Browsing by Author "Holmes, Peter"

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    An assessment of land degradation in the headwater catchment of the Klein Zeekoei River, Great Karoo, South Africa
    (2000) Holland, Ross Matthew; Holmes, Peter
    Bibliography: leaves 113-124.
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    The environmental impacts of upgrading the Olushandja Dam, northern Namibia
    (1995) Hunt, Richard Peter Lewis; Holmes, Peter
    The purpose of this dissertation is to assess and evaluate various water level management options for the upgrading of Olushandja Dam in northern Namibia within the framework of the environmental impact assessment carried out for the project. This will enable the Namibian Department of Water Affairs (DWA) to improve their management of the dam for the benefit of the local communities and consumers in the Oshana Water Region (Figure 5 . 1). The dam has been in existence since 1975 and is part of the Calueque-Olushandja inter-basin water transfer scheme. A pipeline and a series of canals links Calueque Dam , on the Cunene River in Angola , with Olushandja Dam in Namibia and the urban areas to the east and south. In order to provide for the expected increase in water requirements from agricultural and rural development the scheme is presently being upgraded. An environmental impact assessment (EIA) was initiated in 1994 by the DWA as a requirement of the Dutch Government who are funding the project. Biophysical studies were undertaken by staff from the DWA and private consultants from Windhoek. The socio-economic study was carried out by a study team from the Department of Environmental and Geographical Science, University of Cape Town, in association with a consultant from the University's Environmental Evaluation Unit (EEU). The EEU was appointed to compile a full EIA based on the findings of the specialist reports. This report is expected to be completed by October 1995.
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    The morphology, sedimentology and palaeoenvironmental significance of two pan-lunette clusters in the Southwestern Cape of South Africa
    (2003) Gaines, Sarah Margaret; Holmes, Peter; Meadows, Michael E
    Two clusters of pans and associated lunette dunes are distinct landscape featurs in the Swartland and Agulhas Plain regions of the southwestern Cape of South Africa. While occurring in geographic proximity within the Winter Rainfall Region, each of the pan-lunette clusters is hosted by different substrates, subjected to different coastal climate regimes and exhibits different morphology, orientation of features, and sedimentological characteristics. Not only are geomorphic characteristics at variance between regions, but also the alignment of lunettes on the leeside of pans, parallel within the cluster, is at variance with predominant modern wind direction and seasonality of precipitation at both sites, although the difference is more pronounced at Agulhas. In order to elucidate the occurrence and formational processes of these features, a dual-scale approach was employed: a regional cartographic study coupled with detailed local sedimentological analyses. The geomorphic characteristics of these features were quantified using aerial photography and orthophotographic maps. Dry season palaeo-wind direction was inferred from the regional analysis; in Agulhas, winds must have been blowing from WSW during the dry season, similar to modern wet season winds.
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    Natural and human induced late quaternary environmental change on the Noordhoek Valley, Cape Town, South Africa
    (2004) Akunji, E U; Meadows, Michael E; Holmes, Peter
    This research project attempts to determine the relative influences of climate, sea level changes and human activities during the period of sediment accumulation in the Noordhoek basin in the southwestern Cape. South Africa. The research relies on lacustrine sedimentary deposits and their compositional changes as evidence of the dynamic depositional environments from which environmental conditions are inferred. Data on spatial changes on land surfaces have also been employed to complement the sedimentary chronology from catchments beyond historic records. Assessment of the extent of human influence on the Noordhoek basin has been achieved through comparison with the pristine conditions found on the Cape Nature Reserve. Analysis of dated sediment cores from the Noordhoek valley and the Cape Peninsula Nature reserve has facilitated the reconstruction of major environmental changes for the late Pleistocene and Holocene periods. An extended record of environmental change from the longest core (LM-Core) has enabled environmental reconstruction and the determination of the relative influences of climate, sea level change and human activities on the local! environment of the basin during the late Quaternary. Sedimentological evidence from the cores reveals the long-term evolution of the wetlands as being influenced by fluctuating sea levels and climate change until the mid-Holocene. Short-term environmental processes during the late Holocene. resulting from direct anthropogenic activities such as irrational uses of the wetlands for agriculture and urbanisation are responsible for polluting and transforming the status of the wetlands. Heavy metal concentrations in sediment cores from the two Noordhoek wetlands have allowed the elucidation of recent human impacts. The vertical distribution of these metals correlates with and complements the evidence of spatial changes in land use and land cover. Metal enrichment in the modern Noordhoek wetland sediments and increased organic matter content indicates increasing anthropogenic impacts on the valley as agriculture and urbanisation increased. In comparison. there is a much lower concentration of heavy metals at Groot Rondevlei, as its catchment has been less prone to severe local disturbance such as urban development and recent agricultural activities. The absence of a tightly resolved chronology for these cores restricts the understanding of the commencement and duration of major environmental changes, which have been accounted for elsewhere in the region. This limits the opportunity for direct comparison between this and other known sites. However, the Noordhoek valley is a potential resource for longer-term Quaternary environmental study. The application of a multi-disciplinary approach and high-resolution dating are highly recommended for future research in this area.
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    Permaculture as an alternative to present commercial resettlement farming practices in Namibia
    (1998) Stoffberg, Gerrit Hendrik; Holmes, Peter
    The current mono-crop farming practices in the Namibian resettlement farms . there were visited are unsustainable due to soil nutrient, structure and eventually texture destruction. Furthermore, the aridity of Namibia makes crop and livestock farming difficult. Permanent agriculture (permaculture) is a way of living sustainably in the environment and it is proposed as an alternative farming method for the mostly poor and illiterate settlers on resettlement farms. It emphasises self-reliance on basic needs and the creation of artificial ecosystems from which nutrition and infrastructure can be attained in a sustainable manner without exploiting or polluting the environment. Permaculture is not an instant solution but, a long-term sustainable alternative to current agricultural practices in semi-arid and arid areas of Namibia.
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    Sand ramps or climbing dunes? : identification and palaeoenvironmental significance of aeolian deposits in the Southern Kalahari and Breede River valley, South Africa
    (1999) Tyson, Susan Jean; Holmes, Peter; Meadows, Michael E; Thomas, Dave
    The study is primarily concerned with the identification of topographical dunes and their classification as either sand ramps or climbing dunes. Topographical dunes in two semi-arid regions, namely the southern Kalahari (a summer rainfall region) and the Breede River Valley (a winter rainfall region), were investigated. The study also evaluates the palaeoenvironmental significance of the topographical dunes and attempts a palaeoenvironmental reconstruction within the study regions. The two different rainfall regimes facilitated regional comparisons with respect to environmental change, most particularly during the Quaternary. The methodology comprises a review of current literature on topographical dunes, an examination of aerial photography to identify topographical dunes in South Africa and field work to ground truth the dunes. Field sampling, laboratory work (granular composition analysis, pH, conductivity and scanning electron microscopy) as well as statistical analyses (principal component and cluster analyses) were employed to assist in the palaeoenvironmental reconstruction. The results of the laboratory and statistical analyses do not reveal any obvious differences with respect to structure, particle size, pH, conductivity, chemical composition and the surface texture of the grains between, the different topographical dunes. The dunes comprise homogeneous quartz sand that was emplaced against topographical barriers as a result of aeolian processes. They are therefore classified as climbing dunes rather than sand ramps. Three optically stimulated luminescence dates were determined for a topographical dune from each study region. Samples from the Prynnsberg 2 dune in the southern Kalahari are dated to 100 years, and it is suggested that this is due to current reworking of the Kalahari sands from the extensive linear dune field and from the Orange River. It is proposed that the southern Kalahari topographical dunes are currently episodically active. From the Sandput dune in the Breede River Valley, three probable humid phases are identified: 762 kyr, 28.2 kyr and 9.9 kyr. These humid periods may be coupled with episodes of cooling, which supports results from previous studies. This finding has important implications for future climatic changes in the winter rainfall region of South Africa, implying that warming in the Western Cape may be associated with a decrease in precipitation. Lastly, a short historic overview of aerial photographs shows that topographical dunes are susceptible to human impacts in the form of agriculture, overgrazing, sand quarrying and through the construction of dams and weirs on rivers.
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    Soil degradation and associated socio-ecological impacts in the drylands of Nakasongola district, Central Uganda
    (2006) Nakileza, Bob R; Holmes, Peter; Meadows, Michael E
    This study investigated the causes, magnitude and selected socio-ecologlcal effects of soil degradation, with the ultimate goal of explaining and mapping the spatial and temporal variations of degradation in the dryland area of central Uganda.