Development of Pakistan’s New Area Weighted Rainfall Using Thiessen Polygon Method

Faisal N, A Gaffar

Abstract


In this paper effort has been made to re-determine the area weighted rainfall data set of Pakistan, especially after the demarcation of more sub-regions. Monthly rainfall data of 56 climatological stations’ rain gauges for the period of 50 years, from 1961-2010, have been used. The stations selected are almost evenly covering the mountainous and
plain areas of the country. Based on this newly developed area weighted precipitation dataset of 56 stations in Pakistan, temporal and spatial variation of rainfall for Pakistan, as a whole country, and its six sub -regions, have been assessed for the period 1961–2010. The mean annual rainfall, for the fifty years period, of Pakistan comes out to be 297.6 mm with 63.4 mm standard deviation and 21.3 % coefficient of variability. Similarly the mean (1961-2010) annual rainfall for Azad Kashmir, Balochista,n Gilgit-Balitistan, Khyber-Pakhtunkhwa, Punjab &
Balochistan are calculated as 418.7 mm, 160.6 mm, 207.0 mm, 734.6 mm, 386.3 mm & 172.4 mm respectively. Pakistan mean rainfall for winter (Jan-Mar) and Monsoon (Jul-Sep) seasons are 74.3 mm & 140.8 mm respectively, which contributes the 25 & 47 percentage of annual rainfall.


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References


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abrfc/?n=map#arithmetic_mean


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