Earth observation-based analysis of flood extent and impacts on land use and cover in the Cape Town Metropolitan Region, South Africa

IF 4.1 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

Physics and Chemistry of the Earth Pub Date : 2025-08-29 DOI:10.1016/j.pce.2025.104082

Sibuyisele S. Pakati , Cletah Shoko , Timothy Dube

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引用次数: 0

Abstract

This work leverages multi-source data spatial approach in mapping floods extents and their effect on key land use land cover in the Cape Town Metropolitan Region, for the 2023 period. Using the Google Earth Engine cloud computing platform, the study mapped flood extent through Sentinel-1 Synthetic Aperture Radar (SAR), and Sentinel 2- Multispectral Instrument (MSI) for landcover classification before and after a flood event. Landcover classification for the period before and after the flood occurrence were performed using the Random Forest (RF) algorithm. To assess the flood-affected categories, the pre-flood image was overlaid on the flood extent spatial layer. The research findings showed that the central and low-lying areas of the Metropolitan area were significantly affected by the floods. A total land area of about 2074 ha(ha) (84.30 %) was affected. Further results showed that floods mostly affected bare areas (32.64 % equivalent to 803.05 ha) and built-up (46.84 % equivalent to 1152.33 ha) areas. The affected built-up areas were mainly located in low-lying regions, near floodplains, and near water bodies. Overall, the findings of the study underscore the importance of spatially explicit techniques in flood mapping and informing early warning systems for disaster preparedness.

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南非开普敦大都市区洪水范围及其对土地利用和覆盖影响的地球观测分析

本工作利用多源数据空间方法绘制2023年开普敦大都市区洪水范围及其对主要土地利用和土地覆盖的影响。利用谷歌Earth Engine云计算平台，通过Sentinel-1合成孔径雷达（SAR）和Sentinel- 2多光谱仪（MSI）绘制洪水范围，进行洪水前后的土地覆盖分类。采用随机森林（Random Forest， RF）算法对洪涝前后的土地覆盖进行分类。为了评估洪水影响类别，将洪水前的图像叠加在洪水范围空间层上。研究结果表明，首都圈中部和低洼地区受洪水影响较大。受影响的土地面积约为2074公顷（84.30%）。进一步的结果表明，洪水主要影响裸地（32.64%，相当于803.05公顷）和建成区（46.84%，相当于1152.33公顷）。受影响的建成区主要位于低洼地区、洪泛平原附近和水体附近。总的来说，这项研究的结果强调了空间明确技术在洪水制图和为防灾预警系统提供信息方面的重要性。

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来源期刊

Physics and Chemistry of the Earth 地学-地球科学综合

CiteScore

5.40

自引率

2.70%

发文量

176

审稿时长

31.6 weeks

期刊介绍： Physics and Chemistry of the Earth is an international interdisciplinary journal for the rapid publication of collections of refereed communications in separate thematic issues, either stemming from scientific meetings, or, especially compiled for the occasion. There is no restriction on the length of articles published in the journal. Physics and Chemistry of the Earth incorporates the separate Parts A, B and C which existed until the end of 2001. Please note: the Editors are unable to consider submissions that are not invited or linked to a thematic issue. Please do not submit unsolicited papers. The journal covers the following subject areas: -Solid Earth and Geodesy: (geology, geochemistry, tectonophysics, seismology, volcanology, palaeomagnetism and rock magnetism, electromagnetism and potential fields, marine and environmental geosciences as well as geodesy). -Hydrology, Oceans and Atmosphere: (hydrology and water resources research, engineering and management, oceanography and oceanic chemistry, shelf, sea, lake and river sciences, meteorology and atmospheric sciences incl. chemistry as well as climatology and glaciology). -Solar-Terrestrial and Planetary Science: (solar, heliospheric and solar-planetary sciences, geology, geophysics and atmospheric sciences of planets, satellites and small bodies as well as cosmochemistry and exobiology).