Yield modelling and dambreak consequence assessments for proposed Alimit Dam and Ibulao Diversion Weir

SN Aboitiz Power Group engaged HARC to undertake detailed yield, flood hydrology and dambreak consequence assessments for the proposed Alimit Dam and Ibulao Diversion Weir.

HARC was able to derive and validate yield calculations at the locations required despite the paucity of flow and climate data in the region.  Climate change projections developed by the Philippine Atmospheric Geophysical and Astronomical Services Administration were then applied to determine changes to yield under climate change.

The hydrologic model was calibrated and verified to historic events to recommend an inflow design flood for design of the dam and a two-dimensional hydraulic model was used to generate the dambreak inundation extents for the consequence assessment. A feature of this work was the use of international climate data sets, hydrometeorological approaches to the extreme rainfall and flood predictions. The potential impact of climate change on the probable maximum flood was assessed from local and international research and used to inform the selection of the spillway capacity for the dam.