Redesain Pelimpah Bendungan Fila Tukutaha Dengan Pelimpah Samping

Sawalna, Moch. Bima (2026) Redesain Pelimpah Bendungan Fila Tukutaha Dengan Pelimpah Samping. Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Kabupaten Alor yang terletak di ujung timur Provinsi Nusa Tenggara Timur (NTT) memiliki potensi besar dari segi keindahan alam, keanekaragaman hayati, dan budaya, namun di balik kekayaan tersebut wilayah ini menghadapi tantangan serius dalam pengelolaan sumber daya air, terutama keterbatasan air bersih, pencemaran, dan lemahnya manajemen yang berdampak pada kebutuhan dasar masyarakat serta perkembangan sektor pertanian. Untuk mengatasi masalah tersebut, pemerintah melalui Kementerian PUPR merencanakan pembangunan Bendungan Fila Tukutaha di Desa Morba, Kecamatan Alor Barat Daya, yang memanfaatkan aliran Sungai Kikilai sepanjang 9,21 km dengan fungsi utama penyedia air baku, irigasi, dan pengendali banjir. Salah satu komponen penting bendungan adalah spillway (pelimpah) yang berfungsi mengalirkan kelebihan air agar waduk tetap aman, namun desain awal menggunakan tipe ¼ Morning Glory Spillway terbukti kurang optimal berdasarkan uji model fisik di Laboratorium RSDA yang menunjukkan perbedaan debit hingga 27–32% dibanding perhitungan teoritis, sehingga tidak mampu menampung banjir periode ulang Q1000 dan berpotensi menimbulkan overtopping. Kondisi ini menuntut adanya redesain spillway dengan pendekatan analisis hidrologi dan hidraulika yang lebih komprehensif, mempertimbangkan aspek topografi, geoteknik, serta data hidrologi terbaru. Hasil kajian ini diharapkan dapat meningkatkan kapasitas pelimpah, menjamin keamanan bendungan, dan mengoptimalkan fungsi Bendungan Fila Tukutaha dalam mendukung ketahanan air, penguatan sektor pertanian, serta perlindungan masyarakat Alor dari risiko banjir. Hasil analisis menunjukkan bahwa curah hujan rencana periode ulang 1000 tahun sebesar 193 mm, dengan debit banjir rencana sebesar 256 m³/det. Dimensi bangunan pelimpah yang diperoleh terdiri atas mercu Ogee Tipe I (hulu tegak) dengan lebar 35 m, panjang saluran pengatur 40 m, panjang saluran peluncur lurus 200 m, panjang kolam olak 24 m, menggunakan kolam olak USBR Type III, serta mutu beton K-300. Hasil analisis stabilitas menunjukkan bahwa pada kondisi muka air normal diperoleh faktor keamanan terhadap guling sebesar 2,27 dan terhadap geser sebesar 5,33, sedangkan pada kondisi muka air banjir faktor keamanan terhadap guling sebesar 1,81. Tegangan maksimum pondasi sebesar 11,13 t/m² masih lebih kecil daripada tegangan izin tanah sebesar 30 t/m², sehingga seluruh persyaratan stabilitas terhadap rembesan, retak, guling, geser, dan daya dukung tanah dinyatakan memenuhi. Dengan demikian, bangunan pelimpah yang direncanakan mampu mengalirkan debit banjir rencana serta memenuhi persyaratan keamanan dan stabilitas struktur.
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Alor Regency, located at the eastern tip of East Nusa Tenggara Province (NTT), Indonesia, is known for its natural beauty, biodiversity, and cultural richness, yet it faces serious challenges in water resources management, particularly in terms of limited clean water availability, pollution, and ineffective management that affect both community needs and agricultural development. To address these issues, the government through the Ministry of Public Works and Housing (PUPR) has planned the construction of Fila Tukutaha Dam in Morba Village, Alor Barat Daya District, utilizing the 9.21 km Kikilai River, with key functions as raw water supply, irrigation, and flood control. A critical component of the dam is the spillway, which regulates excess water to maintain safety, but the initial design using the ¼ Morning Glory Spillway type proved less effective based on physical model tests at the RSDA Laboratory, revealing discharge discrepancies of 27–32% compared to theoretical calculations, indicating its inability to accommodate floods with a Q1000 return period and the risk of overtopping. This condition necessitates a spillway redesign through comprehensive hydrological and hydraulic analysis, considering topographic, geotechnical, and updated hydrological data. The redesign is expected to enhance spillway capacity, ensure dam safety, and optimize the overall performance of Fila Tukutaha Dam in strengthening water security, supporting agriculture, and protecting Alor communities from flood risks. The results indicate that the 1,000-year design rainfall is 193 mm, while the corresponding design flood discharge is 256 m³/s. The designed spillway consists of a Type I Ogee crest (vertical upstream face) with a width of 35 m, an approach channel length of 40 m, a straight chute channel length of 200 m, and a stilling basin length of 24 m using a USBR Type III stilling basin. The spillway structure is designed with K-300 concrete. Stability analysis shows that under the normal water level condition, the factor of safety against overturning is 2.27 and against sliding is 5.33, while under the flood water level condition, the factor of safety against overturning is 1.81. The maximum foundation bearing pressure of 11.13 t/m² is lower than the allowable bearing capacity of 30 t/m², indicating that the structure satisfies the requirements for seepage, cracking, overturning, sliding, and bearing capacity. Therefore, the proposed spillway design is capable of safely conveying the design flood discharge while meeting the required structural stability criteria.

Item Type:	Thesis (Other)
Uncontrolled Keywords:	Kata kunci: Redesain, Bendungan Fila Tukutaha, Pelimpah. Keywords: Redesign, Fila Tukutaha Dam, Spillway.
Subjects:	T Technology > TC Hydraulic engineering. Ocean engineering > TC555 Spillways. Energy dissipation. Hydraulic jump.
Divisions:	Faculty of Civil Engineering and Planning > Civil Engineering > 22201-(S1) Undergraduate Thesis
Depositing User:	Moch Bima Sawalna
Date Deposited:	30 Jul 2026 02:53
Last Modified:	30 Jul 2026 02:53
URI:	http://repository.its.ac.id/id/eprint/138835

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