A Review of Dam Break Risk Assessment and Hydraulic Modelling for Climate-Resilient Reservoir Management: A Review with Application to Basnagoda Reservoir, Sri Lanka

Abstract

Dam failures can cause severe downstream flooding, infrastructure damage, environmental impacts, and loss of life. Climate related changes in extreme rainfall further emphasize the need for robust dam break risk assessment and flood hazard modelling. This review examines dam failure mechanisms, hydraulic modelling approaches, extreme rainfall assessment, and risk-assessment methods relevant to the Basnagoda Reservoir in the Aththanagalu Oya Basin, Sri Lanka. Published studies were reviewed and grouped according to failure mechanisms, hydrological and hydraulic modelling, uncertainty assessment, and Sri Lankan dam-safety applications. The reviewed literature identifies overtopping, piping and internal erosion, structural instability, and seismic or other natural hazards as important failure mechanisms. Hydrological assessment, including probable maximum precipitation (PMP) and probable maximum flood (PMF), is relevant to defining extreme inflow conditions, while HEC-RAS 1D and 2D models are widely applied to simulate breach flood propagation and estimate inundation depth, velocity, and extent. Case specific dam break modelling and inundation information for Basnagoda Reservoir were not identified in the reviewed literature. Therefore, the reviewed evidence provides a methodological basis for a Basnagoda focused assessment that integrates extreme rainfall analysis, breach scenarios, hydraulic modelling, GIS based hazard assessment, and uncertainty analysis. Moreover, Geographic Information System (GIS)- based Land Use and Land Cover (LULC) analysis is included to assess environmentally sensitive areas and vulnerable infrastructure that may be subject to inundation. The present paper investigates a significant aspect related to dam overtopping features, which are the result of overflowing associated with excessive inflow over the normal capacity in any reservoir system in order to develop an appropriate identification procedure for assessing potential risks linked with various extreme flood scenarios and proposes a

comprehensive methodology for integrating hydrological and hydraulic analyses into reservoir risk assessment While numerically simulating results is outside the capabilities of this preliminary investigation data, the suggested framework lays out a systematic evaluation for dam safety under projected in extreme weather conditions. this review is expected to contribute to improved reservoir design, emergency preparedness, dam breach, and sustainable water resource management in Sri Lanka.