Detrending methods for fluctuation analysis in hydrology: amendments and comparisons of methodologies
Detrending methods for fluctuation analysis in hydrology: amendments and comparisons of methodologies
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DOI：
10.1002/hyp.9637
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发表时间：
2014-01
影响因子：
3.2
通讯作者：
Qiang Zhang;Yu Zhou;V. Singh
中科院分区：
文献类型：
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作者：
Qiang Zhang;Yu Zhou;V. Singh
去趋势化是利用去趋势化波动分析(DFA)研究水文序列长期相关性的一个关键步骤。然而，由于水库修建、人类取淡水等人类活动和降水量时空变化等气候变化的综合影响，水文序列具有不规则的周期性和多种多样的趋势，这给去趋势方法的选择带来了困难。在这项研究中，我们试图解决去趋势化问题，因为去趋势化在基于DFA的尺度分析中具有重要的理论和实践价值。在这种情况下，针对周期趋势的不规则性，采用了一种改进的变参数DFA(VPDFA)，并将其与自适应去趋势算法(ADA)相结合，以消除不规则周期对基于DFA的缩放结果的影响。结果表明，对于不超过20个周期的径流序列，推荐采用VPDFA方法，否则必须采用组合方法。对比研究表明，与DFA、VPDFA和ADA方法相比，平均去除法去除趋势的观测径流序列的标度行为是整个序列的平均年周期附近的周期残差之一，而不是排除所有的年周期。然而，尽管VPDFA对于短观测径流记录的结果与数值模拟序列的结果可以很好地对应，但组合方法分析长记录得到的标度行为看起来很奇怪，与数值分析的结果不同。我们将这种差异归因于复杂的水文结构，以及人类活动和人类活动的综合影响越来越大可能导致的水文变化。如何将最重要的因素纳入到除趋势过程中，仍然是水文过程标度行为分析中的一个具有挑战性的任务。版权所有©2012 John Wiley&Sons，Ltd.
Detrending is a key step in the study of the scaling behaviors using Detrended Fluctuation Analysis (DFA) to explore the long‐range correlation of hydrological series. However, the irregular periodicity and various trends within hydrological series as a result of integrated influences of human activities such as construction of water reservoirs and human withdrawal of freshwater and climate changes such as alterations of precipitation changes in both space and time make difficult the selection of detrending methods. In this study, we attempt to address the detrending problem due to the important theoretical and practical merits of detrending in DFA‐based scaling analysis. In this case, with focus on the irregularity of the periodic trends, a modified DFA, varying parameter DFA (VPDFA), and its combination with adaptive detrending algorithm (ADA) are employed to eliminate the influences of irregular cycles on DFA‐based scaling results. The results indicate that, for streamflow series with no more than 20 cycles, VPDFA is recommended; otherwise, the combined method has to be employed. Comparison study indicates that the scaling behavior of the detrended observed streamflow series by average removed method, when compared to those by DFA, VPDFA, and ADA, is the one of the periodic residues around the averaged annual cycle for the entire series rather than that excluding all annual cycles. However, although the result by VPDFA for short observed streamflow record can well correspond to that for numerically simulated series, the scaling behavior obtained by combined method analyzing long record looks strange and is different from that by numerical analysis. We attribute this difference to the complicated hydrological structure and the possible hydrological alternation due to the increasing integrated impacts of human activities and human activities with the extending record. How to include the most of the important factors into the detrending procedure is still a challenging task for further study in the analysis of the scaling behavior of hydrological processes. Copyright © 2012 John Wiley & Sons, Ltd.