Bambang Agus Kironoto
Teknik Sipil & Lingkungan, Fakultas Teknik, UGM , Jl Grafika no. 2, Yogyakarta 55281

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Journal : Civil Engineering Forum Teknik Sipil

KAJIAN PENANGANAN SEDIMENTASI DENGAN WADUK PENAMPUNG SEDIMEN PADA BENDUNGAN SERBAGUNA WONOGIRI Sardi, Sardi; Kironoto, Bambang Agus; Jayadi, Rachmad
Civil Engineering Forum Teknik Sipil Vol 18, No 3 (2008): SEPTEMBER 2008
Publisher : Civil Engineering Forum Teknik Sipil

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Abstract

High rate of sedimentation in Wonogiri Multipurpose Dam may cause the dam service period to become shorter than the prior plan. The discharge of Wonogiri Multipurpose Dam is an accumulation of inflow from several main rivers, including Keduang River which is located at the east side of the dam. Keduang River supplies very high sedimentation input to the reservoir. One of the steps studied and to be implemented in the sediment countermeasure was the building of sediment pocket dam in Keduang River mouth before it enters the reservoir. The research was conducted to determine the reservoir sedimentation before and after countermeasure through a mathematical model approach. It was done by doing flow and sediment transport simulation using the NCCHE-GUI Program to calculate deposition in the reservoir. Simulation was carried out in existing condition and the condition after the sediment pocket dam was built, with the assumption that discharge was evenly distributed for each month. This simplification method was applied in wich monthly simulation was done for one hour. Simulation result was then multiplied by the number of hours allocated per month to generate the result for one year period. Simulation result indicates that annually sedimentation reduction or net deposition is 30.41% in average after the treatment by sediment pocket dam. It is also identifed from the simulation result that the reduction is relatively small, since simulation was not performed up to the condition where the pocket dam was already filled up by sediment, in which the flushing process has not been optimally simulated.
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

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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 PENANGANAN BENCANA GEMPA DI BANTUL 27 MEI 2006 Didirianti, Desneri; Kironoto, Bambang Agus; Nurrochmad, Fatchan
Civil Engineering Forum Teknik Sipil Vol 17, No 3 (2007): SEPTEMBER 2007
Publisher : Civil Engineering Forum Teknik Sipil

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Abstract

On May 27 th , 2006 at 05:53, 57, a 5,9 Richter scale earthquake occurred. Bantul Regency in Yogyakarta Province was the most severe area. However, existing institutions had limited capability to perform a proper disaster management they also failed to generate the community to participate, especially during the emergency respose period. Therefore, it is required to have an integrated policy for disaster management to meet related parties expectations and to conduct more optimum disaster management. The objective of this study is to obtain best alternatives in handling disaster using the Decission Support System (DSS) eith Analytical Hierarchy Process (AHP) as the method. Three alternatives were analized formatting special office for disaster management (Alternative 1), formatting community based disaster management (Alternative 2), and ascociating the disaster management between interrelated agencies and the local government as the control center (Alternative 3). These alternative were selected based on fuor criterias management, financial, capacity and policy aspect. This study was taken during, the emergency response period performed by SATLAK PBP Bantul. Input for the analysis was questionnaire result given to 120 respondents composing af 30 respondents from bureaucratic element (SATLAK and SATKORLAK PBP members) and 90 respondents from nine villages in three districts. Numeric values were given to each element of the questionnaire result (criterion, sub criterion and alternative). Then, the values were compared to the established comparison scale obtain the lever of interest. Result of this study showed that each criterion of financial, management policy and capacity aspects weighted 0,273, 0,265, and 0,208 respectively. The best alternative of optimum disaster management was alternative 2. The second anf the third were alternative 1 and alternative 3. The community based organizations objective was to improve the people participation in pertaining, preventive, counter measuring and self healing by actively involve in the planning and executing process of disaster management.
ANALISIS LIMPASAN LANGSUNG DENGAN MODEL DISTRIBUSI DAN KOMPOSIT Harsanto, Puji; Kironoto, Bambang Agus; Triatmodjo, Bambang
Civil Engineering Forum Teknik Sipil Vol 18, No 1 (2008): JANUARI 2008
Publisher : Civil Engineering Forum Teknik Sipil

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Abstract

Hydrological models are classified as lumped and distributed. Lumped models ignore the spatial variability of precipitation, and other related processes. Even though lumped model are unable to account for internal variation of hydrological processes, they have the advantage of simplicity. Distributed hydrological model on the other hand account for spatial variation of hydrological processes and parameters. This type of model has the potential to give more accurate results but computationally more complex. The spatially distributed input and analysis required by spatially distributed model can be met by incorporating a system that can manage data on a grid basis. An approach to handle this problem is using geographic information system (GIS). The overall objective of this study was to comparing of distributed and composite model. The SCS curve number method also known as the hydrologic soil cover complex method, is widely used procedure for runoff estimation. This method includes several important properties of the watershed namely soil’s permeability, landuse and antecedent soil water conditions which are taken into consideration. Daily runoff calculations were generated using the SCS curve number method, its based on the retention parameter, S, initial abstractions, Ia (surface storage, interception, and infiltration prior to runoff), and daily rainfall, Rday. Ratio of initial abstraction (Ia) to retention parameter (S) called λ is changes from time to time. Because of its, the hydrology analysis to estimating direct runoff need calibrate for this parameter. Goodness of fit analysis is used to comparing of both, distributed model and composite model. The average of relatif error, correlation factor, and coefficient of determination, R2 for distributed model respectively are 25.70 %, 0.71 and 0.53, from composite model are 30.15 %, 0.66 and 0.44. The result from research is obtained that the distributed model is more accurate than composite model. The average initial abstraction ratio from distrubted model is 0.35 and composite model is 0.04.
PENGARUH ANGKUTAN SEDIMEN DASAR (BED LOAD) TERHADAP DISTRIBUSI KECEPATAN GESEK ARAH TRANSVERSAL PADA ALIRAN SERAGAM SALURAN TERBUKA Kironoto, Bambang Agus
Civil Engineering Forum Teknik Sipil Vol 17, No 2 (2007): MEI 2007
Publisher : Civil Engineering Forum Teknik Sipil

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Abstract

In sediment transport problems, such as the initial motion of sediment particles, scouring process, degradation process, etc., the information about the wall shear velocity, u*, is often needed. How the wall shear velocity variates in transversal direction, as the function of slopes and discharges, either for flows with and without bed load transport will be studied. The wall shear velocities, u*, are evaluated using the Clauser’s method, which is based on the velocity distribution data, due to the simplicity and the accuracy of the method. Hundred and twenty five velocity distributions data with five different slopes and five different discharges are used to study the wall shear velocity in transversal direction. The results of analysis show that the Clauser’s method still remains valid, and can be used to determine the wall shear velocity in transversal direction, as long as the velocity distributions data n the near wall region still follow the logarithmic velocity distribution. Closer to the wall, the shear velocity becomes to decrease, which is not influenced by the existence of bed load transport, as well as by the variations of slopes and discharges variations.