| Sediment management


Right: Figure 4: The Banja Reservoir in Albania is one of the project case studies (c/ Statkraft)


sustainability of development plans that signify an important contribution to the hydropower industry, where at present some 3700 dams (≥1MW) are either planned or under construction worldwide7


. With HYPOS, many activities required from


hydropower plant operators can be simplified, including the identification of sediment baselines and seasonal trends, monitoring of sediment dynamics, calculation of sedimentation rates and flows, and the monitoring of algal bloom evolution in reservoirs. Current satellite- based parameters included in the HYPOS portal are: ● Turbidity [NTU] ● Total Suspended Solids (after calibration with turbidity) [mg/l]


● Chlorophyll-a [µg/l] ● Surface water temperature [°C] ● Secchi disk depth (visibility) [m] Another satellite-derived parameter that can make water managers more aware of water consumption is the estimation of water evaporated from reservoirs. This parameter, coupled with the energy demand of downstream populations, can help in the decision of best withdrawal times and make water management more efficient.


In addition, direct environmental impact changes,


ie resulting from prevention and mitigation counter- measures such as flushing and/or dredging, can be monitored for adaptive planning purposes. The HYPOS solution thus signifies a game changer for the industry, enabling strategic hydropower planning so rarely applied to-date on basin scales, despite studies demonstrating that the strategic planning and operation of dams can greatly improve trade-offs between dam impacts and benefits for sub-basins8


.


Tested on European rivers To date, the HYPOS portal has been tested on four


reservoirs and rivers in Switzerland, Albania and Georgia (see Figure 4), and will go global in 2022, with the official launch of the HYPOS portal expected in April. In Switzerland, the tool is being tested in two cases, Gebidem Dam and hydropower plant (Gebidem), as well as for the Verbois, Chancy-Pougny and Génissiat hydropower plant cascade (Rhône). For Gebidem, annual flushing is required in order to manage the sediment load, requiring the owner/operator to closely monitor sedimentation of the reservoir. The HYPOS tool will be used to identify the sources of sediment, support the monitoring of sedimentation levels, and for documenting changes in longitudinal river water quality (up- and downstream of the dam). Similarly, for the Rhone case study, sedimentation levels are currently subject to continuous monitoring, where HYPOS services will be used to monitor sediment dynamics up- and downstream of the confluence of the Arve and Rhone rivers, as well as up- and downstream of the two dams. In addition, the spatio-temporal impacts of flushing can be monitored using HYPOS services and enable a more


Right: Figure 5: Turbidity dynamics in Banja Reservoir, Albania - based on high-resolution satellite images (c/ HYPOS)


www.waterpowermagazine.com | January 2022 | 27


holistic and strategic operation of the dam for improving environmental impact assessments. The Enguri and Vardnili Dam and hydropower plant cascade in Georgia represents another key use case for demonstrating HYPOS capabilities. Bathymetric surveys conducted by Stucky have shown that sediment accumulations levels in front of the dam are exceeding the sills of the low-level outlets. HYPOS will be used to determine the baseline sedimentation levels in this basin, and to provide continuous monitoring of these levels for ensuring that proper countermeasures are taken in a timely fashion, also in the event of flooding. Finally, the Banja Dam and hydropower plant located in Albania, has used HYPOS services to support the planning of an additional hydropower plant in the catchment. The HYPOS tool will additionally be used to calculate sedimentation rates for the Banja reservoir.


Get involved


On 15 December 2021, the HYPOS tool was introduced to hydropower stakeholders, demonstrating the increased accuracy and more comprehensive view on reservoirs and river catchments made possible through the portal. Additional webinars are planned in February and April 2022, where the latter represents the formal launch of the tool with its full suite of capabilities. ●


For more information about the HYPOs project, please visit https://hypos-project.eu/ or send an email to contact@hypos-project.eu.


Author details:


Ursula McKnight, Project Manager at SMHI (ursula.mcknight@smhi.se)


Fabian von Trentini, Project Manager at EOMAP (trentini@eomap.de)


Erica Matta, Research Fellow at CNR IREA (matta.e@irea.cnr.it)


References


[1] IHA (International Hydropower Association), 2020 Hydropower Status Report: Sector trends and insights. International Hydropower Association Limited. Accessed online [6 December 2021]: https://www.hydropower. org/publications/2020- hydropower-status-report.


[2] Zarfl, C.; Lucia, A., 2018. The connectivity between soil erosion and sediment entrapment in reservoirs. Current Opinion in Environmental Science & Health 5, 53-59.


[3] Schleiss, A.; Franca, M.J.; Juez, C.; De Cesare, G.; 2016. Reservoir Sedimentation. Journal of Hydraulic Research 54, 595-614.


[4] Peters, R.; Berlekamp, J.; Lucia, A.; Stefani, V.; Tockner, K.; Zarfl, C., 2021. Integrated impact assessment for sustainable hydropower planning in the Vjosa Catchment (Greece, Albania). Sustainability 13, 1514.


[5] Basson, G.R., 2009. Management of siltation in existing and new reservoirs. General Report Q. 89. Proc. of the 23rd Congress of the Int. Commission on Large Dams CIGB-ICOLD (vol. 2).


[6] Berg, P.; Donnelly, C.; Gustafsson, D., 2018. Near-real- time adjusted reanalysis forcing data for hydrology. Hydrology and Earth System Sciences 22, 989-1000.


[7] Zarfl, C.; Lumsdon, A.E.; Berlekamp, J.; Tydecks, L.; Tockner, K., 2015. A global boom in hydropower dam construction. Aquatic Sciences 77, 161–170.


[8] Schmitt, R.J.P.; Bizzi, S.; Castelletti, A.; Opperman, J.J.; Kondolf, G.M. 2019. Planning dam portfolios for low sediment trapping shows limits for sustainable hydropower in the Mekong. Science Advances 5: eeaw2175.


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