Investigating nitrate retention capacity, elementary and mineral composition of Kalahari sandy soils at Mashare farm in Namibia, Okavango river basin

In a survey of landscape retention capability results of measurements obtained during the disastrous flood in June 2009 were used. The original method based on the balance among the daily precipitation fallen on the basin with discharges in the final profile was used on the analogy with transformation of the flood discharge through a reservoir. Following basin retention are defined: dynamic Rd, static Rs including the underground retention Rug and evaporation E, and total Rt. Main principal criteria were the effective static retention of the basin Rsef and a coefficient of the effective static basin retention ρsef (3). The coefficient of reducing flood culmination λcul (4) was calculated, too. Also investigated factors having the most influence on a retention capacity of a basin are introduced. Summary of results are shown in the Tab. I. Values of the most important criterion quantities are marked in shadow colour. The results show, for example, that the found out coefficient ρsef is 0.52. It means that the soil (and slightly a vapour, too) in the basin caught 52% of volume of wave in the time of culmination discharge in a basin. Also some further interested findings are introduced in the results and conclusions.

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Water flow dynamics in the Okavango River Basin and Delta––a prerequisite for the ecosystems of the Delta

Physics and Chemistry of the Earth Parts A/B/C ◽

10.1016/j.pce.2003.09.002 ◽

2003 ◽

Vol 28 (20-27) ◽

pp. 1165-1172 ◽

Cited By ~ 35

Author(s):

Lotta Andersson ◽

Thomas Gumbricht ◽

Denis Hughes ◽

Dominic Kniveton ◽

Susan Ringrose ◽

...

Keyword(s):

River Basin ◽

Water Flow ◽

Flow Dynamics ◽

Okavango River

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Bat Species Richness and Community Composition along a Mega-transect in the Okavango River Basin

Diversity ◽

10.3390/d12050188 ◽

2020 ◽

Vol 12 (5) ◽

pp. 188 ◽

Cited By ~ 1

Author(s):

Sina M. Weier ◽

Mark Keith ◽

Götz G. Neef ◽

Daniel M. Parker ◽

Peter J. Taylor

Keyword(s):

Species Richness ◽

Community Composition ◽

River Basin ◽

Total Activity ◽

Environmental Drivers ◽

Conservation Strategies ◽

Miombo Woodlands ◽

Human Land Use ◽

Functional Community ◽

Okavango River

The Okavango River Basin is a hotspot of bat diversity that requires urgent and adequate protection. To advise future conservation strategies, we investigated the relative importance of a range of potential environmental drivers of bat species richness and functional community composition in the Okavango River Basin. During annual canoe transects along the major rivers, originating in the central Angolan highlands, we recorded more than 25,000 bat echolocation calls from 2015 to 2018. We corrected for possible biases in sampling design and effort. Firstly, we conducted rarefaction analyses of each survey year and sampling appeared to be complete, apart from 2016. Secondly, we used total activity as a measure of sample effort in mixed models of species richness. Species richness was highest in the Angola Miombo Woodlands and at lower elevations, with higher minimum temperatures. In total, we identified 31 individual bat species. We show that even when acoustic surveys are conducted in remote areas and over multiple years, it is possible to correct for biases and obtain representative richness estimates. Changes in habitat heterogeneity will have detrimental effects on the high richness reported here and human land-use change, specifically agriculture, must be mediated in a system such as the Angolan Miombo Woodland.

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Dissimilatory nitrate reduction to ammonium dominates soil nitrate retention capacity in subtropical forests

Biology and Fertility of Soils ◽

10.1007/s00374-020-01457-w ◽

2020 ◽

Vol 56 (6) ◽

pp. 785-797 ◽

Cited By ~ 1

Author(s):

Xiuzhen Shi ◽

Jianqing Wang ◽

Christoph Müller ◽

Hang-Wei Hu ◽

Ji-Zheng He ◽

...

Keyword(s):

Nitrate Reduction ◽

Soil Nitrate ◽

Retention Capacity ◽

Subtropical Forests ◽

Nitrate Retention ◽

Dissimilatory Nitrate Reduction

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RESPONSE OF RIPARIAN VEGETATION IN AUSTRALIA"S LARGEST RIVER BASIN TO INTER AND INTRA-ANNUAL CLIMATE VARIABILITY AND FLOODING AS QUANTIFIED WITH LANDSAT AND MODIS

ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ◽

10.5194/isprsarchives-xli-b8-577-2016 ◽

2016 ◽

Vol XLI-B8 ◽

pp. 577-578

Author(s):

M. Broich ◽

M. G. Tulbure

Keyword(s):

River Basin ◽

Vegetation Dynamics ◽

Riparian Vegetation ◽

Rainfall Variability ◽

Annual Rainfall ◽

Spatially Explicit ◽

Rainfall Gradient ◽

Vegetation Degradation ◽

Millennium Drought ◽

Okavango River

Australia is a continent subject to high rainfall variability, which has major influences on runoff and vegetation dynamics. However, the resulting spatial-temporal pattern of flooding and its influence on riparian vegetation has not been quantified in a spatially explicit way. Here we focused on the floodplains of the entire Murray-Darling Basin (MDB), an area that covers over 1M km2, as a case study. The MDB is the country’s primary agricultural area with scarce water resources subject to competing demands and impacted by climate change and more recently by the Millennium Drought (1999–2009). Riparian vegetation in the MDB floodplain suffered extensive decline providing a dramatic degradation of riparian vegetation. We quantified the spatial-temporal impact of rainfall, temperature and flooding patters on vegetation dynamics at the subcontinental to local scales and across inter to intra-annual time scales based on three decades of Landsat (25k images), Bureau of Meteorology data and one decade of MODIS data. Vegetation response varied in space and time and with vegetation types, densities and location relative to areas frequently flooded. Vegetation degradation trends were observed over riparian forests and woodlands in areas where flooding regimes have changed to less frequent and smaller inundation extents. Conversely, herbaceous vegetation phenology followed primarily a ‘boom’ and ‘bust’ cycle, related to inter-annual rainfall variability. Spatial patters of vegetation degradation changed along the N-S rainfall gradient but flooding regimes and vegetation degradation patterns also varied at finer scale, highlighting the importance of a spatially explicit, internally consistent analysis and setting the stage for investigating further cross-scale relationships. Results are of interest for land and water management decisions. The approach developed here can be applied to other areas globally such as the Nile river basin and Okavango River delta in Africa or the Mekong River Basin in Southeast Asia.

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Nitrate retention capacity of milldam-impacted legacy sediments and relict A horizon soils

10.5194/soil-2016-60 ◽

2016 ◽

Author(s):

Julie N. Weitzman ◽

Jason P. Kaye

Keyword(s):

Climatic Variability ◽

Free Water ◽

Field Capacity ◽

Soil Columns ◽

Retention Capacity ◽

Nitrate Retention ◽

Before And After ◽

Flow Through ◽

Legacy Sediment ◽

Stream Waters

Abstract. While eutrophication is often attributed to contemporary nutrient pollution, there is growing evidence that past practices, like the accumulation of legacy sediment behind historic milldams, are also important. Given their prevalence, there is a critical need to understand how N flows through, and is retained in, legacy sediments to improve predictions and management of N transport from uplands to streams in the context of climatic variability and land-use change. Our goal was to determine how nitrate (NO3-) is cycled through the soil of a legacy sediment strewn stream before and after soil drying. We extracted 10.16 cm radius intact soil columns that extended 30 cm into each of the three significant soil horizons at Big Spring Run (BSR) in Lancaster, Pennsylvania: surface legacy sediment characterized by a newly developing mineral A horizon soil, mid-layer legacy sediment consisting of mineral B horizon soil, and a dark, organic-rich, buried relict A horizon soil. Columns were first pre-incubated at field capacity, and then isotopically labeled nitrate (15NO3-) was added and allowed to drain to estimate retention. The columns were then air-dried and subsequently rewet with N-free water and allowed to drain to quantify the drought-induced loss of 15NO3- from the different horizons. We found the highest initial 15N retention in the mid-layer legacy sediment (17 ± 4 %) and buried relict A soil (14 ± 3 %) horizons, with significantly lower retention in the surface legacy sediment (6 ± 1 %) horizon. As expected, rewetting dry soil resulted in 15N losses in all horizons, with the greatest losses in the buried relict A horizon soil, followed by the mid-layer legacy sediment and surface legacy sediment horizons, respectively. The 15N remaining in the soil following the post-drought leaching was highest in the mid-layer legacy sediment, intermediate in the surface legacy sediment, and lowest in the buried relict A horizon soil. Fluctuations in the water table at BSR which affect saturation of the buried relict A horizon soil could lead to great loses of NO3- from the soil, while vertical flow through the legacy sediment-rich soil profile that originates in the surface has the potential to retain more NO3-. Restoration that seeks to reconnect the groundwater and surface water, which will decrease the number of drying-rewetting events imposed on the relict A horizon soils, could initially lead to increased losses of NO3- to nearby stream waters.

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RESPONSE OF RIPARIAN VEGETATION IN AUSTRALIA"S LARGEST RIVER BASIN TO INTER AND INTRA-ANNUAL CLIMATE VARIABILITY AND FLOODING AS QUANTIFIED WITH LANDSAT AND MODIS

ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ◽

10.5194/isprs-archives-xli-b8-577-2016 ◽

2016 ◽

Vol XLI-B8 ◽

pp. 577-578

Author(s):

M. Broich ◽

M. G. Tulbure

Keyword(s):

River Basin ◽

Vegetation Dynamics ◽

Riparian Vegetation ◽

Rainfall Variability ◽

Annual Rainfall ◽

Spatially Explicit ◽

Rainfall Gradient ◽

Vegetation Degradation ◽

Millennium Drought ◽

Okavango River

Australia is a continent subject to high rainfall variability, which has major influences on runoff and vegetation dynamics. However, the resulting spatial-temporal pattern of flooding and its influence on riparian vegetation has not been quantified in a spatially explicit way. Here we focused on the floodplains of the entire Murray-Darling Basin (MDB), an area that covers over 1M km2, as a case study. The MDB is the country’s primary agricultural area with scarce water resources subject to competing demands and impacted by climate change and more recently by the Millennium Drought (1999–2009). Riparian vegetation in the MDB floodplain suffered extensive decline providing a dramatic degradation of riparian vegetation. We quantified the spatial-temporal impact of rainfall, temperature and flooding patters on vegetation dynamics at the subcontinental to local scales and across inter to intra-annual time scales based on three decades of Landsat (25k images), Bureau of Meteorology data and one decade of MODIS data. Vegetation response varied in space and time and with vegetation types, densities and location relative to areas frequently flooded. Vegetation degradation trends were observed over riparian forests and woodlands in areas where flooding regimes have changed to less frequent and smaller inundation extents. Conversely, herbaceous vegetation phenology followed primarily a ‘boom’ and ‘bust’ cycle, related to inter-annual rainfall variability. Spatial patters of vegetation degradation changed along the N-S rainfall gradient but flooding regimes and vegetation degradation patterns also varied at finer scale, highlighting the importance of a spatially explicit, internally consistent analysis and setting the stage for investigating further cross-scale relationships. Results are of interest for land and water management decisions. The approach developed here can be applied to other areas globally such as the Nile river basin and Okavango River delta in Africa or the Mekong River Basin in Southeast Asia.

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