Study on Backwater Effect Due to Polavaram Dam Project under Different Return Periods

Amarnath, C R; Thatikonda, Shashidhar

doi:10.3390/w12020576

Cited by 16 publications

(6 citation statements)

References 15 publications

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“…In general, it is seen that the reduced length of the rise effect is the result of the slope of the riverbed [11,12,13]. Where a large slope will affect the flow velocity.…”

Section: Discussionmentioning

confidence: 99%

Backwater flow analysis due to the construction of the check dam series on Aie Dingin River using HEC-RAS

Daoed

Sunaryo

Arsyad

2023

IOP Conf. Ser.: Earth Environ. Sci.

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River profiles with steep slopes and loose-grained soil types will easily be carried away by river currents. One way to reduce the sediment rate is by constructing a check dam or a series of check dams. However, the effect of a series of check dams can influence each other, due to backwater flow. On the one hand, it is advantageous because the flow velocity is reduced, but it will raise the water level downstream of the dam and increase the height of the embankments and ponds. Based on the foregoing, an analysis of the backwater flow was carried out using HEC-RAS. The results obtained are that water backflow occurs in two water structures, namely the Koto Tuo and Koto Pulai check dams. The backwater flow is quite long, almost reaching the previous check dam. Where the length of the backwater flow is only up to the final threshold and it is advisable to observe local sedimentation behavior due to backwater flow.

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“…In general, it is seen that the reduced length of the rise effect is the result of the slope of the riverbed [11,12,13]. Where a large slope will affect the flow velocity.…”

Section: Discussionmentioning

confidence: 99%

Backwater flow analysis due to the construction of the check dam series on Aie Dingin River using HEC-RAS

Daoed

Sunaryo

Arsyad

2023

IOP Conf. Ser.: Earth Environ. Sci.

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“…Existing methods to obtain backwater estimates in modern river systems are compiled from fourteen publications (Table 3) and are basically twofold; i) direct assessments of the intersection between riverbed and sea level, and ii) indirect estimate by obtaining input parameters river depth and slope and applying Lb = h/S with Lb is backwater length, h is river depth, and S is slope. Backwater effects are also commonly studied in the field of engineering (Csiki & Rhoads, 2010;Maselli et al, 2018;Liro, 2019;Liro et al, 2020;Amarnath & Thatikonda, 2020), where the backwater zone is a river section upstream of a river dam reservoir that is inundated during reservoir stages higher than the normal or average (Liro, 2019), characterized by backwater and drawdown surface water profiles associated with varying low-discharge and high-discharge events (Maselli et al, 2018). In this study, and particularly this section, we focus on backwater length estimates in coastal river systems and unrelated to river dams.…”

Section: Backwater Length Estimates In Modern River Systemsmentioning

confidence: 99%

Obtaining backwater length estimates in modern and ancient fluvio-deltaic settings: review and proposal of standardized workflows

van Yperen,

Holbrook,

Poyatos-Moré

et al. 2023

Preprint

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The backwater effect (i.e. channel flow influence by a body of standing water) is used to predict down-dip changes in fluvial morphodynamics and consequent sediment distribution on delta plains. These changes include downstream fining, decrease in sinuosity, and deepening and narrowing of channel belt deposits. This study reviews existing methods for estimating backwater length in ancient and modern settings and proposes workflows to minimize ambiguity in resultant estimates. The proposed workflows are tailored to both modern and ancient settings and are prioritized based on practicality, accuracy, smallest uncertainty ranges and allow different types of data as input parameters. In modern river systems, we recommend using direct field measurements of bankfull thalweg channel depth and river water elevation to determine the location where riverbed elevation intersects sea level (i.e. the upstream limit of the backwater zone). Alternatively, the backwater length (Lb) can be estimated indirectly by Lb = h/S, with h is bankfull thalweg channel depth and S is slope. In ancient settings, bankfull thalweg depth and grain size representative of bedload transport are the most reliably measurable parameters, obtained at one or a few locations. For the first time, the application of multiple methods to obtain backwater length estimates are tested on a single modern and ancient river system. In the modern case study, the riverbed intersection with sea level matches previously documented major changes in sedimentary trends, such as decreasing channel-belt width/thickness ratios, decreasing meander-bend migration rates, and coarsening grain size followed by distinct downstream fining. However, backwater lengths based on h/S plot downstream of this zone characterized by major changes, when input parameters are derived from discharge and grain size. Therefore, we recommend obtaining bankfull thalweg channel depth from a cross-sectional profile if backwater length is estimated based on h/S. In the ancient case study, bankfull thalweg channel depth derived from fully preserved single story channel fill and slope based on Shields’ empirical relation with grain size, match changes in fluvial architectural style interpreted as a result of backwater effects. Although uncertainty management is improved with the proposed workflows, a degree of uncertainty remains in the resulting backwater length estimates, due to inherent scatter in previously established relationships (e.g. Shields stress relation to obtain slope estimates). This review is a critical step forward in discussing the shortcomings, and listing and acknowledging the uncertainties and ambiguity in obtaining the necessary input parameters to estimate backwater lengths. The proposed workflows facilitate comparability and applicability of future backwater length estimates and their corresponding influence on the hydrodynamic environment and ultimately the stratigraphic record. Potential scaling relationships between the backwater length, sedimentary trends and avulsion nodes makes this of key importance as the latter two also play a crucial role in devastating floods when rivers change course.

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“…These uncertainties complicate the development of a bijective relationship of stage-discharge at hydrometric stations. In this context, the use of a single parametrization rating curve becomes inappropriate [19][20][21]. Consequently, flow measurement errors must then be minimized or the rating curve equation must absolutely be corrected [11].…”

Section: Conventional Flow Measurement Technique In the Presence Of I...mentioning

confidence: 99%

Analysis of the Capacity of a Double Rating Curve to Reproduce the Flows Measured by Doppler Fixed at the Bottom of an Ice Covered River

Eloumou¹,

Berenger²

2022

IJDNE

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The classic approach for estimating river flows is based on the use of a rating curve, which links the flow rates to the water heights measured at a gauging station. This simple approach, has practical and economic advantages but also has limitations related in part to the difficulty of obtaining a representative range of flows, particularly in the presence of ice cover. The objective of this study is to show how it is possible to improve the results obtained by a traditional rating curve using the validated measurements of the Acoustic Doppler Velocity Meter (ADVM) of the Argonaut SW (shallow water) Doppler obtained in continuous, in the presence of ice sheet. The proposed methodology consists in filtering and validating the height measurements provided by the standard gauge as well as the speed and height the measurements provided by the Doppler SW. The validated measurements are then split into two parts: The first part is used for the calibration of a double rating curve that links the series of validated levels obtained by the standard limnimeter, to the flow obtained from the Doppler SW. The second part is used to evaluate the capacity of the double rating curve obtained during the calibration, and to estimate the flow measured by the Doppler SW. The double rating curve thus calibrated reproduces the flow measured by the Doppler SW with an average deviation of 5.03%. In the presence of ice cover, this average difference is 7.68%. These results show the interest of a combined use of the Doppler SW and the double rating curve, for monitoring river flows under ice cover. The Doppler SW makes data available, necessary to calibrate a reliable rating curve, based on a wide range of flow variations covering the winter period.

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Study on Backwater Effect Due to Polavaram Dam Project under Different Return Periods

Cited by 16 publications

References 15 publications

Backwater flow analysis due to the construction of the check dam series on Aie Dingin River using HEC-RAS

Backwater flow analysis due to the construction of the check dam series on Aie Dingin River using HEC-RAS

Obtaining backwater length estimates in modern and ancient fluvio-deltaic settings: review and proposal of standardized workflows

Analysis of the Capacity of a Double Rating Curve to Reproduce the Flows Measured by Doppler Fixed at the Bottom of an Ice Covered River

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