Trend analysis of rainfall using non-parametric method- A case study of Pairi sub-basin of Mahanadi basin

Abstract

The trend of annual and seasonal rainfall for a region would be very much essential in planning and development of water resources, irrigation scheduling, reservoir operations, etc. and also useful to understand the changing pattern of rainfall due to climate change for crop planning. The present study aims to analyse the trend of rainfall for the Pairi sub-basin of Mahanadi basin. In order to examine the trend of rainfall or absence thereof, Mann-Kendall statistical test are performed for trend analysis of three gauging stations and trend value were estimated. The Sen’s slope of Baronda, Sikaser and Sondur gauging stations are -0.218, 9.584 and -35.585 respectively for annual rainfall. Similarly, the Z statistics of Baronda, Sikaser and Sondur gauging stations are 0.00, 0.849 and -3.467 respectively for annual rainfall. The influence area of Baronda and Sikaser gauging stations located in lower and eastern part of middle catchment of sub-basin whereas influence area of Sondur gauging station situated in upper and western part of middle catchment of sub-basin. The study revealed that rainfall of lower and eastern part of middle catchment showed non-significance trend whereas significance negative trend observed in upper and western part of middle catchment both in seasonal and annual rainfall. An area of 1517.89 km2 (47.5 %) of the sub-basin is showing negative trend on annual and seasonal rainfall. Hence, more priority should be given on water management, water conservation structures, ground water recharge for drought proof agriculture in the influence area. Since agriculture is the major livelihood in the sub-basin therefore this study could help in decision making on different aspects of water management, water resource development, crop planning etc.