ESTIMASI SEDIMENTASI WADUK BERDASARKAN EROSI LAHAN Studi Kasus Bendungan Batujai

Batujai Reservoir is located in Central Lombok Regency. It is used to supply the demand for irrigation water and power generation. The development of the upstream area of the reservoir causes a high rate of soil erosion, which in turn triggers the problem of silting up the Batujai reservoir due to the high rate of sedimentation. This study intends to determine the contribution of soil erosion to sedimentation that occurs in the Batujai Reservoir and the direction of land rehabilitation for conservation following the conditions of the Batujai Reservoir watershed so that it can provide useful information for dam preservation. Soil erosion was calculated using the USLE method, so secondary data according to USLE parameters were needed, such as rain data, land use data, soil type data, and topographic data. The amount of sedimentation in the reservoir is calculated based on the bathymetry map of the bottom of the reservoir as measured by the echo-sounding technique. The sedimentation rate in this reservoir is based on the last measurements in 2017. The results showed that the contribution of soil erosion upstream of the Batujai reservoir was 109.974,078 tons/ha/year. With the Trap Efficiency sediment value of 0.094 %, the sediment that entered the Batujai reservoir for 35 years was 1,200,000 m3. From the results of the analysis, it is estimated that the useful life of the Batujai Dam is around 5 years and 10 months, namely in 2021 in June

Analisis Ekonomi Pengendalian Sedimentasi Waduk Mrica

Waduk Mrica sudah mengalami sedimentasi sebanyak 122,073 juta m3. Laju sedimentasi yang terjadi sebesar 4,069 juta m3/tahun dan diperkirakan tidak dapat mencapai umur rencana waduk 50 tahun. Tujuan penelitian ini adalah untuk menganalisa operasi dan pemeliharaan di Waduk Mrica, menentukan alternatif pengendalian sedimentasi, dan menentukan alternatif yang paling ekonomis. Upaya pengendalian yang selama ini dilaksanakan adalah flushing, dredging, dan pembangunan sabo dam. Simulasi operasi dengan beberapa skenario alternatif pengendalian sedimentasi digunakan untuk mengetahui nilai manfaat dari produksi listrik. Analisis ekonomi dilakukan dengan metode BCR dan NPV, kenaikan TDL 5% dan 10%. Pengendalian sedimentasi yang paling ekonomis adalah flushing dengan harga Rp. 3.747,15/ m3. Analisis ekonomi mendapatkan hasil bahwa BCR terbesar diperoleh pengendalian sedimentasi flushing ketika turbin beroperasi memaksimalkan potensi inflow dengan kenaikan TDL 10% yaitu sebesar 17,44 dan NPV terbesar diperoleh pengendalian sedimentasi pembangunan sabo dam ketika turbin beroperasi memaksimalkan potensi inflow dengan kenaikan TDL 10% sebesar Rp. 4.908.510.910.000,00

Implementasi Etika Profesi dan K3L Pada Kegiatan Operasi dan Pemeliharaan Bendungan Jatibarang

[Title: Implementation of Professional Ethics and HSE in Jatibarang Dam Operation and Maintenance Activities] Implementation of Dam Operation and Maintenance (OP) is very important to maintain dam safety and the sustainability of dam function. Operation and maintenance must be carried out in accordance with established procedures and a well-structured OP implementation program according to conditions of dam  and climate change. Dam Operation and Maintenance activities involve a lot of Engineering practice and need to pay attention to Health, and Environment (HSE). This study aims to determine the implementation of Professional Ethics and HSE in the operation and maintenance of the Jatibarang Dam. This research begins with conducting literature review and collecting secondary data. The collected data is then processed and the results are discussed and concluded. The operation and maintenance of the Jatibarang Dam includes operations, maintenance and monitoring activities, which must be planned and then held and reports its implementation. Dam operation is carried out by adjusting the water output of the reservoir. Dam maintenance is done to prevent damage or repair damage. While dam monitoring is carried out to find out symptoms of problems with the dam at an early stage. The implementation of professional ethics is manifested by managers in the form of responsibility, honesty, obedience, competence, teamwork and sustainable utilization. HSE has been implemented but managers have not fully implemented HSE Management System. HSE risk management which includes hazard identification, risk assessment and risk control has just been implemented for the dam safety. For The supporting work activities have not been carried out

Prediksi Pola Distribusi Sedimentasi Waduk Sepaku Semoi

Proses sedimentasi waduk yang diakibatkan erosi lahan Daerah Tangkapan Air (DTA) waduk maupun longsoran tebing di sekeliling area genangan merupakan permasalahan utama waduk karena dapat menganggu pengoperasian waduk dan mengurangi usia rencana waduk. Pembangunan Bendungan Sepaku Semoi di Kabupaten Penajam Paser Utara menghasilkan efek tampungan normal waduk dengan volume 10,06 juta m3 yang direncanakan sebagai sumber air baku untuk memenuhi kebutuhan Kota Balikpapan dan Kabupaten Penajam Paser Utara serta pengendalian banjir di DAS Sepaku. Waduk Sepaku Semoi yang direncanakan memiliki usia guna 50 tahun dengan tampungan mati 1,06 juta m3 tentu tidak terlepas dari permasalahan sedimentasi, sehingga diperlukan analisis untuk memprediksi besarnya volume sedimen menggunakan pendekatan erosi dan pola distribusi sedimen di seluruh permukaan waduk menggunakan metode empiris pengurangan luas (empirical area reduction method) dalam periode 50 tahun. Berdasarkan hasil analisis, selama periode 50 tahun diperoleh volume total sedimen yang masuk waduk adalah 7,69 juta m3, elevasi nol baru pada +15,78 m dengan kapasitas tampungan normal berkurang menjadi 3,77 juta m3. Hal ini mengindikasikan pengurangan volume yang signifikan sampai akhir usia guna waduk sehingga penanganan permasalahan sedimentasi di Waduk Sepaku Semoi perlu menjadi perhatian

Spatial Analysis of Erosion Danger Level at Rambut Watershed Area Tegal District

Erosion is a series of sedimentation processes associated with weathering, releasing, transporting, and settling grains of earth or earth's crust. As a watershed, watersheds are very vulnerable to erosion and sedimentation problems. This research was aimed to predict the erosion danger level at Rambut Watershed Area based on the Universal Soil Loss Equation Formula, by applying a Geographical Information System analysis. Based on the formula, we used four types of maps, i.e. rainfall, soil, slope, and land cover map. On each map, classification was done to get four to five classes based on a specific factor standard. To get the final result from the erosion danger levels which is categorized into five classes, they are very light, light, moderate, heavy, and very heavy, it is necessary to overlay the four types of maps. The results showed that the erosion danger levels at Rambut watershed area ranged from very light to very heavy, with the percentages of the affected areas are 46.91%; 35.13%; 12.47%; 3.67%; and 1.82% respectively. The very heavy and heavy danger areas covered 356.02 ha. And 717.99 ha. respectively. The results are used as a database to make a good planning watershed area management. Keywords: Erosion, GIS, overlay, USLE, watershed management, weatherin

Rasionalisasi Pos Curah Hujan Menggunakan Metode Kagan di DAS Ciliwung untuk Operasi Bendungan Ciawi dan Sukamahi

Hydrological stations are an important element in order to provide preliminary information to dam managers in planning and managing dams. Rainfall data generated from rainfall stations is one of the inputs in hydrological analysis that can be used in dam management. To support the hydrological analysis, an appropriate network of rainfall stations is needed, both in terms of the number and location of rainfall stations. Therefore, it is necessary to study the rationalization of the hydrological station network within the Ciliwung Watershed, so that it can be utilized in dam operations. The purpose of this study is to obtain an efficient and effective network of rainfall stations in the Ciliwung watershed to support the operation of the Ciawi and Sukamahi Dams. In this case, the Kagan method was used in the analysis of the rationalization of the rainfall station network by producing the optimum number of rainfall stations in the Ciliwung watershed, that is 29 rainfall stations. Based on these results, the number of rainfall stations in the Ciliwung watershed has met in terms of number, but the location point needs to be adjusted to the Kagan triangle

PENINGKATAN KINERJA WADUK KEDUNGOMBO DENGAN MENGEMBALIKAN KAPASITAS TAMPUNGANNYA

In every reservoir plan, the volume of dead storage provided is always taken into account to accommodate sediment entering the reservoir during the service life of the reservoir. Several studies on reservoir sedimentation show that 70% of reservoirs have sedimentation problems so the effective life of the reservoir will end before the design life is reached. The rate of sediment entering the reservoir will settle in the dead reservoir and the effective reservoir which will affect the performance of the reservoir. Therefore, it is necessary to take measures to improve the performance of the reservoir, one way is to restore its effective reservoir. Based on the results of bathymetry measurements of the Kedungombo Reservoir from 1989 to 2017, the sediment rate was 1.954 million m3/year. From the analysis of sediment distribution, the dead reservoir of the Kedungombo Reservoir at an elevation of +65.00 will be filled in 2089. The effective reservoir in 2089 at a normal water level of +90.00 of 527.71 million m3 has decreased by 106.89 million m3 from the initial effective reservoir is 634.6 million m3. To improve reservoir performance by restoring its effective reservoir, the Kedungombo Reservoir requires an elevation of the overflow or normal water level as high as 2.26 m with an inundation area of ​​48.72 million m2. Keywords: Sediment Distribution, Storage Capacity, Reservoir Performance, Kedungombo ReservoirDalam setiap perencanaan waduk selalu diperhitungkan volume tampungan mati yang disediakan untuk menampung  sedimen  yang  masuk  ke  waduk  selama  umur  layanan  waduk. Beberapa kajian tentang sedimentasi waduk menghasilkan bahwa 70% waduk memiliki permasalahan sedimentasi, sehingga umur efektif waduk akan berakhir sebelum umur  rencana  tercapai. Laju sedimen yang masuk ke dalam waduk akan mengendap di tampungan mati maupun tampungan efektif yang mana akan mempengaruhi kinerja waduk. Oleh karena itu dibutuhkan upaya penanganan untuk meningkatkan kinerja waduk salah satu cara dengan mengembalikan tampungan efektifnya. Berdasarkan hasil pengukuran batimetri Waduk Kedungombo tahun 1989 hingga 2017 didapatkan laju sedimen sebesar 1,954 juta m3/tahun. Dari analisis distribusi sedimen tampungan mati Waduk Kedungombo pada elevasi +65,00 akan terisi penuh pada tahun 2089. Tampungan efektif pada tahun 2089 di elevasi muka air normal +90,00 sebesar 527,71 juta m3 telah berkurang sebesar 106,89 juta m3 dari tampungan efektif awal sebesar 634,6 juta m3. Untuk meningkatkan kinerja waduk dengan cara mengembalikan tampungan efektifnya maka Waduk Kedungombo memerlukan peninggian pelimpah atau muka air normal setinggi 2,26 m dengan luas genangan menjadi 48,72 juta m2.   Kata Kunci: Distribusi Sedimen, Kapasitas Tampungan, Kinerja Waduk, Waduk Kedungomb

Keakuratan Prediksi Inflow Waduk Dengan Neraca Air Waduk

Dalam perhitungan inflow waduk sering digunakan persamaan neraca air waduk yang menggunakan data seri laporan harian operasi waduk, evaporasi dan curah hujan diwaduk, dan lengkung H-V-A waduk. Pada pengamatan data series laporan harian operasi waduk dan pengukuran kapasitas tampungan waduk, dapat terjadi kesalahan yang disebabkan karena kesalahan faktor manusia maupun faktor alat, hal ini akan menyebabkan kesalahan pula pada besarnya inflow waduk yang dihasilkan. Lebih lanjut di dalam perencanaan, data series inflow waduk ini diperlukan sebagai input pada pemodelan optimasi operasi waduk dan sedimentasi waduk, sehingga keakuratan datanya sangat diperlukan. Tujuan penelitian ini adalah untuk mengevaluasi tingkat akurasi penggunaan neraca air waduk dalam memprediksi inflow waduk. Untuk mengetahui tingkat akurasi dilakukan dengan membandingkan antara inflow waduk dari anak sungai hasil pengukuran dan hasil hitungan dengan persamaan neraca air waduk. Kemudian dilakukan variasi periode pengukuran dan kurva H- V-A yang digunakan. Berdasarkan penelitian yang dilakukan maka pada periode perhitungan yang lebih lama menghasilkan tingkat error yang lebih kecil. Pemakaian kurva waduk yang berbeda menghasilkan inflow yang berbeda. Tingkat error yang didapat masih cukup besar, diatas 30 %, sehingga perhitungan inflow waduk dari anak sungai dengan menggunakan metode neraca air waduk kurang akurat.  [Title: Accuracy of Reservoir Inflow Prediction Using Reservoir Water Balance] In the calculation of reservoir inflow often used reservoir water balance equation using the data series of daily reports reservoir operation, evaporation and precipitation, and H-V-A curve. In observation of the data series of daily reports of reservoir operation and measurement of reservoir storage capacity, the errors may occur due to human error factor and factor appliance. This will cause an error on the reservoir inflow generated. Further, in the planning, this series data of reservoir inflow is required as input to the modeling of reservoir operation optimization and reservoir sedimentation, so the accuracy of the data are required. The purpose of this study was to evaluate the use of the reservoir water balance accuracy rate in predicting inflow. To determine the level of accuracy, the effort is done by comparing the inflow tributary reservoirs of measurement and the count with the reservoir water balance. Then perform variations of the measurement period and curves H-V-A is used. Based on the research conducted in the period longer calculation produces a smaller error. The different H-V-A curve results in the different inflow. Error rate obtained is still quite large, above 30%, so the calculation of tributary inflow reservoirs using reservoir water balance method is less accurate

Optimization of Gunungrowo Reservoir operation

Inaccurate water release has occurred from Gunungrowo Reservoir. In May–June, there is excess water release from Gunungrowo Reservoir while in the period from July to August there is a shortage of water release. Therefore the reservoir operation should be evaluated and updated in order to obtain optimal results and to adjust the changes. The purpose of this study was to evaluate the existing reservoir operation and to carry out an optimization to find the optimal reservoir operation. The objective is to conduct hydrological analysis, evaluate the reservoir operation, formulate a model of reservoir operation, optimize the reservoir operation, and analyse the results of reservoir operation optimization. Optimization of reservoir operation generates the water level of reservoirs and the release of water in each period as well as the objective function value under each scenario of reservoir operation. The existing reservoir operation is not optimal and has a reliability of only 24%. In the operation of the existing reservoir, emptying of the reservoir storage always happens and inaccuracies in the release of water have occurred. The optimal reservoir operation is scenario I, with a reliability of 75%, in which water is released in Planting Season II and Planting Season III

Pemodelan Dry Dam dengan HEC-HMS di Daerah Aliran Sungai Bringin

Banjir yang terjadi di Sungai Bringin menyebabkan kerugian finansial bagi masyarakat di sekitarnya. Penelitian ini bermaksud menentukan system pengendali banjir yang paling efisien dan merespon keinginan masyarakat sekitar Sungai Bringin tentang upaya-upaya pengelolaan banjir. Perhitungan debit banjir dilakukan dengan menggunakan pemodelan (Hydrologic Modeling System) HEC-HMS. Hasil analisis diperoleh bahwa debit untuk kondisi eksisting di hilir Sungai Bringin dengan kala ulang 100th sebesar 425,7 m3/dt. Pada perencanaan, terdapat delapan lokasi embung potensi. Pada analisis di rencanakan 2 simulasi yaitu pengendalian banjir dengan embung dan dry dam. Hasil analisis debit dengan adanya rencana embung, ditinjau pada hilir Sungai Bringin dapat mereduksi banjir sebesar 151,8 m3/dt dengan Persentase 34,5 persen. Sedangkan hasil simulasi menggunakan dry dam dapat mereduksi banjir sebesar 210,8 m3/dt, dengan Persentase sebesar 48,3 persen. Dari hasil analisis diketahui bahwa pembangunan beberapa dry dam merupakan teknik terpilih sebagai upaya peredaman debit. Metode dry dam merupakan metode yang ideal untuk mengatasi banjir di Sungai Bringin