Department of Soil and Water Conservation Engineering, Tamil Nadu Agricultural University, Coimbatore-641 003, India
* email: kumar.nanthu@gmail.com
Online published on 13 January, 2016.
Identification of temporal variation of rainfall trends provides useful information for sustainable planning and management of water resources in a river basin particularly during flood and drought periods. The present study was conducted to determine trends in the annual and seasonal total rainfall over Parambikulam Aliyar sub basin of Tamil Nadu using 30 years (1982–2012) monthly rainfall data at eight rain-gauge stations. The procedure is based on the non parametric Mann-Kendall test for the trend and the non parametric Sen's method for the magnitude of the trend. The results indicated significant positive trend were observed at Weaverly station during North East monsoon rainfall series and significant negative trend has been noticed in the South West monsoon of Topslip. The maximum increase in rainfall was found at Chinnakallar with an annual rainfall of 90.51 mm/year and the maximum reduction in rainfall of-8.60 mm/year was found at Topslip during South West monsoon. The presence of trend in annual and seasonal rainfall series determined by Mann-Kendall Z statistics and Sen's Slope estimator reflected in the linear regression analysis.
Rainfall trend, Mann-Kendall test, Sen's slope estimator, Regression
