A case study - Probability distributions for long term rainfall data in Ludhiana. Mausam

Abstract

The rainfall data of Ludhiana for a period of 32 years of covering 1981 to 2012 have been collected from School of Climate Change and Agricultural Meteorology. the study was planned to find the rainfall variability and amount of rainfall at different probability levels for the year 1981-2012. The rainfall was analyzed on weekly basis to work out the initial and conditional probability for rainfall at different levels, i.e. >5 mm, > 10 mm, > 20 mm, > 30 mm, > 40mm and > 50mm using Markov chain model. In addition to this, incomplete gamma distribution was also used to find out the occurence of rainfall events at different probability levels, i.e. 20, 30, 40, 50, 65 and 75 percent. The study results in estimation of maximum and minimum initial probability and conditional probability wet and dry for standard meteorological week. The results will be useful for deciding the sowing time, irrigation / fertilizer scheduling and harvesting time for different crops. In addition to this study will be useful for determining the runoff volume, peak runoff rate and hence can be used for designing of rainwater harvesting structure.