Spit and inlet dynamics, beach morphology, and sediment characteristics along shore front of Chilika lagoon, East coast of India

Beach morphology and sediment characteristics were investigated on a seasonal scale (January, May, and September 2013) along the shorefront of Chilika lagoon. Shorefront of Chilika lagoon covers 65 km and includes barrier spit and the inlet region (three spits: south, middle, and north). Dynamics of the inlets during pre (1973–1999) and post (2000–2020) hydrological intervention period were studied based on time series satellite data. Seasonal and inter-annual spit dynamics (2009–2020) were investigated based on observed data. Results indicate depositional environment on the barrier spit and south spit while erosional environment on the middle and north spit. After the hydrological intervention period (2000–2020), the south spit enhanced by 5.37 km, resulting in northward migration of the Sipakuda inlet, while the morphological changes of the middle and the north spit were observed considerable both in spatiotemporal scale. The variability of the middle and north spit is attributed to their position on the downdrift side of the inlet leading to short supply of sediments. As a result, the width and elevation of the middle and north spit significantly decreased. Depositional environment of the barrier and south spit can be attributed to their sediment characteristics which are predominantly fine and medium. On the other hand, the erosional environment of the middle and north spit are attributed to the prevalence of coarse sediments. Significant variability in inlet position and morphology along with vulnerability of the middle and north spit are matters of concern for the lagoon environment. Therefore, the study suggests that limiting the northward growth of south spit and adopting measures to control erosion at middle and north spit as two management interventions to restore the stability along the shorefront of Chilika lagoon.