Istiarto Istiarto
Jurusan Teknik Sipil dan Lingkungan (JTSL , Fakultas Teknik, UGM Yogyakarta

Published : 18 Documents
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SIMULASI NUMERIS TIGA DIMENSI KANTONG LUMPUR BENDUNG SAPON Nindito, Dwi Anung; Istiarto, Istiarto; Kironoto, Bambang Agus
Civil Engineering Forum Teknik Sipil Vol 18, No 1 (2008): JANUARI 2008
Publisher : Civil Engineering Forum Teknik Sipil

#### Abstract

The success factor of a settling basin planning is the trap efficiency. In reality, it is difficult to create a detailed physical model of the sedimentation process. In a more detailed way, sedimentation process phenomena can be formulized by using mathematical equation, for this matter numerical simulation is selected to observe the settling basin performance. A three-dimensional numerical model from SSIIMWin 1.1 is used to carry out this settling basin simulation of the Sapon weir planning. The trap efficiency of the sedimentation process is observed in two different situations: at the time when the settling basin is empty and when it is full. During the empty situation, the velocity and the initial trap efficiency process is measured. When the settling basin is full, inspection is performed to check whether the sedimentation trap process remains effective. The trap efficiency depends on the characteristics of the inflowing sediment (fall velocity of the particle) and the water flow characteristic in the settling basin (flow velocity). Flow velocity simulation is demonstrated using a three-dimensional velocity vectors. Velocity distribution simulation indicates that the value of the horizontal flow velocity component from the upstream to the downstream (augmentation of x/b value) is decreased. The minimum horizontal flow velocity occurs in locations close to the bottom of the bed channel and increasing towards z/h to the surface water. Approaching the wall, the horizontal flow velocity is decreasing and reaches it’s maximum at y/B=0.5. The flow vertical velocity component indicates that approaching the bed channel, the vertical velocity is increasing. The lateral flow velocity component indicates a velocity increase at the horizontal expansion. A three-dimensional vortex occurs on the inlet of the settling basin, due to the vertical expansion. The vortex does not exist in the middle location of the settling basin. Another vortex occurs at the bottom of the channel approaching the downstream of the settling basin. The profile of sediment concentration distribution indicates an increase from the water surface to the bottom (bed channel). The sediment concentration is decreased in quantity to the downstream of the channel. The ratio of the incoming sediment that is deposited (trapped) and inflow the sediment mass entering a settling basin is 69,85 % for the upper 0.06 mm diameter particles. Volume changes of the pond, due to the deposit sediment volume, have lead to a decline in the trap efficiency process. When the volume of the sediments reaches a percentage of 71,84 % of the total pond volume, the settling basin is considered ineffective in performing sedimentation trap process.
STUDI ALTERNATIF PENGENDALIAN BANJIR SUNGAI TONDANO DI KOTA MANADO J.B. Nanlohy, Benjamin; Jayadi, Rachmad; Istiarto, Istiarto
Civil Engineering Forum Teknik Sipil Vol 18, No 1 (2008): JANUARI 2008
Publisher : Civil Engineering Forum Teknik Sipil

#### Abstract

Tondano River, along with its tributary Tikala River, is very potential to cause flood in Manado City. There were three big floods occurred in 1996, 2000 and 2005. In order to mitigate the damage risk due to flood, the controlling effort that can be applied soon in the field is required through short term flood control plan using structural measures. The feasible alternative plans should be evaluated to define the best plan based both on the hydraulics point of view and their effects on the river uses. The study is carried out through the 5 year return period flood routing using the version 3.1 HEC-RAS software. The selected design flood hydrograph is obtained using Nakayasu Synthetic Unit Hydrograph method by elaborating design rainfall derived from partially series rainfall data frequency analysis of Tondano and Tikala watersheds. Flow simulation is conducted in steps by modeling the hydrograph from Tikala River as the lateral inflow. The first simulation is carried out using bank full capacity discharge to define the flood characteristic and the critical sections. The second simulation is carried out for the design flood hydrograph using unsteady flow calculation on each plan to study the hydraulics feasibility. The study conducted herein is elaborated on water surface profile and velocity due to the plans affectivity to carry-off the flood discharge safely as well as the effect on river uses.  Based on the existing condition simulation, result shows two reach critical sections of the right bank and one reach critical section of the left bank Tondano River. The results of flood control simulation indicate that there are no significant differences on velocity among plans, but there are disparities on the capacity to carry off flood discharge safely with no overtopping. For the normalization plan, the overtopping is occurred along the critical section, whereas for both dike plan and combination of dike and normalization plan, no overtopping are occurred but the the critical sections are still existed. Revised plans for dike and combination of dike and normalization are equally effective in carrying off flood discharge securely, but have different effects on water utilization during low flow period. Referring to the study result, the best alternative is the revised dike plan.
UNJUK KERJA ALTERNATIF PENGENDALIAN BANJIR BATANG ANAI DAN BATANG KANDIS SUMATERA BARAT Eriza, Corri; Istiarto, Istiarto; Sujono, Joko
Civil Engineering Forum Teknik Sipil Vol 18, No 2 (2008): MEI 2008
Publisher : Civil Engineering Forum Teknik Sipil

#### Abstract

Flood occurs almost every year due to the floatation of Batang Anai and Batang Kandis. In 2001, the local authority made a plan to control the flood in both rivers, which was implemented in Anai-Kandis River Improvement with the alternatives of controlling flood by handling the river courses, such as improving and widening the river channel, and decreasing the peak of discharges by making dams or retarding basin. Performance of flood control structures are made of three alternatives based on the information gathered. First alternatives suggest for repairing the river course and widening the river channel (with levee) in both rivers and floodway in Batang Kandis. Second alternative is similar with the first alternative except negation the leeve in Batang Anai and replenishment of floodgate in Batang Kandis. Third alternative for Batang Anai is identical to the second alternative and also widening the river channel throughout Batang Kandis. The analysis includes the analysis of sufficiency of channel to drain the design discharge and sediment transport analysis for the alternative with the best performance, which both could be doing with auxiliaries of Software HEC-RAS version 4.0 betas. As the result, controlling river by repairing the river course and widening the river channel throughout Batang Anai and Batang Kandis (3rd alternative) gives the best performance comparing to the others alternatives, due to the fact that it could be able to canalize the design discharge of Q50 (1417 m3/s) in Batang Anai and Q25 (293 m3/s) in Batang Kandis. The simulation of transport sediment in Batang Anai with the 3rd alternatives implementation shows the biggest trend of erosion and deposition in a row, located next to National bridge downstream (RS 108) and precisely in downstream of RS 108 i.e., RS 107.
KAJIAN GENANGAN BANJIR SUNGAI MUKE DI KABUPATEN TIMOR TENGAH SELATAN PROVINSI NUSA TENGGARA TIMUR DAN UPAYA PENGENDALIANYA Nahak, Priska G.; Istiarto, Istiarto; Yulistyanto, Bambang
Civil Engineering Forum Teknik Sipil Vol 18, No 2 (2008): MEI 2008
Publisher : Civil Engineering Forum Teknik Sipil

#### Abstract

Muke River is an ephemeral river located in District of Timor Tengah Selatan, Nusa Tenggara Timur Province. Flood occurs during rainy season inundating farm land and residensial area. Previous work has been done by Petrus G Bay (2007) indicated that flood levee and river normalization, could not purent flood from flowing into river bank around Oebelo and Toineke villages. Present work deals with flood prevention by the use of retention area to reduce peak discharge and/or flood water level. Flood simulation was performed by the aid of HEC-RAS mathematical model. The result of simulation show that the main cause of flood retention is the limited flow capacity of the river. Under existing condition and Q10=575 m3/s, river bank overflows occurs in 83.4% of entire river reach. Three retention areas of 3 x 50 ha are proposed along Muke River. These can reduce the peak flow by 73% and river bank overflow by 69%.
PEMASUKAN UDARA ALAMIAH (SELF AIR ENTRAINMENT) PADA ALIRAN SUPERKRITIK DI SALURAN CURAM Sutopo, Yeri; Wignyosukarto, Budi S.; Yulistyanto, Bambang; Istiarto, Istiarto
Sainteknol : Jurnal Sains dan Teknologi Vol 12, No 1 (2014): June 2014
Publisher : Unnes Journal

#### Abstract

Tujuan penelitian ini adalah: (1) identifikasi lokasi point of inception pemasukan udara alamiah (self air entrainment) pada saluran curam di lokasi developing aerated flow; (2) deskripsi distribusi konsentrasi gelembung udara pada kondisi pemasukan udara alamiah (self air entrainment) di lokasi developing aerated flow. Dua tujuan penelitian dicapai menggunakan metode eksperimen yang dilaksanakan di Laboratorium Hidraulika Jurusan Teknik Sipil dan Lingkungan (JTSL) Fakultas Teknik UGM. Pada penelitian ini digunakan saluran curam yang mempunyai panjang 10 m, lebar 0,2 m, tinggi 0,4 m dengan kemiringan berubah-ubah mulai 15Âº, 20Âº, dan 25Âº, yang menyatu dengan dinding bak air. Debit divariasikan mulai dari 9,4 l/s, 11,5 l/s dan 20,9 l/s. Distribusi konsentrasi gelembung udara hasil eksperimen dibandingkan dengan hasil perhitungan menggunakan persamaan Chanson (1995) serta Straub dan Anderson (1958). Hasil penelitian ini adalah (1) letak point of inception eksperimen untuk Î±=15Â° adalah 4,4 m dari inlet flume; untuk Î±=20Â° adalah 4 m dari inlet flume; dan untuk Î±=25Â° adalah 3,4 m dari inlet flume; (2) profil distribusi konsentrasi gelembung udara di titik 6,2 m di hilir inlet flume dapat dikategorikan sebagai partially aerated flow; dan(3) profil distribusi konsentrasi gelembung udara di titik 7,2 m di hilir inlet flume dapat dikategorikan sebagai fully aerated flow.
EVALUASI KINERJA POLA OPERASI WADUK (POW) WONOGIRI 2014 Anggraheni, Dinia; Jayadi, Rachmad; Istiarto, Istiarto
Jurnal Teknisia Vol. XXII, No. 1, Mei 2017
Publisher : Program Studi Teknik Sipil, Fakultas Teknik Sipil dan Perencanaan, Universitas Islam Indon

#### Abstract

Wonogiri Reservoir is one of the reservoirs in Central Java which is a multifunctional reservoir. The reservoir serves many functions as flood control, irrigation and raw water supply, and hydropower (PLTA). For managing the fulfillment of these functions, Wonogiri Reservoir has a Reservoir Operating Rule to adjust the elevation and release discharge every mid-month. However, There was for the condition of Wonogiri Reservoir in October 2014. The water level of October 30, 2014, was at+126,66 m, while in Reservoir Operating Rule, the water level was supposed to be at +127,63 m. Therefore, the operating rule performance needs to evaluate, especially in 2014. The evaluation step began by conducting a water balance study with the demand for irrigation water and raw water, actual release, and inflow into the reservoir. The next step was optimizing the operating rule of the reservoir by the objective function of maximizing the comparison between release and demand for the fulfillment of irrigation water with 10 years data. The final step was evaluating the Wonogiri Reservoir Operating Rule in 2014 using a new operating rule generated from the optimization process. Based on the results of the study can be concluded that the inflow that occurred in 2014 can fulfill the needs of irrigation water and maintain elevation in accordance with the operating rule in 2014.
DEVELOPMENT OF X-BAND RADAR DATA-BASED SNAKELINE FOR PREDICTING SEDIMENT DISASTER Destania, Henggar Risa; Istiarto, Istiarto; Jayadi, Rachmad
Simposium II UNIID 2017 Vol 2 (2017)
Publisher : Simposium II UNIID 2017

#### Abstract

Sediment-related disaster are terrible disaster that can catastrophically impact to facilities and people must to keep in mind to make sediment-related disaster information that can be predicted from rainfall and response of drainage area by using snakeline. This research produce the important indices on precipitation related to debris and shows current status of the stage of response of drainage area against rainfall by using a couple of short and long term indices. It shows the water storage volume in soil layer with calculation of soil water index (SWI) by using X-band MP (Multi Parameter) rainfall radar data that has been installed at the top of Merapi Mountain (Merapi Museum). The snakeline can be used as monitoring and observation tools of SWI changes in response to rainfall intensity in Boyong river (BO-D5) and works as a database for the next research in identifying criteria for warning. Although there was no record of sediment disaster occurrence, at least from the result of snakeline it was confirmed that from June 2016 â June 2017 with 80.28 mm SWI maximum values has not yet become the maximum limit of SWI value for lahar occurrence in Boyong drainage area (BO-D5).
Flood Hazard Mapping of Bogowonto River in Purworejo Regency, Central Java Pawestri, Margaretha Titi; Sujono, Joko; Istiarto, Istiarto
Journal of the Civil Engineering Forum Vol. 2 No. 3 (September 2016)
Publisher : Department of Civil and Environmental Engineering, Faculty of Engineering, UGM

#### Abstract

The overflowing discharge of Bogowonto River in Purworejo Regency, Central Java flooded the surrounding area during the rainy season. A huge amount of losses such as damage of infrastructures, housing, and agricultural area occurs every year. This research mainly aims to develop flood hazard map and study the characteristics of flood in the study area. There are two main analysis; hydrologic and hydraulic, to model a flood event. Hydrologic and hydraulic modelling of flood based on 20 and 50- years return period hydrograph along the river geometryis done using the latest HEC program namely HEC- HMS 4.1 and HECRAS 5.0. Also, ArcGIS 10.3 is used as a terrain pre-processor and post-processor for hazard mapping. The results of this research are flood hazard maps for 20 and 50 years flood and its comparison to the recent major flood events. Flood inundation modelled covered an area of 993.77 Ha and 1,175.86 Ha, with maximum discharge calculated at Boro Weir as starting point are 1206.2 m3/s and 1,397.3 m3/s for 20 and 50 years flood case, respectively.
Cost Comparison of Drainage Channel Construction Considering Uncertainty of Rainfall Distribution Supraba, Intan; Istiarto, Istiarto; Triatmadja, Radianta
Journal of the Civil Engineering Forum Vol. 5 No. 1 (January 2019)
Publisher : Department of Civil and Environmental Engineering, Faculty of Engineering, UGM

#### Abstract

Rainfall data is the main parameter to design drainage channel. The accuracy of rainfall data determines the accuracy of peak discharge estimation that is used for designing the drainage channel for flood mitigation purpose. The previous study presented that uncertainty of peak discharge is associated with the uncertainty of rainfall distribution and uncertainty of water holding capacity. The main purpose of this study is for understanding the sensitivity of rainfall data by comparing the estimated cost to construct drainage channel based on different values of peak discharges using two different rainfall data set which one rainfall data is created by considering 10% uncertainty of rainfall distribution. This study area is located on Plampang, Sumbawa Besar, West Nusa Tenggara. Results showed that the total cost to construct drainage channel increased by 15% if considering 10% uncertainty of rainfall.
ANALISIS PENERAPAN ACTIVITY BASED COSTING (ABC) DALAM RANGKA PENENTUAN BEBAN POKOK PRODUKSI PADA RAMAYANA BAKERY Putri, Anisa Karunia; Istiarto, Istiarto; Suarta, I Made
Valid Jurnal Ilmiah Vol 15 No 2 (2018)
Publisher : Sekolah Tinggi Ilmu Ekonomi AMM Mataram

#### Abstract

This research is a qualitative descriptive research at Ramayana Bakery. This research has three main objectives. First, it aims to know the calculation of the cost of goods manufactured with the traditional system is used by the company. Second, &nbsp;to know the calculation of cost of goods manufactured with activity based costing method. Third, to know comparison the calculation of cost of goods manufactured by using traditional system and activity based costing method at company. Data collection methods used in this research are interviews, documentation and observation. Objects in this research are costs incurred in baking bread at Ramayana Bakery such as raw material cost, direct labor cost, and factory overhead cost. Cost of goods manufactured with traditional system for roti sisir Rp 2.298,67, roti moka Rp 2.200,29, roti bluder Rp 631,65, roti tawar Rp 4.637,40, roti creamball Rp 2.188,10, roti isian coklat Rp 1.106,94 dan roti isian strawberry Rp 1.106,94. Cost of goods manufactured by activity based costing method for roti sisir Rp 2.062,67, roti moka Rp 2.098,96, roti bluder Rp 700,86, roti tawar Rp 4.283,03, roti creamball Rp 2.065,77, roti isian coklat Rp 1.176,25 and roti isian strawberry Rp 1.176,25 . There is a difference in the results of the calculation of the cost of goods manufactured between traditional systems and activity based costing. This is due to the activity that is chosen as a cost driver in the traditional system is much more used for roti sisir, roti moka, roti tawar, and roti creamball than to roti bluder, roti isian coklat and roti isian strawberry. Roti bluder, roti isian coklat and roti isian strawberry use other activities more dominantly and the activity is not used as a basis in traditional systems. In the end, the cost of goods manufactured for roti sisir, roti moka, roti tawar, and roti creamball become overcost and roti bluder, roti isian coklat and roti isian strawberry also becomes undercost.