Flooding Incidence at Aklan River as Affected by Rainfall

Abstract

The Philippines is among the most vulnerable countries in terms of disaster and climate change scenario. Based on previous studies, the provinces in the Philippines are classified according to their vulnerability to temperature change, rainfall change, typhoons, El Niño and flooding incidence. The province of Aklan is included as one of the provinces with high risk related to rainfall change. A 24-hour rainfall of 206.4 mm in December 2005, 246.80 mm in December 2010, and 202.80 mm in November 2011, resulted to flooding in the municipality of Kalibo and a 305.30 mm rain in June 2008 had caused severe damage to the low-lying areas of the region.  But rainfall of only 124.6 mm in December 2012 had inundated some areas of the province. This was due to the incidence of high tide which prevented the river from emptying into the sea. Based on the result of this study, recurring typhoons and increased precipitation were experienced in the province of Aklan specifically during the Northeast Monsoon or Amihan (November and December). There is a weak positive correlation between rainfall and height of water at the Aklan River as indicated by r2 value of 0.011.  This result suggests that changes in the independent variable (rainfall) are not associated with changes in the dependent variable (height of water).  More rain and cooler temperature were noted in summer (March 2012) while least relative humidity, higher temperature, and least rainfall were recorded in August (Habagat season), and temperature ranged from 24.3 to 31.9 0C.  More rainfall was observed in Madalag (295.8 mm), followed by Banga (263.0 mm) and Kalibo (243.0 mm) for 2012-2013. Based on a ten-year rainfall data, abundant rain was observed in June, September to December and started to decline from January to May and August.  Aklan has a mean annual rainfall of 3,325.6 mm while mean temperature is 30.90C.  Dry Spell condition occurred in 2014 since from January to June, rainfall was almost below to way below normal rainfall condition, based on the criteria set by PAGASA.