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Accuracy assessment of water level and river discharge estimates from SWOT satellite observations for major Polish rivers

Staszak, Maciej LU (2026) In Student thesis series INES NGEM21 20261
Department of Earth and Environmental Sciences (MGeo)
Abstract
River water levels and river discharge are key hydrological variables for flood risk assessment, water resource management, drought monitoring and climate change research. However, in-situ river measurements are lacking, and globally many rivers remain ungauged. Satellite altimetry offers an alternative approach to water surface measurement by providing river observations from space. The Surface Water and Ocean Topography (SWOT) satellite mission, launched in 2022, shows a major step forward in this matter, providing spatial coverage of accurate global river water levels and discharge estimates. This Master thesis compares the accuracy of river water surface elevation (WSE) and discharge measurements from the SWOT satellite mission for... (More)
River water levels and river discharge are key hydrological variables for flood risk assessment, water resource management, drought monitoring and climate change research. However, in-situ river measurements are lacking, and globally many rivers remain ungauged. Satellite altimetry offers an alternative approach to water surface measurement by providing river observations from space. The Surface Water and Ocean Topography (SWOT) satellite mission, launched in 2022, shows a major step forward in this matter, providing spatial coverage of accurate global river water levels and discharge estimates. This Master thesis compares the accuracy of river water surface elevation (WSE) and discharge measurements from the SWOT satellite mission for gauges on five major Polish rivers (Vistula, Oder, Warta, Bug and Narew). Accuracy is evaluated using Root Mean Square (RMSE), WRMSE (Weighted Root Mean Square Error) and Spearman correlation against in-situ gauge data for WSE and using RMSE and Spearman correlation for discharge. Water level measurements from SWOT are also compared with measurements from DAHITI altimetry database. Final results show that bias-corrected SWOT measurements achieve high accuracy for both water level and discharge with median WRMSE = 0.3 m for water level and median R = 0.94 for river discharge. Nevertheless, measurements of both water level and discharge contain outliers and biases that have to be taken into consideration. Due to limited temporal resolution, SWOT measurements cannot replace in-situ gauge data, but the spatial coverage of SWOT data offers potential for further studies, especially on narrower, ungauged rivers. (Less)
Abstract (Polish)
Poziomy wód i przepływy rzeczne stanowią kluczowe zmienne hydrologiczne wykorzystywane w ocenie ryzyka powodziowego, zarządzaniu zasobami wodnymi, monitorowaniu suszy oraz badaniach nad zmianami klimatu. Jednak tradycyjne pomiary rzeczne są niewystarczające, a globalnie wiele rzek nie posiada stacji pomiarowych. Altymetria satelitarna oferuje alternatywne podejście do pomiaru poziomu wody, umożliwiając obserwacje rzek z kosmosu. Misja satelitarna Surface Water and Ocean Topography (SWOT), rozpoczęta w 2022 roku, stanowi znaczący krok naprzód w tej dziedzinie, zapewniając przestrzenne pokrycie dokładnymi, globalnymi danymi o poziomach wód rzecznych i szacunkowych przepływach. Niniejsza praca magisterska porównuje dokładność pomiarów rzędnej... (More)
Poziomy wód i przepływy rzeczne stanowią kluczowe zmienne hydrologiczne wykorzystywane w ocenie ryzyka powodziowego, zarządzaniu zasobami wodnymi, monitorowaniu suszy oraz badaniach nad zmianami klimatu. Jednak tradycyjne pomiary rzeczne są niewystarczające, a globalnie wiele rzek nie posiada stacji pomiarowych. Altymetria satelitarna oferuje alternatywne podejście do pomiaru poziomu wody, umożliwiając obserwacje rzek z kosmosu. Misja satelitarna Surface Water and Ocean Topography (SWOT), rozpoczęta w 2022 roku, stanowi znaczący krok naprzód w tej dziedzinie, zapewniając przestrzenne pokrycie dokładnymi, globalnymi danymi o poziomach wód rzecznych i szacunkowych przepływach. Niniejsza praca magisterska porównuje dokładność pomiarów rzędnej zwierciadła wody (WSE) oraz przepływów rzek uzyskanych z misji satelitarnej SWOT z danymi z posterunków wodowskazowych na pięciu głównych rzekach polskich (Wisła, Odra, Warta, Bug i Narew). Dokładność oceniana jest przy użyciu wskaźników RMSE, WRMSE (Weighted Root Mean Square Error) oraz korelacji Spearmana w odniesieniu do naziemnych danych wodowskazowych dla WSE, a także przy użyciu RMSE i korelacji Spearmana dla przepływów. Pomiary poziomu wody z SWOT są również porównywane z pomiarami z bazy danych altymetrycznych DAHITI. Wyniki pokazują, że skorygowane o błąd systematyczny (bias) pomiary SWOT osiągają wysoką dokładność zarówno dla poziomu wody, jak i przepływu, z medianą WRMSE = 0.3 m oraz medianą korelacji przepływów R = 0.94. Niemniej jednak pomiary obu zmiennych zawierają wartości odstające i błędy systematyczne, które należy brać pod uwagę. Ze względu na ograniczoną rozdzielczość czasową pomiary SWOT nie mogą zastąpić naziemnych danych wodowskazowych, jednak zasięg przestrzenny danych SWOT stwarza możliwości dalszych badań, szczególnie na węższych, pozbawionych posterunków pomiarowych rzekach. (Less)
Popular Abstract
River water levels and river discharge (that is, the amount of water flowing through a river at a given time) are key variables for flood risk assessment, water resource management, drought monitoring and studying climate change. However, traditional ground-based river measurements are lacking, and globally many rivers remain unmonitored. Satellites offer an alternative approach to water surface measurement by providing river observations from space. The Surface Water and Ocean Topography (SWOT) satellite mission, launched in 2022, shows a major step forward in this matter, providing spatial coverage of accurate global river water levels and discharge estimates. This thesis compares the accuracy of river water surface elevation (WSE) and... (More)
River water levels and river discharge (that is, the amount of water flowing through a river at a given time) are key variables for flood risk assessment, water resource management, drought monitoring and studying climate change. However, traditional ground-based river measurements are lacking, and globally many rivers remain unmonitored. Satellites offer an alternative approach to water surface measurement by providing river observations from space. The Surface Water and Ocean Topography (SWOT) satellite mission, launched in 2022, shows a major step forward in this matter, providing spatial coverage of accurate global river water levels and discharge estimates. This thesis compares the accuracy of river water surface elevation (WSE) and discharge measurements from the SWOT satellite mission for measuring stations on five major rivers in Poland (Vistula, Oder, Warta, Bug and Narew). Accuracy is evaluated using Root Mean Square (RMSE), WRMSE (Weighted Root Mean Square Error) and Spearman correlation against real measured data for WSE and using RMSE and Spearman correlation for discharge. Water level measurements from SWOT are also compared with measurements from DAHITI, different existing satellite database. Final results show that SWOT measurements after minor corrections achieve high accuracy for both water level and discharge with median WRMSE = 0.3 m for water level and median R = 0.94 for river discharge. Nevertheless, measurements of both water level and discharge contain errors that have to be taken into consideration. Because SWOT overpasses the same location only every 10 to 21 days, SWOT measurements cannot replace ground-based river measurements, but the spatial coverage of SWOT data offers potential for further studies, especially on narrower rivers that remain unmonitored. (Less)
Please use this url to cite or link to this publication:
author
Staszak, Maciej LU
supervisor
organization
course
NGEM21 20261
year
type
H2 - Master's Degree (Two Years)
subject
keywords
SWOT, river discharge, satellite altimetry, WSE
publication/series
Student thesis series INES
report number
771
language
English
id
9247562
date added to LUP
2026-07-31 11:02:02
date last changed
2026-07-31 11:02:02
@misc{9247562,
  abstract     = {{River water levels and river discharge are key hydrological variables for flood risk assessment, water resource management, drought monitoring and climate change research. However, in-situ river measurements are lacking, and globally many rivers remain ungauged. Satellite altimetry offers an alternative approach to water surface measurement by providing river observations from space. The Surface Water and Ocean Topography (SWOT) satellite mission, launched in 2022, shows a major step forward in this matter, providing spatial coverage of accurate global river water levels and discharge estimates. This Master thesis compares the accuracy of river water surface elevation (WSE) and discharge measurements from the SWOT satellite mission for gauges on five major Polish rivers (Vistula, Oder, Warta, Bug and Narew). Accuracy is evaluated using Root Mean Square (RMSE), WRMSE (Weighted Root Mean Square Error) and Spearman correlation against in-situ gauge data for WSE and using RMSE and Spearman correlation for discharge. Water level measurements from SWOT are also compared with measurements from DAHITI altimetry database. Final results show that bias-corrected SWOT measurements achieve high accuracy for both water level and discharge with median WRMSE = 0.3 m for water level and median R = 0.94 for river discharge. Nevertheless, measurements of both water level and discharge contain outliers and biases that have to be taken into consideration. Due to limited temporal resolution, SWOT measurements cannot replace in-situ gauge data, but the spatial coverage of SWOT data offers potential for further studies, especially on narrower, ungauged rivers.}},
  author       = {{Staszak, Maciej}},
  language     = {{eng}},
  note         = {{Student Paper}},
  series       = {{Student thesis series INES}},
  title        = {{Accuracy assessment of water level and river discharge estimates from SWOT satellite observations for major Polish rivers}},
  year         = {{2026}},
}