According to the information now available, the ‘swell wave’ activity in Kerala and Tamil Nadu Coast during 17-21 May was due to a storm originated on the western coast of Australia in the Indian Ocean. The storm which originated at around 30° S latitude travelled towards Africa, south of Madagascar and weaned out on 22nd May. A model was developed by ASR Ltd., New Zealand, based on a request from CESS using information available from NOAA. According to this, though waves of more than 7 feet significant height were generated at the storm site, the ‘swell waves’ which travelled away from the wind source attained about 5 feet (with maximum heights of about 8 feet) when they reached the Indian offshore. These waves travelled all over the Northern Indian Ocean. The wave periods of the swell waves observed in the Kerala coast were of the order of 15 seconds, which matches with the prediction made by the above model. Due to the so called ‘shoaling effect of waves’, at the breaking point, they attained heights upto 10 feet.
The southern Indian coasts, particularly Kanyakumari and Kerala being directly exposed to these waves had received the maximum impact. The higher tidal levels associated with the spring tide and the ‘wave setup’ (piling of water at the coast due to waves) took the impact of these waves to the inland. During the month of March also similar situation was reported along the same stretches due to another storm more or less in the same location of the Indian Ocean.
CESS in collaboration with KSCSTE propose to set up a system to monitor such southern Indian ocean storm events and to predict the waves well in advance to save the life and property in the coastal areas.

Studies on Coastal Erosion and Sediment Movement in the selected islands of Lakshadweep

Coastal erosion is one of the serious problems being faced by the Lakshadweep group of islands. To generate baseline data on erosion/accretion cycle and for the design and selection of proper coastal protection structures, beach monitoring, over a long-term period, studies were carried out by CESS initially in four islands viz., Kavaratti, Agatti, Amini and Bangaram during the period 1990 -1993. As a continuation to this, the second phase of the project was taken up in Kadamat, Chetlet, Kiltan and Bitra islands, covering the period 1997-2001.
The objectives of the study were:

To identify and demarcate the areas of erosion and accretion in the islands     of Kadamat, Chetlet, Kiltan and Bitra and compute the beach volume     changes in these islands.
To study the sediment characteristics and sediment movement around these islands.
To understand the relationship of erosion-cycle and wave diffraction pattern   in these islands.

A net accretion of 21.43 m3/m in Kadamat and 11.05m3/m in Chetlet Island was observed during the study period. Although there is a net accretion in the Kiltan Island, seasonal erosion was observed at certain stretches of the island. In the case of Bitra Island, erosion was noticed mostly on the S & SE sectors of the island. The long-term shoreline change has also been estimated for these islands. In the Chetlet Island, maximum recession of shoreline was observed on the SE and NE corner of the island. In the case of Kiltan Island, major part of the east coast has been undergoing erosion. Bitra Island is undergoing accretion with maximum accretion noticed on the SW part. Good correlation between high diffraction zones and erosion was observed. A baseline data on the erosion/accretion cycle in the Kadamat, Chetlet, Kiltan and Bitra islands of Lakshadweep have been generated. The study has indicated that the erosion pattern in the islands is controlled by the wave diffraction. The effectiveness of the existing shore protection measures in the island has been reviewed and the locations requiring protection measures are cited. Recommendations for further study have been given to the Administration of UTL.