TY - JOUR
T1 - Cascades of sub-decadal, channel-floodplain changes in low-gradient, non-vegetated reaches near a dryland river terminus:
T2 - Salar de Uyuni, Bolivia
AU - Li, Jiaguang
AU - Tooth, Stephen
AU - Yao, Guangqing
N1 - Funding Information:
Acknowledgements—This research was supported by Open Fund (PLC20180502) of State Key Laboratory of Oil and Gas Reservoir Geology and Exploration (Chengdu University of Technology), the National Natural Science Foundation of China (No. 41602121), 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) and the Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry. JL thanks the Hubei Province Chenguang Program for Young Scientists for supporting an international scholar visit.
Publisher Copyright:
© 2018 John Wiley & Sons, Ltd.
PY - 2019/2/5
Y1 - 2019/2/5
N2 - The terminus of the ephemeral Río Colorado is located at the margins of Salar de Uyuni, Bolivia, the world's largest salt lake. The low-gradient (<0.0006 m m
-1 ), non-vegetated reaches approaching the terminus provide an excellent natural laboratory for investigating cascades of channel-floodplain changes that occur in response to quasi-regular flows (at least once annually) and fine-grained sediment supply (dominantly silt and clay). High-resolution satellite imagery (<0.65 m, various dates from 2004 onwards) and field data reveal widespread, pronounced and rapid morphodynamics on sub-decadal timescales, including channel erosion and chute cutoff formation, and development of crevasse channels and splays, floodouts (unchannelled surfaces at channel termini), and erosion cells (floodplain scour-transport-fill features). In particular, following high annual precipitation (>400 mm) in 2004–2005 and two subsequent high magnitude daily precipitation events (~40 mm), all of which led to widespread flooding, numerous crevasse splays formed between 2004 and 2016, avulsions occurred at nearby floodouts, and erosion cells downstream of the splays and floodouts underwent striking morphological changes. High-precision GPS data reveal two preferential localities for erosion cell development: partially or fully abandoned channels with crevasse splay remnants, and topographic lows between channels. In this overall low-gradient setting, comparatively high gradients (up to ~0.0006 m m
-1 ) at the edge of splay deposits and topography created by crevasses and abandoned channels may initiate knickpoint retreat and thereafter erosion cell development. Abandoned channels with splays tend to give rise to narrow, deep erosion cells, while topographic lows promote relatively shallow, wide erosion cells. In both situations, erosion cells may extend upslope and downslope, and eventually connect to form straight channels. The channel-floodplain morphodynamics near the Río Colorado terminus extend previous analyses of low-gradient, dryland river systems, particularly because the lack of vegetation and quasi-regular floods drive cascades of rapid changes on sub-decadal timescales.
AB - The terminus of the ephemeral Río Colorado is located at the margins of Salar de Uyuni, Bolivia, the world's largest salt lake. The low-gradient (<0.0006 m m
-1 ), non-vegetated reaches approaching the terminus provide an excellent natural laboratory for investigating cascades of channel-floodplain changes that occur in response to quasi-regular flows (at least once annually) and fine-grained sediment supply (dominantly silt and clay). High-resolution satellite imagery (<0.65 m, various dates from 2004 onwards) and field data reveal widespread, pronounced and rapid morphodynamics on sub-decadal timescales, including channel erosion and chute cutoff formation, and development of crevasse channels and splays, floodouts (unchannelled surfaces at channel termini), and erosion cells (floodplain scour-transport-fill features). In particular, following high annual precipitation (>400 mm) in 2004–2005 and two subsequent high magnitude daily precipitation events (~40 mm), all of which led to widespread flooding, numerous crevasse splays formed between 2004 and 2016, avulsions occurred at nearby floodouts, and erosion cells downstream of the splays and floodouts underwent striking morphological changes. High-precision GPS data reveal two preferential localities for erosion cell development: partially or fully abandoned channels with crevasse splay remnants, and topographic lows between channels. In this overall low-gradient setting, comparatively high gradients (up to ~0.0006 m m
-1 ) at the edge of splay deposits and topography created by crevasses and abandoned channels may initiate knickpoint retreat and thereafter erosion cell development. Abandoned channels with splays tend to give rise to narrow, deep erosion cells, while topographic lows promote relatively shallow, wide erosion cells. In both situations, erosion cells may extend upslope and downslope, and eventually connect to form straight channels. The channel-floodplain morphodynamics near the Río Colorado terminus extend previous analyses of low-gradient, dryland river systems, particularly because the lack of vegetation and quasi-regular floods drive cascades of rapid changes on sub-decadal timescales.
KW - crevasse splay
KW - dryland river terminus
KW - floodout
KW - floodplain
KW - knickpoint
KW - erosion cells
UR - http://www.scopus.com/inward/record.url?scp=85056789244&partnerID=8YFLogxK
U2 - 10.1002/esp.4512
DO - 10.1002/esp.4512
M3 - Article
SN - 0197-9337
VL - 44
SP - 490
EP - 506
JO - Earth Surface Processes and Landforms
JF - Earth Surface Processes and Landforms
IS - 2
ER -