Journal ID : TRKU-18-10-2020-11251
[This article belongs to Volume - 62, Issue - 10]
Total View : 344

Title : The Limiting Physical Parameter of Synthetic Unit HydrographTime to Peak Model

Abstract :

The Synthetic Unit Hydrograph time to peak model is indispensable in determining the design of water infrastructure in Indonesia, given the many immeasurable watersheds that do not have rainfall and discharge data in determining the design in an area. The typical Indonesian peak time models that have been developed include Gama I, where several other Shyntetic Unit Hydrograph (SUH) still adopt models developed based on watersheds that are not in Indonesia. The Time Peak Model developed in this study will consider several parameters including the area of ​​the watershed (A), the length of the main river (L), the length of the river from the center of the watershed to the outlet (Lc), river slope (S), watershed roughness (n). watershed form factor (Fb), river branching factor (RB), river length factor (RL), and Fractal Dimension (DF). This parameter will be compared with the time peak obtained from the hydrograph calculation of the observation unit using the Collins method. To calculate the hydrograph, the observation unit requires rainfall and discharge data. Meanwhile, to obtain these parameter values, a topographic map, a Digital Elevation Model (DEM) map, and a land use map are needed as well as the help of ArcGIS, Hec-RAS, AutoCAD, and Microsoft Excel software. Rainfall analysis will be tested by RAPS, stationary test, and outlier test, while the discharge data is stationary test and outlier test. The results of research from 10 watersheds spread across Java and Sulawesi obtained peak time (Tp) 3-5 hours, peak discharge (Qp) 1.89-39.93 m3 / s, watershed area 40.62 - 1376.75 km2; length of the main river (L) 24.95-106.48 km; the length of the river from the center of gravity of the watershed to the outlet (Lc) 5.45 - 32.99 km; river slope (S) 0.004-0.138; Watershed roughness (n) 0.035-0.048; watershed form factor (Fb) 0.04-0.70; river branching factor (RB) 3.05-40.51; river length factor (RL) 2.47-6.74; Fractal Dimensions (DF) 0.94-1.85. The results showed that the parameter L had the highest correlation rate followed by parameters A, RL, Lc, RB, DF, S, n and

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