Current asymmetry and its implications for morphological changes in Vembanad Lake, the second largest wetland ecosystem in India

Flow dynamics are a key part of the physical processes that drive the sediment transport in an aquatic system, affecting depositional processes and leading to landform evolution. The current asymmetry (CA) noted in Vembanad Lake (VL), India, have a particularly strong influence on the sediment budget and thus shape its geomorphology. In the present study the Coastal Ocean Model - Finite Volume Coastal Ocean Model (FVCOM) was used to compute the lateral current asymmetries and their implications for the long-term morphological changes in VL during different tidal phases. Model results were utilised to calculate the CA using two criteria: (1) Peak flood/ebb velocities with duration, and (2) Asymmetry Index (AIDV). AIDV values suggest the prevalence of ebb dominance over the entire system except at Cherai and Vallarpadam. However, several isolated pockets were noted on the right/eastern bank (shallow depth) of the system where the peak flood velocity exceeded the ebb, favouring accretion.