River-wetland interaction and carbon cycling in a semi-arid riverine system: the Okavango Delta, Botswana

Akoko, Eric; Atekwana, Estella A.; Cruse, Anna M.; Molwalefhe, Loago N.; Masamba, W.R.L.

doi:10.1007/s10533-012-9817-x

Cited by 28 publications

(31 citation statements)

References 54 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…By contrast, the decreasing discharge in the Kafue Flats combined with a calculated 16 % of the downstream discharge that had been on the floodplain for a certain amount of time (Zurbrügg et al, 2012) indicated that there was still exchange between the river channel and some permanently inundated areas in the downstream reaches of the Kafue Flats. From a regional perspective, the along-floodplain increase in the δ 18 O signal in the Barotse Plains and Kafue Flats during the wet (flooding) season (+0.21 ‰ VSMOV to +0.56 ‰ VSMOV per 100 km) was considerably lower than the increase in the Okavango Delta during the dry (flooding) season (+2.04 ‰ per 100 km) and during wet season (+0.74 ‰ VSMOV per 100 km; calculated from Akoko et al, 2013), indicating that there was significantly A. L. Zuijdgeest et al: Seasonal dynamics of carbon and nutrients less extensive evaporation on the Zambezi catchment floodplains than in the inland Okavango delta.…”

Section: Hydrology and Inundation Dynamicsmentioning

confidence: 92%

Seasonal dynamics of carbon and nutrients from two contrasting tropical floodplain systems in the Zambezi River basin

et al. 2015

View full text Add to dashboard Cite

Abstract. Floodplains are important biogeochemical reactors during fluvial transport of carbon and nutrient species towards the oceans. In the tropics and subtropics, pronounced rainfall seasonality results in highly dynamic floodplain biogeochemistry. The massive construction of dams, however, has significantly altered the hydrography and chemical characteristics of many (sub)tropical rivers. In this study, we compare organic-matter and nutrient biogeochemistry of two large, contrasting floodplains in the Zambezi River basin in southern Africa: the Barotse Plains and the Kafue Flats. Both systems are of comparable size but differ in anthropogenic influence: while the Barotse Plains are still in large parts pristine, the Kafue Flats are bordered by two hydropower dams. The two systems exhibit different flooding dynamics, with a larger contribution of floodplain-derived water in the Kafue Flats and a stronger peak flow in the Barotse Plains. Distinct seasonal differences have been observed in carbon and nutrient concentrations, loads, and export and retention behavior in both systems. The simultaneous retention of particulate carbon and nitrogen and the net export of dissolved organic and inorganic carbon and nitrogen suggested that degradation of particulate organic matter was the dominant process influencing the river biogeochemistry during the wet season in the Barotse Plains and during the dry season in the Kafue Flats. Reverse trends during the dry season indicated that primary production was important in the Barotse Plains, whereas the Kafue Flats seemed to have both primary production and respiration occurring during the wet season, potentially occurring spatially separated in the main channel and on the floodplain. Carbon-to-nitrogen ratios of particulate organic matter showed that soil-derived material was dominant year-round in the Barotse Plains, whereas the Kafue Flats transported particulate organic matter that had been produced in the upstream reservoir during the wet season. Stable carbon isotopes suggested that inputs from the inundated floodplain to the particulate organic-matter pool were important during the wet season, whereas permanent vegetation contributed to the material transported during the dry season. This study revealed effects of dam construction on organic-matter and nutrient dynamics on the downstream floodplain that only become visible after longer periods, and it highlights how floodplains act as large biogeochemical reactors that can behave distinctly differently from the entire catchment.

show abstract

Section: Hydrology and Inundation Dynamicsmentioning

confidence: 92%

Seasonal dynamics of carbon and nutrients from two contrasting tropical floodplain systems in the Zambezi River basin

et al. 2015

View full text Add to dashboard Cite

show abstract

“…By contrast, the decreasing discharge in the Kafue Flats combined with a calculated 16 % of the downstream discharge that had been on the floodplain for a certain amount of time (Zurbrügg et al, 2012) indicated that there was still exchange between the river channel and some permanently inundated areas in the downstream reaches of the Kafue Flats. From a regional perspective, the along-floodplain increase in the δ 18 O signal in the Barotse Plains and Kafue Flats during the wet (flooding) season (+0.21 ‰ VSMOV to +0.56 ‰ VSMOV per 100 km) was considerably lower than the increase in the Okavango Delta during the dry (flooding) season (+2.04 ‰ per 100 km) and during wet season (+0.74 ‰ VSMOV per 100 km; calculated from Akoko et al, 2013), indicating that there was significantly less extensive evaporation on the Zambezi catchment floodplains than in the inland Okavango delta.…”

Section: Hydrology and Inundation Dynamicsmentioning

confidence: 92%

Seasonal dynamics of carbon and nutrients from two contrasting tropical floodplain systems in the Zambezi River Basin

Zuijdgeest¹,

Zurbrügg²,

Blank³

et al. 2015

Preprint

View full text Add to dashboard Cite

Floodplains are important biogeochemical reactors during fluvial transport of carbon and nutrient species towards the oceans. In the tropics and subtropics, pronounced rainfall seasonality results in highly dynamic floodplain biogeochemistry. The massive construction of dams, however, has significantly altered the hydrography and chemical characteristics of many (sub)tropical rivers. In this study, we compare organic-matter and nutrient biogeochemistry of two large, contrasting floodplains in the Zambezi River basin in southern Africa: the Barotse Plains and the Kafue Flats. Both systems are of comparable size but differ in anthropogenic influence: while the Barotse Plains are still in large parts pristine, the Kafue Flats are bordered by two hydropower dams.The two systems exhibit different flooding dynamics, with a larger contribution of floodplain-derived water in the Kafue Flats and a stronger peak flow in the Barotse Plains. Distinct seasonal differences have been observed in carbon and nutrient concentrations, loads, and export and retention behavior in both systems. The simultaneous retention of particulate carbon and nitrogen and the net export of dissolved organic and inorganic carbon and nitrogen suggested that degradation of particulate organic matter was the dominant process influencing the river biogeochemistry during the wet season in the Barotse Plains and during the dry season in the Kafue Flats. Reverse trends during the dry season indicated that primary production was important in the Barotse Plains, whereas the Kafue Flats seemed to have both primary production and res-piration occurring during the wet season, potentially occurring spatially separated in the main channel and on the floodplain.Carbon-to-nitrogen ratios of particulate organic matter showed that soil-derived material was dominant year-round in the Barotse Plains, whereas the Kafue Flats transported particulate organic matter that had been produced in the upstream reservoir during the wet season. Stable carbon isotopes suggested that inputs from the inundated floodplain to the particulate organic-matter pool were important during the wet season, whereas permanent vegetation contributed to the material transported during the dry season. This study revealed effects of dam construction on organic-matter and nutrient dynamics on the downstream floodplain that only become visible after longer periods, and it highlights how floodplains act as large biogeochemical reactors that can behave distinctly differently from the entire catchment.Published by Copernicus Publications on behalf of the European Geosciences Union.

show abstract

“…The flood pulse in the floodplains also facilitates bacterial consumption of DOC [26]. There are higher DOC concentrations along the delta [26] and also between channel and floodplains habitats [53], which has been attributed primarily to evapo-concentration [26,53]. Therefore, river-wetland interactions and evapo-concentration are the key drivers of carbon cycling in the Delta [26,53].…”

Section: Nutrient Dynamics and Primary Productionmentioning

confidence: 99%

Review of Aquatic Biodiversity Dynamics in the Okavango Delta: Resilience in a Highly Fluctuating Environment

Mosepele¹,

Mosepele²

2021

Inland Waters - Dynamics and Ecology

View full text Add to dashboard Cite

Wetlands are key ecosystems of high biological diversity that provide valuable ecosystem services. These are particularly important in water stressed semi-arid countries, which enhances their vulnerability to degradation. The Okavango Delta, a key wetland in Botswana, is characterised by dynamic inter and intra specific interactions. There are dynamic biotic and abiotic interactions in the system that enhances its resilience. The flood pulse is the main factor mediating bio-physical dynamics in this system. Despite the various perturbations that have been experienced in the system, the Delta has always been able to absorb them and retain its character at the general ecosystem level. These notwithstanding, there have been some changes at the local scale where the Delta has shifted regimes and entered into altered states as a consequence of either channel or lagoon failure. Management of these systems should ensure that their dynamic characteristics are maintained, and this is enshrined within the panarchy concept. Adopting the resilience framework in natural resources management allows for flexibility in devising management strategies to respond to future unexpected events.

show abstract

River-wetland interaction and carbon cycling in a semi-arid riverine system: the Okavango Delta, Botswana

Cited by 28 publications

References 54 publications

Seasonal dynamics of carbon and nutrients from two contrasting tropical floodplain systems in the Zambezi River basin

Seasonal dynamics of carbon and nutrients from two contrasting tropical floodplain systems in the Zambezi River basin

Seasonal dynamics of carbon and nutrients from two contrasting tropical floodplain systems in the Zambezi River Basin

Review of Aquatic Biodiversity Dynamics in the Okavango Delta: Resilience in a Highly Fluctuating Environment

Contact Info

Product

Resources

About