Climate Change and Climate Variability
In the context of global warming, regional droughts might vary considerably in time and extent. The spatial and temporal characteristics of drought are investigated for Luanhe River basin, using monthly precipitation data from 26 stations covering the common period of 1958-2011. The spatial pattern of drought was assessed by applying Principal Component Analysis (PCA) to the Standardized Precipitation Index (SPI) computed on 1-, 3-, 6- and 12-month time scales. For all four cases, three distinctive sub-regions with different temporal evolution of droughts are well identified, respectively representing the southeast, middle and northwest of the Luanhe River basin. The Mann-Kendall (MK) trend test and continuous wavelet transform (CWT) were used to further detect the temporal trends and periodical features of drought condition in each sub-region. Results of MK test show a general tendency of intensification in summer drought over the entire basin, while a significant mitigating trend in spring drought. On an annual scale, a significant aggravating trend of drought severity is discovered in both northwestern and southeastern sub-regions. Based on the CWT, the drought variability in the basin is generally dominated by 16- to 64-month cycles. Furthermore, a cross wavelet analysis was performed to examine the possible links between the drought conditions and large-scale climate patterns. The teleconnections of ENSO, NAO, PDO and AMO show significant influences on the regional droughts principally concentrated in the 16- to 64-month period, maybe responsible for the physical causes of the cyclical behavior of drought occurrences. PDO and AMO also highlight a noteworthy correlation with drought variability on a decadal scale (around 128-month period). The findings of this study will provide valuable references for regional drought mitigation and water resource management under a changing environment.
Wednesday, January 4
10:00 AM – 5:00 PM