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pools and riffles to riffles is reduced to 1000 m and 750 m, respectively, with an average width of 213 m. Overall, the data shows a significant increase in pool depth and a decrease in spacing between pools and riffles as we move from the upstream reaches to the immediate downstream section from the Barrage. Additionally, there is a notable reduction in the average width of the river in the downstream region. Fig.4: Channel Width changes in different Cross-sections (1931 - 2023)

Figure 4 pools and riffles to riffles is reduced to 1000 m and 750 m, respectively, with an average width of 213 m. Overall, the data shows a significant increase in pool depth and a decrease in spacing between pools and riffles as we move from the upstream reaches to the immediate downstream section from the Barrage. Additionally, there is a notable reduction in the average width of the river in the downstream region. Fig.4: Channel Width changes in different Cross-sections (1931 - 2023)

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99 m. A pickup barrage has been constructed at the Fulbari- Mahananda Barrage in Jalpaiguri District to facilitate the passage of the Teesta canal. Additionally, the construction of this Barrage serves multiple purposes, including the establishment of a hydroelectric power project and flood control measures. The ength of the Barrage is 220 metres with 10 metre height from the river bed. Currently, the Public Health Engineering Directorate supplies approximately 5.0 million cubic meters of drinking water per year to the Siliguri Municipal Corporation area from the reservoir of the Mahananda Barrage. After a distance of 2 kilometres downstream from the Barrage, the river continues its course through Bangladesh, and it also serves as an important international boundary for this region. Fig.1: Location Map of the Study Area
99 m. A pickup barrage has been constructed at the Fulbari- Mahananda Barrage in Jalpaiguri District to facilitate the passage of the Teesta canal. Additionally, the construction of this Barrage serves multiple purposes, including the establishment of a hydroelectric power project and flood control measures. The ength of the Barrage is 220 metres with 10 metre height from the river bed. Currently, the Public Health Engineering Directorate supplies approximately 5.0 million cubic meters of drinking water per year to the Siliguri Municipal Corporation area from the reservoir of the Mahananda Barrage. After a distance of 2 kilometres downstream from the Barrage, the river continues its course through Bangladesh, and it also serves as an important international boundary for this region. Fig.1: Location Map of the Study Area
On the other hand, downstream from the Barrage, the pool and riffle sequence becomes more pronounced, with five pools and four riffles observed. Overall, the survey findings highlight the distinct differences in pool and riffle patterns between the upstream and downstream regions of the Barrage. The downstream section exhibits more pool and riffle features, indicating a more dynamic and varied riverbed topography. Fig.2: Longitudinal Profile, Pool, and Rifle location of the Mahananda River in the reach under study.
On the other hand, downstream from the Barrage, the pool and riffle sequence becomes more pronounced, with five pools and four riffles observed. Overall, the survey findings highlight the distinct differences in pool and riffle patterns between the upstream and downstream regions of the Barrage. The downstream section exhibits more pool and riffle features, indicating a more dynamic and varied riverbed topography. Fig.2: Longitudinal Profile, Pool, and Rifle location of the Mahananda River in the reach under study.
Fig.3: Changing Channel Width (1931 - 2023) In Richards! (1976) straightforward explanation, pools, and riffles are identified as negative and positive deviations from a trend line representing the channel bed configuration. On the other hand, Knighton (1984) defines pools and riffles based on the "scale of distance" between the alternating deep sections (pools) and shallow sections (tiffles). He notes that these distinct features tend to occur at intervals approximately 5 to 7 times the width of the channel. In the upstream reaches, the average depth of pools is about 3 meters, and this depth nearly doubles to 5 meters in the immediate downstream section from the Barrage. Furthermore, the mean spacing between pools to pools and riffles to riffles in the upstream section is around 1500 m and 1700 m, respectively, with an average width of 413m.
Fig.3: Changing Channel Width (1931 - 2023) In Richards! (1976) straightforward explanation, pools, and riffles are identified as negative and positive deviations from a trend line representing the channel bed configuration. On the other hand, Knighton (1984) defines pools and riffles based on the "scale of distance" between the alternating deep sections (pools) and shallow sections (tiffles). He notes that these distinct features tend to occur at intervals approximately 5 to 7 times the width of the channel. In the upstream reaches, the average depth of pools is about 3 meters, and this depth nearly doubles to 5 meters in the immediate downstream section from the Barrage. Furthermore, the mean spacing between pools to pools and riffles to riffles in the upstream section is around 1500 m and 1700 m, respectively, with an average width of 413m.
The analysis of the cross-sectional variation of channel parameters demonstrates significant changes in river morphology downstream of the Barrage. These variations in channel depth, width, and cross-sectional area indicate potential impacts on river hydraulics and sediment transport. Understanding these morphological changes is crucial for effective river management, flood control, and ecosystem preservation. Proper management strategies should consider these findings to ensure the long-term sustainability of the river system. Further studies and field observations must validate and supplement these findings for more comprehensive river management and restoration efforts. Fig.5: A-Wetland development upstream left side from the Mahananda barrage. B-Formation is a permeant point bar from the upstream of the Barrage. C- Settlement expansion of the Near Active Channel. D- Teesta Mahananda canal is an example of channelization of the river.
The analysis of the cross-sectional variation of channel parameters demonstrates significant changes in river morphology downstream of the Barrage. These variations in channel depth, width, and cross-sectional area indicate potential impacts on river hydraulics and sediment transport. Understanding these morphological changes is crucial for effective river management, flood control, and ecosystem preservation. Proper management strategies should consider these findings to ensure the long-term sustainability of the river system. Further studies and field observations must validate and supplement these findings for more comprehensive river management and restoration efforts. Fig.5: A-Wetland development upstream left side from the Mahananda barrage. B-Formation is a permeant point bar from the upstream of the Barrage. C- Settlement expansion of the Near Active Channel. D- Teesta Mahananda canal is an example of channelization of the river.
Fig.6: A-Location of the Fulbari-Mahanada Barrage. B- A Bridge Constructed Downstream from the Barrage. C- A point bar formation Downstream from the Barrage
Fig.6: A-Location of the Fulbari-Mahanada Barrage. B- A Bridge Constructed Downstream from the Barrage. C- A point bar formation Downstream from the Barrage
Table -1: Key Characteristics of the Mahananda Barrage Table - 2: Temporal Changing Scenario of Braiding Index and Sinuosity Index of the Channel Reach under study
Table -1: Key Characteristics of the Mahananda Barrage Table - 2: Temporal Changing Scenario of Braiding Index and Sinuosity Index of the Channel Reach under study
Computed by the Authors
Computed by the Authors
Source: Field survey Computed by the Authors Table — 3: Channel Parameters of the Reach under study
Source: Field survey Computed by the Authors Table — 3: Channel Parameters of the Reach under study
Related topics:
Physical GeographyFluvial GeomorphologyHuman Impact on Environment
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