ABSTRACT
Human impacts on landforms and geomorphic effects on humans through natural hazards clearly involve interactions between humans and geomorphic systems. The human dimension of geomorphology is a vital area of research that has been largely neglected beyond the local and sub-regional scale. In this regard, anthropogenic geomorphology is introduced as an emerging systemic field that overlaps with climate change and natural hazards research, and it is a sub-field of geomorphology concerned with the study of landforms created or modified by human activity. Regardless of underlying causes, whether natural, purposeful or unintended/accidental, all river systems, like Bhagirathi–Hooghly River System of the Ganga–Brahmaputra Delta, are subject to disturbance events that promote adjustments to their behavioural regime. Most tropical rivers of Southeast Asia have suffered detrimental effects of human disturbance because the alluvial plains and deltas are the most densely populated region of the world. These impacts have gathered momentum over time, especially since the 19th century, renowned as Anthropocene. The construction of structures such as dams, levees, concrete-lined trapezoidal channels, bridges, roads, railways and activities such as sand/gravel extraction have induced enormous damage and modification to river morphology and floodplain function of the Bhagirathi–Hooghly River System. Intended modifications have resulted in a range of unintentional consequences, such as changes to flow and sediment transfer regimes, patterns and rate of erosion and sedimentation, hydraulic resistance, flow velocity and changes in flood peaks. Within the domain of anthropogenic geomorphology, the present chapter tries to synthesise the emerging concepts, ideas and issues of fluvial response to human disturbance in the river basins of the Bhagirathi–Hooghly River System. Alongside, following the key principles of vulnerability, susceptibility and river sensitivity, a River Style Framework is developed to provide a coherent set of scientific procedures for understanding the human impact on fluvial dynamics and to integrate catchment-scale geomorphic perceptive of river forms, processes and linkages.
