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Journal of Arid Land  2021, Vol. 13 Issue (8): 835-857    DOI: 10.1007/s40333-021-0078-1
    
Synergistic effects of multiple driving factors on the runoff variations in the Yellow River Basin, China
WANG Junjie1, SHI Bing1,*(), ZHAO Enjin1,2, CHEN Xuguang1,*(), YANG Shaopeng3
1 College of Engineering, Ocean University of China, Qingdao 266100, China
2 Hubei Key Laboratory of Marine Geological Resources, China University of Geosciences, Wuhan 430074, China
3 College of Ocean Science and Engineering, Shandong University of Science and Technology, Qingdao 266590, China
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Abstract  

River runoff plays an important role in watershed ecosystems and human survival, and it is controlled by multiple environmental factors. However, the synergistic effects of various large-scale circulation factors and meteorological factors on the runoff on different time-frequency scales have rarely been explored. In light of this, the underlying mechanism of the synergistic effects of the different environmental factors on the runoff variations was investigated in the Yellow River Basin of China during the period 1950-2019 using the bivariate wavelet coherence (WTC) and multiple wavelet coherence (MWC) methods. First, the continuous wavelet transform (CWT) method was used to analyze the multiscale characteristics of the runoff. The results of the CWT indicate that the runoff exhibited significant continuous or discontinuous annual and semiannual oscillations during the study period. Scattered inter-annual time scales were also observed for the runoff in the Yellow River Basin. The meteorological factors better explained the runoff variations on seasonal and annual time scales. The average wavelet coherence (AWC) and the percent area of the significant coherence (PASC) between the runoff and individual meteorological factors were 0.454 and 19.89%, respectively. The circulation factors mainly regulated the runoff on the inter-annual and decadal time scales with more complicated phase relationships due to their indirect effects on the runoff. The AWC and PASC between the runoff and individual circulation factors were 0.359 and 7.31%, respectively. The MWC analysis revealed that the synergistic effects of multiple factors should be taken into consideration to explain the multiscale characteristic variations of the runoff. The AWC or MWC ranges were 0.320-0.560, 0.617-0.755, and 0.819-0.884 for the combinations of one, two, and three circulation and meteorological factors, respectively. The PASC ranges were 3.53%-33.77%, 12.93%-36.90%, and 20.67%-39.34% for the combinations one, two, and three driving factors, respectively. The combinations of precipitation, evapotranspiration (or the number of rainy days), and the Arctic Oscillation performed well in explaining the variability in the runoff on all time scales, and the average MWC and PASC were 0.847 and 28.79%, respectively. These findings are of great significance for improving our understanding of hydro-climate interactions and water resources prediction in the Yellow River Basin.



Key wordssynergistic effects      precipitation      runoff variations      atmospheric circulations      multiple wavelet coherence      Yellow River Basin     
Received: 22 February 2021      Published: 10 August 2021
Corresponding Authors:
Cite this article:

WANG Junjie, SHI Bing, ZHAO Enjin, CHEN Xuguang, YANG Shaopeng. Synergistic effects of multiple driving factors on the runoff variations in the Yellow River Basin, China. Journal of Arid Land, 2021, 13(8): 835-857.

URL:

http://jal.xjegi.com/10.1007/s40333-021-0078-1     OR     http://jal.xjegi.com/Y2021/V13/I8/835

Fig. 1 Sketch map of the Yellow River Basin (YRB). DEM, digital elevation model.
Station Data period Distance to estuary
(km)
Catchment area
(×104 km2)
Mean annual runoff
(×108 m3)
TNH 1950-2019 3911 12.20 202.17
SZS 1950-2019 2815 30.91 270.62
TDG 1956-2019 2146 36.79 207.86
LM 1950-2019 1269 49.76 258.97
HYK 1950-2019 768 73.00 368.83
LJ 1950-2019 104 75.19 293.80
Table 1 Information about the hydrological stations selected in this study
Fig. 2 Continuous wavelet spectra of the runoff time series at six hydrological stations. (a), Tangnaihai hydrological station; (b), Shizuishan hydrological station; (c) Toudaoguai hydrological station; (d), Longmen hydrological station; (e), Huayuankou hydrological station; (f), Lijin hydrological station.
Station AO NAO PDO SOI SST PRE TEP ET WET
TNH 0.385 0.364 0.358 0.334 0.320 0.535 0.485 0.560 0.514
SZS 0.378 0.355 0.353 0.370 0.342 0.379 0.446 0.460 0.434
TDG 0.420 0.366 0.342 0.351 0.332 0.366 0.384 0.439 0.424
LM 0.412 0.357 0.342 0.363 0.354 0.461 0.476 0.420 0.472
HYK 0.403 0.337 0.348 0.356 0.345 0.537 0.423 0.407 0.473
LJ 0.383 0.338 0.372 0.350 0.345 0.462 0.452 0.446 0.435
Table 2 Average wavelet coherence (AWC) between the runoff and individual circulation and meteorological factors at the six hydrological stations
Station AO NAO PDO SOI SST PRE TEP ET WET
TNH 11.44 5.91 12.47 4.53 3.64 33.77 26.85 28.33 33.14
SZS 9.18 5.82 9.27 9.24 4.41 15.36 21.10 19.43 19.48
TDG 15.03 5.84 6.70 5.14 4.22 11.77 10.07 15.96 12.12
LM 12.86 6.13 8.14 7.76 3.53 18.49 19.91 15.67 16.72
HYK 12.68 4.28 5.94 7.05 4.42 22.71 16.54 15.65 22.74
LJ 11.19 4.58 7.29 6.24 4.43 21.38 19.45 21.23 19.55
Table 3 PASC values (%) for the wavelet coherence between the runoff and individual circulation and meteorological factors at the six hydrological stations
Fig. 3 Bivariate wavelet coherence (WTC) between the runoff and individual circulation factors at six hydrological stations. (a), Tangnaihai hydrological station; (b), Shizuishan hydrological station; (c) Toudaoguai hydrological station; (d), Longmen hydrological station; (e), Huayuankou hydrological station; (f), Lijin hydrological station. PDO, Pacific Decadal Oscillation; AO, Arctic Oscillation. Each driving factor can best explain the variations in the multiscale characteristics of the runoff for all of the circulation factors. The black semi-circular line is the cone of influence domain. The regions enclosed by the thick black contour lines indicate the 95% significance level. The directions of the arrows indicate the relative phase relationship between the two time series, with the positive phase pointing right and the negative phase pointing left.
Fig. 4 WTC between the runoff and individual meteorological factors at six hydrological stations. (a), Tangnaihai hydrological station; (b), Shizuishan hydrological station; (c) Toudaoguai hydrological station; (d), Longmen hydrological station; (e), Huayuankou hydrological station; (f), Lijin hydrological station. PRE, precipitation; TEP, temperature; ET, evapotranspiration; WET, the number of rainy days. Each driving factor can best explain the variations in the multiscale characteristics of the runoff for all of the meteorological factors.
Station Two factors MWC PASC (%) Two factors MWC PASC (%) Two factors MWC PASC (%)
TNH AO-SOI 0.617 13.09 PRE-NAO 0.750 34.30 PRE-WET 0.755 36.90
SZS AO-SOI 0.618 12.93 PRE-AO 0.701 21.85 PRE-WET 0.697 26.98
TDG AO-PDO 0.639 15.44 PRE-AO 0.688 24.60 PRE-WET 0.671 23.32
LM AO-PDO 0.648 13.65 PRE-AO 0.708 26.67 PRE-ET 0.683 20.62
HYK AO-NAO 0.628 13.02 PRE-SOI 0.707 25.20 PRE-WET 0.713 25.18
LJ AO-NAO 0.627 13.46 PRE-SOI 0.705 25.28 PRE-TEP 0.718 26.88
Table 4 Multiple wavelet coherence (MWC) and PASC between the runoff and two combined factors
Fig. 5 Multiple wavelet coherence (MWC) between the runoff and combinations of two circulation factors at six hydrological stations. (a), Tangnaihai hydrological station; (b), Shizuishan hydrological station; (c) Toudaoguai hydrological station; (d), Longmen hydrological station; (e), Huayuankou hydrological station; (f), Lijin hydrological station. SOI, Southern Oscillation Index; NAO, North Atlantic Oscillation.
Fig. 6 MWC between the runoff and combinations of one meteorological factor and one circulation factor at six hydrological stations. (a), Tangnaihai hydrological station; (b), Shizuishan hydrological station; (c) Toudaoguai hydrological station; (d), Longmen hydrological station; (e), Huayuankou hydrological station; (f), Lijin hydrological station.
Fig. 7 MWC between the runoff and the combinations of two meteorological factors at six hydrological stations. (a), Tangnaihai hydrological station; (b), Shizuishan hydrological station; (c) Toudaoguai hydrological station; (d), Longmen hydrological station; (e), Huayuankou hydrological station; (f), Lijin hydrological station.
Station Three factors MWC PASC (%) Three factors MWC PASC (%) Three factors MWC PASC (%)
TNH WET-AO-SOI 0.855 35.95 PRE-ET-AO 0.864 39.34 PRE-ET-WET 0.846 34.76
SZS WET-AO-SOI 0.822 24.11 PRE-WET-AO 0.837 29.67 TEP-ET-WET 0.823 29.37
TDG