Olga Silantyeva

• Burkhart, John; Matt, Felix Nikolaus; Helset, Sigbjørn; Abdella, Yisak Sultan; Skavhaug, Ola & Silantyeva, Olga (2021). Shyft v4.8: A Framework for Uncertainty Assessment and Distributed Hydrologic Modelling for Operational Hydrology . Geoscientific Model Development. ISSN 1991-959X. 14(2), s. 821–842. doi: 10.5194/gmd-14-821-2021. Fulltekst i vitenarkiv
• Bhattarai, Bikas Chandra; Silantyeva, Olga; Teweldebrhan, Aynom Tesfay; Helset, Sigbjørn; Skavhaug, Ola & Burkhart, John (2020). Impact of Catchment Discretization and Imputed Radiation on Model Response: A Case Study from Central Himalayan Catchment. Water. ISSN 2073-4441. 12( 9). doi: 10.3390/w12092339. Fulltekst i vitenarkiv

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• Silantyeva, Olga; Bhattarai, Bikas Chandra; Tallaksen, Lena M.; Burkhart, John Faulkner; Skavhaug, Ola & Helset, Sigbjørn (2021). Modeling Sensitivity To Mesh Size And Shape: A Case Study At Central Himalayan Catchment Revealing Importance Of Regional Dataset. Vis sammendrag

  The complex terrain, high seasonal variability, complexity in precipitation patterns and cold region hydrology at Budhi-Gandaki catchment in central Himalaya, Nepal, presents a challenge for hydrological modeling. Regional or local forcing data, especially with high spatial resolution is preferred over coarser global dataset. However, such data is not always available. The Budhi-Gandaki catchment is subject to significant hydropower development, so accurate discharge simulation is important. Shyft is a novel hydrologic modeling software for streamflow forecasting targeted for use in hydropower production environments and research (Burkhart et al, 2021). It allows easy manipulation with configurations, which is a great tool in decision-making processes in the power production chain. The new functionality of Shyft.hydrology allows capturing of detailed terrain topography using triangular irregular networks (tin) and “on the fly” slope and aspect correction of radiation forcing. We compare discharge simulations using two different forcing datasets: WFDEI global dataset (0.5o x 0.5o) and HI-AWARE regional dataset (5x5 km precipitation and temperature) in both a grid and tin-based configurations. Simulated discharge is compared to observed discharge for ten-year period (2000-2010) using two performance measures, Nash- Sutcliffe efficiency (NSE) and Kling-Gupta efficiency (KGE). We show that the regional dataset combined with a tin configuration performs better than using a rectangular grid resolution, both in terms of NSE and KGE. Furthermore, correcting radiation for slope and aspect at each cell improves the resultant NSE and KGE even more. However, for the global dataset a configuration based on tin performs worse than grid, which is partly attributed to the complexity of the precipitation distribution over the catchment area. One WFDEI grid cell covers the whole catchment, so it is only represented by one precipitation value, which does not allow the interpolation routines in the Shyft.hydrology to separate between windward and leeward areas. However, for less complex terrain and precipitation patterns, like in the Marsyangdi catchment, studied previously (Bhattarai et all, 2020), good results obtained even with the coarse resolution WFDEI dataset. Here introducing a tin configurations improved agreement between simulated and observed discharge as compared to using a rectangular grid. We conclude on the advantages of using a tin-based configurations for water planning in hydropower production in the region. This work contributes to LATICE (Land Atmosphere Interactions in Cold Environments) project at the University of Oslo Keywords: Central Himalaya; Budhi-Gandaki; Hi-AWARE; Shyft; TIN; Discharge simulation; References 1. Burkhart, J. F., Matt, F. N., Helset, S., Sultan Abdella, Y., Skavhaug, O., and Silantyeva, O.: Shyft v4.8: a framework for uncertainty assessment and distributed hydrologic modeling for operational hydrology, Geosci. Model Dev., 14, 821–842, https://doi.org/10.5194/gmd-14-821-2021, 2021. 2. Bhattarai, B. C., Silantyeva, O., Teweldebrhan, A. T., Helset, S., Skavhaug, O., and Burkhart, J. F.: Impact of Catchment Discretization and Imputed Radiation on Model Response: A Case Study from Central Himalayan Catchment, Water, 12, 2020.

• Silantyeva, Olga; Burkhart, John Faulkner; Bhattarai, Bikas Chandra; Skavhaug, Ola & Helset, Sigbjørn (2020). Operational hydrology in highly steep areas: evaluation of tin-based toolchain. Vis sammendrag

  Triangular Irregular Network (TIN) is known to be an efficient way to represent surface topog- raphy (Marsh et al. 2018). However, little attention has been given to assess direct benefits of the TIN-based terrain representation in operational hydrology. We connect Shyft-hydrology, a part of Shyft open-source project dedicated to distributed hydrologic modelling in operational environment, with Rasputin software intended for conversion of digital elevation models into simplified triangular meshes. Shyft is known for its high flexibility: the framework lets researcher test different function- ing hypothesis with very little programming effort. We implemented new routine in Shyft-hydrology, which allows translation of solar radiation onto inclined surfaces based on (Allen et al. 2006). Thus, Shyft and Rasputin is a unique toolchain to study impact of hillslope variations in solar radiation onto snowmelt, evapotranspiration and discharge simulation. We conducted several experiments on subcatchments of Narayani river located in Central Nepal. This area is known to be very steep, with meteorological stations, located mainly in the low-land. The re-analysis data for the area is coarse and prone to different kind of issues (Bhattarai et al 2020). The outcomes are promising: tin-based solution outperfoms regular grid, when running with Shyft-hydrology model most used in the operations. The new model with translated radiation also works well, giving us no decrease in performance of discharge simulations, but some more insights in snow modelling. We clearly see, what we expect from observations: sunny slopes melt earlier while shady ones keep snow for longer periods. Acknowledgments. This project contributes to LATICE (Land Atmosphere Interaction in Cold Environments) initiative at the University of Oslo. References Marsh, C. B., Spiteri, R. J., Pomeroy, J. W., and Wheater, H. S.: Multi-objective unstructured triangular mesh generation for use in hydro- logical and land surface models, Computers and Geo- sciences, 119, 4967, 2018. Richard G. Allen, Ricardo Trezza, and Masahiro Tasumi. Analytical integrated functions for daily solar radiation on slopes. Agricultural and Forest Meteorology, 139:5573, 2006. Bhattarai, B. C., Burkhart, J. F., Tallaksen, L. M., Xu, C.-Y., and Matt, F. N.: Evaluation of forcing datasets for hydropower inflow simulation in Nepal, Accepted for publication. Hydrology research, 2020 1

• Silantyeva, Olga; Burkhart, John; Tallaksen, Lena M.; Helset, Sigbjørn & Skavhaug, Ola (2019). Shyft - Hydrologic Forecasting Toolbox: current state and future work.
• Silantyeva, Olga; Tallaksen, Lena M.; Burkhart, John; Skavhaug, Ola & Helset, Sigbjørn (2019). Analysis on the added value of accounting for slope/aspect and shading effects in hydrologic simulations.
• Silantyeva, Olga; Tallaksen, Lena M. & Burkhart, John (2019). Understanding terrain topography impact on snowmelt at catchment scale.

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