Controls on the formation of Wakkerstroom Vlei, Mpumalanga province, South Africa:
- Joubert, R, Ellery, William F N
- Authors: Joubert, R , Ellery, William F N
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/144421 , vital:38344 , DOI: 10.2989/16085914.2012.762897
- Description: The present study investigated controls on the formation of Wakkerstroom Vlei, an 1 000 ha unchannelled valley-bottom wetland on the South African Highveld. Along the uppermost and lowermost reaches of the wetland, where dolerite outcrops occur along the main valley, hydrogeomorphic features typical of geological control on wetland formation are present, including a meandering river channel, oxbow lakes and greater than 3 m deep organic-poor alluvial fill. Along the main body of the wetland, however, floodplain features are absent, alluvial fill is up to 4.5 m deep and contains up to 2 m deep accumulations of peat. These characteristics deviate from the traditional model of dolerite control on wetland formation described by several other studies on Highveld wetland systems.
- Full Text:
- Authors: Joubert, R , Ellery, William F N
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/144421 , vital:38344 , DOI: 10.2989/16085914.2012.762897
- Description: The present study investigated controls on the formation of Wakkerstroom Vlei, an 1 000 ha unchannelled valley-bottom wetland on the South African Highveld. Along the uppermost and lowermost reaches of the wetland, where dolerite outcrops occur along the main valley, hydrogeomorphic features typical of geological control on wetland formation are present, including a meandering river channel, oxbow lakes and greater than 3 m deep organic-poor alluvial fill. Along the main body of the wetland, however, floodplain features are absent, alluvial fill is up to 4.5 m deep and contains up to 2 m deep accumulations of peat. These characteristics deviate from the traditional model of dolerite control on wetland formation described by several other studies on Highveld wetland systems.
- Full Text:
Epidemic transmission of intestinal schistosomiasis in the seasonal part of the Okavango Delta, Botswana:
- Appleton, C C, Ellery, William F N, Byskov, Jens, Mogkweetsinyana, S S
- Authors: Appleton, C C , Ellery, William F N , Byskov, Jens , Mogkweetsinyana, S S
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/144364 , vital:38339 , DOI: 10.1179/136485908X311867
- Description: A well documented epidemic of human intestinal schistosomiasis caused by Schistosoma mansoni occurred at Maun in the seasonal part of the Okavango Delta, Botswana, building from very few cases in the 1950s and early 1960s to a peak prevalence of greater than80% in the 1980s. A retrospective analysis was performed on all available records of the prevalence of S. mansoni in the Maun area and the corresponding flow records of the Thamalakane River. These revealed a statistically significant correlation between prevalence and flow, but only when a lag period was introduced. The correlation was greatest with a lag period of 5–6 years between the rise and fall of discharge and the rise and fall of transmission. Since the hydrological events in the delta follow a cyclical pattern, another epidemic around 2020 appears likely.
- Full Text:
- Authors: Appleton, C C , Ellery, William F N , Byskov, Jens , Mogkweetsinyana, S S
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/144364 , vital:38339 , DOI: 10.1179/136485908X311867
- Description: A well documented epidemic of human intestinal schistosomiasis caused by Schistosoma mansoni occurred at Maun in the seasonal part of the Okavango Delta, Botswana, building from very few cases in the 1950s and early 1960s to a peak prevalence of greater than80% in the 1980s. A retrospective analysis was performed on all available records of the prevalence of S. mansoni in the Maun area and the corresponding flow records of the Thamalakane River. These revealed a statistically significant correlation between prevalence and flow, but only when a lag period was introduced. The correlation was greatest with a lag period of 5–6 years between the rise and fall of discharge and the rise and fall of transmission. Since the hydrological events in the delta follow a cyclical pattern, another epidemic around 2020 appears likely.
- Full Text:
Halting degradation of Southern Cape peatlands in agricultural landscapes
- Job, Nancy, Ellery, William F N
- Authors: Job, Nancy , Ellery, William F N
- Date: 2013
- Subjects: Peatlands -- South Africa -- Southern Cape Wetland ecology -- South Africa -- Southern Cape South Africa -- Social conditions
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/50013 , vital:25951
- Description: Palmiet peatlands in the agricultural landscape are viewed by farmers as problematic. They obstruct the effective passage of water along watercourses and therefore promote localized flooding of lands and infrastructure, and they trap sediment delivered along watercourses that drowns fields and infrastructure with sedimentary deposits. These events are problematic for farmers trying to make a living off the land. Wetlands are also often viewed as wastelands that should be put to more productive use. The obvious thing to do is to bring in machinery to drain the wetlands and improve the flow of water and sediment through these wetlands.
- Full Text:
- Authors: Job, Nancy , Ellery, William F N
- Date: 2013
- Subjects: Peatlands -- South Africa -- Southern Cape Wetland ecology -- South Africa -- Southern Cape South Africa -- Social conditions
- Language: English
- Type: text
- Identifier: http://hdl.handle.net/10962/50013 , vital:25951
- Description: Palmiet peatlands in the agricultural landscape are viewed by farmers as problematic. They obstruct the effective passage of water along watercourses and therefore promote localized flooding of lands and infrastructure, and they trap sediment delivered along watercourses that drowns fields and infrastructure with sedimentary deposits. These events are problematic for farmers trying to make a living off the land. Wetlands are also often viewed as wastelands that should be put to more productive use. The obvious thing to do is to bring in machinery to drain the wetlands and improve the flow of water and sediment through these wetlands.
- Full Text:
The landscape holds answers to more questions than we have yet learned to ask : perspectives of an environmental scientist
- Authors: Ellery, William F N
- Date: 2013
- Language: English
- Type: Text
- Identifier: vital:584 , http://hdl.handle.net/10962/d1018944
- Description: [From the text] Implicit in the title of my talk is the idea that the landscape has a voice – it "holds answers". Our understanding of landscapes depends on the questions we ask about their appearance and dynamics. What I love about the voice of landscapes is its gentle nature – it whispers. It's a seductive voice, inviting one to hear secrets. I have long been curious about the intimate language of landscapes and this has stemmed from a personal connection with nature from a very early age. My interests led me into the fields of ecology and geomorphology, both of which have allowed me to unravel some of these secrets. So, in tonight’s talk there are a number of narratives that form a part of my story. The first narrative is about science. It’s about how we uncover nature’s secrets and thus create new understanding.
- Full Text:
- Authors: Ellery, William F N
- Date: 2013
- Language: English
- Type: Text
- Identifier: vital:584 , http://hdl.handle.net/10962/d1018944
- Description: [From the text] Implicit in the title of my talk is the idea that the landscape has a voice – it "holds answers". Our understanding of landscapes depends on the questions we ask about their appearance and dynamics. What I love about the voice of landscapes is its gentle nature – it whispers. It's a seductive voice, inviting one to hear secrets. I have long been curious about the intimate language of landscapes and this has stemmed from a personal connection with nature from a very early age. My interests led me into the fields of ecology and geomorphology, both of which have allowed me to unravel some of these secrets. So, in tonight’s talk there are a number of narratives that form a part of my story. The first narrative is about science. It’s about how we uncover nature’s secrets and thus create new understanding.
- Full Text:
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