Adam Pamudji Rahardjo, Adam Pamudji
Departemen Teknik Sipil dan Lingkungan, Fakultas Teknik, Universitas Gadjah Mada, Yogyakarta.

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ANALISIS TRANSPOR SEDIMEN SERTA PENGARUH AKTIVITAS PENAMBANGAN PADA SUNGAI SOMBE, KOTA PALU, SULAWESI TENGAH Pratama, Muhammad Iqbal; Legono, Djoko; Rahardjo, Adam Pamudji
Jurnal Teknik Pengairan Vol 10, No 2 (2019)
Publisher : Jurusan Teknik Pengairan, Fakultas Teknik, Universitas Brawijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.21776/ub.pengairan.2019.010.02.02

Abstract

Sedimentation problems occuring in Sombe River is a phenomenon of sediment grainsor particles entrained from the riverbank avalanche. The problem is exacerbated when there is moderate to high intensity rainfall, causing sediment material transported by a flood. Moreover, sand mining activities also affect the changes in the riverbed. The research aims to identify and estimate the quantity of sediment transport and the effect of the mining activities on the riverbed changes in Sombe River. In this research, direct measurement in Sombe river and observation of the mining activities in Sombe River are conducted to collect sediment samples and river morphology data. Thenceforth, the collected data will be analyzed using Rottner and Van Rijn method. According to the result of the calculation, the average of sediment discharge in Sombe River with a return period of 1 year, 2 years, 5 years and 10 years are Rottner method is 2.1 x 10 7 - 3.8 x 10 7 Tons/year; Van Rijn method is 4.0 x 10 7 ? 6.9 x 10 7 Tons/years.
Hydrology and Hydraulic Analysis of Nasiri Flash Flood Disaster Event on the 1st August 2012 Hidayatulloh, Imam Syarif; Rahardjo, Adam Pamudji; Kironoto, Bambang Agus
Journal of the Civil Engineering Forum Vol. 4 No. 1 (January 2018)
Publisher : Department of Civil and Environmental Engineering, Faculty of Engineering, UGM

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22146/jcef.28301

Abstract

Nasiri lays in the Luhu village, Huamual district, West Seram Regency, Maluku province. Nasiri experienced in flash flood on August 1st, 2012 which had never happened before. There was no rainfall station and water level recorder at that time. It is rather difficult to find out the cause and yet Nasiri River was only 8 meters wide. The research started with identifying base flow, soil characteristics, learning flood video record, routing the river reach, finding the nearest rainfall station, and also interviewing some peoples there. Field data area was complemented with satellite radars. AutoCAD 2007, IFAS 2.0.1.2, Geostudio 2004, ArcGIS 10.2, HEC-HMS 4.2.1, and HEC-RAS 5.0.3 were used to perform simulations of the natural river with and without precipitation calibration, and also with and without landslide dam in the river. HEC-RAS was subject to perform 2 (two) dimensional flood routing. The result was fairly satisfying. Nasiri watershed was experiencing in flash flood caused by 2 (two) landslide dams which collapsed in 2 (two) different times. The first landslide dam was 7.55 meters high which collapsed at 09:52 (UTC+9) with 83.58 m3/s of peak discharge. The second landslide dam was 8.91 meters high which collapsed at 14:24 (UTC+9) with 54.16 m3/s of peak discharge
Warning Time Analysis of Nasiri River Flash Flood due to Several Possible Natural Dam Break Events Styawan, Andry Putra; Rahardjo, Adam Pamudji; Sujono, Joko
Journal of the Civil Engineering Forum Vol. 4 No. 1 (January 2018)
Publisher : Department of Civil and Environmental Engineering, Faculty of Engineering, UGM

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (756.479 KB) | DOI: 10.22146/jcef.27241

Abstract

Flash flood disasters caused by natural dam break have already occurred several times in Indonesia which contributes so much life loss and material damage. This research was aimed to study threat level on flash food disasters on the possibility of the locations where the natural dam was formed by the landslide on the river cliffs at the watershed. The flash flood in Nasiri River on August 1st, 2012 would be used for the model in this research. Therefore, hydrology and hydraulic simulations would be conducted on the process of natural dam break at specified altitudes which were predicted to occur in five locations along the Nasiri River. Several big rain event data sets that could occur on specified years from the previous studies would be used to obtain rain event with the hydrological model. Natural dam break was modeled with HEC-HMS 4.1. The hydraulic simulation used the dynamic flow model in the HEC-RAS 5.3 software. The natural dam collapse would be approached by considering the event that has existed around the study location, and also the local geological condition. The result showed that for all the natural dam break scenarios, it could be concluded that the storage filling time was in the time range of 2 hours 26 minutes up to 5 minutes. The flood travel time was ranged from 27 minutes to 2 minutes. The available warning time was quite short, which was less than 3 hours; therefore the need of early warning system’s facilities and infrastructure are absolutely necessary as one of mitigation effort for flash flood disaster in Nasiri Village.
Unit Hydrograph Modeling using Geomorphological Instantaneous Unit Hydrograph (GIUH) Method Sulistyowati, Anantri; Jayadi, Rachmad; Rahardjo, Adam Pamudji
Journal of the Civil Engineering Forum Vol. 4 No. 3 (September 2018)
Publisher : Department of Civil and Environmental Engineering, Faculty of Engineering, UGM

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (733.505 KB) | DOI: 10.22146/jcef.38860

Abstract

Flood forecasting at Wonogiri Reservoir is restricted on the availability of hydrologic data due to limited monitoring gauges. This issue triggers study of unit hydrograph modeling using Geomorphological Instantaneous Unit Hydrograph (GIUH) which is based on Geographic Information System (GIS). Analysis of physical watershed parameters was conducted on Digital Elevation Model (DEM) data using software Watershed Modeling System (WMS) 10.1 and ArcGIS. Nash model and S-curve method were used to process triangular GIUH into hourly Instantaneous Unit Hydrograph (IUH) and Unit Hydrograph (UH) and then was compared with the observed UH of Collins method. A sensitivity analysis was conducted on parameter of RL and Nash-model k. Evaluation of accuracy of the simulated GIUH runoff hydrograph was also conducted. The GIUH model generated UH with smaller peak discharge Qp, also slower and longer of tp and tb values than the observed UH. Accuracy test of the simulated GIUH runoff hydrograph using Nash-Sutcliffe Efficiency (NSE) shows that Keduang watershed gives a satisfying result, while Wiroko watershed gives less satisfactory result. The inaccuracies occur due to limited flood events used to derive the observed UH and stream tributaries that were not properly modeled based on Strahler method.
The Implementation of Combined Roughness and Reflected Model (CRRM) in Tsunami Run-up Simulation through Coastal Vegetation Benazir, Benazir; Triatmadja, Radianta; Rahardjo, Adam Pamudji; Yuwono, Nur
Journal of the Civil Engineering Forum Vol. 4 No. 3 (September 2018)
Publisher : Department of Civil and Environmental Engineering, Faculty of Engineering, UGM

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (963.746 KB) | DOI: 10.22146/jcef.36857

Abstract

Hydraulics resistance is commonly used to simulate or replace drag and inertia forces due to vegetation when modeling tsunami run-up. A new numerical method was proposed which was named Combined Roughness and Reflected Model (CRRM). This method accommodates the reflection process of tsunami flow by tree surfaces. A series of experimental work was performed in laboratory to verify the numerical results. The physical process of laboratory work was discussed to explain the interaction between tsunami and vegetation models. The relation of some notable parameters was reviewed for both models. The physical model verified that the deviations between the physical and the numerical model were below 20%. With such numerical method, more challenging forest layout such as zigzag arrangement can be studied more accurately. It is concluded that the zigzag arrangement of trees layout and higher density of trees were capable of reducing tsunami run-up on land significantly. 
EVALUASI DATA HUJAN SATELIT UNTUK PREDIKSI DATA HUJAN PENGAMATAN MENGGUNAKAN CROSS CORRELATION Pratiwi, Destiana Wahyu; Sujono, Joko; Rahardjo, Adam Pamudji
Prosiding Semnastek PROSIDING SEMNASTEK 2017
Publisher : Universitas Muhammadiyah Jakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar

Abstract

Setiap analisis hidrologi membutuhkan data hujan. Permasalahannya, pada beberapa daerah tidak tersedia data hujan yang mencukupi untuk kebutuhan analisis, baik data hujan harian harian dengan periode panjang ataupun data hujan jam-jaman dengan periode tertentu.  Penginderaan jarak jauh dengan satelit mampu mengatasi permasalahan ketersediaan data hujan tersebut. Data hujan pengamatan berupa besarnya  hujan titik yang terjadi di lapangan, sedangkan data hujan satelit TRMM 3B42, TRMM 3B42RT, GPM dan PERSIANN CCS berupa besarnya hujan di atmosfer dengan resolusi spasial tertentu. Butiran hujan dari atmosfer membutuhkan waktu tertentu untuk jatuh ke bumi. Oleh karena itu, perlu evaluasi apakah data hujan satelit dapat memprediksi data hujan yang terjadi di lapangan. Evaluasi dilakukan dengan mencari time lag (d) antara penginderaan hujan oleh satelit dengan hujan yang terjadi di lapangan menggunakan cross correlation. Penelitian menunjukkan bahwa, prediksi data hujan pengamatan dapat memperoleh hasil yang baik jika menggunakan satelit TRMM 3B42 (d=0) dengan nilai r, BIAS, MBE, RMSE dan NRMSE  sebesar 0.88, 19.99%, 33.91, 82.94 dan 0.034 untuk periode tahunan; satelit GPM (d=0) dengan nilai r, BIAS, MBE, RMSE dan NRMSE sebesar  0.92, -1.64%, -2.88, 57.01 dan 0.010 untuk periode bulanan; satelit GPM (d= +1) dengan nilai r, BIAS, MBE, RMSE dan NRMSE sebesar 0.66, 0.66%, 0.04, 9.38 dan 0.034 untuk periode harian.
Snake Line Performance Applying Single Pixel X-Band MP Radar Data (Case of Mt. Merapi Area, Indonesia) Hairani, Ani; Rahardjo, Adam Pamudji; Legono, Djoko; Istiarto, Istiarto
Journal of the Civil Engineering Forum Vol. 5 No. 3 (September 2019)
Publisher : Department of Civil and Environmental Engineering, Faculty of Engineering, UGM

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (2429.136 KB) | DOI: 10.22146/jcef.44781

Abstract

The short-duration-rainfall monitoring techniques have become important recently due to the high demand for disaster risk miti­gation. Such techniques produce important information on the rainfall intensity during heavy rainfall in the form of snake line. At the same time, use of X-Band Multi-Parameter Radar (XMP Radar) in rainfall monitoring has increased significantly be­cause of its capacity to cover wide area. An assessment on the snake line performance that was developed based on XMP Radar and ground rainfall monitoring instrument (i.e. Automatic Rainfall Recorder or ARR) has been applied to Mt. Merapi area, Java, Indonesia. Selected rainfall data of November-December 2018 were examined. The assessment used a single pixel of radar data at the location of the ARR. The result shows that rainfall data obtained from XMP Radar are lower than those from ARR. The computed snake line obtained from XMP Radar differs from that from ARR data. The XMP Radar underestimates the warning level by about two level out of four.
POTENSI WILAYAH TERDAMPAK KERUNTUHAN BENDUNGAN MATENGGENG DI SUNGAI CIJOLANG Utomo, Bagus Prio; Rahardjo, Adam Pamudji; Legono, Djoko
Jurnal Geografi Lingkungan Tropik Vol 3, No 1 (2019): February
Publisher : Open Journal System

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1229.363 KB) | DOI: 10.7454/jglitrop.v3i1.66

Abstract

Abstrak. Bendungan Matenggeng yang rencana akan dibangun di Sungai Cijolang merupakan bendungan multifungsi yang memiliki banyak manfaat bagi masyarakat diantaranya untuk mengairi lahan irigasi, air baku, pengendalian banjir, pembangkit tenaga listrik, dan pariwisata. Selain memiliki banyak manfaat, pembangunan bendungan juga menyimpan potensi bahaya yang sangat tinggi. Salah satu potensi bahaya yang dapat terjadi adalah keruntuhan bendungan yang diakibatkan adanya rekahan karena limpasan air pada puncak bendungan (overtopping) ataupun rekahan karena adanya rembesan di tubuh bendung (piping). Keruntuhan Bendungan akan menimbulkan banjir bandang yang sangat besar sehingga dapat menyebabkan timbulnya korban jiwa dan kerusakan harta benda. Dengan menggunakan program HEC-RAS 5.0.3, didapatkan hasil bahwa pada skenario keruntuhan overtopping, dimensi pelimpah Bendungan Matenggeng masih mampu untuk melewatkan debit maksimum (QPMF) sebesar 9.067 m3/s sehingga air tidak sampai melimpas ke puncak bendungan. Pada skenario keruntuhan piping, diperkirakan luas genangan mencapai 17.568 ha yang akan menggenangi 92 desa, 416 km jalan, dan 169 fasilitas umum.  Lebih dari separuh luas wilayah yang tergenang masuk kategori bahaya banjir tinggi hingga ekstrim dengan lahan sawah merupakan wilayah yang paling banyak masuk dalam kategori tersebut. Kata kunci: genangan, kategori bahaya banjir, bendungan.