Knowledge Resource Center for Ecological Environment in Arid Area
| 典型流域冰川消融及径流估算 | |
| 其他题名 | The Estimation of Ice Ablation and Runoff in Glacierized Catchments |
| 卿文武 | |
| 出版年 | 2012 |
| 学位类型 | 博士 |
| 导师 | 刘时银 ; 陈仁升 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 中国西部山地冰川是我国西北干旱和半干旱地区水资源的重要组成部分。受气候变暖影响，全球多数冰川萎缩并呈加剧趋势，冰川变化已经对干旱区水资源、高寒生态环境、海平面升降以及全球气候格局产生了重要的影响。在我国西北干旱区，随着冰川的加剧退缩和部分小冰川的消失，短期内带来了丰富的水资源，但随着冰川进一步萎缩，冰川水资源逐渐减少，势必会对我国西部气候、生态与环境安全及水资源可持续利用产生广泛而深刻的影响。探讨全球变暖背景下冰川水资源的变化规律已经成为当今冰冻圈科学及水科学领域的关键和热点科学问题之一，其核心科学问题就是冰川消融过程及其融水径流估算及变化预估方法研究。\n本论文在我国已有消融和径流估算方法的基础上，结合典型监测冰川观测资料，对现有冰川消融和径流估算模型进行了分析和改进，探索了在较少资料条件下冰川消融及其径流估算的方法。主要取得了以下几点认识：\n（1）利用典型冰川流域气温、降水和流量长期观测资料，深入探讨了气温、降水与冰川径流的关系。\n（2）分别利用目前较少应用的观测项目（地温）和研究较多的因子（气温）与冰川流域径流进行回归和相关分析，发现在日尺度上地温比气温更具统计关系，其相关性表现为随土层深度增加先变大后变小的规律，即存在一个所谓的“最优深度”。\n（3）针对传统度日模型方法在我国冰雪消融估算应用的情况及模型本身原理的缺陷，通过引入周围山体遮蔽系数计算方法并建立了改进度日模型，对传统度日模型和改进度日模型在冰川消融和物质平衡方面的模拟能力进行了对比。\n（4）针对冰川表面能量平衡总体特征及研究较少的现状，探讨了有资料和无资料冰川流域的太阳辐射估算方法，扩展了分布式消融能量平衡模型的应用范围。全国范围内辐射结果表明：干旱和干旱地区的估算精度要普遍高于湿润和半湿润地区。科其喀尔巴西冰川总辐射估算结果表明，在小流域/区域尺度上，应用地面气象资料估算太阳辐射的方法要明显好于宽带辐射传输算法。\n（5）采用分布式能量平衡消融模型对科其喀尔巴西冰川不同海拔高度的冰面消融进行了模拟，结果表明：计算总消融量值和实测值存在较好的一致性，模拟值基本反映了实际的消融值。\n（6）针对大多数中大型山地冰川汇流水系的复杂性，构建了一个动态变化的、包含5个子库的线性水库，并对科其喀尔巴西冰川的融水径流进行了模拟。校准和验证期日流量模拟与实测值均存在较好的一致性，模型结果评价系数NSE分别为0.83和0.75。 |
| 英文摘要 | The glacier, as a key component of the cryosphere, is extremely sensitive to climate change. The mountain glacier is an important water resource in arid and semi-arid areas in Northwest China. It is due to the presence of glaciers and snow cover, which makes many hinterlands arid areas become the oasis and also makes the arid areas in China is different from the other zones of the world's arid areas. However, since the mid-20th century most mountain glaciers have generally experienced retreat and shrinkage by the effects of global warming. With the shrinking of the glacier and some small glaciers disappeared, abundant water resource could be bring in the short term. But the glacier runoff will be reduced with the further shrinking of the glacier, which could significant affect the climate, ecological and environmental security, water resources and the sustainable use of runoff in Northwest China. Glacier runoff variation and its influence is currently becoming one of the hot research areas in water science under the background of global warming, and its core scientific problem is that the process of ablation and meltwater runoff estimation.\nOver the past few decades, the glaciologists have created a lot of relatively mature theory and various numerical models to estimate the glacier ablation. These models include simple experience models, energy-balance models and conceptual statistical models. However, the glacier confluence study is still at the exploratory stage due to various factors such as the distribution and variation of englacial and subglacial drainage system, the ablation and refreezing process within glacier, the glacial lake suddenly outbreak, the hydrothermal coupling process, the glacier movement and surge. Thought the glacier hydrology studies have received many influential achievements in China, compared with the overseas researches, the theories and models still need improved. For this reasons, the dissertation aims to establish a simple and robust method for estimating ice ablation and glacier runoff ased on existed researches under little field observations. Four typical glacier catchment, Dongkemadi Glaicer catchment, Tibetan plateau, Koxkar Glacier catchment and the Headwater catchment of Urumqi River, Tianshan, Hulugou Qilianshan are selected as the typical glacier, on which the field hydro-meteorological experiments have carried for many years. The proposed models were tested against the observational data from the field experiment and the relevant discussion was also made. Some of the conclusions from this study are recieved as follows:\n1) The long-term relationships between air temperature, precipitation and glacial runoff based on a single site and multiple sites are detailed discussed with the multiple regression method at 3 typical glacier basins, respectively. The results show there is a big difference between the estimated and the measured daily runoff using the multiple regression method based on a single site, and there exist a good relationship between the estimated and the measured daily runoff based on multiple sites in glacierized catchments. The reason is that the multiple regression method based on a multiple sites takes into account the difference of temperature, precipitation and other meteorological conditions in different regions of the basin, which may have different effects on runoff process and result in the model estimation results with high accuracy. \n2) Glacial runoff in 3 typical glacier catchments, Dongkemadi Glaicer catchment, Tibetan plateau, Koxkar Glacier catchment and the Headwater catchment of Urumqi River, Tianshan Mountains was evaluated and compared by using air temperature and ground temperature data of the corresponding period. It is confirmed that the correlations between glacial runoff and ground temperature versus a certain depth revealed a more signification and accurate relationship in compared with air temperature at daily time step, which could basically met the requirements of glacier water resources estimation. However, the universality of this method still needed further study. The coefficient of determination of exponential relationship between glacial runoff and soil temperature presented as parabolic curve regime with depth increasing, which indicated there existed a so-called best depth. The analysis on variation of efficiency R2 for three stations on debris in Koxkar Glacier catchment indicated that the depth decreased with the ascent of the altitude. In general, the so-called best ground depth presented negative correlation with altitude in three investigated catchments.\n3) The defect of the use of the traditional degree day model, which had been widely used in glaciology in China, was firstly discussed. An improved degree day model, which considers the surrounding mountains shelter coefficient, is applied to estimate the ice ablation and mass balance at Koxkar Glacier and Shiyi Glacier. In additional, the comparison of the model result from the traditional degree day model and the improved degree day mode was also made. It is found that the surrounding mountains shelter coefficient present clearly daily variations and yearly variations during a year. The sunshine is quite different at different position in an alpine basin under the same weather conditions. The estimated ice ablation and mass balance using the traditional degree day model and the improved degree day model are both consistent with the observed data, but the estimation of the improved degree day mode is better than that calculated by the traditional degree day model.\n4) Knowledge of the geographical distribution of solar irradiance over glacierized catchments is important for the use of distributed energy balance model. An enhanced broadband solar irradiance model based on satellite data is present to estimate direct radiation and total radiation in China. It uses ozone optical depth and water vapour from the reanalysis data of the NCEP/NCAR, aerosol optical depth from the OMAERUV Level-2 data product derived from the EOS-AURA satellite, total cloud and cloud classification analysis from FY-2C geostationary satellite. 27 ground stations in China where the direct radiation and the total radiation are routinely measured are used for model calibration and verification. The simulation result show that daily estimated the direct radiation and the total radiation both correlated well with measured solar irradiance in arid and semi-arid regions, while the accuracy of the estimation in humid and semi-humid areas are slightly lower than that in arid and semi-arid regions. Another method to estimate the solar irradiance based on ground meteorological data is also discussed in this paper. The results of two methods to estimate the total radiation at Koxkar Glacier catchment show the precision of the method based on ground meteorological data is better that the broadband solar irradiance model on a small watershed / regional scale.\n5) A distributed energy balance model is used to estimate the glacier surface ablation at different altitudes on Koxkar Glacier. The results demonstrate that the ablation estimation reflects basically the observed ablation value. The simulation error of single point ablation was increased gradually along with the increasing of altitude distance between the lattice and automatic weather station. Consider the snow effect, the simulation error of the higher elevations observation points significantly reduce.\n6) Discharge of Koxkar Glacier catchment was simulated by five parallel linear reservoirs, which represent the snow, firn, ice, debris and other underlying surface. The result show that the simulated runoff is in good agreement the measured runoff during the calibration and validation period, with the evaluation coefficient NSE 0.83 and 0.75, respectively. The water production of each sub-reservoir runoff showed that: the bare ice areas and supraglacial debris covers are the main runoff yield zone, followed by the area above the equilibrium line and the other underlying surface. |
| 中文关键词 | 冰川消融 ; 径流估算 ; 度日因子模型 ; 能量平衡模型 ; 线性水库模型 |
| 英文关键词 | Ice ablation Runoff estimation Degree day model Energy balance model Linear reservoir model |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 自然地理学 |
| 来源机构 | 中国科学院西北生态环境资源研究院 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/287096 |
| 推荐引用方式 GB/T 7714 | 卿文武. 典型流域冰川消融及径流估算[D]. 中国科学院大学,2012. |
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