Watershed modeling can help assess the impacts of increased population, tourism, and land use changes on the Puerto Galera watersheds in the Philippines. Modeling the Balatero and Aninuan watersheds shows that complete deforestation leads to rapid increases in stream discharge and high peak flows, while reforestation results in more gradual discharge patterns. Continuous monitoring also reveals discharge dynamics not seen with intermittent sampling. The conclusions emphasize that watershed modeling is a useful tool for understanding how land cover changes affect river discharge over time and supporting environmental decision-making.

1. Puerto Galera Watersheds Increasing population Tourism boom Increased demand for resources ( e.g. land, water, food) Land use / cover change More wastes generated

2. How can watershed modeling help Puerto Galera? Assessing water supply potential Quantifying material fluxes, also from built-up areas Assessing the effect of clear-cutting and deforestation Evaluating risk of flash flooding White Beach forest 2005 deforested 2005 (from 2001)

3. Puerto Galera Watersheds Balatero watershed Aninuan watershed SRTM 3” DEM

4. Balatero Watershed Present LC All Forest All Bare

5. Balatero Watershed Present LC Rapid increase in stream discharge High peak discharge All Forest All Bare Gradual increase/decrease in stream discharge More gradual increase/decrease in stream discharge Low peak discharge

6. Aninuan Watershed Aninuan Watershed Aninuan Watershed All Bare All Forest

7. Conclusions Long-term continuous monitoring reveals discharge dynamics not adequately captured by intermittent grab sampling Land cover composition and landscape patterns have significant influence on river/stream discharge Watershed modeling is a useful tool for understanding effects of land cover change, among other factors, and hence for supporting decision-making in a coastal environment.

8. Maraming salamat po!