Evaluation of rainfall and temperature trends in Brunei Darussalam

Climate change is acknowledged as the world’s significant environmental predicament. Rainfall and temperature have been widely studied in correlation with climate change. This paper demonstrates the result of the trend analysis of rainfall variables over the period of 1984 to 2013 and temperature variables over the period of 1979 to 2013 in Brunei Darussalam. Mann-Kendall trend test was applied to analyse and detect trends for the variables. This study revealed that the observed rainfall has a statistically significant increasing trend with increasing rainfall duration and decreasing intensity. The annual rainfall has increased significantly at a rate of 26.16 mm per annum. Mann-Kendall test for rainfall data reveals an increasing trend at confidence level of 95% for the annual total rainfall and confidence of level 90% for of annual maximum rainfall. The observed temperature also exhibits a statistically significant increasing trend at a rate of 0.031°C per year. Results of Mann-Kendall test for temperature data indicate a positive trend at a confidence level of 99.9% for the annual average temperature, average day time temperature, minimum day time temperature, average night time temperature and minimum night time temperature and at a confidence level of 95% for maximum night time temperature. The progressive effect of both the observed rainfall and temperature changes will contribute to greater surfaces run off and create flooding problem. Too much rainfall will threaten slope stability while dry periods of increased temperature will cause soil erosion.