Effect of Rainfall Abnormalities on Rice Yield in Hambanthota District, Sri Lanka


  • Henegama Liyanage Kelum Sanjaya Department of limnology, University of Ruhuna, Matara, Sri Lanka
  • Tilak Priyadarshana Department of limnology, University of Ruhuna, Matara, Sri Lanka
  • Nimal Wijayaratna Department of Civil Engineering, University of Moratuwa, Sri lanka


Rain fall distribution, Rice yield, Crop seasons, Climate change


The sown area is continuously being increased in Hambanthota district; the rice production has not fulfilled its expected optimum yield. As the agriculture is mainly based on the rainfalls received to this region, the sentiment of the farmers on this matter is the shift of the crop season due to the climatic consequences. However, no proper scientific investigation has been done to see whether the rainfall pattern and intensity has changed. Neither future projection is available. Therefore, there is an urgent need to study the shifting the rainy seasons to re-determine the crop season in order to enhance the rice production in the district. It was collected available monthly rainfalls data for three stations called Hambanthota, Tissamaharama and Mamadala from 1869 to 2010. The recent data related to the rice production and cultivated area was obtained for last six years. Changes of the rainfall data were analyzed with the help of SPSS 16.0 and trends, percentage attainment of rainfalls during the Yala, and Maha seasons were calculated. It is clear that the expected yield has not been attained, though it receives 61.7%, 68.4% and 61.2% of the annual rainfall in Hambanthota, Tissamaharama and Mamadala respectively during the Maha season. The trend of mean annual rainfall moves along a steady line for next two decades. There is not a significant spatial variation (p>0.05) of the rainfalls among three different stations as well as monthly rainfall data over the last century in Hambanthota district. Since there is not a significant shift of rainy season, the reduction of expected rice yield cannot be introduced as a cause of an abnormality in rainfalls in the district.


Ottmar, E., Madruga, R.P., Sokona.Y, 2012. Renewable Energy Sources and Climate. 1st ed. USA: Cambridge University Press.

Lal, M., Sign, K., Rathore, L.S., Srinivasan, G., Saseendran, S.A., 1998. Vulnerability of rice and wheat yield in NW in India to future changes in climate. Agriculture and forest meteorology. 89, pp.101-114.

Jalota, S.K, K., Harsimran, K., Samanprteet, B.B., Vashisht. 2013. Impact of climate change scenarios on yield, water and nitrogen balance and use efficiency of rice-wheat croping system. Agricultural water management. 116, pp.29-38.

Smarten, P.G., Jayakody, P., Molle, F., Jinapala, K. 2005. Small tank cascade systems in Walawe River Basin. Colombo, Sri Lanka: IWMI. 46p. (Working paper 92 ).

Amarasinghe, U. A., Mutuwatta, L. and Sakthivadivel, R. 1999. Water scarcity variations within a country: A case study of Sri Lanka. Research Report 32. Colombo, Sri Lanka: International Water Management Institute.

Census of population and housing 2012. Population of Sri Lanka by district. Department of census and statistics, Colombo.

Chandrapala, L. 1996a. Calculation of areal precipitation of Sri Lanka on district basis using Voronoi Tessalation Method. Proceedings of National Symposium on Climate Change, Central Environmental Authority, Colombo, Sri Lanka, March 7-8, 1996.

Chandrapala, L. 1996b. Long term trends of rainfall and temperature in Sri Lanka. In: Climate variability and agriculture, eds., Abrol, Y. P., Gadgil, S., Pant, G. B. (eds). New Delhi, India: Narosa Publishing House.

Jayathilake, H.M., Chandrapala, L., Basnayake, B.R.S.B. and Dharmaratne, G.H.P. 2005, Water Resources and Climate Change Proceedings, Workshop on Sri lanka National Water Development Report, eds. Wijesekera, N.T.S., Imbulana, K.A.U.S. and Neupane, B., World Water Assessment Program. Paris, France.

Peiris, T.S.G., Wijerathna, M., Ranasinghe, C.S., Ananda Kumaraswamy, A., Fernando, M.T.N., Jayakody, A., Rathnasiri, J. 2004. Impact of Climate change on Coconut and Tea industry in Sri Lanka. Paper presented at the 2nd AIACC Regional workshop for Asia and Pacific, Manila, Philippines.

De Silva, C. S.; Weatherhead, E. K.; Knox, J. W.; Rodriguez-Diaz, J. A. 2007. Predicting the impacts of climate change – a case study of paddy irrigation water requirements in Sri Lanka. Agricultural Water management 93(1-2):19-29.

Nakgava, K., Edgawa, H., Nakamura, V., Aoki, M., 1995. Long-term hydro-meteorological data in Sri Lanka; Data book of Hydrological cycle in humid, Tropical ecosystems, Part I, Japan; University of Tsukuba.

Momani, P.E.N.M., “Time Series Analysis Model for Rainfall Data in Jordan: Case Study for Using Time Series Analysisâ€, American Journal of Environmental Sciences, vol. 5, no. 5, pp. 599-604, 2009.

Haan, C. T. 1994. Statistical Methods in Hydrology. Iowa State University Press. Ames.

Panabokke, C. R., R. Sakthivadivel; A. D. Weerasinghe. 2002. Evolution, present status and issues concerning small tank systems in Sri Lanka. Colombo, Sri Lanka: International Water Management Institute.

Sakthivadivel, R., N. Fernando, and J. D. Brewer. 1997. Rehabilitation planning for small tanks in cascades: A methodology based on rapid assessment. Research Report 13. Colombo, Sri Lanka: International Irrigation Management Institute.

.Nimal P.De Silva,D.L.O. Mendis, V.E.A. Wikramanayaka, 1995. Scientific principles seen in ancient artifacts and monumental structures. Science education series.

.Basnayake, H.T, 2005. Purana lankawe jala shistacharaya. 2nd ed. colombo,10: samanthi publishers




How to Cite

Sanjaya, H. L. K., Priyadarshana, T., & Wijayaratna, N. (2014). Effect of Rainfall Abnormalities on Rice Yield in Hambanthota District, Sri Lanka. Asian Journal of Agriculture and Food Sciences, 2(6). Retrieved from https://ajouronline.com/index.php/AJAFS/article/view/1905