ASSESSING THE HYDROLOGIC EFFECTS OF URBANIZATION THROUGH NUMERICAL MODELING USING SWAT: A CASE STUDY OF LAGUNA DE BAY BASIN

This study presents a three-dimensional hydrodynamic study of Laguna Lake to understand the physical processes that govern and influence lake hydraulics for various water uses. Modelling analysis on the lake’s flood detention function revealed different shore-land flood inundation areas and recession durations for varying lake-flood detention levels that warrants the need for a more comprehensive and sustainable flood management operation in the metropolis.

On the average, twenty typhoons pass through the Philippine Area of Responsibility each year. Five of which are usually considered destructive. In November 2020, Typhoon Vamco costed the Philippines over 19 billion pesos in damages (approximately 347 million US dollars). One of the heavily hit areas is the floodplain of Marikina River Basin. This study analyzed the flood development within the floodplain of the said basin during Typhoon Vamco using a calibrated flood model simulation.

Due to complex root system structures, representing the impacts of Rhizophora mangroves on flow in hydrodynamic models has been challenging. This study presents a new drag and turbulence model that leverages an empirical model for root systems. The model can be applied without rigorous measurements of root structures and showed high performance in flow simulations; this may provide a better understanding of hydrodynamics and related transport processes in Rhizophora mangrove forests.