Spit and Inlet Morphodynamics of a Tropical Coastal Lagoon

Abstract

The morphological changes of spits and inlets of the Chilika lagoon, the largest brackish water tropical coastal lagoon in Asia, are investigated using real-time kinematic GPS observation and numerical models during 2009–2013. The seasonal/interannual variations of the spit and inlet cross-sectional areas with varying widths and depths are recorded in association with different physical processes. The results show significant changes in spit morphology: particularly, the south spit accreted continuously, while the middle and north spits eroded. The cross-sectional depth of inlets becomes narrower and deeper during summer and winter seasons, while they are wider and shallower during the monsoon. The model results show that sediment transport rate is larger during monsoon and summer, while it is relatively less during the winter. Alongshore, sediment transport is predominantly northward throughout the study period. The result shows that gain/loss of the spits and closure/opening of inlets are significantly controlled by the high wave power, longshore drifts, and river discharge. The study demonstrates that the combined use of observational and numerical models is very effective to understand the changes of spit and inlet morphology and their impact on ecological conditions of the lagoon environment.

Keywords:

• Chilika inlets
• longshore sediment transport
• numerical model
• spit morphology
• river discharge
• wave power

Acknowledgments

The authors are thankful to the NCCR-PD, Government of India for providing their funding support and necessary facilities. The authors would like to thank Dr. Pravakar Mishra, Scientist F, NCCR for his guidance and help. The ECMWF ERA-Interim data used in this study were obtained from the ECMWF data server (http://apps.ecmwf.int/datasets/data/interim_full_daily/: accessed 16^th April 2014).

Additional information

Funding

The present study is part of the Ph.D research of the corresponding author in connection with the research project “Ecosystem modeling of Chilika lagoon” collaborative with Chilika Development Authority (CDA), and National Centre for Coastal Research (NCCR) Project Directorate, Chennai, sponsored by Ministry of Earth Sciences, Government of India.