Assessing the Benefits, Threats and Conservation of Reservoir‐Based Wetlands in the Eastern Himalayan River Basin

Ghosh, Kausik; Chakraborty, Poulomi

doi:10.1002/9781119692621.ch8

Cited by 4 publications

(3 citation statements)

References 49 publications

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“…Anthropogenic activities like dam operation and water diversion significantly perturb the seasonal variations of natural wet and dry channels. More than 13 run-of-the-river (RoR) cascading dams operate within the basin's upstream mountain zone, generating $3500 MW of hydroelectricity in different stages since 2003 (Figure 1; Ghosh & Chakraborty, 2021). Additionally, while the Gazaldoba Barrage for diverting water for irrigation was ready for operations in 1987, actual diversion began only after 1997.…”

Section: River Regulation In the Tista Basinmentioning

confidence: 99%

A new braiding index to assess river regulation effects in multi‐thread channels: Insights from a highly regulated Himalayan river

Ghosh,

Chakraborty,

Patel

2024

River Research & Apps

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River regulation by dams and embankments drastically reduce/alter flow, which affects the natural channel pattern. Existing braiding indices have seldom incorporated the effects of diurnal flow variations caused by hydropeaking, leading to over/underestimation of the braiding intensity. These indices consider only the visible wet channels, ignoring the existence of dry channels that are activated only episodically during phases of water release from hydropower dams. We have extracted the dry channels (those that are periodically wet) coursing across the channel belt of the highly regulated River Tista from Landsat images between 1977 and 2014, using Normalized Difference Wetness Index values. These were combined with existing wet channel widths and numbers to formulate the Regulated Braiding Index (RBi) for characterizing channel braiding in the Tista's course over the Himalayan foothill plains. Overall, the widths and numbers of wet channels decreased by 63% and 25%, respectively, during the regulated years (2003 and 2014) as compared to pre‐dam years (1977 and 1995) due to the collective operation of 14 upstream dams/barrages (having cumulative ~89 million m3 reservoir capacity), whose operations reduced the braiding intensity (eliciting lower RBi values). Further, the number of high braiding reaches decreased by half while low braiding stretches rose by 10% in comparison to the pre‐dam period due to reduced/regulated flow. Comparative analysis of derived RBi values with three existing braiding indices revealed that RBi values consistently decreased near barrages, bridges, and within embankment‐confined reaches, unlike the other indices, thus providing a better framework for assessing expected river regulation effects.

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Section: River Regulation In the Tista Basinmentioning

confidence: 99%

A new braiding index to assess river regulation effects in multi‐thread channels: Insights from a highly regulated Himalayan river

Ghosh,

Chakraborty,

Patel

2024

River Research & Apps

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“…The cumulative storage capacity of these reservoirs is estimated at around 81.42 Mm 3 (Ghosh & Chakraborty, 2021). Notably, two-thirds of the total RoR storage are held by TLDP III and IV dams (55.36 Mm 3 of the total RoR reservoir's capacity of 81.42 Mm 3 ).…”

Section: Intervention Structures In the River Basinmentioning

confidence: 99%

“…All the RoR dams (except Rangit III, which started construction around 1995) were constructed between 1998 and 2010, out of which 11 dams subsequently became functional after 2010 (Table S2). The cumulative storage capacity of these reservoirs is estimated at around 81.42 Mm 3 (Ghosh & Chakraborty, 2021). Notably, two‐thirds of the total RoR storage are held by TLDP III and IV dams (55.36 Mm 3 of the total RoR reservoir's capacity of 81.42 Mm 3 ).…”

Section: The Background Setting and Regulation Structuresmentioning

confidence: 99%

Impact of human intervention structures on the rivers: An investigation of the spatiotemporal variation of grain size in the Tista River, eastern Himalayas

Ghosh

Chakraborty

2022

Earth Surf Processes Landf

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In order to investigate the effect of intervention structures like dams and barrage on the sediment grain size distribution, we examined a $75 km stretch of the Tista River in the foothill alluvial plain of the eastern Himalayas. However, studies on the impact of dams on streamflow and sediment in the Himalayan rivers are constrained due to inadequate historical gauge data. Therefore, we employed a simple method to track the initial formation of some of the existing river landforms that formed before the dam/barrage operations from yearly satellite images for in situ sediment sample collection. Hence, the collected sediment grain sizes analysis is used here as a proxy to comprehend the pre-, syn-and post-dam river sediment-transport pattern. We have grouped 23 landforms into three temporal clusters: (i) those formed before 1997, earlier than the dams/barrage interventions (TOL); (ii) formed between 1998 and 2010 during the upstream dam construction (TML) and (iii) formed after 2010 (TNL) when upstream dams and the barrage were fully operational. A total of 116 sediment samples from these landforms indicate the overall grain size reduction for TML and TNL sediment due to reservoir sequestration of coarser grains. In comparison, the coarsest TOL sediment with downstream fining trend represents the pristine river condition. The coarsening trend with a poor correlation coefficient of TML is primarily assigned to partial trapping of the coarse bedload and massive sediment generation by the upstream under-construction dams, resulting in the downstream erosion of the riverbed and transport of the coarser bedload further down.Similarly, post-dam sediment trapping and controlled flow were responsible for the weaker trend with a distinctly finer size of TNL. The historical satellite images and data on streamflow and suspended sediment reveal that contemporary river behaviour is consistent with the earlier interpretation.

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Trend analysis of hydro-climatological parameters and assessment of climate impact on dam seepage using statistical and machine learning models

Ishfaque,

Dai,

Wahid

et al. 2023

Environ Earth Sci

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Assessing the Benefits, Threats and Conservation of Reservoir‐Based Wetlands in the Eastern Himalayan River Basin

Cited by 4 publications

References 49 publications

A new braiding index to assess river regulation effects in multi‐thread channels: Insights from a highly regulated Himalayan river

A new braiding index to assess river regulation effects in multi‐thread channels: Insights from a highly regulated Himalayan river

Impact of human intervention structures on the rivers: An investigation of the spatiotemporal variation of grain size in the Tista River, eastern Himalayas

Trend analysis of hydro-climatological parameters and assessment of climate impact on dam seepage using statistical and machine learning models

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