ITB Golden Ratio Spillway Crest: An Innovative Spillway Geometry For Design Simplicity And Optimal Hydraulic Performance

Jurnal Teknik Sipil; Dantje Kardana Natakusumah; Syaeful Anas; Joko Nugroho; Eka Oktariyanto Nugroho; Arno Adi Kuntoro; Fitra Adinata

doi:10.5614/jts.2026.33.1.3

Authors

Jurnal Teknik Sipil Institut Teknologi Bandung
Dantje Kardana Natakusumah Water Resources Engineering Research Group, Faculty of Civil and Environmental Engineering, Institut Teknologi Bandung
Syaeful Anas Water Resources Engineering Research Group, Faculty of Civil and Environmental Engineering, Institut Teknologi Bandung
Joko Nugroho Water Resources Engineering Research Group, Faculty of Civil and Environmental Engineering, Institut Teknologi Bandung
Eka Oktariyanto Nugroho Water Resources Engineering Research Group, Faculty of Civil and Environmental Engineering, Institut Teknologi Bandung
Arno Adi Kuntoro Water Resources Engineering Research Group, Faculty of Civil and Environmental Engineering, Institut Teknologi Bandung
Fitra Adinata Consultant PT. Sapta Adhi Pratama

DOI:

https://doi.org/10.5614/jts.2026.33.1.3

Keywords:

Golden Ratio, spillway, spillway capacity, spillway design curve

Abstract

Abstract

A spillway is a vital structure in dams or weirs, designed to safely discharge excess water when reservoir levels exceed operational limits. Its performance depends greatly on crest geometry. In Indonesia, the Ogee and cylindrical spillways are the most commonly used. The Ogee spillway is recognized for its superior hydraulic efficiency and ability to maintain low-pressure profiles; however, it requires complex geometry and high construction precision. Conversely, the cylindrical spillway is easier to construct but lacks consistent design standards, particularly for defining the crest radius, which may complicate in design and construction. To address the need for a practical yet theoretically sound alternative, the ITB Golden Ratio Spillway was introduced. This design applies the mathematical golden ratio (? ? 1.618) to the crest geometry, aiming to achieve hydraulic performance comparable to traditional Ogee crest spillways while simplifying design and construction. The result is a spillway geometrical structure that combines visual simplicity with engineering functionality. The performance of the ITB Golden Ratio Spillway?types a and b?was evaluated using numerical simulations with Flow-3D, and the results were validated through hydraulic physical model tests. The Golden Ratio Spillway delivers comparable flow capacity to ogee and cylindrical spillway. This makes the ITB Golden Ratio Spillway a compelling and innovative alternative, offering simplicity in field application and optimal hydraulic performance.

Keywords : Golden ratio, spillway, spillway capacity, spillway design curve.

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