Scott Watson, C. and Gyawali, Januka and Creed, Maggie and Elliott, John R. (2024) City-scale high-resolution flood models and the role of topographic data: a case study of Kathmandu, Nepal. Geocarto International, 39 (1): 2387073. ISSN 1010-6049
AI Summary:
The study evaluated the impact of topographic data source and resolution on flood model outputs. The results showed that high-resolution topographic data was necessary for accurate flood modeling, but physically complex flood models were not required.AI Topics:
Topographic data is a fundamental input to flood hazard models and controls the quality of the outputs. However, open-access global digital elevation models (DEMs) are dated and limited to 30 m resolution, which hinders modelling efforts in urban or topographically complex environments. We used the flood prone and expanding city of Kathmandu, Nepal, to evaluate the impact of topographic data source and resolution on flood model outputs. All DEMs evaluated featured spatially correlated topographic sinks with depths exceeding 20 m that required hydrological conditioning before being used in flood modelling. Incomplete hydrological conditioning appeared related to the overestimation of flood extent and therefore limited agreement when comparing a global 90 m resolution flood hazard model with a bespoke city-scale model at 10 m resolution (F1 score = 0.40). Instead, we found that the height above nearest drainage (HAND) metric was better able to replicate the higher resolution flood map as an indicator of flood susceptibility requiring only topographic information as an input. We also found that the computationally efficient FastFlood model was able to match the inundation extent (F1 score = 0.79) and flood depths (mean absolute error and root mean square error of 0.46 and 0.76 m respectively) of a published 10 m physics-based flood hazard model whilst requiring 212 times less computation time. Our analysis demonstrated that mapping city-scale flood inundation required hydrologically conditioned high-resolution topographic data but not physically complex flood models, highlighting the need for greater availability of high quality open access topographic data.
Scott Watson, C.
Author
Thapa, Saraswati and Sinclair, Hugh D. and Creed, Maggie J. and Mudd, Simon M. and Attal, Mikael and Borthwick, Alistair and Ghimire, Bhola N. and Scott Watson, C. (2024) The impact of sediment flux and calibre on flood risk in the Kathmandu Valley, Nepal. Earth Surface Processes and Landforms, 49 (2). pp. 706-727. ISSN 0197-9337
Scott Watson, C. and Gyawali, Januka and Creed, Maggie and Elliott, John R. (2024) City-scale high-resolution flood models and the role of topographic data: a case study of Kathmandu, Nepal. Geocarto International, 39 (1): 2387073. ISSN 1010-6049
Shrestha, Dibesh and Basnyat, Divas B. and Gyawali, Januka and Creed, Maggie J. and Sinclair, Hugh D. and Golding, Brian and Muthusamy, Manoranjan and Shrestha, Shankar and Scott Watson, C. and Subedi, Divya L. and Haiju, Rojina (2023) Rainfall extremes under future climate change with implications for urban flood risk in Kathmandu, Nepal. International Journal of Disaster Risk Reduction, 97: 103997. ISSN 2212-4209
See full publications listGyawali, Januka
Author
Scott Watson, C. and Gyawali, Januka and Creed, Maggie and Elliott, John R. (2024) City-scale high-resolution flood models and the role of topographic data: a case study of Kathmandu, Nepal. Geocarto International, 39 (1): 2387073. ISSN 1010-6049
Shrestha, Dibesh and Basnyat, Divas B. and Gyawali, Januka and Creed, Maggie J. and Sinclair, Hugh D. and Golding, Brian and Muthusamy, Manoranjan and Shrestha, Shankar and Scott Watson, C. and Subedi, Divya L. and Haiju, Rojina (2023) Rainfall extremes under future climate change with implications for urban flood risk in Kathmandu, Nepal. International Journal of Disaster Risk Reduction, 97: 103997. ISSN 2212-4209
See full publications listCreed, Maggie
Author
Thapa, Saraswati and Sinclair, Hugh D. and Creed, Maggie J. and Borthwick, Alistair and Watson, C. Scott and Muthusamy, Manoranjan (2024) Sediment transport and flood risk: impact of newly constructed embankments on river morphology and flood dynamics in Kathmandu, Nepal. Water Resources Research, 60 (10): e2024WR037. ISSN 1944-7973
Thapa, Saraswati and Sinclair, Hugh D. and Creed, Maggie J. and Mudd, Simon M. and Attal, Mikael and Borthwick, Alistair and Ghimire, Bhola N. and Scott Watson, C. (2024) The impact of sediment flux and calibre on flood risk in the Kathmandu Valley, Nepal. Earth Surface Processes and Landforms, 49 (2). pp. 706-727. ISSN 0197-9337
Scott Watson, C. and Gyawali, Januka and Creed, Maggie and Elliott, John R. (2024) City-scale high-resolution flood models and the role of topographic data: a case study of Kathmandu, Nepal. Geocarto International, 39 (1): 2387073. ISSN 1010-6049
See full publications listElliott, John R.
Author
Scott Watson, C. and Gyawali, Januka and Creed, Maggie and Elliott, John R. (2024) City-scale high-resolution flood models and the role of topographic data: a case study of Kathmandu, Nepal. Geocarto International, 39 (1): 2387073. ISSN 1010-6049
See full publications listAvailable under License Creative Commons Attribution.
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