River channel migration and land-use/land-cover change for Padma River at Bangladesh: a RS- and GIS-based approach

This study has been carried out to evaluate the river shifting and assessment of related effect on the land-use/land-cover using geographic information system (GIS) and remote sensing (RS) techniques between 1955 and 2016 for Padma River at Bangladesh. Alluvium is eroding chronically due to the rushing stream flow; therefore, people of this region are poor and government loss national assets each year that reflects the direct effect on the economy. The standard topographical map of 1955 and satellite images of 1973, 1987, 1999, 2011 and 2016 were used in the study. Impact assessment on land use/land cover around 5 km from the stream centerline of 1973 was obtained. This studied has been carried out in three steps: (1) analyzed migration rate from 1955 to 1973; (2) analyzed migration rate from 1973 to 2016 and (3) assessed migration rate impact on land-use/land-cover change using GIS and RS techniques. Normalized difference of water index technique was used for identification of land and water boundary. The maximum likelihood supervised image classification was applied to detect the land-use/land-cover type and identify erosional impact with best accuracy. Results of long-term river channel migration showed that the land area is influencing with river erosion, settlement area is increasing, vegetation area is decreasing, but sand bar, water body and cultivated land area are oscillating. The satellite images were collected during winter and dry seasons (from November to January), when stream flow is limited for a lower amount of rainfall. Maximum erosion and management plan are critical for area at section 2 right bank 1955 to 1973. On the other hand, a minor improvement of embankment is necessary at section 2 because erosion occurs from 1973 to 1987, 1973 to 1999 and 1973 to 2011 at left bank; at section 4 because erosion occurs from 1973 to 2011 at right bank; and at section 5 because erosion occurs from 1955 to 1973 at left bank. New land developments occur at section 3 left bank from 1973 to 2016; without it, the maximum occurrence of accretion number was found from 1973 to 2016 at section 2 right bank, section 3 left bank, section 4 left bank, section 5 left bank that help for river bank management, large-scale planning to prevent flood and reduce the property loss.

Automated summary

The research indicates that long-term river channel migration affects the land area, with settlement areas increasing and vegetation decreasing, while sand bars, water bodies, and cultivated land areas fluctuate. Areas with severe erosion require rigorous management, while improvement of embankments is necessary in other areas to prevent further erosion and losses.