Analisis Potensi Subsurface Dam sebagai Sistem Tampungan Air Tanah pada Endapan Aluvial Tukad Ketes, Desa Bunutan, Karangasem, Bali

Anwar Makmur; Djoko Pitoyo

doi:10.51988/jtsc.v7i3.616

Authors

Anwar Makmur Faculty of Engineering, Universitas Sangga Buana, Bandung
Djoko Pitoyo Faculty of Engineering, Universitas Sangga Buana, Bandung

DOI:

https://doi.org/10.51988/jtsc.v7i3.616

Keywords:

Subsurface dam, groundwater, alluvial deposit, water conservation, Bunutan Karangasem

Abstract

Bunutan Village, Abang District, Karangasem Regency, East Bali, experiences water shortages during the dry season due to rocky geology, low rainfall, limited groundwater discharge, and increasing domestic, irrigation, and tourism demand. Pumping from coastal alluvial deposits may also increase the risk of seawater intrusion because the freshwater layer is relatively thin. This study assesses the potential of a subsurface dam as a groundwater conservation and storage system in the alluvial deposits of Tukad Ketes. A descriptive-quantitative case study method was applied through geological, hydrogeological, and hydrological analyses, supported by an estimation of groundwater storage capacity. Results indicate that the Tukad Ketes valley contains 30–35 m thick alluvial deposits composed of sand, gravel, cobbles, and boulders, which can function as an underground reservoir. Alluvial permeability ranges from 10?² to 10?? cm/s, while volcanic breccia bedrock acts as a natural impermeable boundary. With a reservoir length of 1,000 m, an effective width of 700 m, a cutoff wall depth of 40 m, and an effective porosity of 10%, the theoretical storage capacity reaches approximately 2.8 million m³. Therefore, a subsurface dam at Tukad Ketes is feasible for further development as a solution for groundwater conservation and raw water supply.

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