Impact of Climate Change on the Frequency and Severity of Floods in the Pasig-Marikina River Basin

Abstract

This study assessed impacts of climate change on the frequency and severity of floods in the Pasig-Marikina River basin. Researchers used the historical data from PAG-ASA (Philippine Atmospheric, Geophysical and Astronomical Services Administration), specifically from Science Garden weather station. The historical data are coupled with a global climate model, the Hadley Center Model version 3 (HadCM3) to account for the natural variability of the climate system in the area. The observed data and the hydroclimatic data from HadCM3 was processed in Statistical Downscaling Model (SDSM) that results to rainfall data from 1961-2017 and change in temperature data from 2018-2048. A rainfall time series for the river basin was generated considering average seasonal effects in the area. A flood frequency curve was modelled. From that, flood value for 2048 was derived to be at 3950cu.m/s. Additionally, the rapid urbanization in the area has contributed to the changes in the river system making it more vulnerable to floods. The results of this study supports the claim that the Pasig-Marikina River basin will be affected by the climate variability in terms of the increase in rainfall depth and average temperatures, higher flood frequency and more massive floods in the future. This study could help local government units to enforce improvement and mitigation in their area to prevent these from happening.