水控制，随海拔的变化特征呈现降水效应；强消融期(6~8月)物质平衡随海拔升高线性增加，而消融期末由9月初延后至9月底，整体上近期冰川物质亏损仍在继续，但亏损速率有所减缓。七一冰川物质平衡对气温变化的敏感性为-178.7 mm w.e. °C-1 a-1，而对降水变化的敏感性为+2.93 mm w.e. mm-1 a-1，即61 mm的降水增加才能弥补暖季气温升高1°C引起的冰川物质损失。(2) 历史时期北大河流域的冰川变化及影响因素分析 1957~2013年北大河流域冰川的多年平均物质平衡为-271.6 mm w.e.，冰储量减少3.99 Gt。相应地，多年平均ELA为4916 m a.s.l.，ELA的年际变化呈上升趋势，56年间升高了242 m。与地形和冰川形态因子相比，气候因子对冰川物质平衡和ELA变化的影响更为显著。物质平衡对气温变化的敏感性为-238.85 mm w.e. °C-1 a-1，而对降水变化的敏感性为+1.14 mm w.e. mm-1 a-1。北大河流域多年平均冰川融水径流量为1.51×108 m3，占地表径流的15.20%。冰川融水径流序列的突变年份为2000年，突变前后冰川融水对地表径流的贡献率从13.9%增加到20.4%。冰川融水和地表径流都集中在夏季，年内变化呈单峰型。随着气候变暖，夏季融水径流明显增加，突变前后的平均增加量为0.59×108 m3/a。而冷季基流(冷季主要的补给水源)对地表径流的补给作用逐渐减弱。(3) 基于CMIP5多模式的气候变化情景 在RCP2.6、RCP4.5和RCP8.5三种未来情景下，2006~2050年研究区气温持续升高，与历史时期相比，气温增幅为1.79~2.05°C。整体上气温增长率分别是0.29、0.39和0.52 °C/10a。未来降水比历史时期略有增加，增幅为21.3~28.9 mm，降水增加主要来自于春季，约占总增幅的一半。(4) 基于度日和能量平衡的分布式模型在七一冰川的模拟 2016~2050年，在RCP2.6、RCP4.5和RCP8.5三种未来情景下，七一冰川的末端持续退缩，35年间的退缩距离分别为175、190和220 m，退缩速度与历史时段(5.9 m/a)接近。冰川面积持续萎缩，预计到2050年，七一冰川面积分别是2.649、2.639和2.625 km2，较之1975分别减小了7.8%、8.1%和8.6%。冰川的年平衡均为负值，冰储量持续亏损，且亏损速率呈增加趋势。在低、中和高三种排放路径下，多年平均物质平衡分别为-521.2、-666.8和-861.8 mm w.e.，远低于历史时期的-152.8 mm w.e.，冰储量损失量达到49.2、62.7和80.7 Mt。多年平均ELA由历史时期的4822 m a.s.l.分别上升至低、中和高排放路径下的4940、4980和5021 m a.s.l.。未来冰川物质平衡趋向负平衡的主要原因是暖季(特别是7、8月)消融量激增，而暖季降雪量的减少也在一定程度上加剧了冰川物质亏损。从能量平衡的组分来看，冰川消融能量的最大收入项净短波辐射未来显著增加，而7、8月份消融能量的增加主要由于净短波辐射的增加(~61%)，其次是净长波辐射的减少(~29%)。(5) 未来气候变化背景下冰川和径流的情景模拟 2016~2050年北大河流域冰川的年平衡均为负值，冰储量持续减少，在低、中和高三种排放路径下，多年平均物质平衡分别为-508.9、-646.8和-838.0 mm w.e.，冰储量损失为4.90、6.23和8.07 Gt。多年平均ELA分别为4981.2、5029.5和5079.5 m a.s.l.，ELA的年际变化呈持续升高趋势，35年间分别上升了92.8、221.2和354.9 m。多年平均河流径流量分别是34.12、36.83和38.02 m3/s，较之历史时期(1957~2013)分别增加了10.60%、19.38%和23.22%。从径流组分来看，北大河径流增加主要来源于气候变暖引起的的冰川融水径流的激增，冰川融水河流径流的补给贡献率由历史时期的15.20%分别增长至低、中和高排放路径下的21.34%、22.83%和26.33%。此外，在未来气候变化的影响下，北大河汛期开始的时间由6月提前到了5月。而流域冰川消融季的结束时间由9月初延迟至9月底。 |
| 英文摘要 | The Hexi Corridor Region, which is located in the northeast edge of Tibetan Plateau, is the key area and supporting point of the Silk Road. It is very important to the development of the Silk Road Economic Belt. However, the regional water resources shortage, which severely restricts the sustainable development of economy and environment, is a major issue in the Belt and Road Initiatives. Recently, under the influence of climate warming, glaciers continue to retreat and intensely melt in this region, the mass loss is serious, and the glacier meltwater runoff increase generally. As the important freshwater resources and runoff component, the past and future glacier variation has a profound effect on the regional water cycle, and it also has significant potential impact for downstream oasis farming, regional water supplies and the sustainability of aquatic ecosystems. Therefore, it has important theoretical and practical significance to study the past and future glacier variation and its potential impact on river runoff. In view of this, the Beida River Catchment in the northeast of Tibetan Plateau was selected as the study area. Based on the meteorology-mass balnce observations in Qiyi Glacier of this catchment, combined with the meteorological, hydrological and remote sensing data, by using two distributed glacier models that were based on degree-day and energy balance, respectively, the research of glacier variation rule, driving factors and future pridiction between Qiyi Glacier and glaciers in the Beida River catchment were carried from the historical and future periods. In addition, an improved SWAT hydrological models, which coupled a glacier energy-mass balance scheme, was used to simulate and predict the hydrological processes and future runoff change of the Beida River catchment, and to study the potential impact of glacier melt water variation on the river runoff. The results of this study are as follows:(1) The mass variation of Qiyi Glacier and its response to climate changeDuring 2011-2016, the average annual mass balance of Qiyi Glacier was -476 mm w.e., the average ELA was 4941 m a.s.l., and the mass balance gradient was 2.9 mm/m. Affected by climate warming and snowdrift, the glacier melting tended to accelerate from November to March of the next year, which was a negative balance during this period. Mass in April and September is governed by precipitation, and the change with altitude showed the precipitation effect. Mass balance increased with altitude linearly from June to August, and the end of glacier melting season had delayed from early September to the end of September. Recently the mass loss of Qiyi Glacier continues, but the rate has been slowing. Mass balance sensitivity to air temperature change was -178.7 mm w. e. °C-1 a-1, while to precipitation change was +2.93 mm w. e. mm-1 a-1. A 61 mm increase in precipitation was needed to compensate for the net mass loss induced by an air temperature increase of 1°C. (2) The analysis of glacier change and its influencing factors in the Beida River catchment during historical periodThe average annual mass balance was -271.6 mm w.e., with an ice loss of 3.99 Gt in the Beida River catchment during 1957-2013. Correspondingly, average annual ELA was 4916 m a.s.l.. Assuming a continuous linear trend, ELA had risen by 242 m a.s.l. in the last 56 years. Compared with morpho-topographic variables, climatic control was a more important factor on affecting glacier mass balance and ELA. Mass balance sensitivity to air temperature change was -238.85 mm w. e. °C-1 a-1, while to precipitation change was +1.14 mm w. e. mm-1 a-1. The average annual glacier meltwater runoff was 1.51×108 m3 in the Beida River catchment during 1957-2013, which accounting for 15.20% of surface runoff. Annual meltwater runoff series changed abruptly in 2000, and its contributions to surface runoff increased from 13.9% to 20.4% before and after abrupt change year. Glacier meltwater and surface runoff were both concentrated in summer. Seasonal variation presented unimodal distribution. With climate warming, recharge of glacier meltwater was significantly increased in summer, with an increment of 0.59×108 m3. While the role of base flow, the dominating water supply in wintertime, supplying to surface runoff weakened gradually.(3) The climate change in the future scenarios that based on multi-modals in the CMIP5In the RCP2.6, RCP4.5 and RCP8.5 future scenarios, temperature will continue to rise in the study area during 2006~2050. Compared with the temperature in historical period, it will increase by 1.79~2.05°C, and the temperature growth rate are 0.29, 0.39 and 0.52 °C/10a, respectively. Accordingly, future precipitation will increase slightly, with an increase of 21.3~28.9 mm comparing to historical period. The increase of precipitation mainly comes from the spring, which accounts for almost half of the total growth.(4) Applications of two distributed glacier models that based on degree-day and energy balance in Qiyi GlacierIn the RCP2.6, RCP4.5 and RCP8.5 future scenarios, the terminal of Qiyi Glacier will continue to retreat during 2016~2050, and the glacier will retreat 175, 190 and 220 m among 35 years, respectively, which were close to the retreating rate (5.9 m/a) during historical period. Glacier areas will continue to shrink. In 2050, glacier area will shrink to 2.649, 2.639 and 2.625 km2, with a decreasing rate of 7.8%, 8.1% and 8.6% compared to the area in 1975. The annual mass balances are all negative. The ice will continue to lose, and the loss rate will increase. In the RCP2.6, RCP4.5 and RCP8.5 future scenarios, Multi-years average mass balances are -521.2, -666.8 and -861.8 mm w.e., which were far lower than the mass balance (-152.8 mm w.e.) in historical period, with the ice losses of 4.92, 6.27 and 8.07 Mt. Multi-years average ELA will rise to 4940, 4980 and 5021 m a.s.l., which were obviously higher than the ELA (4822 m a.s.l.) in historical period. Future glacier mass balance will tend to more negative. The main reason is the rapidly increase of glacier melting in the warm season (especially July and August), while the decrease of snowfall has contributed to the mass loss to a certain extent. In the components of energy balance, the net shortwave radiation, which is the most important energy income, will increase significantly. In July and August, the increase of melting energy mainly comes from the increase of net shortwave radiation (~ 61%), followed by the net long wave radiation (~ 29%).(5) The prediction of glaciers and streamflow change in the future scenarios under the background of climate changeThe glacier annual balances are all negative in the Beida River catchment during 2016-2050, and ice continues to lose. In the RCP2.6, RCP4.5 and RCP8.5 future scenarios, Multi-years average mass balances are -508.9, -646.8 and -838.0 mm w.e., with the ice losses of 4.90, 6.23 and 8.07 Gt. Multi-years average ELA will rise to 4981.2, 5029.5 and 5079.5 m a.s.l., and the ELA will increase by 92.8, 221.2 and 354.9 m in the future 35 years. Multi-years average streamflow are respectively 34.12, 36.83 and 38.02 m3/s, with the increase of 10.60%, 19.38% and 23.22% comparing to the runoff from 1957 to 2013. The increase of streamflow in the catchment mainly comes from the rapid increase of the glacier meltwater under the background of climate warming. The contribution of glacier meltwater to streamflow has increased from 15.20% (the historical period) to 21.34% (RCP 2.6), 22.83% (RCP 4.5) and 26.33% (RCP 8.5). Under the influence of climate change in the future, the start time of flood season has changed from June to May in advance, and the end of the glacier melting season has delayed from early September to the end of September. |
| 中文关键词 | 冰川物质平衡 ; 能量平衡 ; SWAT模型 ; 七一冰川 ; 北大河流域 |
| 英文关键词 | Glacier Mass Balance Energy Balance SWAT Model CMIP5 Qiyi Glacier the Beida River Catchment |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 自然地理学 |
| 来源机构 | 中国科学院青藏高原研究所 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/288039 |
| 推荐引用方式 GB/T 7714 | 王盛. 祁连山北大河流域冰川变化及其对河流径流的影响[D]. 中国科学院大学,2018. |
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