Correlations between Summer Discharge and South Asian Summer Monsoon Subsystems in Mekong River Basin

Abstract

Hydrological conditions are strongly regulated by monsoon systems in the Mekong River Basin (MRB), while relevant studies investigating the intensity of the rainy season are still insufficient. This study employed the Mann-Kendall (M-K) test, Sen’s slope estimator, and innovation trend analysis to detect the variation of summer discharge in the MRB. Wavelet analysis is used to investigate the correlation between discharge and two South Asian summer monsoon subsystems (SAMI1 and SAMI2). Results show that the summer discharge in the MRB generally shows significant downward trends during 1970–2016 with a Z value range of −3.59–−1.63, while the high discharge at Vientiane, Mukdahan, and Pakse increases after 1970. The mutation years of the summer discharge series are around 2010 for Chiang Sean and Vientiane, and in 2015 for Luang Prabang, which resulted from the newly built large dams, Xiaowan and Nuozhadu. The wavelet analysis shows that the SAMI1 can be used to predict the summer discharge at Chiang Sean at a ~8-year timescale, while the SAMI2 correlates with the summer discharge well at a 1–8-year scale, especially at Mukdahan and Kratie during 1980–2016.

Insight into Municipal Reactive Nitrogen Emissions and Their Influencing Factors: A Case Study of Xiamen City, China

“…As for the results, when the Z value is negative, a falling trend is recognized, and when the Z value is positive, a rising trend is discerned. At a significance level of 0.05 (0.01, 0.001), Z > 1.96 (2.58) and Z < −1.96 (−2.58) indicate significant increasing and decreasing trends, respectively [35].…”

“…Theil-Sen is a nonparametric alternative to ordinary least-squares regression. Sen's slope has an advantage compared to linear regression, in that the test is not affected by the number of outliers and data errors [35]. The Sen's slope equation is written as follows:…”

Understanding Rainfall Distribution Characteristics over the Vietnamese Mekong Delta: A Comparison between Coastal and Inland Localities

“…Firstly, we applied the Mann-Kendall statistical test to detect monotonic trends in data. A large bevy of previous studies have used this statistical test to ascertain the presence of statistically significant trends in meteorological and climatic timeseries datasets [18][19][20][21][22][23]. Furthermore, Sen's slope estimator can yield a trend slope estimate and is comparatively robust to outliers.…”