eversvd,+02 (6)

Kulasi River in the eastern slopes of Mt. Isarog crosses several key roads via culverts, many of which were destroyed during Typhoon Ulysses (VAMCO). The study documents the post-typhoon condition of these culvert crossings and develops hydrologic models to estimate their capacity under extreme storm events. Using GIS, DEM data, topographic and field surveys, and precipitation data from the Mines and Geosciences Bureau, the author derives a hydrologic model for actual river discharge and applies Manning’s equation to compute the discharge capacity of one-meter diameter concrete culvert pipes. The analysis compares actual discharge (based on rainfall, watershed area, slope, and other parameters) with culvert capacity to assess whether existing installations can safely convey flood flows. Results, summarized in tabular form, express the capacity of culvert pipe lines in terms of actual precipitation and corresponding discharge at specific locations along Kulasi River. The procedure is proposed as a transferable method that can be applied to other crossings along Kulasi River and to similar rivers elsewhere.