GIS And Geostatistical Analysis of Tetrital Grains of Gadilam River Basin, Tamil Nadu India

Abstract

Most river sediments are polymodal and the peak heights shift from upstream (-0.04f and 1.24f) to downstream (0.29f and 1.17f), whereas the beach sediments show much reduced complexity (2.61f). The river sediments are coarse sand (0.3f - 1.24f) poorly sorted (1.73f - 2.82f), coarse skewed (-0.3 to 0.78) and mesokurtic (2.9) in upstream and leptokurtic in downstream (5.15), whereas the textural parameters of beach sediments show medium grain (2.61f) well sorting (1.4f), near symmetrically skewness (-0.13) and platykurtic (2.87). The effectiveness of bivariant plots is confined from the clear segregation of river and beach samples in the respective zones. The mean and skewness establish a negative correlation with standard deviation (r=-0.55). The distribution of the samples in the NOP sector in the CM diagram proves the prevalence of high energy environment in the river and graded suspension in the beach sediments. Visher's log probability curves reveal the maximum traction population in the upstream, saltation in the downstream and excellent double saltation population in the beach. The linear discriminant values prepared from the statistical parameters have concurred with the respective environment in the present study. The sudden change in textural parameters, i.e. coarse grains in the river bed and medium grains in the beach are attributed to the possibilities of an additional source. The USGS Sedimentological Tool, Geostatistical analysis, CM pattern and Visher's diagram also supplement such probabilities.