A machine learning based estimation method of beach slopes at a national scale: a case study of New Zealand

Beach slope is a critical parameter for understanding coastal geomorphological dynamics, yet the acquisition of comprehensive datasets at large scales remains a significant challenge. This study bridges this gap by presenting a novel methodology for estimating beach slopes across New Zealand’s sandy...

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Main Authors: Hao Xu, Nan Xu, Chi Zhang, Shanhang Chi, Yuan Li, Wenyu Li, Yifu Ou, Jiaqi Yao, Han-Su Zhang, Fan Mo, Hui Lu
Format: Article
Language:English
Published: Taylor & Francis Group 2025-07-01
Series:Geo-spatial Information Science
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Online Access:https://www.tandfonline.com/doi/10.1080/10095020.2025.2522142
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author Hao Xu
Nan Xu
Chi Zhang
Shanhang Chi
Yuan Li
Wenyu Li
Yifu Ou
Jiaqi Yao
Han-Su Zhang
Fan Mo
Hui Lu
author_facet Hao Xu
Nan Xu
Chi Zhang
Shanhang Chi
Yuan Li
Wenyu Li
Yifu Ou
Jiaqi Yao
Han-Su Zhang
Fan Mo
Hui Lu
author_sort Hao Xu
collection DOAJ
description Beach slope is a critical parameter for understanding coastal geomorphological dynamics, yet the acquisition of comprehensive datasets at large scales remains a significant challenge. This study bridges this gap by presenting a novel methodology for estimating beach slopes across New Zealand’s sandy coastlines. We developed robust coastal slope estimation models for sandy beaches by integrating 12 environmental factors with high-precision LiDAR-derived slope data, employing four machine learning regression techniques: Random Forest (RF), Gradient Boosting Decision Tree (GBDT), eXtreme Gradient Boosting (XGBoost), and Category Boosting (CatBoost). These models were trained on datasets from 1,241 beaches with LiDAR-derived Digital Elevation Models (DEMs) and subsequently applied to predict coastal slopes for an additional 509 beaches lacking LiDAR data. The results reveal that the XGBoost model outperformed the others, achieving the highest accuracy with an R2 of 0.93 and an MAE of 0.02, demonstrating the effectiveness of machine learning in coastal slope estimation. This innovative approach, leveraging DEM datasets and environmental variables, provides a robust and cost-effective tool for estimating coastal slopes across global sandy beaches compared to high-cost field measurement methods. We also emphasized that our method can estimate beach slopes for beaches without topography data based on constructed machine learning methods and environmental factors. Future studies should focus on incorporating additional environmental covariates, and extending the model’s applicability to diverse coastal environments, thereby enhancing its predictive accuracy and utility, supporting sustainable coastal development worldwide.
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spelling doaj-art-1209fea4c75a47bc807440da3eafed0a2025-08-20T03:28:58ZengTaylor & Francis GroupGeo-spatial Information Science1009-50201993-51532025-07-0112010.1080/10095020.2025.2522142A machine learning based estimation method of beach slopes at a national scale: a case study of New ZealandHao Xu0Nan Xu1Chi Zhang2Shanhang Chi3Yuan Li4Wenyu Li5Yifu Ou6Jiaqi Yao7Han-Su Zhang8Fan Mo9Hui Lu10School of Earth Sciences and Engineering, Hohai University, Nanjing, ChinaSchool of Earth Sciences and Engineering, Hohai University, Nanjing, ChinaThe National Key Laboratory of Water Disaster Prevention, Hohai University, Nanjing, ChinaThe National Key Laboratory of Water Disaster Prevention, Hohai University, Nanjing, ChinaThe National Key Laboratory of Water Disaster Prevention, Hohai University, Nanjing, ChinaDepartment of Geography and Planning, University of Toronto, Toronto, ON, CanadaDepartment of Geography, Hong Kong Baptist University, Hong Kong, ChinaAcademy of Ecological Civilization Development for JING-JIN-JI Megalopolis, Tianjin Normal University, Tianjin, ChinaSchool of Artificial Intelligence and Information Technology, Nanjing University of Chinese Medicine, Nanjing, ChinaLand Satellite Remote Sensing Application Center (LASAC), Ministry of Natural Resources of PR China, Beijing, ChinaDepartment of Earth System Science, Institute for Global Change Studies, State Key Laboratory of Hydroscience and Engineering, Tsinghua University, Beijing, ChinaBeach slope is a critical parameter for understanding coastal geomorphological dynamics, yet the acquisition of comprehensive datasets at large scales remains a significant challenge. This study bridges this gap by presenting a novel methodology for estimating beach slopes across New Zealand’s sandy coastlines. We developed robust coastal slope estimation models for sandy beaches by integrating 12 environmental factors with high-precision LiDAR-derived slope data, employing four machine learning regression techniques: Random Forest (RF), Gradient Boosting Decision Tree (GBDT), eXtreme Gradient Boosting (XGBoost), and Category Boosting (CatBoost). These models were trained on datasets from 1,241 beaches with LiDAR-derived Digital Elevation Models (DEMs) and subsequently applied to predict coastal slopes for an additional 509 beaches lacking LiDAR data. The results reveal that the XGBoost model outperformed the others, achieving the highest accuracy with an R2 of 0.93 and an MAE of 0.02, demonstrating the effectiveness of machine learning in coastal slope estimation. This innovative approach, leveraging DEM datasets and environmental variables, provides a robust and cost-effective tool for estimating coastal slopes across global sandy beaches compared to high-cost field measurement methods. We also emphasized that our method can estimate beach slopes for beaches without topography data based on constructed machine learning methods and environmental factors. Future studies should focus on incorporating additional environmental covariates, and extending the model’s applicability to diverse coastal environments, thereby enhancing its predictive accuracy and utility, supporting sustainable coastal development worldwide.https://www.tandfonline.com/doi/10.1080/10095020.2025.2522142Beachcoastal slopeLiDARmachine learningsea level rise
spellingShingle Hao Xu
Nan Xu
Chi Zhang
Shanhang Chi
Yuan Li
Wenyu Li
Yifu Ou
Jiaqi Yao
Han-Su Zhang
Fan Mo
Hui Lu
A machine learning based estimation method of beach slopes at a national scale: a case study of New Zealand
Geo-spatial Information Science
Beach
coastal slope
LiDAR
machine learning
sea level rise
title A machine learning based estimation method of beach slopes at a national scale: a case study of New Zealand
title_full A machine learning based estimation method of beach slopes at a national scale: a case study of New Zealand
title_fullStr A machine learning based estimation method of beach slopes at a national scale: a case study of New Zealand
title_full_unstemmed A machine learning based estimation method of beach slopes at a national scale: a case study of New Zealand
title_short A machine learning based estimation method of beach slopes at a national scale: a case study of New Zealand
title_sort machine learning based estimation method of beach slopes at a national scale a case study of new zealand
topic Beach
coastal slope
LiDAR
machine learning
sea level rise
url https://www.tandfonline.com/doi/10.1080/10095020.2025.2522142
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