Identifying tree characteristics to determine the blocking effects of water conveyance for natural flood management in urban rivers

Abstract Plants, especially trees, provide ecological functions but may harm the flood conveyance efficiency of rivers. Understanding the impacts of tree heights, tree areas, and tree locations on flood levels is crucial for floodplain management. This study aims to present a methodology to improve...

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Autores principales:	Shang‐Shu Shih, Po‐Chih Chen
Formato:	article
Lenguaje:	EN
Publicado:	Wiley 2021
Materias:	blocked obstructions floodplains natural flood management unmanned aerial vehicle vegetation River protective works. Regulation. Flood control TC530-537 Disasters and engineering TA495
Acceso en línea:	https://doaj.org/article/f67aa5de94c0456eb402a0bfaba3c418
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spelling	oai:doaj.org-article:f67aa5de94c0456eb402a0bfaba3c4182021-11-11T05:32:09ZIdentifying tree characteristics to determine the blocking effects of water conveyance for natural flood management in urban rivers1753-318X10.1111/jfr3.12742https://doaj.org/article/f67aa5de94c0456eb402a0bfaba3c4182021-12-01T00:00:00Zhttps://doi.org/10.1111/jfr3.12742https://doaj.org/toc/1753-318XAbstract Plants, especially trees, provide ecological functions but may harm the flood conveyance efficiency of rivers. Understanding the impacts of tree heights, tree areas, and tree locations on flood levels is crucial for floodplain management. This study aims to present a methodology to improve the performance of hydrodynamic modeling by considering plant resistance with the goal of analyzing flood risk reduction strategies that support ecological conservation enhancement. An unmanned aerial vehicle was used to collect floodplain topography, landcover, and tree characteristic data. A modified maximum likelihood classification scheme was developed by incorporating the tree height information to improve the landcover classification. The water‐blocking effect of trees, which represents the reduced flood conveyance area, was investigated by establishing tree obstructions in hydrodynamic models. Two hydrodynamic models were established with different tree obstruction setups and Manning's n values, including blocked obstructions (BOs) and conventional high n‐values (Adj‐n). Among the model setups, the Manning's n values of the trees remained the same as that of the soil in the BO model, in which trees were modeled as blocking obstructions. The n‐values of trees were determined to be 0.022 in the BO model and refined to 0.055 in the Adj‐n model after the model calibration and verification processes. The results indicated that the simulated flood levels of the BO model were very similar to those of the Adj‐n model. The NSE values were 0.98 and 0.97 in the simulations of two historical typhoon events, indicating that the BO model could obtain reliable predictions without altering the n‐values. The verified BO model was used to evaluate the degrees of influence of tree heights, tree coverage areas, and tree locations on flood levels. Several nature‐based solutions were proposed to analyze the tradeoffs between reducing flood prevention and enhancing wetland restoration using the verified BO model, suggesting a win–win strategy for natural river management.Shang‐Shu ShihPo‐Chih ChenWileyarticleblocked obstructionsfloodplainsnatural flood managementunmanned aerial vehiclevegetationRiver protective works. Regulation. Flood controlTC530-537Disasters and engineeringTA495ENJournal of Flood Risk Management, Vol 14, Iss 4, Pp n/a-n/a (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	blocked obstructions floodplains natural flood management unmanned aerial vehicle vegetation River protective works. Regulation. Flood control TC530-537 Disasters and engineering TA495
spellingShingle	blocked obstructions floodplains natural flood management unmanned aerial vehicle vegetation River protective works. Regulation. Flood control TC530-537 Disasters and engineering TA495 Shang‐Shu Shih Po‐Chih Chen Identifying tree characteristics to determine the blocking effects of water conveyance for natural flood management in urban rivers
description	Abstract Plants, especially trees, provide ecological functions but may harm the flood conveyance efficiency of rivers. Understanding the impacts of tree heights, tree areas, and tree locations on flood levels is crucial for floodplain management. This study aims to present a methodology to improve the performance of hydrodynamic modeling by considering plant resistance with the goal of analyzing flood risk reduction strategies that support ecological conservation enhancement. An unmanned aerial vehicle was used to collect floodplain topography, landcover, and tree characteristic data. A modified maximum likelihood classification scheme was developed by incorporating the tree height information to improve the landcover classification. The water‐blocking effect of trees, which represents the reduced flood conveyance area, was investigated by establishing tree obstructions in hydrodynamic models. Two hydrodynamic models were established with different tree obstruction setups and Manning's n values, including blocked obstructions (BOs) and conventional high n‐values (Adj‐n). Among the model setups, the Manning's n values of the trees remained the same as that of the soil in the BO model, in which trees were modeled as blocking obstructions. The n‐values of trees were determined to be 0.022 in the BO model and refined to 0.055 in the Adj‐n model after the model calibration and verification processes. The results indicated that the simulated flood levels of the BO model were very similar to those of the Adj‐n model. The NSE values were 0.98 and 0.97 in the simulations of two historical typhoon events, indicating that the BO model could obtain reliable predictions without altering the n‐values. The verified BO model was used to evaluate the degrees of influence of tree heights, tree coverage areas, and tree locations on flood levels. Several nature‐based solutions were proposed to analyze the tradeoffs between reducing flood prevention and enhancing wetland restoration using the verified BO model, suggesting a win–win strategy for natural river management.
format	article
author	Shang‐Shu Shih Po‐Chih Chen
author_facet	Shang‐Shu Shih Po‐Chih Chen
author_sort	Shang‐Shu Shih
title	Identifying tree characteristics to determine the blocking effects of water conveyance for natural flood management in urban rivers
title_short	Identifying tree characteristics to determine the blocking effects of water conveyance for natural flood management in urban rivers
title_full	Identifying tree characteristics to determine the blocking effects of water conveyance for natural flood management in urban rivers
title_fullStr	Identifying tree characteristics to determine the blocking effects of water conveyance for natural flood management in urban rivers
title_full_unstemmed	Identifying tree characteristics to determine the blocking effects of water conveyance for natural flood management in urban rivers
title_sort	identifying tree characteristics to determine the blocking effects of water conveyance for natural flood management in urban rivers
publisher	Wiley
publishDate	2021
url	https://doaj.org/article/f67aa5de94c0456eb402a0bfaba3c418
work_keys_str_mv	AT shangshushih identifyingtreecharacteristicstodeterminetheblockingeffectsofwaterconveyancefornaturalfloodmanagementinurbanrivers AT pochihchen identifyingtreecharacteristicstodeterminetheblockingeffectsofwaterconveyancefornaturalfloodmanagementinurbanrivers
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Identifying tree characteristics to determine the blocking effects of water conveyance for natural flood management in urban rivers

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