Subjects: Other Disciplines >> Synthetic discipline submitted time 2023-03-28 Cooperative journals: 《中国科学院院刊》
Abstract： The Tibetan Plateau is the source zone of major rivers, which provide water resources for more than 2 billion people downstream. Compared with runoff, riverine sediment load is considered as a more sensitive variable in response to climate and land surface process changes, and also as an important index to quantify regional land degradation and soil resource changes. In this study, 8 major rivers originated in the Tibetan Plateau, including Yerqiang River, Shule River, Heihe River, Yarlung Tsangpo River, Nujiang River, Yellow River, Yangtze River, and Lancang River, were selected to study the variation of sediment load in the source zone or upper reaches. Firstly, the general amount and spatial variation of runoff and sediment load of these rivers were explored. Secondly, the changes of riverine sediment load in recent decades (1960–2017) were analyzed, with the spatial and temporal variations of sediment load compared to climate (temperature, precipitation) and land surface process (glacier, frozen soil, vegetation cover) factors. Thirdly, the uncertainty of sediment load variation associated with interaction of multi-factors was discussed. Finally, the significant impacts of sediment load variation on the ecological environment and the safety of hydropower projects was pointed out with typical cases. Nowadays, the scarcity of hydrometeorological data is a major challenge to understand the variation of riverine sediment load from the Tibetan Plateau and assess the impacts. It is urgent to strengthen observation and modeling studies to reveal the complex mechanism of sediment transport changes, so as to provide scientific basis for the sustainable utilization of water and soil resources on the Tibetan Plateau and the downstream water resources management, so as to serve the national ecological security.
Subjects: Environmental Sciences, Resource Sciences >> Basic Disciplines of Environmental Science and Technology submitted time 2020-06-21 Cooperative journals: 《干旱区研究》
Abstract：利用中国区域地面气象要素数据集(CMFD) 和GLDAS数据集的1979—2017年格点气温(2 m)、降水、比湿、风速(10m)、太阳辐射资料，运用线性回归、累积距平、滑动平均及Mann-Kendall突变检验方法，研究了近39 a来色林错流域气候特征和时空变化规律。结果表明：色林错流域多年平均气温为-1.8℃，降水量为389.4mm，比湿为3.2g·kg-1，太阳辐射为236.2W·m-2，风速为3.7m·s-1。色林错流域的月平均气温仅在5—9月高于0℃，流域平均气温以0.049℃·a-1的速率呈显著升高之势。流域降水集中在6—9月，占全年降水量的80%以上，流域平均年降水量以4.65mm·a-1的速率显著增大。气温的升高和降水的增加暗示了色林错流域在近几十年来呈现显著的暖湿气候背景。1979—2017年，流域年均风速变化在空间上表现为南部增大、北部减小，减小速率以流域东北部最大。多年平均太阳辐射空间分布整体呈自东向西逐渐增大的趋势，时间变化以-0.29W·m-2·a-1的速率显著减小，1980s中期至2000s中期减小尤为明显。流域的年均比湿变化趋势并不显著，但2006年开始呈显著减小之势。本研究结果对该流域的湖泊扩张机制、生态系统对气候变化的响应以及物候变化等研究具有指示意义。
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