Abstract
Changes in precipitation patterns greatly impact regional drought/flood risk management and utilization of water resources. The main purpose of this paper was to investigate spatio-temporal variability of precipitation concentration in the transitional zone between Qinling Mountains (QDM), Guanzhong Plain (GZP) and the Loess Plateau (LPNS) in China, using monthly-scale precipitation concentration index (PCI) and daily-scale concentration index (CI) from daily rainfall records. The Mann-Kendall method was employed to illustrate the change in trend of PCI and CI, the Kriging interpolation method was adopted to measure spatial distribution, and the Wavelet transforms were used to explore their spatio-temporal correlation with the Arctic Oscillation (AO) & Western Pacific Subtropical High (WPSH) for revealing the potential attribution of precipitation concentration variation. Also, the regional implication of CI was investigated in the zone to provide local knowledge of the index application. Results showed that annual precipitation demonstrated a north-south increasing layered spatial distribution in the zone, representing a generally decreasing trend. The CI change generally exhibited a more significant decreasing trend than did PCI in LPNS and GZP due to AO slowly increasing over time, with a spatially weak layered or radial north-south decay, and an insignificant increasing trend in QDM impacted by the enhancing WPSH, with an obvious layered or radial spatial distribution. The spatiotemporal pattern of PCI variation represented similar characteristics in attribution with CI, but an inverse spatial distribution due to the phase difference (positive and negative effects) of AO and WPSH influencing seasonal precipitation. Regional analysis of CI showed that the CI value with over 0.62 indicated that approximately 80% of precipitation was contributed by 25% of the rainiest days in this zone. Fortunately, the area with this high CI has been getting smaller, implying a positive trend toward regional flash flood and debris flow control.
Highlights
In recent years, the uneven spatial and temporal distribution of precipitation exacerbated by climate change has attracted much attention [1, 2]
This province lies in the transitional zone between Qinling Mountains and Loess Plateau from climate varying from humid to arid [37], covering three geomorphic units: Qinling Dabashan Mountains (QDM), Guanzhong Plain (GZP), and Loess Plateau in North Shaanxi (LPNS)
The low precipitation of 200–400 mm mainly fell in the Mu US Desert in Northwest Shaanxi, and the medium precipitation ranging from 400 to 800 mm covered most of LPNS, GZP, and the north foot of QDM, and the high precipitation of more than 800 mm occurred in the south area of QDM
Summary
The uneven spatial and temporal distribution of precipitation exacerbated by climate change has attracted much attention [1, 2]. The intensity [3], frequency [4], and pattern [5] of precipitation are expected to change, which can cause changes in evaporation and temperature [6], and more extreme weather events, such as floods [7] and droughts [8], are more likely to occur alternately. The wet periods were shortened in the Wei River basin during 1955–2012 [11] and precipitation had a negative trend with a 5% decline per century in Italy [12]. Several change points were found in the precipitation extremes in the Wei River basin, China [14], there was no significant change in the annual precipitation. Some researchers have argued that the changes in precipitation concentration represent seasonal characteristics of precipitation [15,16,17]
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