Chute cut-off processes along a small alluvial channel: a case study of Sangra Khal, sub-tributary of Gour Nadi, West Bengal, India

Abstract

Meandering cutoff is a natural feature of low land alluvial river. It is an inseparable part of it and it is two types, such as neck cutoff and chute cutoff. Among them chute cutoff appears to be complicated and poorly understand. Here, we have observed and tried to describe the mechanisms of chute cutoff within uniform floodplain topography and its locational factors of development. Most of the studies had put their greater emphasis over cutoff formation on larger rivers and they owe it to nick point generation, swale development and embayment formation resulting from overbank flow. Our insitu observations of several years indicate that small agricultural stream with higher return period of over bank flow showing that embayment, nick point formation, weathering, mass wasting and earthworm’s activity are working together to form a chute cutoff. Although their relative degree of dominance in chute formation varies depending on the nature of return period of over bank flow, nature of flood plain and landuse, discharge, vegetation cover, meander properties and channel bank properties.