Proposed Angat river water impounding and flood mitigation project

Along the Angat River in Bulacan, central Philippines, three existing dams (Ipo, Bustos, and Angat, dams) is installed which serve different purposes. These dams release huge volume of water, which contributes to the floods downstream the reservoir. This research aims to reduce floodwater downstream and to impound floodwater from Ipo and Angat dams. The researchers conducted data gathering, preliminary investigations and flood simulations using Global Mapper, ArcGIS and HEC-HMS respectively to compute the maximum decision flood (MDF) for the basis of the dam. The proposed structure is a gated spillway-gravity dam subdivided into 15 flood storages where water surface elevations were set as critical levels. Decision floods are formed by dividing the MDF into 15 sub-hydrographs. Because of routing simulations of the decision floods, a set of 15 spillway gate openings is identified where all floods from very small magnitudes to the MDF may be routed without overpassing the crest of dam. A 15-stage operation rules are then identified where the gate openings of the primary stages are decreased as the critical levels increased systematically, with the objective of attenuating smaller floods more effectively and releasing higher outflows for larger floods close to and including the MDF.