Estimated Soil Loss of Makatipo Catchment Under Different Climate Scenarios

Abstract

Soil erosion threatens sustainability of watershed resources in the Philippines as it reduces not only the on-site fertility and productivity of the land but also adversely impacts domestic water supply of downstream communities. Since the movement and transport of soil particles are predominated by rainfall as its agent especially in the humid tropics, climate change can affect soil erosion process. For critical watersheds such as Makatipo Catchment which supplies water to downstream communities in the Municipality of Lucban, assessing potential impacts of climate change on soil erosion is very important. The study was conducted to model soil erosion in Makatipo Catchment using Universal Soil Loss Equation (USLE) as modified by David (1998). Biophysical parameters, as input to USLE, were collected and analyzed using GIS. A2 and B2 climate scenarios from Coupled Global Climate Model (CGCM2) were downscaled using SDSM 4.2 and used as inputs for soil loss assessment.

Projections using scenarios showed that soil loss in the study area could increase during the next decades due to climate change. A2 projected an average increase of 33.32% from present (1981–2010) estimated soil loss of 17.06 t h-1 yr-1 while B2 projected a relatively lower increase of 9.73 t h-1 yr-1. Results also showed that areas experiencing high level or severe soil erosion would increase for both scenarios. The increase in soil erosion impairs water quality for various uses in downstream communities hence implementation of programs to rehabilitate erosion-prone areas, promote adoption of soil and water conservation strategies, and build climate resilient communities is highly recommended.