TY - JOUR
T1 - Assessment of trends in point rainfall using Continuous Wavelet Transforms
AU - Rashid, Md Mamunur
AU - Beecham, Simon
AU - Chowdhury, Rezaul Kabir
N1 - Funding Information:
This study was funded by the South Australian Government’s Goyder Institute for Water Research through Grant C.1.1. The Goyder Institute also provided additional scholarship funding for the first author. The researchers are also grateful to the Australian Bureau of Meteorology for providing meteorological data.
Publisher Copyright:
© 2015 Elsevier Ltd.
PY - 2015/8/1
Y1 - 2015/8/1
N2 - The existence of trends in hydro-climatic variables such as rainfall is an indication of potential climate variability and climate change and the identification of such trends in rainfall is essential for the planning and design of sustainable water resources. This study focuses on identifying existing trends in annual, seasonal and monthly rainfall at thirteen stations in the Onkaparinga catchment in South Australia during the period 1960-2010. A relatively new trend detection approach, which combines a Continuous Wavelet Transform (CWT) with the Mann Kendall (MK) test, was applied in this study. The original rainfall time series was decomposed to different periodic components using a CWT and then the MK test was applied to detect the trends. One station showed a statistically significant (at the 5% level) negative trend for annual rainfall. Winter rainfall exhibited significant positive trends at four stations. In the case of monthly rainfall, significant positive trends were observed in June (at seven stations), November (at one station) and December (at one station). The study showed that the periodic components might have significant trends even when there are no significant trends in the original data. The periodic component that dominates the trend in the original data varies from season to season. A sequential Mann-Kendall analysis was found useful for identifying the trend turning points. Most of the trends, whether positive or negative, started during the mid-1970s to mid-1980s. The technique developed in this study may also be applied for trend detection of other hydro-climatic variables in other catchments, particularly where temporal and spatial variabilities are high.
AB - The existence of trends in hydro-climatic variables such as rainfall is an indication of potential climate variability and climate change and the identification of such trends in rainfall is essential for the planning and design of sustainable water resources. This study focuses on identifying existing trends in annual, seasonal and monthly rainfall at thirteen stations in the Onkaparinga catchment in South Australia during the period 1960-2010. A relatively new trend detection approach, which combines a Continuous Wavelet Transform (CWT) with the Mann Kendall (MK) test, was applied in this study. The original rainfall time series was decomposed to different periodic components using a CWT and then the MK test was applied to detect the trends. One station showed a statistically significant (at the 5% level) negative trend for annual rainfall. Winter rainfall exhibited significant positive trends at four stations. In the case of monthly rainfall, significant positive trends were observed in June (at seven stations), November (at one station) and December (at one station). The study showed that the periodic components might have significant trends even when there are no significant trends in the original data. The periodic component that dominates the trend in the original data varies from season to season. A sequential Mann-Kendall analysis was found useful for identifying the trend turning points. Most of the trends, whether positive or negative, started during the mid-1970s to mid-1980s. The technique developed in this study may also be applied for trend detection of other hydro-climatic variables in other catchments, particularly where temporal and spatial variabilities are high.
KW - Continuous Wavelet Transform
KW - Mann-Kendall trend test
KW - Periodicity
KW - Rainfall
KW - Trend analysis
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U2 - 10.1016/j.advwatres.2015.04.006
DO - 10.1016/j.advwatres.2015.04.006
M3 - Article
AN - SCOPUS:84928683667
SN - 0309-1708
VL - 82
SP - 1
EP - 15
JO - Advances in Water Resources
JF - Advances in Water Resources
ER -