Flood risk analysis and mapping of the Penaranda River basin using hydrological-hydraulic approach

Abstract. One of the approaches to flood risk mapping is through hydrological-hydraulic models. A hydrological-hydraulic model can calculate the areas of inundation for any degree of rainfall. The model selected for this study is a steady non-uniform flow model, particularly the gradually varied flow. This is applied to Penaranda River in Nueva Ecija covering a total stream length of 17.3 km out of the total 25 km. The study area considered begins at where Pampanga River Forms a junction with Penaranda River and ends 900 meters from the PENRIS (Penaranda River Irrigation System) dam. The model consists of three computer programs to input the necessary data, calculate the resulting water surface elevations, and show graphical images of each cross-section. Water surface elevations were calculated for floods of different return periods. These were then used to delineate the areas of inundation