Nutrient Budget in the Seasonal Wetland of the Okavango Delta, Botswana

2006 ◽  
Vol 14 (3) ◽  
pp. 253-267 ◽  
Author(s):  
Martin Krah ◽  
Terence S. McCarthy ◽  
Philippa Huntsman-Mapila ◽  
Piotr Wolski ◽  
Harold Annegarn ◽  
...  
Keyword(s):  
Nutrient Budget ◽  
Okavango Delta ◽  
Seasonal Wetland

Methane and carbon dioxide emissions from two contrasting wetlands in the Okavango Delta, Botswana.

2020 ◽  
Author(s):  
Carole Helfter ◽  
Mangaliso Gondwe ◽  
Mike Murray-Hudson ◽  
Ute Skiba
Keyword(s):  
Carbon Dioxide ◽  
Soil Moisture ◽  
Eddy Covariance ◽  
Carbon Dioxide Emissions ◽  
Methane Emissions ◽  
Okavango Delta ◽  
Natural Soil ◽  
River Channels ◽  
Seasonal Wetland ◽  
Permanent Wetland

<p>We report on two years of continuous monitoring of methane (CH<sub>4</sub>) and carbon dioxide (CO<sub>2</sub>) emissions at two contrasting sites in the Okavango Delta, North-Western Botswana, an inland delta bordered by the Kalahari Desert. Approximately 60% of the annual water influx into the Okavango Delta results from seasonal river discharges originating in the Angolan Highlands, and the remainder comes from direct rainfall. 96-98% of the 16.1 billion m<sup>3</sup> entering the Delta annually are lost through evapo-transpiration (1500 mm.year<sup>-1</sup>). Flooding is gradual and it takes the pulsed influx ca. 4-5 months to travel the 250 km separating the inlet in Mohembo from the main outlet in Maun. The wetlands of the Okavango Delta are in pristine condition and can be separated into three categories: permanently flooded, seasonally flooded (3-6 months per year) and occasionally flooded (typically once per decade). </p><p>Two eddy-covariance systems were set up in August 2017, one at Guma Lagoon (18°57'53.01" S;  22°22'16.20" E) at the edge of an extensive papyrus bed in the permanently-flooded section of the delta, and the second one at Nxaraga on the SW edge of Chief’s Island (19°32'53'' S; 23°10'45'' E) in the seasonal floodplain. In addition, monthly measurements of methane and carbon dioxide fluxes were taken using a clear dynamic chamber at the Nxaraga site along transects chosen to span the natural soil moisture gradient (very dry to waterlogged soils).</p><p>The emissions of methane exhibited contrasting spatial and temporal patterns between sites. At the seasonal wetland, very low fluxes of CH<sub>4</sub> were typically observed from January to June. Emissions increased abruptly from July-August onwards after flood waters rewetted the flooplain in that area of the Delta. Throughout the year, local emission hotspots of CH<sub>4</sub> were observed along the vegetated river channels within the flux footprint of the eddy-covariance system, whereas CH<sub>4</sub> oxidation was recorded in persistently dry areas where the soil is sandy and salt-crusted. The chamber measurements corroborated the findings of the eddy-covariance measurements and soil moisture is likely the dominant control of methane fluxes at the seasonal wetland.</p><p>The methane emissions from the floating papyrus mat in the permanent wetland exhibited a marked seasonal cycle, characterised by relatively high emissions (of the order of 250 nmol.m<sup>-2</sup>.s<sup>-1</sup>; 2.5 larger than peak emissions recorded at the seasonal wetland) in the summer months (November-March) and minimum emissions in winter (typically 50 nmol.m<sup>-2</sup>.s<sup>-1</sup> in June-August). At the seasonal timescale, methane emissions were strongly correlated to the phenological cycle of papyrus (lowest emissions during the senescence phase), suggesting that plant-mediated transport is the dominant control. The annual budgets of CH<sub>4</sub> and CO<sub>2</sub> in the permanent wetland were estimated at 153.4 ± 27.9 tons.km<sup>-2</sup> (3835.0 ± 697.5 CO<sub>2</sub>-eq) and -874.0 ± 200.4 tons.km<sup>-2</sup> respectively, making the permanent wetland a potent net source of carbon to the atmosphere.</p>

Inundation frequency and viability of microcrustacean propagules in soils of temporary aquatic habitats of lower Okavango Delta, Botswana

Ecohydrology ◽  
2012 ◽  
pp. n/a-n/a ◽  
Author(s):  
Nqobizitha Siziba ◽  
Moses J. Chimbari ◽  
Ketlhatlogile Mosepele ◽  
Hillary Masundire ◽  
Lars Ramberg
Keyword(s):  
Okavango Delta ◽  
Aquatic Habitats ◽  
Inundation Frequency

scholarly journals A new MONERIS in-Stream Retention Module to Account Nutrient Budget of a Temporary River in Cyprus

2014 ◽  
Vol 28 (10) ◽  
pp. 2917-2935 ◽  
Author(s):  
O. Tzoraki ◽  
D. Cooper ◽  
G. Dörflinger ◽  
P. Panagos
Keyword(s):  
Nutrient Budget ◽  
Temporary River

Nutrients budget and effluents characteristics in polyculture of scampi (Macrobrachium rosenbergii) and Indian major carps ponds using organic inputs

2012 ◽  
Vol 66 (7) ◽  
pp. 1540-1548 ◽  
Author(s):  
Subhendu Adhikari ◽  
Bharat Chandra Sahu ◽  
Lambodar Dey
Keyword(s):  
Macrobrachium Rosenbergii ◽  
Nutrient Budget ◽  
Catla Catla ◽  
Average Weight ◽  
Cow Dung ◽  
Nutrient Loads ◽  
Feed Conversion ◽  
Indian Major Carps ◽  
Main Input ◽  
Major Carps

Experiments were conducted for the study of nutrient budget in farmers' ponds (0.4–0.6 ha) in Orissa, India, at stocking densities of 0.30–0.38/m2 for scampi (Macrobrachium rosenbergii) and 0.60–0.70/m2 for Indian major carps (Catla catla, Labeo rohita and Cirrhinus mrigala). The average initial body weights of scampi and the major carps were 0.02 and 8–10 g, respectively. The culture period was 272–292 days. Feed was the main input. The FCR (feed conversion ratio) varied from 1.78 to 1.83. Feed and cow dung were applied to these ponds as organic inputs. At harvest time, the average weight of scampi and carps varied from 73 to 92 g and from 718 to 820 g, respectively. Among all the inputs, feed alone accounted for 97.60% total nitrogen (N), 97.90% total phosphorus (P) and 94.72% total organic carbon (OC), respectively. The harvest of scampi and carps accounted for recovery of 52.45% N, 19.43% P and 18.12% OC, respectively. N, P and OC accumulated in sediment were 38.31, 71.40 and 69.50%, respectively. The median nutrient loads in the fish pond effluents were equivalent to 0.58 kg of inorganic N, 0.135 kg of P and 8.83 kg of total OC per ton of Indian major carps and scampi production.

The role of remote sensing in hydrological modelling of the Okavango Delta, Botswana

2009 ◽  
Vol 90 (7) ◽  
pp. 2252-2260 ◽  
Author(s):  
Christian Milzow ◽  
Lesego Kgotlhang ◽  
Wolfgang Kinzelbach ◽  
Philipp Meier ◽  
Peter Bauer-Gottwein
Keyword(s):  
Remote Sensing ◽  
Hydrological Modelling ◽  
Okavango Delta

Incremental aggradation on the Okavango Delta-fan, Botswana

Geomorphology ◽  
1988 ◽  
Vol 1 (3) ◽  
pp. 267-278 ◽  
Author(s):  
T.S. McCarthy ◽  
I.G. Stanistreet ◽  
B. Cairncross ◽  
W.N. Ellery ◽  
K. Ellery ◽  
...  
Keyword(s):  
Okavango Delta
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