The Bay of Bengal and the adjacent Gangetic delta is an understudied area. There is paucity of scientific studies on the dynamics of physico-chemical characteristics of water induced by cyclones and subsequent tidal surges. The present study describes the impact of AILA (a severe tropical cyclone which persisted from 23rd to 26th May, 2009) in the Hooghiy-Matla estuarine stretch of Indian Sundarbans, on three important hydro logical parameters namely salinity, pH and dissolved oxygen (DO). The authors conducted in situ studies before and just after AILA at 12 sampling stations in and around the Matla estuarine complex. They also extended the studies further (ten days after the storm hit the Gangetic delta complex) to visualize the situation of the aquatic phase. ANOVA results exhibit significant differences in surface water salinity, pH and DO due to intrusion of saline water from Bay of Bengal. The salinity of surface water increased from 14.32% to 24.18%. The DO decreased in all the sampling stations within the range 2.44% to 29.91% and the pH value increased in a few selected stations. Ten days after the AILA incidence was over the salinity, pH and DO exhibited gradual restoration within the range 7.14% to 14.77% (for salinity), 2.41% to 32.68% (for DO) and almost to pre-AILA values for pH. Such drastic oscillation of hydro logical parameters due to natural calamities may pose an adverse impact on the ecology of the deltaic complex. It requires a systematic planning to combat the ecological impact of disaster.