SEARCH

SEARCH BY CITATION

Keywords:

  • monthly rainfall trend;
  • seasonal rainfall trend;
  • Holt's test;
  • Kendall's Tau test;
  • Spearman's Rho test;
  • Langat River Basin

ABSTRACT:

Climate change is a global issue that has impact on every living being in the world. One of the most noticeable consequences of these global phenomena is the inevitable water cycle modification, with precipitation being a major component in these processes. Consequently, research into the occurrence and distribution of precipitation has increased over the past few decades. As Malaysia is located in the tropical area where there is no distinct four seasons, analysing rainfall has therefore become one of the common assessment tools for climate change. In this study, rainfall trends of Langat River Basin were examined on a monthly and seasonal basis (monsoon and non-monsoon) for the period of 1970–2012. Only rainfall time series with duration more than 25 years and missing data less than 10% have been considered for this study. The Holt's test has been employed to model the rainfall trends for the 10 selected time series; while Kendall's Tau test and Spearman's Rho test were used to test, compare and support for the significance of the trends. For monthly rainfall trends analysis, it was found that March, July and November are among the months those have most of the stations with increasing rainfall trends; while May and September are the months with the highest number of stations showing decreasing rainfall trends. Specifically, station 2815001 shows the highest number of months with changing rainfall trends throughout the year; while station 44255 has the least number of months with changing rainfall trends. Based on the seasonal rainfall trend analysis, there are seven stations during the Northeast Monsoon that revealed upward trends and the result is found to be consistent with the monthly rainfall trend analysis.