Trend analysis in precipitation at individual and regional levels in Baluchistan, Pakistan.

Abstract

Pakistan’s largest province by area, is Baluchistan hosts deep sea Gawadar port and is playing a vital role in one belt one road (OBOR) plan. CPEC, a Regional route comes under OBOR which connect Pakistan’s Gwadar port to Chinese Xinjiang Province. CPEC Corridor upon construction is expected to revolutionize the infrastructure, economy, trade, finance, demography, environment, culture, socio-economic conditions, of Pakistan. Much of western and central CPEC routes pass through it. However, Baluchistan, due to its topography and rugged terrain, is under constant risk of rainfall driven flash floods. Flash floods are responsible for colossal damages to the infrastructure, especially roads, bridges, trade, communication that ultimately badly affects the humans, economy and the environment. The intensity and frequency of rainfall are increasing due to climate change and flash floods put everything at high risk. In this view, the assessment of changes in rainfall has got significant importance. More or less no appreciable studies have been conducted on the precipitation trend analysis and in Baluchistan. This research is focused on assessment of trend analysis in precipitation of Baluchistan using 40 years (1977-2016) data of 13 stations in Baluchistan. The data has been obtained from the Pakistan Meteorological Department (PMD). Precipitation data sample is checked for normal distribution, abrupt changes, cycles, outliers and missing values. Normal distribution of precipitation data set is done by conducting tests for normality like the Shapiro-Wilk W test, Anderson–Darling, Lilliefors, and Jarque–Bera test. Statistical tests, being the most direct methods of detecting changes in extreme rainfall intensities were adopted. Two nonparametric tests Mann-Kendall (MK) and Spearman’s rho (SR) have been used to find the trends in annual and seasonal precipitations. Nonparametric methods are selected as they are less sensitive to data gaps if it exists. Theil Sen slope estimator has been used to compute the magnitude of the trend. The seasonal and regional MK test has also been applied to test the seasonal and regional trends.