Indra Agus
Jurusan Teknik Sipil Politeknik Negeri Padang, Kampus Limau Manis, Padang.

Published : 3 Documents
Articles

Found 3 Documents
Search

Perbandingan Hidrograf Satuan Teoritis Terhadap Hidrograf Satuan Observasi DAS Ciliwung Hulu Agus, Indra; Hadihardaja, Iwan K.
Jurnal Teknik Sipil Vol 18, No 1 (2011)
Publisher : Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (763.331 KB)

Abstract

Abstrak. Banjir dan kekeringan dalam suatu wilayah (DAS) terjadi akibat fenomena iklim yaitu distribuasi curah hujan dengan intensitas tinggi atau periode kemarau yang terjadi lebih panjang. Penyebab banjir berasal dari masukan (hujan) dan sistem DAS. Masukan (hujan) meliputi faktor intensitas hujan, lama hujan dan distribusi hujan. Sedangkan sistem DAS meliputi faktor topografi, jenis tanah, penggunaan lahan dan sistem transfer hujan dalam DAS. Perkiraan debit banjir yang berdasarkan hujan lebat dapat diklasifikasikan dalam tiga cara yaitu, dengan cara rumus empiris, dengan cara statistik (kemungkinan) dan dengan cara hidrograf satuan. Curah hujan dan debit adalah dua hal penting untuk mendapatkan himpunan hidrograf hasil observasi dan teoritis. Curah hujan merupakan nilai yang efektif dan dihitung menggunakan metode indeks. Aliran langsung (limpasan langsung) didapat dari segregasi total limpasan dengan baseflow dan dengan menerapkan metode Straight Line. Ordinat hidrograf hasil observasi dihasilkan dengan membagi ordinat aliran langsung (direct overflow) dengan hujan efektif. Hasil dari satuan hidrograf observasi dibandingkan dengan satuan hidrograf teoritis dan dihitung dengan menggunakan metode Least Square, Forward Subtitution dan Linear Reservoar Cascade. Pebandingan dilakukan terhadap Time base (Tb), Time peaks (Ts), Q peak. Abstract. Flood and dryness in a region watershed was caused by a climate phenomenon, that is high intensity rainfall distribution or longer drought period. Flood is the existence of rainfall input and watershed system. Rainfall covers rain factor of stress intensity, rainfall duration and rain distribution. System watershed covers topography factor, soil type,land use and rain system transfer in watershed. Flooding debit approximation based on torrential rains can be classified in three ways such empiric formula, statistic or probability and unit hydrographer. Rainfall and discharge are important things in getting observed and theoretical hydrographer set. Applying Rainfall is the effective precipitation calculated using index method. Whereas direct overflow (direct  run off) was earned by total run off segregation with base flow applies Straight Line Method. Observed Hydrographer ordinates is created by dividing direct overflow ordinate with effective rain. Observed unit hydrograph result was compared with teoritic unit hydrograph and calculated by using Least Square Method, Forward Subtitution Method and Linear Reservoar Cascade Method. Comparation was done to Time base (Tb), Time peaks (Ts), Q peak.
Analisis Kapasitas Penampang Sungai Batang Mahat Terhadap Besaran Debit Banjir Menggunakan Pendekatan Model Matematik Dalrino, Dalrino; Sadtim, Sadtim; Hartati, Hartati; Agus, Indra
Jurnal Ilmiah Rekayasa Sipil Vol 15 No 2 (2018): Edisi Oktober 2018
Publisher : Politeknik Negeri Padang

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (772.907 KB) | DOI: 10.30630/jirs.15.2.124

Abstract

Batang Mahat watershed has a total area of 772.87 km2 with a total length of the main rivers around 44.06 km. With the topographic condition on the upstream side was a mountainous terrain and steep slope relatively into downstream. The problem was can be classified as river siltation, narrowing of the river, and riverbank erosion that has caused flood and threaten a public facilities. Numerical simulations using the application of the HEC RAS model were conducted to determine the capability of the river storage capacity into various discharge values. The results of the analysis show that with the discharge condition Q2 there has been flood caused by the high surface elevation of water that was overtopping of the left and right embankments elevation at the upstream and midstream areas. The water surface elevation will increase with the increasing of flood discharge. River normalization efforts with additional depth and widening of river channel were recommended.
SCOUR DEPTH ESTIMATION ON ABUTMENT WITH HEC RAS AND SOME EMPIRICAL EQUATION Agus, Indra; Alwys, Munafri; Wisafri, Wisafri; Dalrino, Dalrino; Yolanda, Noftar; yani, Welfi
Jurnal Ilmiah Rekayasa Sipil Vol 17 No 1 (2020): Edisi April 2020
Publisher : Politeknik Negeri Padang

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1005.876 KB) | DOI: 10.30630/jirs.17.1.271

Abstract

Toe Scour around abutment will be very dangerous and cause loss of stability on the bridge. The case of structure failure on Batang Kalu bridge in Korong Pasa Usang Nagari Kayu Tanam, Padang Pariaman Regency on Monday (10 December 2018) is a clear example of toe scouring. A case study of toe scour was on the Batang Kalu River bridge structure has been carried out. Rainfall data closest to the study location, Kandang Empat Station was used to minimize the errors in the calculation of flood discharge design. Numerical modeling with HEC RAS and scouring estimation with some empiric equation was conducted to predicting scour depth on abutment. Simulation results show scour depth results to an average of 2.731 m and close to the scour depth that occurred in the field (2.83 m). Results showed that the local scouring in the Batang Kalu River bridge structure can be suspected as the influence of the increasing river steepness. Discharge that is triggered by heavy rain with a long duration and increased river flow velocity due to steepness has the potential to create a very intense scouring. Increasing of steepness may have been caused by sand mining activities in the upper reaches. Further studies are needed to see the potential slope changes due to exploitation in the Batang Kalu River upper reaches