Meandering nature of Barak River in subtropical climate of Southern Assam, Northeast India-A Geospatial analysis

In the present paper a geospatial analysis is performed to understand the meandering behaviour of Barak River in southern Assam between 1988 and 2010. Landsat images (with Thematic mapper and Enhanced thematic mapper-plus sensors) for years 1988, 1999, and 2010 are considered for the study. River Barak within the study area is digitized as polygons for three years and sinuosity index (SI) are calculated for three different segments; segment-1 (23 km), 2 (71 km), and 3 (40 km) situated at western, central, and eastern part of the study area. The SI ranged from 1.34 to 1.39, 3.21 to 3.20, and 2.05 to 1.69 in segments-1, 2, and 3 respectively, with an overall SI for all the segments together ranging from 2.29 to 2.16. Except segment-1, all the other segments exhibited a decreasing trend in the sinuosity. The decrease in sinuosity is observed due to development of a significant cutoff near Sonai, decreasing the overall length of the river by around 9 km between 1988 and 2010. Channel shifts ranging from 4.59 m/year to 26.14 m/year at various places have resulted in the formation of neck cutoff and translation type meander loop developments. The study may be helpful for the overall river management and planning for future prevention of loss of properties due to meander migration.