School of Environmental Science and Engineering, Chang'an University, Xi'an 710054, China.
Key Laboratory of Subsurface Hydrology and Ecological Effect in Arid Region, Ministry of Education, Chang'an University, Xi'an 710054, China.
Int J Environ Res Public Health. 2020 Apr 2;17(7):2410. doi: 10.3390/ijerph17072410.
The purpose of this study is to illustrate intrinsic correlations and their temporal evolution between hydro-meteorological elements by building three-element-composed system, including precipitation (P), runoff (R), air temperature (T), evaporation (pan evaporation, E), and sunshine duration (SD) in the Wuding River Basin (WRB) in Loess Plateau, China, and to provide regional experience to correlational research of global hydro-meteorological data. In analysis, detrended partial cross-correlation analysis (DPCCA) and temporal evolution of detrended partial-cross-correlation analysis (TDPCCA) were employed to demonstrate the intrinsic correlation, and detrended cross-correlation analysis (DCCA) coefficient was used as comparative method to serve for performance tests of DPCCA. In addition, a novel way was proposed to estimate the contribution of a variable to the change of correlation between other two variables, namely impact assessment of correlation change (IACC). The analysis results in the WRB indicated that (1) DPCCA can analyze the intrinsic correlations between two hydro-meteorological elements by removing potential influences of the relevant third one in a complex system, providing insights on interaction mechanisms among elements under changing environment; (2) the interaction among P, R, and E was most strong in all three-element-composed systems. In elements, there was an intrinsic and stable correlation between P and R, as well as E and T, not depending on time scales, while there were significant correlations on local time scales between other elements, i.e., P-E, R-E, P-T, P-SD, and E-SD, showing the correlation changed with time-scales; (3) TDPCCA drew and highlighted the intrinsic correlations at different time-scales and its dynamics characteristic between any two elements in the P-R-E system. The results of TDPCCA in the P-R-E system also demonstrate the nonstationary correlation and may give some experience for improving the data quality. When establishing a hydrological model, it is suitable to only use P, R, and E time series with significant intrinsic correlation for calibrating model. The IACC results showed that taking pan evaporation as the representation of climate change (barring P), the impacts of climate change on the non-stationary correlation of P and R was estimated quantitatively, illustrating the contribution of climate to the correlation variation was 30.9%, and that of underlying surface and direct human impact accounted for 69.1%.
本研究旨在通过构建包括降水（P）、径流量（R）、空气温度（T）、蒸发量（蒸发皿蒸发量，E）和日照时间（SD）在内的三要素组成系统，阐明黄土高原武定河流域（WRB）水文气象要素之间的固有相关性及其时间演变，并为全球水文气象数据的相关研究提供区域经验。在分析中，采用去趋势部分交叉相关分析（DPCCA）和去趋势部分交叉相关分析的时间演变（TDPCCA）来展示固有相关性，并使用去趋势交叉相关分析（DCCA）系数作为比较方法，以检验 DPCCA 的性能。此外，提出了一种新的方法来估计一个变量对两个其他变量之间相关性变化的贡献，即相关性变化的影响评估（IACC）。WRB 的分析结果表明：（1）DPCCA 可以通过去除复杂系统中相关第三变量的潜在影响，分析两个水文气象要素之间的固有相关性，为变化环境下要素之间的相互作用机制提供见解；（2）在所有三要素组成的系统中，P、R 和 E 之间的相互作用最强。在要素中，P 和 R 之间以及 E 和 T 之间存在固有且稳定的相关性，而其他要素之间在局部时间尺度上存在显著相关性，即 P-E、R-E、P-T、P-SD 和 E-SD，表明相关性随时间尺度而变化；（3）TDPCCA 绘制并突出了 P-R-E 系统中任何两个要素之间不同时间尺度上的固有相关性及其动力学特征。P-R-E 系统的 TDPCCA 结果还表明，相关性是非平稳的，这可能为提高数据质量提供一些经验。在建立水文模型时，适合仅使用具有显著固有相关性的 P、R 和 E 时间序列进行模型校准。IACC 结果表明，以蒸发皿蒸发量表示气候变化（不计 P），定量估计气候变化对 P 和 R 非平稳相关性的影响，表明气候对相关性变化的贡献为 30.9%，下垫面和直接人为影响的贡献为 69.1%。
