Fig. 1. Map showing locations of post-tsunami survey. Fig. 4. Beach profile plot for Periyakalapet. region (Jena, 1997; Jena et al., 2001). The daily longshore currents measured at Nagapattinam region during 1998-1999 showed that the average longshore current speed was 0.25m/s and was predominantly toward the monsoon winds and waves whereas it was northerly during April and October 2005. Stronger longshore currents were seen during October. Earlier studies during 1995-1996 showed similar trend in the longshore currents along this Fig. 3. Beach profile plot for Mahabalipuram. Fig. 2. Beach profile plot for Uroor Alcott Kuppam. LST estimated during 2005-2006 using the littoral environmental parameters observed during the field in- Studies on the estimation LST using ship reported wave data and CERC formula in Shore Protection Manual (1984) has been reported by Chandramohan et al. (1990) and Chandramohan and Nayak (1991). These studies provided an estimate of LST along the Indian and Sri October and January. During January 2006 the net LST was higher than that of January 2005 indicating that the transport is active in the post-tsunami period. LST in the region north of Poompuhar was seen to be higher than that in the southern region (Table 2). measured offshore wave data off Nagapattinam, was 0.006 x 10°m? in the northerly direction and annual gross sediment transport was 0.6 x 10°m? (Jena et al., 2001). Thus it can be seen that the gross LST rates are of same order of magnitude as that of pre-tsunami but the quantities are almost double ascertaining the ongoing processes of recovery of the coastal profile. Lankan coasts. Annual gross and net transport rates about 1.79 x 10° and 0.44 x 10°m? were estimated for the coast between Pondicherry and Pt. Calimere (Chandramohan et al., 1990) with a net northward transport. Studies along the coastline between Periyakalapet and Nagapattinam based on littoral environmental observations and Walton’s equation indicate annual gross LST of 0.175 x 10°m? in the northerly direction (March—October) and 0.273 x 10°m* in the southerly direction (November—February) and annual net sediment transport of 0.098 x 10°m? in the southerly direction and the annual gross sediment trans- port was 0.448 x 10°m? (Jena, 1997). Comparison of LST at four locations (Table 3) for the pre- and post-tsunami indicates that the gross transport during 2006 is higher than that during 1995. Higher gross sediment transport rate means more quantities of sediments in motion thereby indicating that the recovery of the tsunami effect is very much in the process. The annual net sediment transport estimated using CERC formula (Shore Protection Manual, 1984) and the computed wave data in the surfzone, using 4. Conclusions Due to deposition of sediments in the hinterland by the tsunami and removal of sediments from the beach due to retreating tsunami, the January 2005 profile was lowered in the backsho during Apri re. Considerable recovery of the beach is seen and October in terms of increased foreshore widths and depositions of the sediments in the backshore region whic h is attributed to the seasonal variation. The recession observed in January 2006 profile compared to January 2005 profile might not be a real recession in the true sense d ue to the possibility of January 2005 profiles Monthly variations of littoral environmental parameters at various locations H,, = breaking wave height; T = wave period; «, = wave breaking angle respect to coast; W = surface zone width. “LSC Long-shore current speed (—) towards North (+) towards south. Table |
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