Modeling sediment accumulation in Pare Reservoir using HEC-RAS 2D: Assessing storage capacity over a 10-year period

Abstract

• HEC-RAS 2D simulated sediment deposition dynamics in Pare Reservoir over a 10-year period. • Sediment accumulation reached 13% of the capacity, primarily in low-velocity zones. • Reservoir altered flow dynamics, converting erosion-prone areas into sediment deposition zones. • Identified sedimentation-prone zones enable more targeted sediment management strategies. • A lifecycle-based framework is proposed to mitigate sedimentation and extend reservoir lifespan. Reservoir sedimentation represents a critical global challenge in water resources management, significantly impacting storage capacity, operational lifespan, and hydraulic efficiency of water infrastructure systems. This study aims to investigate sedimentation dynamics and their impacts on reservoir performance, focusing on the Pare Reservoir, Central Lombok, Indonesia. As a multifunctional reservoir serving irrigation, raw water supply, and flood control needs, it is crucial to maintain its capacity for effective operational functions. The HEC-RAS 2D model is utilized to simulate sediment transport and deposition over 10 years. Field data, including topography, reservoir bed bathymetry, daily river discharge, and sediment samples, were incorporated into the modeling. The simulation results estimated sediment accumulation at 6,847 m³ with an average sediment height of 0.47 meters, equaling 13% reservoir capacity reduction (1.3% annual average reservoir storage reduction). Following such modeling results, key management priorities have been identified, including sedimentation-prone zones and analyzing the hydraulics factors that affect sedimentation transport patterns in the Pare reservoir. The findings from this study provide valuable insights for stakeholders in formulating effective management strategies in the Pare Reservoir to ensure the reservoir's effective operations.

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