EFFECT OF CYCLONE ON THE MAINTENANCE DREDGING AT PARADIP PORT

摘要

Severe cyclonic storms are known to cause devastating damage to the Port and Harbour structures and adjacent coastal areas. This is particularly the case when ports and coastal areas are situated in highly active littoral zones. The damage caused by storms is not just restricted to the coastal structures and the inundation of land, but also to the harbour areas such as the approach channels, turning circle, sand-trap etc. These areas undergo tremendous changes in the form of heavy siltation or erosion of the bed. India is subjected to many cyclonic storms (amounting to 15 % of the World's yearly crop of tropical cyclones). The ports and harbours situated along the East Coast of India, which iare in a highly active littoral-drift zone, are frequently subjected to such cyclonic storms. The "Super-cyclone" of the 20th century, which struck the Paradip Port, caused heavy damage and loss to life, property and inundation of large coastal areas. It was reported that winds of about 250 Kilometers per hour were generated during the storm generating waves of 8metres in the harbour area. A peculiarity of the storm was that it remained stationary at the Paradip Port area for more than 24 hours. This "Stationarity" of the storm was very unusual and previously unheard of. The high waves caused damage to the port structures and also caused heavy siltation in the sand-trap, approach channel, turning circle as well as along the adjacent shoreline. This paper deals with the tremendous siltation caused in the harbour area due to the super cyclonic storm. Fortunately, the Paradip Port Authority has been collecting siltation data for the sand trap, approach channel area etc. for many years. Based on these data, analysis has been carried out and the extent of the voluminous siltation caused by a single storm has been computed. The paper also deals with an estimation of the realistic annual littoral drift quantity along the East Coast of India and in particular at the Paradip Port.