Sediment deposition patterns in a tropical floodplain, Tana River, Kenya

Omengo, Fred; Alleman, Tine; Geeraert, Naomi; Bouillon, Steven; Govers, Gérard

doi:10.1016/j.catena.2016.03.024

Cited by 27 publications

(17 citation statements)

References 33 publications

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“…The results showed that the dominant drivers considerably varied according to season and the location within the catchment (Tena et al, 2014). Furthermore, in (sub)tropical catchments, there is often a marked difference between factors controlling SS transport in the dry seasons compared to the wet seasons (Dominic et al, 2015;Franz et al, 2014;Omengo et al, 2016). A PCA applied in two tropical sub-catchments of the Klang River (Malaysia) shows that total rainfall and rainfall intensity are strongly related to SS hysteresis patterns in the dry season, while soil moisture plays a more important role in determining SS hysteresis patterns during the wet season (Dominic et al, 2015).…”

Section: Driversmentioning

confidence: 99%

Suspended sediment transport dynamics in rivers: Multi-scale drivers of temporal variation

Vercruysse

Grabowski

Rickson

2017

Earth-Science Reviews

325

181

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Suspended sediment is a natural part of river systems and plays an essential role in structuring the landscape, creating ecological habitats and transporting nutrients. It is also a common management problem, where alterations to sediment quantity and quality negatively impact ecological communities, increase flood hazard and shorten the lifespan of infrastructure. To address these challenges and develop appropriate sustainable management strategies, we need a thorough understanding of sediment sources, pathways and transport dynamics and the drivers that underlie spatial and temporal variability in suspended sediment transport in rivers. However, research to date has not sufficiently addressed the temporal complexity of sediment transport processes, which is limiting our ability to disentangle the hydro-meteorological, catchment, channel and anthropogenic drivers of suspended sediment transport in rivers. This review critically evaluates previously published work on suspended sediment dynamics to demonstrate how the interpretation of sediment sources and pathways is influenced by the temporal scale and methodology of the study. To do this, the review (i) summarizes the main drivers of temporal variation in suspended sediment transport in rivers; (ii) critically reviews the common empirical approaches used to analyze and quantify sediment sources and loads, and their capacity to account for temporal variations; (iii) applies these findings to recent case studies to illustrate how method and timescale affect the interpretation of suspended sediment transport dynamics; and finally (iv) synthesizes the findings of the review into a set of guidelines for a multi-timescale approach to sediment regime characterization. By recognizing a priori that study design and temporal scale have an impact on the interpretation of SS dynamics and employing methods that address these issues, future research will be better able to identify the drivers of suspended sediment transport in rivers, improve sediment transport modelling, and propose effective, sustainable solutions to sediment management problems.

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Section: Driversmentioning

confidence: 99%

Suspended sediment transport dynamics in rivers: Multi-scale drivers of temporal variation

Vercruysse

Grabowski

Rickson

2017

Earth-Science Reviews

325

181

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“…Sedimentation rates were based on Omengo et al [2016] where radionuclides and a postflood survey of fresh flood deposits was used to quantify floodplain sedimentation rates. , suggesting that average long-term rates were somewhat higher than the deposition rates observed in 2013 or that the sample sites may have, on average, higher sedimentation rates than the floodplain as a whole.…”

Section: Laboratory Analysesmentioning

confidence: 99%

“…Indeed, the OC content of the floodplain sediments at depths below 60 cm is greatly reduced in comparison to the surface sediments. Based on the radionuclide inventories measured at the coring sites, such a depth corresponds to an age of circa 50-60 year [Omengo et al, 2016]. The OC that remains in the soil at greater depths is more recalcitrant and rather slowly mineralized, leading to a more limited change in overall stocks below this depth.…”

Section: Floodplain Oc Mineralization Ratesmentioning

confidence: 99%

“…Sedimentation rates were based on Omengo et al [2016] where radionuclides and a postflood survey of fresh flood deposits was used to quantify floodplain sedimentation rates. An average 50 year mean sedimentation rate of 1.21 ± 0.35 g cm À2 yr À1 based on 137 Cs inventories and a 100 year mean of 1.01 ± 0.50 g cm À2 yr À1 based on 210 Pb xs was obtained for the coring sites.…”

Section: Laboratory Analysesmentioning

confidence: 99%

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Deposition and fate of organic carbon in floodplains along a tropical semiarid lowland river (Tana River, Kenya)

et al. 2016

Self Cite

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Inland waters organic carbon (OC) burial by sedimentation has recently been shown to be an important component in river catchment carbon (C) budgets. However, data on OC burial by sedimentation are hitherto largely limited to temperate zones. We investigated the deposition and fate of sediment-associated OC in the floodplains of the tropical lowland Tana River (Kenya), between two main gaging stations (Garissa and Garsen). Freshly deposited surface sediments and sediment cores were sampled and analyzed for OC, total nitrogen content, stable isotope signatures (δ 13 C) of OC, and grain size distribution. In addition, we incubated sediment cores to quantify CO 2 production as a proxy for OC mineralization. While the floodplain receives sediment with a relatively low OC content (1.56 ± 0.42%), sediments are enriched with OC inputs from floodplain vegetation to levels above 3%. Sediment cores show a sharp decrease of OC with depth, from 3 to 12% OC in the (sub) surface to less than 1% OC below approximately 60 cm depth. Relatively elevated OC mineralization rates (0.14 ± 0.07 mol. CO 2 kgC À1 d À1) were recorded. We used these data to make a first assessment of the C burial efficiency of the Tana River floodplain. In contrast to what is observed in temperate environments, over 50% of C present in the top layers is lost in less than a century. While significant amounts of OC are buried in the Tana River floodplain, the high rates of postdepositional loss limit the development of a long-term C sink within this tropical floodplain.

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“…As pointed out by Steiger, Tabacchi, Dufour, Corenblit, and Peiry (), overbank sedimentation processes, rates and patterns are controlled by many different factors from basin (e.g., sediment production, Latrubesse & Restrepo, ) to local scales (e.g., formation of a sediment tail, i.e., an obstacle mark, in the lee of a floodplain tree; Rodrigues et al, ; Corenblit et al, ). Therefore, the spatial variability of floodplain sedimentation tends to be inherently complex in terms of quantity and quality (e.g., texture, nutrient and contaminant content; Walling & Bradley, ; Asselman & Middelkoop, ; Steiger & Gurnell, ; Aalto, Wesley, & William, ; Schwendel, Nicholas, Aalto, Sambrook Smith, & Buckley, ; Omengo, Alleman, Geeraert, Bouillon, & Govers, ).…”

Section: Introductionmentioning

confidence: 99%

Multi‐annual contemporary flood event overbank sedimentation within the vegetated lower Orinoco floodplain, Venezuela

Rodríguez

Steiger

Rosales

et al. 2019

River Research & Apps

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Multi‐annual contemporary flood event overbank sedimentation rates were quantified on the World's third largest river in terms of discharge, the tropical lower Orinoco. We discuss the role of variables at the basin and reach scales that contributed to the complexity of spatio‐temporal overbank sediment deposition patterns. Monitored in situ plots were characterized by distance to the main channel, hydroperiod, different geomorphological units, and vegetation cover. Flood event sedimentation rates showed a high spatial variability ranging from the absence of sediment deposition up to 225.46 kg m‐2 yr‐1. Banks and levees received relatively high amounts of sediment (39.6 kg m‐2 yr‐1), whereas observed mean sedimentation rates on the more distant floodplain and backswamps tended to be lower (17.7 kg m‐2 yr‐1). Significant differences in sedimentation rates were observed in two major vegetation types: dense herbaceous and shrubby vegetation (42.2 kg m‐2 yr‐1) and floodplain forest (12.7 kg m‐2 yr‐1). However, overbank sedimentation patterns also reflected imbricated hydrosedimentary and biogeomorphological vegetation feedbacks that co‐construct fluvial landforms. The incidence of an El Niño–Southern Oscillation–La Niña episode during the study period on sediment availability and floodplain sedimentation suggests that within whitewater rivers, where suspended sediment concentrations are naturally high, hydrological connectivity seems to be more important for floodplain sedimentation than variations in suspended sediment concentrations. These results may provide a good basis for future biogeomorphological investigation projects using complementary methodologies, in order to better anticipate global change and fluctuations in the occurrence, strength or duration of El Niño–La Niña episodes in the tropical zone and their consequences for flood discharge and sediment dynamics during channel–floodplain exchanges.

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Sediment deposition patterns in a tropical floodplain, Tana River, Kenya

Cited by 27 publications

References 33 publications

Suspended sediment transport dynamics in rivers: Multi-scale drivers of temporal variation

Suspended sediment transport dynamics in rivers: Multi-scale drivers of temporal variation

Deposition and fate of organic carbon in floodplains along a tropical semiarid lowland river (Tana River, Kenya)

Multi‐annual contemporary flood event overbank sedimentation within the vegetated lower Orinoco floodplain, Venezuela

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