Perigean spring tides along the Indian coast

Sea level measurements from tide-gauges, installed in harbours along the Indian coast by the Survey of India, are used to illustrate the differences in high tides during spring tides that occurred during lunar perigee and apogee (closest and farthest position of the moon in its elliptical orbit around the earth) in January and August 1974 respectively. The difference in maximum tidal heights between 9 January and 4 August of the year for Mumbai tidal record is about 87 cm, whereas for Chennai, Visakhapatnam and Paradip, the differences vary between 20 and 25 cm. Kochi record shows a difference of about 13 cm, whereas the difference in predicted high tides at Bhavnagar is more than 1 m. Similar results are found for March and April 1980 during spring tides close to perigee and apogee respectively. Perigean spring tides can cause flooding in low-lying coastal areas along the northern parts of the Indian coast, which will get enhan-ced in future with mean sea-level rise due to global war-ming.