Kallady Bar mouth sand spit breaching: Batticaloa floodgate dynamics and lagoon flushing?

During the dry summer months, longshore wave drift builds a massive natural sand barrier across the Kallady bar mouth, closing Batticaloa Lagoon off from the open sea. When heavy Northeast monsoon rains (November to January) swell the lagoon, water levels rise to flood surrounding low-lying paddy tracts and homesteads. Irrigation Department excavators breach the sand spit at a designated low point. High-velocity lagoon water rushes through the pilot channel, scouring millions of tons of sand into the ocean in hours, dropping lagoon flood levels and restoring tidal saltwater flushing.