46. Textural Variation of Sediments in the Course of a Small River: A case study from Khurar River, Khajuraho, Chhaterpur District, Madhya Pradesh, India

Textural (grain size) analysis is one of the parameter that helps in determining sedimentary environment. In the present investigation, texture was analysed from sixteen stations in the Khurar River, Madhya Pradesh. Grain size analysis was carried out employing mechanical sieving method using a sonic shaker. Frequency and cumulative frequency curves were prepared from the grain size data on centimetre and arithmetic probability papers, respectively. The phi values were determined and used to calculate the statistical parameters such as mean, standard deviation, skewness and kurtosis. It is found that the mean value varies from -0.63 to 0.80 with a graphic mean distribution ranging from -0.27 to 0.40 φ, indicating that the size of the river sand is very coarse- to coarse-grained. The standard deviation (sorting) shows a range of 0.69 to 1.65 φ, while the skewness values of the sediment samples range from 0.19 to 0.29 φ, thus indicating the presence of fine fraction to near-symmetrical fraction in the population. The kurtosis varies between 1.03 and 1.09 φ, indicating that 25% of the samples are leptokurtic, 6.25% are very leptokurtic, 50% are mesokurtic and 12.5% are platykurtic. The platykurtic nature in few cases suggests mixing of the sediments from two sources. Bivariate plots prepared combing different textural parameters were used to interpret their behaviour in the river sediments. C-M plot was also prepared to understand the dominant mode of transportation in the Khurar River sediments. In this river all the sediments are dominantly characterized by the rolling process of deposition. This study reveals that sorting varies from poorly sorted to moderately well sorted from upstream to downstream part of the river may be because of dominance of winnowing and selective sorting in the lower reaches of the river.