Precipitation Trend Analysis by MK Test in Garhwal Region Districts of Uttarakhand (1901–2010)

Abstract

Climate change has disrupted the major climatic parameters at a global level. However, the changes having localized intensity are not equal for all regions especially in India. These changes must be quantified locally to manage the natural water resources more effectively. Precipitation is one of the most important climatic parameters. It has been widely measured as a starting point towards the apprehension of global climate change. The purpose of this study is to observe the temporal variability of rainfall for the period of 1901–2010 (110 years), to improve the hydrological status of the Garhwal region districts of Uttarakhand. The aim of the study is to determine the trend in annual precipitation time series using the Mann-Kendall and Sen's T tests. The magnitudes of trend in precipitation have been estimated by Sen's estimator method. Auto correlation effect is reduced before applying the Mann-Kendall test for the trend in precipitation. On the annual basis, analysis of Mann-Kendall test shows increasing (positive) non-significance trend in rainfall time series over the Garhwal region districts of Uttarakhand. These areas experiences heavier spells of rainfall for shorter duration. This leads to more runoff in these areas, leaving very less scope for groundwater recharge. Thus, these findings give a broad overview of the regional rainfall behavior in the study area.

Keywords: Rainfall, non-parametric tests, trend analysis, auto correlation, Mann-Kendall and Sen's T tests