Asia · Sri Lanka
Kalutara sand spit reconstruction
A modelling study to inform decision makers on how best to reconstruct the Kalutara sand spit, which disintegrated after ad hoc artificial breaching during high river flow in 2017, exposing low-lying development behind it. The work advances sand spit rehabilitation modelling techniques that can be applied to similar natural or artificial breaches elsewhere.
Our experts contributed to
- Engineering approach evaluating four conceptual reconstruction options using soft engineering (sand nourishment at 40,000 m³/day).
- Site review of coastal and river processes governing the timing and sequencing of reconstruction.
- Design and layout derived from bathymetric data and satellite imagery, resembling the historic sand spit.
- Morphodynamic modelling of all concepts in Delft3D (2DH), during and after reconstruction.
- Sediment transport, sedimentation and erosion assessment feeding method and timing recommendations.
- Recommended window: December–March, during the calmer North East monsoon, with the inlet in the southern position to return the spit to a stable pre-breached state.
Image from the MSc thesis “Designing an effective engineering approach to rebuild a sand spit… Kalutara Lagoon, Sri Lanka”, D. B. Kühn, IHE Delft, 2021.