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.
