1173 | 87 | Channel Adjustments to anthropogenic alterations in the Sub-Himalayan River system for the last five decades | Suman Mitra and Dr. Lakpa Tamang
This study aims at analyzing the impacts of anthropogenic alterations on channel planform adjustments of the Sub-Himalayan Mahananda-Balason River system for 52 years (1968-2020). A total of 6 satellite images, 10 equidistant reaches, have been used to measure anthropogenic interventions that include embanking, sediment extraction, landuse changes, longitudinal obstructions and channel planform properties, such as channel width, area, length, bar coverage and channel pattern. Considering the nature of generated data structure, firstly a two- tailed ‘t’-test was performed to measure the statistical significance of the change rate of the indicators followed by the panel data regression using the Fixed Effect Model (FE) to measure the intensity of ongoing alterations on channel planform adjustments. Results showed that with significantly increasing alterations, channels narrowed by >50%. Alike to channel width, the channel length and bar coverage were also reduced in R2-R5, and R7-R9. This resulted in braided planforms becoming sinuous ones in reaches adjacent to Siliguri (R3, R4, R9 and R10). Obtained R 2 values inferred that the anthropogenic interventions were highly responsible for such intensive channel adjustments. Adjustments in channel planform and altered bed morphology had disturbed the habitat condition of riverine fish assemblage. Excessive sediment extraction from channel beds has led to the incision of channels by & >2m thus lowering the groundwater level too. Moreover, largely increased finer particles ended up clogging the channels and undersupply of sediments at the reaches adjacent to Siliguri town and gradual engulfment of rural areas for urbanization are driving these reaches towards adjusting their channels accordingly. An economically viable and robust assessment like this is needed to prevent the possible undersupply of riverine resources and to develop policies on its sustainability.
Suman Mitra and Dr. Lakpa Tamang
Department of Geography, University of Calcutta, India
ID Abstract: 87