Variations in texture of beach sediments in the vicinity of the Tirumalairajanar river mouth of India

The distribution of grain size parameters along 11 km stretch of the beach sediments between Karikal and Nagore, reveals that the mean grain size exhibits a marked decreasing trend on either side of the mouth of the Tirumalairajanar River which flow from west to east. The sediments are mainly of medium to coarse grained, moderately sorted, near-symmetrical skewed to fine skewed and leptokurtic to mesokurtic in nature. Interrelationship of various parameters shows bimodal nature of sediments having dominance of medium to coarse sand. The major part of the sediment fall in a coarse to fine grained category (sand and silt). Based on the CM (Coarser one percentile value in micron) pattern, the sediment fall in rolling and suspension field. These factors includes the sediments discharged from the river mixes with offshore sediments and with the sediments eroded from a source rock. The effect of wave sorting, and the northward drifting of sediments by littoral current are understandable. Results indicate that the Tirumalairajanar River is the most important source for modern sediments in the study area. The agitation by waves is an important sorting mechanism in the study area, and the net sediment transport in the study area is northward. The findings are based on the grain sizes and also corroborated by shortterm observations of the beach sediment dynamics and transport during the monsoon and summer seasons between Karaikal and Nagore region.