Uji model fisik hidrolika yang dilakukan di laboratorium dimaksudkan untuk mengetahui perilaku hidrolika aliran pada bangunan hidrolik yang diujikan. Tujuan uji model bangunan pelimpah Bendungan Sakagilas ini adalah untuk mengetahui profil aliran yang terjadi pada sistem pelimpah, meliputi kedalaman aliran, kecepatan, tekanan aliran air dan bilangan Froude. Juga untuk mengetahui unjuk kerja hidrolik desain pelimpah, saluran transisi, saluran peluncur, kolam olak/peredm energi, dan saluran hilir (escape channel). Tekanan akibat aliran air yang terjadi pada sistem pelimpah (ambang pelimpah, saluran transisi, dan terutama saluran peluncur) diukur dan dianalisa untuk mengetahui kondisi keamanan bangunan terhadap bahaya kavitasi dan aliran getar. Pelimpah pada Bendungan Saka Gilas merupakan side channel spillway (Fixed+Gated) dengan mercu pelimpah berbentuk Ogee. Bentuk pelimpahnya adalah melingkar seperempat lingkaran (45⁰). Pengamatan awal pada uji model fisik dilakukan pada kondisi Original Design, yang apabila terdapat perilaku hidrolika aliran yang tidak baik, maka akan dilakukan modifikasi desain. Modifikasi desain dimaksudkan untuk mendapatkan perilaku hidrolika aliran terbaik, sesuai standar kriteria desain sistem bangunan pelimpah.

ABSTRAK : Bangunan pengelak terdiri dari terowongan pengelak dan bendungan pengelak. Bangunan yang harus dibangun pada awal konstruksi sebuah bendungan, memiliki fungsi untuk mengalihkan aliran air sungai selama periode pembangunan bendungan. Perencanaan terowongan pengelak Bendungan Kualu didesain menggunakan bentuk tapal kuda shape F , hulu terowongan berada di kedalaman 41,625 m dan elevasi dasar hulu +695,5 m. Dalam studi ini dilakukan penelusuran banjir dengan debit banjir kala ulang 25th sebesar 709,331 m 3 /dt dan didapatkan diameter terowongan 9 m, kemudian direncanakan cofferdam setinggi 15 m. Dilakukan perhitungan pembebanan dan dihitung 4 kombinasi pembebanan yaitu kondisi setelah dibangun, kondisi setelah dibangun (gempa), kondisi setelah beroperasi, dan kondisi setelah beroperasi (gempa). Dari hasil kombinasi pembebanan dilakukan perhitungan momen menggunakan metode Beggs dan metode Staad Pro. Dilakukan analisa pemilihan momen maksimum yang kemudian digunakan untuk perhitungan penulangan pada terowongan. Setelah melakukan analisis, dapat diketahui bahwa terjadi perbedaan letak titik momen maksimum, hal ini diakibatkan pada metode Beggs tumpuan diasumsikan sebagai gaya vertikal atau beban vertikal.Kata kunci: Terowongan Pengelak, kombinasi pembebanan, momen maksimum, penulangan, Analisis Struktur.ABSTRACT: Diversion structure consists of diversion tunnel and Cofferdam. These two contructions should built in the early construction of the dam, have function to divert the river flow during the period of dam construction. The plans of Kualu dam diversion tunnel designed using horseshoe shape F, upstream of the tunnel at a depth of 41.625 m and upstream elevation + 695.5 m. In this study there was flood routing with Q25th which is 709,331 m 3 /s and obtained using 9 m diameter, then a cofferdam is planned to build as high as 15 m. Based on the calculation of loading and calculated four load combinations, they are : after contruction condition, after contruction under earthquake condition, at the operation time condition, and at the operation time under earthquake condition. From the results of the load combinations, the structure was analyzed using Beggs method and Staad Pro method. These two methods were used to figure the maximum moment of the structure and to determine the needed reinforcement in the tunnel construction. After the analysis, it is noticed that there is a difference position of the maximum moment, this is caused by the support in the Beggs method assumed to be a vertical loads.

Karangnongko Weir is planned to be located in the Bengawan Solo River (Lower Solo River Basin) about 15 km downstream of the confluence of Bengawan Solo River with the Madiun River in Ngelo Village, Margomulyo Sub-District, Bojonegoro Regency, and Ngrawoh Village in Kradenan Sub-District, Blora Regency. This study aims to determine the Depth and pattern of scouring in downstream energy dissipation through physical model tests based on initial planning. Downstream protection of energy dissipation in the original design model combines 50 m of riprap rocks and 50 m of riprap concrete for a total length of 100 m of protection. The maximum scouring pattern occurred at elevation + 17.64 m, where the scouring was 4.36 m deep, from the planned essential height of Height 00 m. Thus, the downstream protection of energy dissipation was extended to 112 m in riprap concrete blocks for the final design model. Scouring at the end of riprap was 3.04 m, the original elevation of the river bottom of + 22.00 m, down to + 18.96 m. It is concluded that the protection is effective in reducing scouring by up to 30.27%.

Increasing the population in Kota Bangun Sub-District, Kutai Kartanegara Regency, in line with the consequence that growing needs for drinking water and raw water for local communities become a top priority. Public complaints about the increasing difficulty of obtaining clean water seem to be an obstacle that the Regional Government has yet to resolve fully. The production capacity of PDAM Kota Bangun is currently only 30 liters/sec, which is far from sufficient for the needs of all people in the Kota Bangun Sub-District. Economic feasibility calculation analysis utilized the NPV, IRR, and BCR methods and sensitivity analysis to obtain the economic feasibility for the value of developing intake and raw water networks. The results indicate, with a reasonable life condition of 30 years, the construction of water networks in Kota Bangun is still economically feasible. Reasonable with the minimum requirement of BCR = 1, with sensitivity analysis on two scenarios, considerations of 30% and 20% leakage, and 30.55% and 25% administrative costs. The results of the research show that IRR = 17.70%. If the analysis conditions are that investment costs increase by 10% with Fixed Benefits, the payback period is 6.8 years.

Perencanaan rehabilitasi bangunan pelimpah(spillway) bertujuan untuk mengetahui besar debit banjir, merencanakan desain dimensi bangunan, dan menganalisis kestabilan bangunan. Perencanaan ini dilakukan di Embung Takisung Kabupaten Tanah Laut Kalimantan Selatan. Tahap awal perencanaan ini adalah dengan meninjau secara detail debit inflow yang masuk ke waduk yang selanjutnya digunakan untuk perhitungan penelusuran banjir. Hasil dari penelusuran banjir berupa debit outflow yang akan digunakan sebagai dasar perencanaan pelimpah, profil muka air, serta perencanaan peredam energi. Hasil perencanaan yaitu besar debit menggunakan metode HSS Nakayasu sebagai debit inflow dengan kala ulang 100 tahun dan kala ulang 1000 tahun sebagai kontrolnya. Debit inflow sebesar Q100th = 61,729 m3/detik; Q1000th = 72,541 m3/detik serta debit outflow sebesar Q100th = 30,453 m3/detik; Q1000th = 37,767 m3/detik. Kemudian hasil perencanaan pelimpah yang sesuai dengan kondisi daerah studi dari topografi, hidrologi dan hidrolikamenggunakan Q100th. Perhitungan stabilitas pelimpah dengan keadaan air kosong, muka air normal dalam kondisi normal dan gempa, dan muka air banjir debit Q1000th serta keadaan ekstrim diperoleh hasil aman terhadap guling, geser dan daya dukung tanahnya tidak melebihi dari tegangan ijin tanah sehingga memenuhi syarat. Spillway rehabilitation planning aims to determine the discharge of major floods, dimensional design of the structure, and analyze the stability. This planning was carried out at the Takisung Retarding basin, Tanah Laut Regency, South Kalimantan. The initial stage of this planning is to review in detail the incoming discharge that enters the reservoir which is then used for flood routing on the spillway. The result of flood routing is in the form of outflow which will be used as the basis for planning the spillway, the water level profil, and the planning of the stilling basin. The result of the planning is a large discharge using the HSS Nakayasu method as an inflow discharge with a return period of 100 years and a return period of 1000 years as the control. Inflow discharge of Q100th = 61,729 m3/second; Q1000th = 72,541 m3/second and an outflow discharge of Q100th = 30,453 m3/second; Q1000th = 37.767 m3/second. Then the spillway planning results are in accordance with the conditions of the study area from topography, hydrology and hydraulics using Q100th. Analyze of the stability with the load with empty water, normal water level in normal and earthquake conditions, and flood water level with Q1000th discharge and extreme conditions which results in safety against overturning, shearing and soil carrying capacity not exceeding the allowable stress of the soil so that it meets the requirements.