Sediment removal from run-of-the-river hydropower reservoirs by hydraulic flushing

ABSTRACT

The concept of sustainable development is gaining popularity and hydroelectric projects designed and operated on this concept require sediment management as prime design criteria. Drawdown flushing is being practised in such projects for sediment management. Investigations using hydraulic models are required for the projects to address the site-specific design concerns. In the present study, simulations conducted using hydraulic model for sediment removal by drawdown flushing of the reservoir of Punatsangchhu hydroelectric project, Bhutan, is presented. The experiments on 1:100 geometrically similar scale model indicated that flushing is effective in maintaining the power intake area clear of sediment deposition. Deposition from the upstream reaches could not be flushed hydraulically. Furthermore, based on wide range of experimental data from hydraulic model studies, empirical equations have been developed for predicting the quantity of sediment that can be flushed from the reservoirs. The present equations have been developed including more parameters than those used in equations already available in literature. Two equations have been developed for different riverbed slope ranges with steep slope (0.005–0.04) and moderate slope (0.001–0.005). The equations developed were validated against different sets of data and it indicated that the predictions could be made within reasonable accuracy. These equations can be effectively used for hydraulic design of sediment removal from run-of-the-river hydropower reservoirs.

KEYWORDS:

• Empirical equation
• hydraulic flushing
• hydraulic models
• one-dimensional models
• run-of-the-river hydropower project
• reservoir sedimentation

Acknowledgements

The authors acknowledge with thanks the permission given by Dr (Mrs) V. V. Bhosekar Director-In-Charge, CWPRS, Pune, India, for publishing the paper and using the data. The contribution and support from various organizations such as NHPC LTD. India, SJVN LTD., India MHPA, Bhutan and PHPA Bhutan for sponsoring the studies at CWPRS is also thankfully acknowledged. Authors are also thankful to the officers and staff members of Sediment Management division and River Engineering Group of CWPRS: Shri. P. S. Kunjeer Scientist-C, Shri. P. D. Patil, Shri. S. A. Kamble, and Mrs Harsha P. Chaudhary (Scientist-B) and Mrs Snehal B. Tayade, and Shri. F. D. Momin (Assistant Research Officers), for their support in conducting the model studies. The contributions of Shri. V. K. Kulkarni, Shri. K. N. Appukuttan and Shri. P. V. Awate, former officers of sediment management division of CWPRS is greatly acknowledged. The authors express their sincere gratitude to the Editors and Reviewers for their critical comments, which helped to improve the manuscript significantly.

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

T. I. Eldho http://orcid.org/0000-0003-4883-3792