Penelusuran Hidraulik Waduk Retensi Dalam Kesesuaiannya Dengan Peraturan Pemerintah( Hydraulic Routing of Dumping Reservoir and its Relation to Apropriate Goverment Regulation)

River is a natural stream where its presence may give benefit either loss to human life, depending upon the way how this river is managed. The negative impacts of the river may become very complex when the development activities are such a way that its influence to the hydraulic performance of the mentioned rivers is considerably large. This paper deals with the research of hydraulic routing model of damping reservoir which is mainly aimed to obtain a sufficient degree of flood retention. The development of FRSPILL1 as the first release computer program becomes FRSP1LL4 is a valuable output of the research, since such program may be utilized to rout the hydraulic performance of the reservoir provided with not only spillway facility, but also the bottom out let facility. The environmental condition which is mainly dominated by heavy population of houses in the inundation in accordance with the government regulation, called Peraturan Pemerintah No. 63 Taltun 1993, is also taken into account in the determination of optimum elevation of spillway crest. The results of the hydraulic routing of Kali Pesanggrahan damping reservoir shows that optimum capacity of the routing is obtained at damping efficiency of 24% and 20 Ha inundation as a result of the government regulation implementation in the form of 50 m right of way of the river. The above values also indicate the optimum hydraulic size of the damping reservoir (i.e., the width and crest elevation of the spillway), to suit the environmental situation of the surrounding area, by means of its least negative impact

Kelayakan hidro-ekonomi pembangunan waduk limo (Hydro-Economy Feasibility of Limo Dam)

The feasibility evaluation of the dam development often meets a complex situation due to the difficulty in determining the benefit. At one side, sufficient number of water availability may have a very considerable strength that the dam is sufficiently reasonable to be developed. At the other side, increasing the reservoir volume might require additional consideration on either technical or non-technical condition. Obviously, the current situation has made the tendency of requiring more consideration on any attempt of the water resources development such as dam development. This paper evaluates the hydro-economy feasibility of the Limo Dam development. Firstly, the water availability is evaluated through the hydrology approach, routing of two types inflow, i.e., high flow and low flow are carried out by the utilization of Muskingum method. Three types of outflow are introduced throughout the routing, i.e., outflow through the spillway crest, outlet system, and direct pumping. Secondly, the economic evaluation is carried out by initially studying the bill of quantity and the unit cost, followed by estimating the cost of dam construction. The total cost of dam construction includes what so called environment cost, i.e. all costs related to land acquisition and resettlement of people from the inundation area. Finally, the economic evaluation is carried out by analyzing the possible benefit that might be withdrawn from the presence of the Limo Dam, and the feasibility parameters are then presented. The results show that the estimate total cost of Limo Dam construction is about Rp. 45,061,476,498.00, this includes the land acquisition and people resettlement. The presence of Limo Dam is anticipated to control flood of Jakarta (with 3-10% damping retention), to produce 2.96 MCM water for DMI purposes of Depok District, and to produce 7.78 MCM water for town flushing of some places downstream of Limo Dam. Assuming the US. currency is remain stable at Rp. 9,000.00 along 30 years, the Benefit Cost Ratio (BCR) is 1.15, the Net Present Value (NPV) is Rp. 7,460,162,552.00, at beginning 2003, and the Financial Internal Rate of Return (FIRR) of 13.63%. Keywords: Hydraulics, economy, feasibility, Limo Dam

Laboratory Study on Comparison of the Scour Depth and Scour Length of Groundsill with the Opening and Groundsill without the Opening

River bed control structure what so called groundsill or bottom sill is built for controlling a river bed to remain stable against degradation. Unlike other river obstacles, the presence of groundsill might cause sediment retention upstream of the structure; hence it reduces the supply of sediment to the downstream part of the river. At some extent, the above situation might create unexpected negative impact, not only cease the sediment migration but also disable fish migration, as well as the utilization of river for navigation. This paper presents the hydraulic investigation on various models of groundsill, i.e. groundsill without the opening and groundsill with a certain type of the opening. Series of laboratory experiments were conducted on an open channel flow of 0.75m width and longitudinal slope of 0.05%. There were two types of groundsill, i.e. groundsill without the opening with 0.75m width and 0.05m height, and groundsill with the opening of 0.39m width and 0.005m height of crest at the opening and 0.05m at the wings. Various flow rates were then introduced, necessary data were taken, and the hydraulic phenomena were studied. The results showed that groundsill without the opening produced non-dimensional (relative to the channel width) scour depth of 0.036, and scour length of 0.253. Groundsill with the opening produced scour depth of 0.013 and 0.024 near the downstream end of the wing section and the opening respectively. The scour length of the groundsill with the opening is 0.080 and 0.293 near the downstream end of the wing section and the opening section respectively. Moreover, it can be noted that the presence of the scour depth and scour length of the groundsill with the opening was generally much smaller rather than that of groundsill without the opening. The above results give the evidence that groundsill with the opening is much friendlier and also more suitable for the environment needs.Keywords: control structure, environmentally sound, groundsill, hydraulic phenomeno

Kriteria Terjadinya Aliran Debris k. Ngobo, g. Kelud.

Angkutan material sungai gunung berapi yang dipandang besar daya perusaknya adalah angkutan material berupa aliran debris. Tahap awal untuk menganalisa aliran debris dimulai dengan mencari kriteria kapan terjadinya aliran tersebut. Suatu metoda yang dikemukakan oleh Takahashi digunakan untuk menetapkan kriteria terjadinya aliran debris pada K. Ngobo, G. Kelud

Hydraulic Simulation of Spillway Routing of Lake Beratan, Bali

Lake Beratan is situated in Bali Islan of Indonesia. The lake is mainly functioned as aplace of interest or a recreation aea, and secondly funtioned as to provide the surrounding people from their daily water need. the culture of the island has made the lake Beratan has some frequent activities such as ritual ceremony of Hindu religion. The paper deals with the hydraulic simulation of the water surface elevation of Lake Beratan, to optimize the need of protecting the ritual ceremony as well as to conserve the water in Lake Beratan. Result of sumulatin shows that by the width of the spillway of 30.000 m and spillway crest elevation of 1235.00 m, gives the maximum inundation at the temples yard of 0.30 m, with the periode of inundation of 0 - 109 day in a year. At the mentioned situation, the averagr volume of the lake water veing spliied is about 8.639 million m3

EFFECTIVE SEDIMENT CONTROL IN A RESERVOIR

Sedimentation in a reservoir cannot be avoided. The average rate of sedimentation on the storage volume reduction of a reservoir in the world is about 1 % per year (Yoon,1992), meanwhile, the storage volume reduction in several reservoir in Indonesia reaches 1,64% to 2,83% per year (Atmojo,2012). These sediment’s accumulations in the reservoir will continually reduce the storage volume, thus the intended functions of reservoirs for flood control (Atmojo, 2013), irrigation and water supply, electric generation, etc. will also reduced and not optimal. Some of sediment control measures have been practiced in reducing sediment accumulation in reservoirs around the world. In principle, there are two approaches i.e., reduce the sediment input to a reservoir by land conservation, construction of check dam, sand pocket, diversion channel, etc. and reduce the sedimentation in the reservoir by sluicing, turbidity current, dredging, and flushing (Morris and Fan, 1998; Emamgholizadeh et al., 2006). This paper presents the performance of sediment’s reduction from a reservoir by flushing, sluicing, and disturbing flushing based on some laboratories results (Atmojo,2012). It is expected that this paper can contribute to elicits some finding on the selection of which suitable method for sediment reduction from a reservoir

Persamaan-Persamaan Rancang Bangun untuk Sungai dengan Dasar Kerikil yang Bergerak.

Kata kunci: Rancang Bangun Untuk Sungai

Decision Support System Mitigasi Bencana Banjir(Decision Support System For The Mitigation Of Flood Disaster)

Flood is the presence of exessive water where at a certain level creates considerable negative impact. The characteristic of flood is uncertain, either in the magnitude, the time of occurrence, as well as the duration of the occurrence. The uncertainty of the flood occurrence might cause difficulties in anticipatiny its counter measure, at some level of countermeasure, this might contribute impression like to much expenditure, but in the other hand, this might be too careless. Mitigation itself means decreasing, there fore, in flood disaster countermeasure means that negative impact is impossible to be eliminated totally. A method is therefore should be⢠established of how to make best choice of action in the respect of flood disaster mitigation. ⢠This paper deals with the establishment of Decision Support System (DSS), especially to support the flood disaster mitigation program. Some methods of the development of DSS model are briefly introducedwith the method of Analytical Hierarchy Process disaster mitigation is presented as the main target of this paper. The approach of model establishment is made into two separate cases, i.e., for the make use of the short term (operational) and that for the make use of the long term (planning). The results show that the flood disaster mitigation by the make use of the DSS model might guide to the considerably flood selection (if not the best). The best selection of short term mitigation produces the relative mark of 0.360, comprises the action of logistic supply 50%, evacuation 20%, and diking 50%. The best selection of long-term mitigation has the relative mark of 0.67, comprises the action of conservation program 30%, land use improvement 20%, and operation-maintenance program 50%. The presence of DSS for flood disaster mitigation is indeed necessary and continuous improvement of the DSS (i.e., application evaluation â upgrade) should be carried out. Keywords: Flood, mitigation, natural disaste

MODEL TANGKI UNTUK PREDIKSI DEBIT SEDIMEN PADA DAERAH ALIRAN SUNGAI

Uncontrolled erosion and sedimentation will cause to substantial losses, either in the form of declining productivity of land as well as hydro structure damage and the occurrence of sediment in reservoirs. This is because the availability of sediment discharge data is quite limited, a number of models for the prediction of surface erosion and sediment discharge have been widely developed. The application of the model requires the availability of input data is sufficient, diverse and extensive, both for calibration and verification. The process of soil surface erosion and sediment discharges in watersheds affected by rain and surface runoff can be represented in the type of storage. In this it conducted the approach uses Tank Model. The objective is to develop tank model for prediction of sediment discharge a Watershed. The steps are setting experimentation field for data acquisition as input data model, and setting model analysis by making the structure and formulation of the tank model. There are four proposed tank models: Tank Model 1 (three tank 1, series and cascade), Tank Model 2 (two cascade tanks), Tank Model 3 (three cascade tanks), and Tank Model 4 (one tank) model, with the input data model includes hypothetical data, observation data (Kreo sub watershed), and other watershed data (Lesti River sub Watershed of East Java, Hirudani sub Watershed of Japan). The parameters of the model are determined by using the Genetic Algorithm method optimization approach program in MatLab. The results of the analysis show that 4 tank models can be developed for the prediction of sediment discharge in the Watershed. A good tank model configuration for the prediction of sediment discharge in a watershed is Tank 4 Model, the model composed of 1 (one) tank consists of 2 (two) side holes, and 1 (one) bottom hole, applied in Kreo sub Watershed, Lesti River Sub watershed of East Java, Hirudani sub Watershed of Japan. This is based on the value criterion precision models in Kreo sub Watershed, the value of R between 0.77 - 0.88, the value of VE between 8.32 - 24.60%, the value of RE between 315.54 - 485.64%, the value of RMSE between 358 , 11 - 501.77, in Lesti River sub Watershed of East Java, the value of R = 0.8, the value of VE = 4.40%, the value of RE = 94.10%, and the value of RMSE = 1222.64, then in Hirudani sub Watershed of Japan, the value of R = 0.9, the value of VE = 11.48%, the value of RE = 68.33%, and the value of RMSE = 5.08. But the values of the parameters in the Watershed have different values according to the conditions of the Watershed observed. And the result of this analysis there is still the range of difference between simulated and measured sediment discharge value of varying magnitude, it is possible cause is the pattern of rain dispersion in the hydrological process, synchronization of measurement process and length of data and possible assumption of model parameters . Keywords: sediment discharge, runoff, rainfall, tank mode

EVACUATION ROUTE MAPPING AGAINST SLAMET VOLCANO DISASTER AT GUNUNGSARI VILLAGE, PULOSARI SUB DISTRICT, PEMALANG DISTRICT

oai:jurnal.ugm.ac.id:article/18896Villages inside the hazard zone of Slamet Volcano should have an evacuation map, as an anticipation and guidance to guide people evacuate when volcanic activity on the area arise to dangerous level. The experience which occurred at 2009 and 2010 indicate the necessity of the development of evacuation map for 7 villages inside the hazard zone in the Pemalang residential district, such as village of Gunung Sari. The main purpose of the developing an evacuation map is to make the village of Gunung sari becoming more vigilant to anticipate the danger of Slamet Mount eruption. Qualitative methods were used in this study, by handing out preliminary questionnaire to investigate the characteristic of the residents. The development of evacuation map also relies on the participation of the residents, then the resulted map were evaluated by assessing how far people can understand and comprehend any information provided on the map. The result of the investigation shows that Gunungsari’s resident wants an evacuation map, shown by high enthusiasm on the questions of the necessity of an evacuation map and disaster preparedness team that is equal to 97% of the residents on Dusun Sipendil, 83% on dusun Sibedil, 67% on Dusun Silegok, and 63% on Dusun Krajan. The residents also understand and comprehend the information provided on the map nicely, especially about the timing and rendezvous location for the evacuation. It is indicated by high proportion of residents that answer the questions asked accurately, which is 100% on Dusun Sipendil, 97% on Dusun Sibedil, and 80% for both Dusun Silegok and Dusun Krajan.Keywords: disaster prone area, evacuation map, society characteristi