A remote sensing-based evaluation of channel morphological characteristics of part of lower river Niger, Nigeria

Abstract

River bank erosion, accretion and lateral channel migration are important geomorphological processes, which attract a great deal of attention of river engineering scientists in many parts of the world. The present study assesses the morphological characteristics of parts of the lower section of River Niger, where field data are scarce and difficult to access for security and cost implications. Multi-date (1990, 2002 and 2017) Landsat imageries were used for the study, the imageries were corrected for geometric and radiometric errors, classified and analysed for changes in major land cover classes within the river channel, to assess river planform, riverbank pattern, channel width, bankline migration and centreline using ArcGIS software. The results revealed a decrease in water body and riparian vegetation by 27.64% and 9.77%, respectively, between 1990 and 2017. Sediment yield, however, increased by 75.61%. In addition, the river channel exhibited significant spatial changes within the study period; centreline at left flange shifted eastwards by about 1347.3 m at the upper section but westward at the lower section by 123.1 m. The bankline shifted prominently eastwards at right flange and westwards at the right flange. The study concluded that the studied channel had actually undergone some critical morphological changes greatly affected by erosion and accretion processes that are easily captured with remote sensed imageries.

Assessing the bridge construction effect on river shifting characteristics through geo-spatial lens: A case study on Dharla River, Bangladesh

“…The middle part of the river has seen to be more stable. Moreover, according to the study on lower part of river Niger ( Ibitoye, 2021 ), the nature of the river channel centerline was not constant both at the left and right flange of the river flow paths throughout the years as the centerline shifted towards the east in the earlier years of study (1990–2002) but migrated greatly in the later years of study (2002–2017) in the westward direction. They also found that the shifting of the bank line was abundant to eastwards at right flange and westwards at the left flange.…”

“…Over all, it can be said that a maximum of width changes 10.21% was observed for 1993–98 (before construction of the Bridge) at F and increase of 12.14% at E, and the reduction of width changes was not significant for the year 2003–08 (after construction of the Bridge) but increasing of 15.55% at B was observed. According to the study on lower part of river Niger ( Ibitoye, 2021 ), the river channel width was showed diverse reduction and growth at various indicated sections of the channel reach.…”

“…The studies ( Biswas, 2010 ; Madej et al., 1994 ) revealed that the neighboring areas of the stream are constricted by the bridge piers and eventually effect in the river bank shifting. A remote sensing-based assessment of channel morphological characteristics using Landsat imageries ( Ibitoye, 2021 ) showed the bank line shifted blatantly eastwards and westwards. The study ( Ibitoye, 2021 ) does not much focus to evaluate the thalweg line shifting characteristics and percentage of channel width variations in details and did not consider the hydraulic structural effect on the river for changing its shifting characteristic.…”

“…A remote sensing-based assessment of channel morphological characteristics using Landsat imageries ( Ibitoye, 2021 ) showed the bank line shifted blatantly eastwards and westwards. The study ( Ibitoye, 2021 ) does not much focus to evaluate the thalweg line shifting characteristics and percentage of channel width variations in details and did not consider the hydraulic structural effect on the river for changing its shifting characteristic. As well, various studies have been carried out ( Bhakal et al., 2005 ; Yeasmin and Islam, 2011 ; Sarma and Acharjee, 2012 ; Chakraborty and Datta, 2013 ; Yang et al., 1999 ) on some worldwide major rivers for detecting Spatio-temporal channel changes with remote sensing and GIS technique and with Google Earth Engine technique ( Boothroyd et al., 2021 ) and with air photographs ( Gurnell, 1997 ).…”

Monitoring and Modelling Morphological Changes in Rivers Using RS and GIS Techniques

“…In the literature, many international studies were carried out to identify the morphological and spatio-temporal pattern of the river planform and their bankline migration with the aid of GIS and remote sensing tools [13][14][15][16][17][18]. Remote sensing has been used by researchers for more than thirty years to investigate the surface of the earth [19], of which supervised remote sensing techniques have been widely used for the analysis of satellite images.…”