青藏高原河网结构和水沙通量

Facing the serious situation of water resources, protection of strategic water source area and its runoff attention today, the total runoff and its changing characteristics of river source area has become an important basis for strategic decision on the national water security. However, the Qinghai Tibet Plateau Asia's water tower is a typical hydrological area lacking data. The network structure and characteristics of runoff is still in lack of in-depth understanding, and the related research is just in the beginning. The project takes the Qinghai-Tibet Plateau's river network and runoff characteristics as the main object, the space-earth stereoscopic observation and the Tsinghua University’s Global river network database as the data source. Through comparison and analysis of the regularity, particularity and main controlling factors of large river systems such as the Yangtze, Yellow, Yarlung Zangbo, and Lancang Rivers, the project will reveal the control mechanism for variation in the Qinghai-Tibet Plateau's river network, as well as the space distribution characteristics of water and sediment fluxes along the river network structure. The research results can provide basic data, knowledge and scientific tools for the strategic protection and utilization of the water resources of the Asia's water tower; and can also provide a typical case and the understanding breakthrough for the international research of river network. The project undoubtedly has great practical significance and scientific value.

在水资源形势严峻、战略水源地保护及其径流变化受到高度关注的今天，江河源区的径流总量和变化特性已成为国家水安全战略决策的基本依据。然而，青藏高原亚洲水塔仍是典型的水文缺资料地区，其河网结构和径流特性尚缺乏深入认识，相关研究刚刚起步。本项目拟以青藏高原河网水系和径流特性为主要对象，以空-地立体观测和清华大学全球河网数据库为数据源，对比分析长江、黄河、雅鲁藏布江、澜沧江等大型水系形态结构的规律性、特殊性和主控因素，揭示青藏高原河网结构变异的控制机制及河网水系水沙通量的空间分布规律。研究成果可为亚洲水塔的水资源战略保护与开发利用提供基础数据、基本认识和科学工具，也为河网水系国际研究提供典型案例和认识突破,无疑具有重大现实意义和科学价值。

江河源区的径流总量和变化特性是国家水安全战略决策的基本依据。青藏高原是典型的水文缺资料地区，该区地质构造运动活跃、气候独特、生态脆弱，河网结构和径流、输沙特性尚缺乏深入认识，相关研究刚刚起步。本项目以青藏高原河网水系和径流特性为主要研究对象，开展青藏高原河网水系提取与分层编码研究，以此剖析河网结构特征与控制机制，分析河网水系的河相关系与分布特点，揭示水沙通量的空间分布规律。.通过优化DEM填洼算法及内流区的精确识别，改进了全球河网Hydro30，建立了新的青藏高原高精度线性河网数据库；基于开发的河流表面与河宽自动提取算法，建立了青藏高原主要河流平滩河宽数据库；基于水文站长时序观测资料，建立了青藏高原主要河流水动力学参数、河相关系及水沙通量数据库，为开展青藏高原河流系统结构特征、河流地貌演变、河相关系及水沙通量分布特征研究提供了数据支撑。.青藏高原东部河流系统受大地构造背景塑造的地形控制，印度板块的持续东北向挤压为青藏高原东部河流系统演化提供了动力，奠定了河流系统的宏观结构。青藏高原东部河网处于局部最优状态，低级别河网表现出良好的自相似性，而高级别河网偏离Horton定律。本项目揭示了外生构造运动和内生河流自组织过程在不同层次河流系统演化中的相对贡献，并突出了局部最优化河网模型在全球构造活跃地区的重要性。.聚焦青藏高原山区河流间断分布的冲积河段，指出河段水力几何形态参数在沿程空间上具有较一致的分布规律。将山区河流上、下游间断冲积河段之间所具有的断面/沿程河相关系、多断面河相关系、多频率沿程河相关系，称为山区河流广义河相关系，该关系反映了山区河流间断冲积河段断面形态的空间联系，是冲积河流河相关系概念向山区河流的扩展。.青藏高原主要外流河与内流水系的多年下泄水通量为3849亿m3，沙通量为4.963亿t。青藏高原主要河流的水通量由北向南逐渐增加，而沙通量有相反的变化趋势，即高原北部纬度较高的河流普遍具有更高的径流含沙量。