Preface: proceedings of the 13th IASWS international conference
- Authors: Foster, Ian , Rowntree, Kate M , Ellery, William F N , Ogrinc, Nives , Oldham, Carolyn
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/144465 , vital:38348 , DOI 10.1007/s11368-015-1276-2
- Description: Rhodes University, Grahamstown, South Africa, was the venue for the 13th IASWS International Conference, held from 15 to 18 July, 2014. This international meeting built upon and expanded developing research in South Africa on sediment processes and followed on from a successful meeting organized by Rowntree and Foster on behalf of the Southern African Association of Geomorphologists (SAAG) held in Grahamstown in 2010 and the publication of a special issue of the journal Land Degradation and Development edited by Rowntree et al. (2012).
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- Date Issued: 2015
Extreme weather events in the Sneeuberg, Karoo, South Africa: a case study of the floods of 9 and 12 February 2011
- Authors: Fox, Roddy C , Rowntree, Kate M
- Date: 2013
- Language: English
- Type: Article
- Identifier: vital:6672 , http://hdl.handle.net/10962/d1004468
- Description: Two destructive flood events occurred in rapid succession in the semi-arid Sneeuberg Mountains of the Karoo, South Africa in February 2011. The temporal and spatial characteristics of these two extreme events are examined in this paper through analysis of data from an unusually dense, and reliable, network of farm rain gauges. These analyses add to our understanding derived from existing rain gauge information. Comparisons are then made with patterns from a range of modeled products derived from remote sensed information: the Modern-Era Retrospective Analysis for Research and Applications (MERRA), the Tropical Rainfall Measuring Mission (TRMM) and the Global Land Data Assimilation System (GLDAS). We found that the first flood event was widespread and precipitation was related strongly to altitude. The second was highly localised, with no relationship to altitude. Both had very sharply peaked rainfall intensities. These findings are of significance to the studies of flooding and landscape change in the area as such events have become more pronounced over the past 50 yr and it is likely that this trend will accelerate. The modeled patterns are derived largely from remote sensing and we found that they are reliable for drawing out monthly and annual variations but they make noticeable underestimates. They are poor estimates, however, both for the spatial distribution of precipitation, and the short term trends as they struggle to estimate the impact of topography and other local forcing factors. This finding corroborates information derived from other analyses at broader spatial scales using more widely spread, established rain gauge stations. Ten percent of southern Africa has been classified as mountainous and these areas provide much of our water resources so our findings are significant to water managers throughout this and similar mountainous regions.
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- Date Issued: 2013
The Evil of sluits : a re-assessment of soil erosion in the Karoo of South Africa as portrayed in century-old sources
- Authors: Rowntree, Kate M
- Date: 2013
- Language: English
- Type: Article
- Identifier: vital:6725 , http://hdl.handle.net/10962/d1006803
- Description: Deep, linear gullies are a common feature of the present landscape of the Karoo of South Africa, where they were known locally in the early twentieth century as ‘sluits’. Recent research has shown that many of these features are now stable and are no longer significant sediment sources, although they are efficient connectors in the landscape. Because most of the gully networks predate the first aerial photographs, little is known in the scientific literature about the timing of their formation. One secondary source, however, throws interesting light on the origin of these features, and the early response by landowners to their rehabilitation. The Agricultural Journal of the Cape of Good Hope at the turn of the Twentieth Century carried a number of articles by farmers and agricultural officers concerning the "evil of sluits". The authors gave accounts of widespread incision of valley bottoms by deep, wide gullies. Many of these gullies had been in existence for some thirty years but apparently had formed within living memory. A number of attempts to prevent further erosion had been put in place at the time of writing. This paper presents a review of land degradation, specifically gully erosion, and rehabilitation recommendations as given by authors writing in this journal. It reflects on the findings in the context of assessing land degradation processes through the local knowledge portrayed in the journal.
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- Date Issued: 2013
Changing sediment yield and sediment dynamics in the Karoo uplands, South Africa : post-European impacts
- Authors: Foster, I D L , Rowntree, Kate M , Boardman, J , Mighall, T M
- Date: 2012
- Language: English
- Type: Article
- Identifier: vital:6684 , http://hdl.handle.net/10962/d1006683
- Description: We provide an overview of published results and a significant body of new data from an ongoing research programme designed to reconstruct sediment yields and sources in small (<60 km2) catchments in the Eastern Cape, South Africa over the last 150 years. Our analysis of four catchments has determined that sediment yield increased significantly in the latter half of the 20th Century but that the exact timing of these increases was different in each of the four catchments. In two high altitude locations, sediment yield increases were not associated with a significant change in sediment source, although in one case areas of former cultivation appear to have made a slightly greater contribution since the 1960s. In a third catchment, increases in sediment yield appear to have been driven by the development of badlands and by an increase in connectivity between the badlands and the main channel network in the 1960s. In the fourth catchment, increased connectivity between the main catchment and dam occurred as a result of the construction of a causeway to carry a main road and by the construction of culverts beneath the road. Occasional changes in sediment source have also been identified in the sedimentary record but these were not linked directly to road construction. Research to date shows the complexity of sediment delivery in these semi-arid catchment systems and emphasises the need to combine sediment yield with source ascription in order to better understand the dynamics of these systems.
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- Date Issued: 2012
Futures studies for the southern African region : ‘from Africa’ not ‘on Africa’
- Authors: Fox, Roddy C , Rowntree, Kate M , Kaskinen, J
- Date: 2012
- Language: English
- Type: Conference paper
- Identifier: vital:6668 , http://hdl.handle.net/10962/d1006685
- Description: Futures studies is well established in the Nordic region and its history can be readily charted, but in Africa it barely exists in an institutional form and its evolution and impact is little known or understood. The first two sections of our paper briefly examine the history of futures studies, spending most attention on the African experience. We go on to show that the Higher Education landscape in the Southern African Development Community (SADC) region is very different to that in the Nordic region. Recent futures reports present forecasts and scenarios that show a differentiated Higher Education landscape in the SADC; there are few Higher Education Institutions (HEIs) and even the most optimistic forecasts show that the region as a whole will not meet the international enrollment norm of 30% by 2050. The last part of the paper examines our experience of collaboration with Finland and its well developed linkages between state and Universities. One outcome of three years of collaboration from 2007 to 2009 between two SANORD members, the Finland Futures Research Centre (now a part of the University of Turku) and Rhodes University, was a proposal to develop a multi-disciplinary, inter-institutional futures studies program intended to help Africa find its own voice in futures studies. The final part of our presentation reflects on the unsuccessful experiences that we have had to date in finding funding. We conclude by asking whether our experience can be seen as highlighting some of the challenges SANORD may be positioned to overcome if the SADC region’s HEIs are to achieve the Knowledge Village scenario and begin to match their Nordic counterparts.
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- Date Issued: 2012
Exploring risk related to future climates through role-playing games: the African catchment game
- Authors: Rowntree, Kate M , Fraenkel, Linda A , Fox, Roddy C
- Date: 2009
- Language: English
- Type: Conference paper
- Identifier: vital:6671 , http://hdl.handle.net/10962/d1006807
- Description: Risk is the result of two interacting components: hazard and vulnerability. Climatic hazards are related to extrinsic factors such as drought or severe storms. Vul- nerability is the result of intrinsic factors that often arise from the socio-political- economic context. The interplay of risk and vulnerability is difficult to predict. Although computer models have been widely used to forecast climate related risk, albeit with con- siderable uncertainty, they can never capture sufficiently the vulnerability of human sys- tems to these hazards. Role-playing games can be used more realistically to simulate pos- sible outcomes of different climate change scenarios, and allow players to reflect on their significance. The authors have developed the African Catchment Game to simulate a wa- ter scarce African country. Risk can be modelled mechanistically by changing the nature of the annual rainfall input. Vulnerability can in part be modelled by changing the start- ing parameters (such as access to land and resources) and, secondly, through the unpredictable response of players to game dynamics. Players’ reflections demonstrate that through the game they become more aware of the concept of risk and the complex response of individuals and societies that determine their vulnerability to climatic hazards. This paper reflects on the potential for developing the game further as a tool for participatory learning around climate change, based on the authors’ experience of playing the game with participants from South Africa.
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- Date Issued: 2009
Integrating environmental flow requirements into a stakeholder driven catchment management process
- Authors: Rowntree, Kate M , Birkholz, Sharon A , Burt, Jane C , Fox, Helen E
- Date: 2009
- Language: English
- Type: Conference paper
- Identifier: vital:6670 , http://hdl.handle.net/10962/d1006804
- Description: South Africa's National Water Act (NWA no 36 of 1998) recognizes the need for environmental protection through the ecological Reserve, defined in the Act as the quantity and quality of water required to protect aquatic ecosystems in order to secure ecologically sustainable development through the constrained use of the relevant water resource. Further more the NWA stipulates that the allocation of licenses to new water users, or the granting of increased water use to established water users, can only take place once the the Reserve for the river has been determined and approved by the Minister. This means that water users' needs (beyond those required for basic human needs) take second place behind the environment. Whether or not the inclusion of the ecological Reserve in South Africa's water legislation leads to sustainable use of South Africa's water resources depends on its successful implementation. This in turn depends on the will of both the Department of Water Affairs and Forestry (DWAF), the implementing agent, and the end water users who need to be convinced of the priority given to environmental needs. In this paper we look at the process of implementing the ecological Reserve in the Kat Valley in the Eastern Cape of South Africa as part of a stakeholder driven process of developing a water allocation plan for the catchment that prioritized participation by water users. The extent to which DWAF and the water users expedited or thwarted the process is examined in the light of national and international calls for local-level participation in water resource management processes.
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- Date Issued: 2009
Topographic thresholds in gully development on the hillslopes of communal areas in Ngqushwa Local Municipality, Eastern Cape, South Africa
- Authors: Kakembo, V , Xanga, W W , Rowntree, Kate M
- Date: 2009
- Language: English
- Type: Article
- Identifier: vital:6691 , http://hdl.handle.net/10962/d1006726
- Description: The relationships between the spatial distribution of gully erosion and topographic thresholds in the form of slope angle, position and configuration, as well as land use change in the form of abandoned lands were examined in several affected catchments of the Eastern Cape Province, South Africa. Land use and permanent gullies were mapped, digitized from orthophoto maps in Arc/info 3.5.2 GIS and converted to shapefiles using ArcView 3.2 GIS. Relationships between the mapped phenomena and topographic variables were sought using a Digital Elevation Model (DEM) in Idrisi Kilimanjaro GIS. A comparison between areas with a high potential for gullying and actual gully erosion was made using the Stream Power Index (SPI) as a surrogate for critical flow shear stress. Field surveys were also conducted to assess the present condition of the gullied sites as well as to validate DEM derivations. Seventy five percent of the gullied area was noted to lie on abandoned lands. A predominance of gullying in concave bottom lands was also identified. The SPI values highlighted a distinct preferential topographic zone for gully location. A conceptual model depicting the interaction between land use and topographic parameters to induce gully erosion was developed. This should assist local authorities to develop a policy regarding management of abandoned lands.
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- Date Issued: 2009
Topographic controls on the invasion of Pteronia incana (Blue bush) onto hillslopes in Ngqushwa (formerly Peddie) district, Eastern Cape, South Africa
- Authors: Kakembo, V , Rowntree, Kate M , Palmer, Anthony R
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6689 , http://hdl.handle.net/10962/d1006708
- Description: The role of topographic factors in the invasion of hillslopes by Pteronia incana, an unpalatable shrub, was investigated. The study combined field observations with image analysis based on high-resolution infrared imagery. A Digital Elevation Model (DEM) of 20 m spatial resolution was used to derive terrain parameters. The Topographic Wetness Index (WI), a component of the TOPMODEL, was derived from the DEM and its relationship with the spatial distribution of P. incana was explored. The absence/presence of P. incana was noted to be strongly influenced by slope angle and aspect. The probability for P. incana occurrence increased with slope steepness and southerly slope orientation. Abandoned and grazing lands were identified as the main invasion hotspots on hillslopes. The combined influence of slope gradient and aspect, and land use was noted to have promoted the invasion. This is borne out by the concentration of the invasion on abandoned steep slopes with a southerly orientation. The WI confirmed the bearing local topographic variations have on P. incana spatial distribution such that, P. incana was associated with the low WI values of convexities. The coupling between local topography and soil surface crusting underpins soil moisture variability. This in turn determines the competition between the patchy P. incana and grass species and the eventual replacement of the latter by the former. Restoration efforts of the invaded lands should focus on trapping of sediment and litter, and moisture retention on the inter-patch bare areas.
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- Date Issued: 2007
Active learning for understanding land degradation : African Catchment Game and Riskmap
- Authors: Rowntree, Kate M , Fox, Roddy C
- Date: 2006
- Language: English
- Type: Conference paper
- Identifier: vital:6669 , http://hdl.handle.net/10962/d1006793
- Description: Land degradation is the result of the intersection of a complex set of biophysical and socio-economic factors. The capacity of an individual or community to address land degradation is likewise constrained. While it is quite possible for professionals and learners to grasp the main issues around land degradation from a theoretical perspective, internalizing the reality of what it means to be the resource degrader is more difficult. We have developed two active learning methods that aim to address this problem. The first is the African Catchment Game, a role-playing game based on Graham Chapman’s Green Revolution Game, adapted for the southern Africa context and incorporating a land degradation component. In this game participants play out the complex dynamics of rural-urban-global linkages against a background of environmental hazards. The second is based on Save the Children Fund’s RiskMap computer simulation that models risk in terms of rural livelihoods for different income groups. Ethiopia is used as the example. This paper evaluates the two active learning techniques as tools for exploring the relationships between land degradation and poverty through an evaluation of participants’ experiences.
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- Date Issued: 2006
On the fast track to land degradation? A case study of the impact of the Fast Track Land Reform Programme in Kadoma District, Zimbabwe
- Authors: Fox, Roddy C , Rowntree, Kate M , Chigumira, Easther C
- Date: 2006
- Language: English
- Type: Conference paper
- Identifier: vital:6663 , http://hdl.handle.net/10962/d1006668
- Description: The Fast Track Land Reform Programme is the defining instrument for Zimbabwe’s future development prospects. In the three year period from 2000 to 2002 300,000 families were resettled on 11 million hectares thus witnessing the end of the colonial division of land which had seen 15.5 million hectares still in European hands in 1980, the start of the post-colonial period. The process which displaced the commercial farm workers and farm owners was chaotic, violent and disorderly and so has been called jambanja. Subsequent legislation and government agricultural initiatives have attempted to impose, retroactively, technocratic order to the sweeping changes that have taken place. Our study shows that the dire macro-economic situation coupled with trends of HIV/AIDS prevalence means that developing sustainable land use practices is going to be a very difficult proposition. At the local scale, our case studies show that there have been multiple outcomes with low investment, very limited government support and resource extraction leading to land degradation and unsustainable farming practices. In some instances, however, individual households have benefitted in the short term from the process but this has only occurred where climatic and soil conditions have been particularly favourable.
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- Date Issued: 2006
Water resources in Botswana with particular reference to the savanna regions
- Authors: du Plessis, A J E , Rowntree, Kate M
- Date: 2003
- Language: English
- Type: Article
- Identifier: vital:6676 , http://hdl.handle.net/10962/d1006654
- Description: Production and development in the savanna regions of southern Africa are primarily determined by interactions between the limitations imposed by ecological determinants (such as rainfall and soil quality) and the management strategies of the specific region. Good planning, focussing on both the short and long-term effects of water use, is needed in water management strategies. Botswana is already experiencing so-called 'water stress' which is related to a number of factors such as rapidly increasing population leading to a sharp increase in water demand, low and variable rainfall, high rates of evaporation, and the high cost of exploiting existing water resources. At the current rates of abstraction, the lifetime of surface and groundwater resources is limited to decades. Botswana shares four river basins with its neighbouring countries. This results in a situation where 94% of the fresh water resources which Botswana can theoretically access originates outside its borders, making water resource management highly complex. Transnational sharing and management of water resources, therefore, plays a major role in securing sustainability of this precious resource.
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- Date Issued: 2003
The land question in South Africa, Zimbabwe and Kenya: a geographical perspective on resource endowment
- Authors: Fox, Roddy C , Rowntree, Kate M
- Date: 2002
- Language: English
- Type: Conference paper
- Identifier: vital:6664 , http://hdl.handle.net/10962/d1006671
- Description: In sharp contrast to the debates concerning land policy, land tenure and sustainable resource management in South Africa is any input concerning the geographical distribution of land productivity. This paper attempts to redress this imbalance by providing an empirical investigation of land potential in South Africa. In this way we intend to provide the crucial context for policy and academic studies of the land issue in South Africa. Furthermore, we will undertake our study in such a way that comparison can be made to Zimbabwe and Kenya where the land issue has been such a critical component of the post-colonial development process. Theoretically our work is contextualised within the debates surrounding the importance of geographical endowments, institutions and policies in the development process.
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- Date Issued: 2002
The development of a geomorphological classification system for the longitudinal zonation of South African rivers
- Authors: Rowntree, Kate M , Wadeson, Roy A , O'Keeffe, Jay H
- Date: 2000
- Language: English
- Type: Article
- Identifier: vital:6722 , http://hdl.handle.net/10962/d1006799
- Description: The recognition of the Reserve by the new South African Water Law poses new challenges for river scientists. The ecological water requirement or environmental flow is recognised by that part of the Reserve known as the ecological Reserve. If the ecological Reserve is to be implemented, it must first be defined and quantified for all river systems subject to water related developments. Standard procedures are being developed through the Resource Directed Measures (RDM) of the Department of Water Affairs and Forestry while monitoring the health of South Africa's rivers is taking place through the National River Health Programme (NRHP). Cost effective methods of developing spatial frameworks for both the RDM and NRHP are required. Concepts of longitudinal river zonation were developed by river ecologists in the 1960s and 1970s to assist in the classification of ecologically uniform stretches of rivers. This paper reviews the different zonation concepts and presents a geomorphological classification of South African river zones that is being applied to the RDM and NRHP. The classification is tested on three rivers, the Sabie, Buffalo and Olifants.
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- Date Issued: 2000
Vegetation controls on channel stability in the Bell River, Eastern Cape, South Africa
- Authors: Rowntree, Kate M , Dollar, Evan S J
- Date: 1999
- Language: English
- Type: Article
- Identifier: vital:6720 , http://hdl.handle.net/10962/d1006796
- Description: Channel instability has occurred in the Bell River in the form of meander cutoffs, a number of which have occurred since 1952. Increased sediment loading from widespread gully erosion in the catchment has been proposed as the trigger for this instability. Willow species of the Salix family, in particular S. caprea, have been planted along the banks in an effort to prevent further channel shifting. This study reports the results of an investigation into the effect of vegetation on channel form and stability over a 17 km stretch of channel. Results indicate that riparian vegetation has significant effects on channel form which have implications for channel stability. Riparian vegetation increases bank stability and reduces channel cross-sectional area, thereby inducing stability at flows less than bankfull. Evidence indicates that narrow stable stretches are associated with relatively high levels of riparian vegetation. Wider, unstable channels are associated with relatively less riparian vegetation. The effectiveness of riparian vegetation relative to bank sediments was investigated. A dense growth of willows was found to have an equivalent effect to banks with a silt-clay ratio of about 70 per cent. The channel narrowing induced by vegetation may contribute to channel shifting at high flows. The reduced channel capacity is thought to result in more frequent overbank flooding which may ultimately lead to channel avulsion. Thus where increased sediment loading is pushing the channel towards instability, vegetation may be effective in imparting local stability, but it is unable to prevent long-term channel shifts, and may rather help to push the system towards more frequent avulsions.
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- Date Issued: 1999
Controls on channel form and channel change in the Bell River, Eastern Cape, South Africa
- Authors: Rowntree, Kate M , Dollar, Evan S J
- Date: 1996
- Language: English
- Type: Article
- Identifier: vital:6723 , http://hdl.handle.net/10962/d1006801
- Description: Channel instability has occurred in the Bell River in the form of meander cutoffs, incipient meander cutoffs, and general channel instability. This paper examines the incidence of channel instability in relation to the spatial variability of factors controlling channel form. The locations of channel change were mapped from aerial photographs for a 40 year period. Channel form characteristics were measured over a 17 km stretch of channel. Data collected from this stretch included pattern, width, depth, form ratio, channel gradient, particle-size distribution of bed and bank materials and riparian vegetation. Results indicate that the two primary spatial controls on channel form and pattern are riparian vegetation and bed-material size. Evidence indicates that narrow stable stretches are associated with finer bed-material and relatively high levels of riparian vegetation. Riparian vegetation increases bank stability and reduces channel cross-section, thereby inducing stability at flows less than bankfull. However, at flows greater than bankfull, reduced channel capacity results in more frequent flooding which may ultimately lead to channel avulsion. Wider, unstable channels are associated with larger calibre bed material and relatively less riparian vegetation. Predicted threshold slopes for braiding have indicated that most reaches in the Bell river are close to or above the threshold slope for braiding. Since riparian vegetation serves to increase bank stability, steeper threshold slopes are required for braiding in channels with high vegetation density Recent incidences of channel instability have been identified as occurring in the transitional zone between the upper, coarser reach and lower, finer channel reach.
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- Date Issued: 1996
Hydroclimatic trends, sediment sources and geomorphic response in the Bell River catchment, eastern Cape Drakensberg, South Africa
- Authors: Dollar, Evan S J , Rowntree, Kate M
- Date: 1995
- Language: English
- Type: Article
- Identifier: vital:6677 , http://hdl.handle.net/10962/d1006655
- Description: The Bell River in the Eastern Cape Drakensberg of South Africa has shown recent signs of channel instability as evidenced by avulsion, sinuosity reductions, gradient steepening and general channel instability. Analysis of rainfall data did not provide evidence for progressive long term change in rainfall pattern for the catchment. However, annual and seasonal rainfall cycles with variance peaks every 16-19 years were found, from which it can be inferred that flood events following years of below average rainfall may cross the threshold limit for channel stability. Channel instability is often followed by a major flood event after sustained low rainfall periods, a sequence referred to as the Flood and Drought Dominated Regimes by Warner (1987). Evidence presented also indicates an increase in catchment erosion in the past century with attendant sediment production increases to the channel. This may be due to catchment land use and management practices (following settlement by commercial farmers) superimposed on long term climatic changes. The conclusions are that catchment and channel processes are inseparable, and that disequilibrium in the catchment will be transferred to the channel.
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- Date Issued: 1995