TY - JOUR
T1 - Visualisation of flooding along an unvegetated, ephemeral river using Google Earth Engine
T2 - Implications for assessment of channel-floodplain dynamics in a time of rapid environmental change
AU - Li, Jiaguang
AU - Tooth, Stephen
AU - Zhang, Kun
AU - Zhao, Yang
N1 - Funding Information:
This research was supported by: the National Natural Science Foundation of China (No. 41972114, No. 41602121); the Wuhan Applied Foundational Frontier Project (No. 2020020601012281); the Fundamental Research Funds for the Central Universities, China University of Geosciences (Wuhan) (No. CUG150616); and Open Fund (TPR-2017-01) of Key Laboratory (Ministry of Education) of Tectonics and Petroleum Resources (China University of Geosciences, Wuhan, China). J.L. thanks colleagues Oswaldo Eduardo Ramos Ramos, Rafael Cortez, and students Edson Wilder Ramos Mendoza, Wilhelm Alex Mendizabal Cuevas, Samir Nikolar Pacheco, Erick Marcelo Cabero Caballero, Julian Franz Cortez Garvizu (all from Universidad Mayor de San Andrés) for the fieldwork arrangements and assistance near Salar de Uyuni in Bolivia. J.L. also thanks German Aerospace Center for the TanDEM-X data (Grant no. GEOL2320).
Funding Information:
This research was supported by: the National Natural Science Foundation of China (No. 41972114 , No. 41602121 ); the Wuhan Applied Foundational Frontier Project (No. 2020020601012281 ); the Fundamental Research Funds for the Central Universities , China University of Geosciences (Wuhan) (No. CUG150616 ); and Open Fund ( TPR-2017-01 ) of Key Laboratory ( Ministry of Education ) of Tectonics and Petroleum Resources ( China University of Geosciences, Wuhan , China). J.L. thanks colleagues Oswaldo Eduardo Ramos Ramos, Rafael Cortez, and students Edson Wilder Ramos Mendoza, Wilhelm Alex Mendizabal Cuevas, Samir Nikolar Pacheco, Erick Marcelo Cabero Caballero, Julian Franz Cortez Garvizu (all from Universidad Mayor de San Andrés) for the fieldwork arrangements and assistance near Salar de Uyuni in Bolivia. J.L. also thanks German Aerospace Center for the TanDEM-X data (Grant no. GEOL2320 ).
Publisher Copyright:
© 2020 Elsevier Ltd
PY - 2021/1/15
Y1 - 2021/1/15
N2 - Given rapid environmental change, the development of new, data-driven, interdisciplinary approaches is essential for improving assessment and management of river systems, especially with respect to flooding. In the world's extensive drylands, difficulties in obtaining field observations of major hydrological events mean that remote sensing techniques are commonly used to map river floods and assess flood impacts. Such techniques, however, are dependent on available cloud-free imagery during or immediately after peak discharge, and single images may omit important flood-related hydrogeomorphological events. Here, we combine multiple Landsat images from Google Earth Engine (GEE) with precipitation datasets and high-resolution (<0.65 m) satellite imagery to visualise flooding and assess the associated channel-floodplain dynamics along a 25 km reach of the unvegetated, ephemeral Río Colorado, Bolivia. After cloud and shadow removal, Landsat surface reflectance data were used to calculate the Modified Normalized Difference Water Index (MNDWI) and map flood extents and patterns. From 2004 through 2016, annual flooding area along the narrow (<30 m), shallow (<1.7 m), fine-grained (dominantly silt/clay) channels was positively correlated (R2 = 0.83) with 2-day maximum precipitation totals. Rapid meander bend migration, bank erosion, and frequent overbank flooding was associated with formation of crevasse channels, splays, and headward-eroding channels, and with avulsion (shifting of flow from one channel to another). These processes demonstrate ongoing, widespread channel-floodplain dynamics despite low stream powers and cohesive sediments. Application of our study approaches to other dryland rivers will help generate comparative data on the controls, rates, patterns and timescales of channel-floodplain dynamics under scenarios of climate change and direct human impacts, with potential implications for improved river management.
AB - Given rapid environmental change, the development of new, data-driven, interdisciplinary approaches is essential for improving assessment and management of river systems, especially with respect to flooding. In the world's extensive drylands, difficulties in obtaining field observations of major hydrological events mean that remote sensing techniques are commonly used to map river floods and assess flood impacts. Such techniques, however, are dependent on available cloud-free imagery during or immediately after peak discharge, and single images may omit important flood-related hydrogeomorphological events. Here, we combine multiple Landsat images from Google Earth Engine (GEE) with precipitation datasets and high-resolution (<0.65 m) satellite imagery to visualise flooding and assess the associated channel-floodplain dynamics along a 25 km reach of the unvegetated, ephemeral Río Colorado, Bolivia. After cloud and shadow removal, Landsat surface reflectance data were used to calculate the Modified Normalized Difference Water Index (MNDWI) and map flood extents and patterns. From 2004 through 2016, annual flooding area along the narrow (<30 m), shallow (<1.7 m), fine-grained (dominantly silt/clay) channels was positively correlated (R2 = 0.83) with 2-day maximum precipitation totals. Rapid meander bend migration, bank erosion, and frequent overbank flooding was associated with formation of crevasse channels, splays, and headward-eroding channels, and with avulsion (shifting of flow from one channel to another). These processes demonstrate ongoing, widespread channel-floodplain dynamics despite low stream powers and cohesive sediments. Application of our study approaches to other dryland rivers will help generate comparative data on the controls, rates, patterns and timescales of channel-floodplain dynamics under scenarios of climate change and direct human impacts, with potential implications for improved river management.
KW - Channel dynamics
KW - Flood mapping
KW - Floodplain
KW - Google Earth Engine
KW - Meandering river
KW - Unvegetated channel
KW - Hydrology
KW - Colorado
KW - Humans
KW - Agriculture
KW - Rivers
KW - Floods
UR - http://www.scopus.com/inward/record.url?scp=85094195515&partnerID=8YFLogxK
U2 - 10.1016/j.jenvman.2020.111559
DO - 10.1016/j.jenvman.2020.111559
M3 - Article
C2 - 33137686
AN - SCOPUS:85094195515
SN - 0301-4797
VL - 278
JO - Journal of Environmental Management
JF - Journal of Environmental Management
IS - Pt 2
M1 - 111559
ER -