Reliability of the Gama I Synthetic Unit Hydrograph after 15 years of its development as applied in South Sulawesi

Author(s):  
Farouk Maricar ◽  
Sri Br
Author(s):  
Dandy Achmad Yani ◽  
Ery Suhartanto

ABSTRAK Kurangnya ketersediaan data hidrograf merupakan kendala bagi perencanaan bangunan air. Kendala ini menjadikan model-model HSS akan memberikan manfaat yang cukup besar. Idealnya setiap DAS mempunyai Hidrograf Satuan dengan ciri tertentu. Studi ini bertujuan untuk mengamati karakteristik hidrograf pengamatan di tiap DAS dan semua DAS di Propinsi Sulawesi Selatan. Tujuan utama studi ini adalah membuat rancangan Model Hidrograf Satuan Sintetis antara lain persamaan debit puncak banjir (Qp) dan waktu mencapai puncak banjir (Tp) yang antara lain merupakan fungsi dari luas DAS (A), panjang sungai terpanjang (L), dan faktor bentuk DAS. Faktor bentuk DAS merupakan rasio dari keliling (K) dan luas area (A) DAS. Analisis model menggunakan regresi dengan berbagai alternatif. Hasilnya permodelan hidrograf satuan sintetis (HSS) dengan variabel luas DAS (A), panjang sungai terpanjang (L), dan faktor bentuk DAS (FD) dan tentunya sesuai dengan kriteria dari koefisien determinasi, diharapkan mempunyai sensitivitas yang cukup tinggi. Faktor bentuk DAS (FD) diharapkan mempunyai hubungan linear dengan parameter hidrograf satuan sintetis.Kata kunci: debit puncak banjir, waktu mencapai puncak, luas DAS, panjang sungai terpanjang, faktor bentuk DAS   ABSTRACT The lack of hydrograph data availability is an obstacle for water building planning. This constraint makes HSS models will provide considerable benefits. Ideally each watershed has a Hydrograph Unit with certain characteristics. This study aims to observe the hydrograph characteristics of observations in each watershed and all watersheds in South Sulawesi Province. The main objective of this study is to design a Synthetic Unit Hydrograph Model, including the peak flood discharge equation (Qp) and the time to reach the flood peak (Tp), which among others is a function of the watershed area (A), longest river length (L), and form factor Watershed. The watershed form factor is the ratio of perimeter (K) and area (A) of the watershed. Model analysis uses regression with various alternatives. The result is synthetic unit hydrograph modeling (HSS) with a broad variable watershed (A), longest river length (L), and DAS (FD) form factor and of course according to the criteria of the coefficient of determination, it is expected to have a high enough sensitivity. The DAS (FD) form factor is expected to have a linear relationship with the parameters of synthetic unit hydrographs. 


2021 ◽  
Vol 331 ◽  
pp. 07015
Author(s):  
Dian Pratiwi ◽  
Arniza Fitri ◽  
Arlina Phelia ◽  
Nabila Annisa Amara Adma ◽  
Kastamto

In the urban area, flooding becomes the most common disaster that has not been resolved until today. The utilization of river border area into housing and lack of absorption area becomes the trigger factor of urban flooding, as what is happening around Way Halim River on Seroja street. In this area, floods often happen during the rainy season, with the latest events recorded on January 21st, 2021. Analysis of flood intensities and discharges can be parameters for the decision-making of flood mitigation strategies. This study aims to analyze the flood discharges along Way Halim River, Seroja street by comparing the flood discharges resulting from three analysis methods of Synthetic Unit Hydrograph (SUH) including Gama I SUH, Nakayasu SUH, and Snyder SUH. Finally, suitable flood mitigation strategies were also proposed in this study based on the flood discharges and rain intensities. The results showed that Nakayasu SUH had the highest peak flood discharge than Snyder SUH and Gama I SUH. Based on the results of the investigation of land suitability; and analysis of rainfall intensities and flood discharges, the proposed flood mitigation in Seroja street is by installing biopore infiltration holes along Seroja street for storing water and reducing the risk of flooding in the area.


GANEC SWARA ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 126
Author(s):  
MUHAMAD YAMIN

This study aims to analyze the parameters that influence the Snyder synthetic unit hydrograph method. The study was conducted on 11 watersheds in South Sulawesi Province, 8 watersheds for modeling and 3 other watersheds for reliability testing (model verification).     With rainfall data, the discharge data and watershed characteristics obtained from each watershed were analyzed for parameters that affected the hydrograph breakdown of the Snyder HSS method. Then compared to the hydrograph of the observation unit which was analyzed by the Collins method.     After calibration was done with the NASH criteria obtained Peak Time (Tp) = 97.996%; Peak Discharge (Qp) = 98.331% and Basic Time (Tb) = 99.700%. The curved delineation of the hydrograph uses the auxiliary point W, which gives the result of volume deviation, namely: 7.980%, 9.227%; 6.855%; 4.966%; 10.972% and 9.843% are relatively small when compared to the model using Alexejeyev Arch with deviations: 22.362%; 29.991%; 26,319%; 19.602%; 29,786% and 17,633%.


2014 ◽  
Vol 23 (1) ◽  
pp. 53-59 ◽  
Author(s):  
Izabela Pietrusiewicz ◽  
Agnieszka Cupak ◽  
Andrzej Wałęga ◽  
Bogusław Michalec

Abstract The paper presents the results of using two models: a conceptual model of Wackermann and a NRCS-UH synthetic unit hydrograph, for flow calculation in uncontrolled catchment of the Słonka, Poland. These models were chosen because of simplicity of models’ parameters evaluation, what is important from engineering calculation point of view. Flows with the probability of exceed amounting to 0.5%, 1%, 2%, 5%, 10%, 20%, and 50% and for different levels of the catchment moisture were evaluated. The flood waves generated in the Wackermann model were characterized by a short duration (over 2 hours), shorter concentration time (about 1 hour), and by about 70% higher peak flow values than those generated using the NRCS-UH method. A common feature of both methods were higher values of peak flows for the third level of the catchment moisture, as compared to the second level. It is also worth noticing that in both methods no flood wave was generated for the probabilities of 10, 20 and 50% and for the second level of the catchment moisture. It was assumed that hydrographs made with use Wackermann model better describe flood wave in mountain river, which Słonka is.


2015 ◽  
Vol 29 (15) ◽  
pp. 5765-5782 ◽  
Author(s):  
M. K. Bhuyan ◽  
Sanjay Kumar ◽  
Joygopal Jena ◽  
P. K. Bhunya

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