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The ITB Unit Hydrograph Method: A Novel Approach to User-Defined Unit Hydrograph Development (Part I)

Dantje K. Natakusumah, Waluyo Hatmoko, Dhemi Harlan, Eka O. Nugroho, Arno A. Kuntoro, Mohammad Farid, Fitra Adinata, Jovian Javas

Abstract


All synthetic unit hydrographs can be considered user-defined to some degree, reflecting the inherent influence of user input in their development. This paper constitutes the first part of a two-part series titled The ITB Unit Hydrograph Method: A Novel Approach to User-Defined Unit Hydrograph Development. It focuses on foundational concepts, the verification of existing SUH methods, and the creation of simple user-defined Synthetic and Natural Unit Hydrographs. The verification process involves reproducing established hydrographs, including the SCS-Triangular, SCS-Curvilinear, and SCS-Delmarva models, by computing their Peak Rate Factor (Kp) and Peak Discharge (Qp) values using ITB-UH formulas. Results demonstrate high accuracy, with discrepancies in Kp values consistently below 1%, confirming the reliability of the ITB-UH Method in replicating existing models. Furthermore, the study highlights the ITB-UH Method’s capability to develop user-defined synthetic hydrographs, as exemplified by the Double Triangle Synthetic Unit Hydrograph and the HKR Natural Unit Hydrograph. The Double Triangle model introduces a simple unit hydrograph with distinct geometric properties, while the HKR model effectively represents a natural unit hydrograph derived from rainfall-runoff dynamics in a watershed. Both models were applied to flood discharge simulations in the Pinamula Watershed using consistent steps for effective rainfall excess distribution and convolution. The results demonstrate that all hydrographs, despite differences in shape and peak characteristics, yield consistent total flood volumes. These findings underscore the ITB-UH Method’s potential to generate unit hydrographs based on user-defined models—whether defined by equations or tables. It should be noted that the simple user-defined unit hydrographs presented in this paper do not include calibration capabilities, a topic that will be explored in Part II of the series.

 

Doi: 10.28991/CEJ-2025-011-04-021

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Keywords


ITB-UH Method; SCS SUH (Triangle, Curvilinear, Delmarva); ITB Double Triangle Synthetic UH; HKR Natural UH.

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Full Text: PDF

DOI: 10.28991/CEJ-2025-011-04-021

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Copyright (c) 2025 Dantje Kardana Natakusumah, Waluyo Hatmoko, Dhemi Harlan, Eka Oktariyanto Nugroho, Arno Adi Kuntoro, Mohammad Farid, Fitra Adinata, Jovian Javas

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