Rainfall fluctuation and changing patterns of agriculture practices

Rainfall fluctuations and the resulting changes in agricultural practices are investigated in this study. The basis for the study is total rainfall and number of rainy days for the period 1961-2002 for 22 meteorological stations scattered throughout the country and the changing pattern of agricultural practices in the crop calendars of 15 reservoirs under the Mahaweli Authority from 1983-2008. From the regression analysis carried out for the 22 rainfall stations, the study recorded declining trends of rainfall in all the wet and intermediated zone stations that were considered, while only Jaffna, Pothuvil and Mulathivue recorded increasing trends. In terms of the number of rainy days, only the Nuwara Eliya station recorded an increasing trend, while all the other stations recorded declining trends. The spatial analysis indicates that the annual total rainfall, which is below 1,600 mm, tends to expand towards the central and south western part of the country. By inspecting the \u2018Crop Calendar\u2019 it was found that both yala and maha seasons start later, especially in the yala season. Also, in the irrigation schemes, the quantity of water issued and the number of days that it is issued for have declined over the years for both seasons.