{"title":"Quantify water quality variation of urban river from hyperspectral images through ripple propagation network with spatially inconsecutive sampling","authors":"Yishan Zhang , Lun Wu","doi":"10.1016/j.ejrh.2025.102765","DOIUrl":null,"url":null,"abstract":"<div><div>Study region</div><div>Huangyang River, Zhuhai city, Guangdong province, China</div><div>Study focus</div><div>High-quality water environment is indispensable to industrial and agricultural advancement. Present methods predicted concentrations of various water quality parameters (WQPs) using their individual models, which suffered calculation instability on various WQPs and needed spatially successive water sampling covering the entire monitoring area to keep calculation accuracy. This study proposed a feature interaction ripple network (FIRN) to retrieve concentrations of WQPs including total phosphorus (TP), total nitrogen (TN), chlorophyll a (Chl-a), chemical oxygen demand (COD), biochemical oxygen demand (BOD), and total suspended solids (TSS). FIRN reduced dependence of prediction accuracy on spatial continuity of water sampling and the amount of training samples. All above WQPs were quantified in a unified framework from unmanned aerial vehicle (UAV) hyperspectral images, where sampled and unsampled regions were correlated through information sharing and delivery.</div><div>New hydrological insights for the region</div><div>Spatial distributions of various WQPs concentrations of Huangyang River in 2024 were visualized by FIRN, where the water quality degraded from 03/2024 to 06/2024 and improved from 06/2024 to 09/2024 with respect to the average WQPs concentrations. Multi-aspect analysis of impact by environmental factors including temperature, daylength, precipitation, and PM2.5 upon water quality was conducted, elucidating the correlation among environmental factors and spatial distributions of WQPs. Spatial distribution visualization of WQPs concentrations indicated locations of potential contamination sources in different time periods. The proposed method was applied to monitor variation of water quality of Huangyang River over time, laying theoretical and technical foundation to formulate water environment management scheme of urban rivers. Experimental results showed that the best mean absolute percent error (MAPE) and coefficient of determination (<span><math><msup><mrow><mi>R</mi></mrow><mrow><mn>2</mn></mrow></msup></math></span>) of FIRN were 7.85% and 0.96 respectively.</div></div>","PeriodicalId":48620,"journal":{"name":"Journal of Hydrology-Regional Studies","volume":"62 ","pages":"Article 102765"},"PeriodicalIF":5.0000,"publicationDate":"2025-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Hydrology-Regional Studies","FirstCategoryId":"89","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S2214581825005944","RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"WATER RESOURCES","Score":null,"Total":0}
引用次数: 0
Abstract
Study region
Huangyang River, Zhuhai city, Guangdong province, China
Study focus
High-quality water environment is indispensable to industrial and agricultural advancement. Present methods predicted concentrations of various water quality parameters (WQPs) using their individual models, which suffered calculation instability on various WQPs and needed spatially successive water sampling covering the entire monitoring area to keep calculation accuracy. This study proposed a feature interaction ripple network (FIRN) to retrieve concentrations of WQPs including total phosphorus (TP), total nitrogen (TN), chlorophyll a (Chl-a), chemical oxygen demand (COD), biochemical oxygen demand (BOD), and total suspended solids (TSS). FIRN reduced dependence of prediction accuracy on spatial continuity of water sampling and the amount of training samples. All above WQPs were quantified in a unified framework from unmanned aerial vehicle (UAV) hyperspectral images, where sampled and unsampled regions were correlated through information sharing and delivery.
New hydrological insights for the region
Spatial distributions of various WQPs concentrations of Huangyang River in 2024 were visualized by FIRN, where the water quality degraded from 03/2024 to 06/2024 and improved from 06/2024 to 09/2024 with respect to the average WQPs concentrations. Multi-aspect analysis of impact by environmental factors including temperature, daylength, precipitation, and PM2.5 upon water quality was conducted, elucidating the correlation among environmental factors and spatial distributions of WQPs. Spatial distribution visualization of WQPs concentrations indicated locations of potential contamination sources in different time periods. The proposed method was applied to monitor variation of water quality of Huangyang River over time, laying theoretical and technical foundation to formulate water environment management scheme of urban rivers. Experimental results showed that the best mean absolute percent error (MAPE) and coefficient of determination () of FIRN were 7.85% and 0.96 respectively.
期刊介绍:
Journal of Hydrology: Regional Studies publishes original research papers enhancing the science of hydrology and aiming at region-specific problems, past and future conditions, analysis, review and solutions. The journal particularly welcomes research papers that deliver new insights into region-specific hydrological processes and responses to changing conditions, as well as contributions that incorporate interdisciplinarity and translational science.