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2017 1

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Trend detection and stochastic simulation prediction of streamflow at Yingluoxia hydrological station

Chenglong ZHANG,Mo LI,Ping GUO

《农业科学与工程前沿（英文）》 2017年第4卷第1期页码 81-96 doi: 10.15302/J-FASE-2016112

摘要： Investigating long-term variation and prediction of streamflow are critical to regional water resource management and planning. Under the continuous influence of climate change and human activity, the trends of hydrologic time series are nonstationary, and consequently the established methods for hydrological frequency analysis are no longer applicable. Five methods, including the linear regression, nonlinear regression, change point analysis, wavelet analysis and Hilbert-Huang transformation, were first selected to detect and identify the deterministic and stochastic components of streamflow. The results indicated there was a significant long-term increasing trend. To test the applicability of these five methods, a comprehensive weighted index was then used to assess their performance. This index showed that the linear regression was the best method. Secondly, using the normality test for stochastic components separated by the linear regression method, a normal distribution requirement was satisfied. Next, the Monte Carlo stochastic simulation technique was used to simulate these stochastic components with normal distribution, and thus a new ensemble hydrological time series was obtained by combining the corresponding deterministic components. Finally, according to these outcomes, the streamflow at different frequencies in 2020 was predicted.

关键词： Monte Carlo nonstationary trend detection streamflow prediction decomposition and ensemble Yingluoxia

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Changes in Headwater Streamflow from Impacts of Climate Change in the Tibetan Plateau

Zhengxin Bao,Jianyun Zhang,Yanqing Lian,Guoqing Wang,Junliang Jin,Zhongrui Ning,Jiapeng Zhang,Yanli Liu,Xiaojun Wang,

《工程（英文）》 doi: 10.1016/j.eng.2023.05.025

摘要： The Tibetan Plateau (TP) is the headwater of the Yangtze, Yellow, and the transboundary Yarlung Tsangpo, Lancang, and Nujiang Rivers, providing essential and pristine freshwater to around 1.6 billion people in Southeast and South Asia. However, the temperature rise TP has experienced is almost three times that of the global warming rate. The rising temperature has resulted in glacier retreat, snow cover reduction, permafrost layer thawing, and so forth. Here we show, based on the longest observed streamflow data available for the region so far, that changing climatic conditions in the TP already had significant impacts on the streamflow in the headwater basins in the area. Our analysis indicated that the annual average temperature in the headwater basins of these five major rivers has been rising on a trend averaging 0.37 °C·decade−1 since 1998, almost triple the rate before 1998, and the change of streamflow has been predominantly impacted by precipitation in these headwater basins. As a result, streamflow in the Yangtze, Yarlung Tsangpo, Lancang, and Nujiang River headwater areas is on a decreasing trend with a reduction of flow ranging from 3.0–5.9 × 109 m3·decade−1 (−9.12% to −16.89% per decade) since 1998. The increased precipitation in the Tangnahai (TNH) and Lanzhou (LZ) Basins contributed to the increase of their streamflows at 8.04% and 14.29% per decade, respectively. Although the increased streamflow in the headwater basins of the Yellow River may ease some of the water resources concerns, the decreasing trend of streamflow in the headwater areas of the southeastern TP region since 1998 could lead to a water crisis in transboundary river basins for billions of people in Southeast and South Asia.

关键词： Tibetan Plateau Streamflow Change Trend Climate Change