Temporal Analysis for Detection of Anomalies in Precipitation Patterns over a Selected Area in the Indus Basin of Pakistan

Abstract

For efficient adaptation strategies, investigation of the variability in climatic data and its impact on meteorological drought is critical, particularly in semi-arid and arid regions. Innovative trend analysis (ITA), Mann–Kendall (MK) and Sen’s slope estimator (SSE) tests were employed to analyze the variations in precipitation (1981–2018) on annual, seasonal and monthly scale across 12 meteorological stations over the selected areas of the lower Indus basin (LIB) of Pakistan. The reliability of the ITA method was also compared and analyzed with both MK and SSE methods for 48 seasonal precipitation times series. Annual precipitation results indicated a significant increasing trend, i.e., 2.09 mm/year, at only one station (Rahim Yar Khan (RYK)-Khanpur), with MK test statistic Zmk = 2.09 and Sen’s slope estimator β = 2.56. On a monthly scale, the maximum number of positive significant trends were noted during June, with Zmk values of 2.01 to 3.24 and β values of 1.06–3.06, while the maximum number of negative trends was found during January, February, November and December. On a seasonal scale, ITA methods showed significant increasing trends during the summer at 12 selected meteorological stations, with trend indicator (B) values ranging from 0.22 to 2.46. Moreover, performance of the ITA method was found to be consistent with both MK and SSE test results at a verified significance level. The results of the study can help to increase our understanding of the annual, seasonal and monthly precipitation variability in the LIB that may be helpful in developing strategies for the proper management of water resources over the area.