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Erosion Rate Analysis and Land Conservation Direction Based on Geographic Information System in Way Rarem Subwatershed, Lampung Province Napitupulu, Ruth Erditha; Andawayanti, Ussy; Lufira, Rahmah Dara; Pratama, Rizki Ramadhani
Civil and Environmental Science Journal (CIVENSE) Vol. 7 No. 2 (2024)
Publisher : Fakultas Teknik Universitas Brawijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.21776/ub.civense.2024.007.02.10

Abstract

The Ministry of Forestry has designated the Way Rarem sub-watershed, part of Tulang Bawang, a critical watershed, as a priority. Several reasons cause land criticality, including deforestation and inappropriate land use, which cause erosion and sedimentation. In this case, the criticality of the watershed occurs due to the high erosion rate, which impacts flooding in the Way Rarem subwatershed area. Over the past year, there have been flood disasters at five points in the Tulang Bawang watershed. Based on information from BNPB (National Disaster Management Agency), the flood disaster affected 140 families. The losses that occur due to flooding that arise due to erosion and sedimentation need to be studied in more depth; therefore, the situation in the Way Rarem Sub-watershed is important to study further. The objectives of this study are to determine the Erosion Hazard Index, measure the erosion rate in the Way Rarem sub-watershed using the USLE method, and provide adequate conservation strategies. The required data are rainfall data, soil type, slope, and land use in 2019 and 2023 as a comparison. GIS was used to process all the data. The results showed that the erosion rate in 2019 was 21933.9 tons/ha/year, whereas in 2023, it was 14187.4 tons/ha/year, with the Erosion Hazard Index dominated by the 'Very High' category. For conservation direction, three alternative conservation activities are carried out, namely by vegetative, mechanical, and vegetative-mechanical methods. Based on the results of the analysis, the appropriate conservation direction to reduce the erosion rate is vegetative-mechanical conservation, which can reduce the erosion rate by 66.9% of the existing erosion rate. From the results obtained, it is hoped that new concepts in land conservation that have not yet been implemented in the Way Rarem Sub-watershed can be taken into consideration. Combining two conservation methods, vegetative and mechanical, can be an alternative to controlling erosion that occurs in the Way Rarem Sub-watershed.
Decision-Ready Composite Performance Index for Raw Water Supply Systems: PLS-SEM and GRG Andawayanti, Ussy; Suhartanto, Ery; Lufira, Rahmah Dara; Siswoyo, Hari; Sudiarti, Sri Utami; Pratama, Rizki Ramadhani
Jurnal Presipitasi : Media Komunikasi dan Pengembangan Teknik Lingkungan Article in Press 2026 (For Upcoming Issue)
Publisher : Universitas Diponegoro

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/presipitasi.v0i0.%p

Abstract

Dependable raw-water service depends on asset condition, institutional capability, and watershed context, existing checklists in Indonesia fail to produce a validated, decision-ready performance score.  This study develops a composite performance indicator for raw water infrastructure that incorporates technical (Tk), institutional/non-technical (NT), and environmental (Li) dimensions. Data were collected from 21 schemes in Lombok–Sumbawa, West Nusa Tenggara Province, Indonesia (NTB), with 160 respondents, using field assessments and 1–4 scale questionnaires. Estimated reflective formative PLS-SEM, then applied GRG calibration to minimize deviation from field scores under non-negativity and unit sum constraints for interpretability and portability. All pillars contribute positively and significantly to the composite index, which exhibits high explanatory power (R² = 0.997). The calibrated index is PIRWSS = 0.440 PITk + 0.340 PINT + 0.220 PILi, with SSR ≈ 83.412, RMSE ≈ 0.522, MSE ≈ 5.721, and ≈ 99.70% accuracy relative to field benchmarks. Cross-site analysis shows higher performance in Lombok than in Sumbawa, reflecting hydroclimatic conditions and conveyance configurations. The index provides utilities and regulators with a transparent, reproducible framework for benchmarking and prioritizing operations, maintenance, rehabilitation, and source-water protection.
Analisa Stabilitas Tubuh Bendungan Utama Pada Bendungan Semantok, Nganjuk, Jawa Timur Pratama, Rizki Ramadhani; Suprijanto, Heri; Asmaranto, Runi
Jurnal Teknologi dan Rekayasa Sumber Daya Air Vol. 1 No. 1 (2021): Jurnal Teknologi dan Rekayasa Sumber Daya Air (JTRESDA)
Publisher : Fakultas Teknik, Universitas Brawijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.21776/ub.jtresda.2021.001.01.08

Abstract

By the changes of embankment material and foundation treatment on Semantok Dam, it is necessary to analyze the dam stability. This study aimed to know about the material specification, the geologic conditions & the foundation treatment, and the dam stability. The specification result shows that core material and fine filter material meet the criteria. The geologic conditions consist of Sand, Sandstone, and Claystone. The alternative for foundation treatment proposed using Secant Pile Cut-Off Wall and Cut-Off Trench. The rock bearing capacity and the core zone settlement is safe. The foundation's elastic deformation is estimated at 3,56 cm ~ 4,36 cm. The filtration flow stability using SEEP/W shows seepage discharge, piping, and boiling potential are safe. The slope stability by Bishop method using SLOPE/W shows static condition; OBE 100; and OBE 200 are safe, but MDE 10000 is unsafe. Permanent deformation analysis for MDE 10000 by Makdisi Seed method and Swaisgood shows the deformation is safe.Dengan adanya perubahan material timbunan dan perbaikan pondasi pada Bendungan Semantok, perlu dilakukan analisa stabilitas bendungan tersebut. Studi ini bertujuan untuk mengetahui spesifikasi material, kondisi geologi dan perbaikan pondasi, serta stabilitas bendungan. Hasil spesifikasi menunjukkan bahwa material inti dan filter halus memenuhi kriteria. Secara geologi pondasi Bendungan Semantok terdiri dari Pasir, Batu pasir, dan Batu lempung. Alternatif perbaikan pondasi diusulkan menggunakan Secant Pile Cut-off Wal dan Cut-off Trench. Daya dukung batuan pondasi dan penurunan zona inti bendungan aman. Deformasi elastis pondasi sebesar 3,56 cm ~ 4,36 cm. Stabilitas terhadap aliran filtrasi dengan SEEP/W menunjukkan debit rembesan, gejala buluh, dan gejala sembulan aman. Stabilitas lereng metode Bishop dengan SLOPE/W menunjukkan kondisi statis, OBE 100, dan OBE 200 aman, tapi untuk MDE 10000 tidak aman. Deformasi permanen untuk MDE 10000 dengan Metode Makdisi dan Swaisgood aman.