Modelling Morphological Response of Large Tidal Inlet Systems to Sea Level Rise: UNESCO-IHE PhD Thesis

The research presented in this work qualitatively investigates the morphodynamic response of a large tidal inlet/basin system to future relative sea level rise (RSLR) using the state-of-the-art Delft3D numerical model. Understanding the potential impacts of RSLR on these systems is a prerequisite for their sustainable management due to their rich bio-diversity and the increase in economic activities and local communities in recent decades.The adopted approach used a highly schematised model domain analogous to the Ameland inlet in the Dutch Wadden Sea. Model simulations were undertaken applying tidal and wave boundary forcings with three IPCC projected RSLR scenarios (no RSLR, low RSLR and high RSLR). Predicted inlet evolution indicated a channel/shoal pattern typically observed at the Ameland inlet. RSLR enhances the existing flood-dominance of the system leading to erosion on the ebb-tidal delta and accretion in the basin. Under the no RSLR case, resulting bed evolution of the process-based model (Delft3D) tends to agree with empirical-equilibrium relations of the ASMITA model. Application of the low RSLR scenario resulted in quite stable tidal flat evolution. Model simulations with the high RSLR scenario indicated disappearing the tidal flats over time and turning the system into a lagoon. Applying nourishment hardly compensated the RSLR induced sediment demand of tidal flat evolution.

Pushpa Kumara Dissanayake (1974, Onegama, Sri Lanka) obtained his primary education in Hingurakgoda and studied civil engineering at the University of Peradeniya. He was research engineer for Lanka Hydraulic Institute (2000-2003) mainly engaged in numerical modelling of coastal projects. In 2003 he did a post-graduate scholarship at UNESCO-IHE Institute for Water Education, which was funded by the Netherlands Fellowship Programme. He studied in Coastal Engineering and obtained MSc in 2005. His thesis project, undertaken at WL|Delft Hydraulics (presently Deltares), investigated the effect of bed roughness formulations on morphodynamics of the Western Scheldt Estuary, the Netherlands. After graduation, he returned to Sri Lanka and worked for Lanka Hydraulic Institute as a senior modelling engineer.In February 2006, he started his PhD research at UNESCO-IHE on the responding morphodynamic evolution of large tidal inlet/basin systems to sea level rise, which was funded by Delft Cluster Research Programme. In January 2010, he moved to Norderney, Germany where he completed the final preparation of his thesis while working with his present employer NLWKN- Forschungsstelle Kuste where he works on climate change adaptation strategies on the Lower Saxony Coast, East Frisian Wadden Sea.