The Impact of Land Cover and Climate Change on Present and Future Watershed Condition. Study case: Tugasan, Alanib and Kulasihan Subwatershed of Manupali Watershed, Lantapan, Bukidnon, Philippines

Manupali watershed where is located in central Bukidnon, northern Mindanao provides various ecosystem service for communities particularly on water source. Some recent studies said that the water quantity in Manupali watershed has started to declined. Climate and land cover change is suspected to be one of the causes of this water degradation. Tugasan, Alanib dan Kulasihan subwatershed of Manupali watershed in municipality of Lantapan were selected as the focus area in this study to see the impact of climate and land cover change on water quantity.
The objective of this study is to assess the impact of climate and land cover change on present and future water balance in Tugasan, Alanib and Kulasihan sub-watershed using the GenRiver model. This objective was accomplished through some activities, such as gathering secondary climate and hydrology data, analysis of climate, hydrology and special data, development of land cover and climate change scenario, simulation of GenRiver model and analysis of simulation result.
The present water balance was simulated based on the actual climate and land cover data from 1990- 2015. The future water balance (2016-2050) was simulated based on four scenarios of land cover change: Business As Usual (BAU), crop expansion, banana plantation expansion and agroforestry, which combined with the prediction of climate change (rainfall and temperature) for the Bukidnon area.
The result of GenRiver model for the present condition (1990-2015) did not show any significant change of water balance in Tugasan, Alanib and Kulasihan sub-watershed since not much land cover change over the last 25 years. The analysis result for the future sub-watershed condition showed that the agroforestry can be considered as the best scenario while crop expansion as the worse scenario, while the climate change scenario will lead to an increase of evapotranspiration and reduce the river flow.