Climatic and cyclone induced storm surge impact on salinity intrusion along the bangladesh coast

Global climate change will accelerate sea level rise that will continue to affect Bangladesh coast through increased salinity intrusion of low-lying areas. The situation becomes more critical when a severe cyclone makes landfall in the coastal region resulting sudden propagation of huge amount of landward saline water intrusion through estuaries. In this study, a SIDR like cyclone (i.e. intensity same as SIDR but hydrodynamic condition different) is selected to simulate changes of salinity intrusion. A calibrated and validated salinity model (Delft3D) and storm surge model (Delft Dashboard) was used to simulate the surface water salinity values. Salinity isohaline lines, comparing normal dry condition and climatecyclone driven scenarios were drawn to generate an overview on the level of resulting landward salinity intrusion. Upstream and downstream (including the sea level rise) boundaries are generated by using results from hydrology and ocean models. Estuarine salinity will increase and propagate landwards through estuaries significantly due to sea level rise and changed upstream discharge. During a cyclonic event, major changes in salinity intrusion occurs, due to sea level rise associated with changed upstream flow, compared to a normal dry condition. Result showed that impact of cyclone on salinity intrusion for different hydrodynamic condition was noticeable in eastern and central estuaries, especially in eastern estuarine system (Lower Meghna and Tentulia). KEWORDS: Cyclone, Storm surge, Climatic impact, Salinity intrusion, Salinity and storm surge model.