Thesis (BS Applied Mathematics) -- University of the Philippines Mindanao, 2003

El Nino and La Nina phenomena can cause anomalies in rainfall patterns but the quantification of these anomalies is paid less attention. This study was conducted to determine the rainfall anomalies during the El Nino and La Nina episodes using the 21-year daily rainfall data gathered from a nonrecording rain gauge at PAGASA Station in Sasa, Davao City. El Nino and La Nina episodes from 1980 to 2000 were accessed from Climatology and Agrometeorology Branch of PAGASA. From these episodes, the normal rainfall was calculated from the non-El Nino and non-La Nina periods. The rainfall anomalies were quantified by using ratios, deviation means, ranges and t-test. It was found that during El Nino and La Nina episodes, there were inconsistencies in the anomalies. T-test revealed that not all the El Nino episodes had significantly below normal rainfall while all the La Nina episodes did not have significantly above normal rainfall. Generally, El Nino had less impact on rainfall and even lesser remarkable impact during La Nina in some areas in Davao City upon evaluating the rainfall records from 1980 to 2000. This may be attributed to the uniformly distributed rainfall in Southern Mindanao and the national declarations used in this study. National declarations may not necessarily agree with the local manifestations of El Nino and La Nina specifically in Davao City since rainfall type also vary in different regions.