Academic literature on the topic 'Crocodile river catchment area south africa'

The Crocodile River catchment lies in an area which currently has one of the highest rates of sustained economic growth in South Africa and supports a diverse array of land uses. Water quality management is vital to resource management strategies for the catchment. A Geographic Information System (GIS) was used to display specific catchment characteristics and land uses, supplemented with integrative overlays depicting land-use impacts on surface water resources and the consequences of management actions on downstream water quality. The water quality requirements of each water user group were integrated to optimise the selection of rational management solutions for particular water quality problems. Time-series water quality data and cause-effect relationships were used to evaluate different water supply scenarios. The GIS facilitated the collation, processing and interpretation of the enormous quantity of spatially orientated information required for integrated catchment management.

Abstract. Global climate change has received much attention worldwide in the scientific as well as in the political community, indicating that changes in precipitation, extreme droughts and floods may increasingly threaten many regions. Drought is a natural phenomenon that causes social, economical and environmental damage to society. In this study, we assess the drought intensity and severity and the groundwater potential to be used as a supplementary source of water to mitigate drought impacts in the Crocodile River catchment, a water-stressed sub-catchment of the Incomati River catchment in South Africa. The research methodology consists of three parts. First, the spatial and temporal variation of the meteorological and hydrological drought severity and intensity over the catchment were evaluated. The Standardized Precipitation Index (SPI) was used to analyse the meteorological drought and the Standardized Runoff Index (SRI) was used for the hydrological drought. Second, the water deficit in the catchment during the drought period was computed using a simple water balance method. Finally, a groundwater model was constructed in order to assess the feasibility of using groundwater as an emergency source for drought impact mitigation. Results show that the low-rainfall areas are more vulnerable to severe meteorological droughts (lower and upper crocodile). Moreover, the most water stressed sub-catchments with high level of water uses but limited storage, such as the Kaap located in the middle catchment and the Lower Crocodile sub-catchments, are more vulnerable to severe hydrological droughts. The analysis of the potential groundwater use during droughts showed that a deficit of 97 Mm3 yr−1 could be supplied from groundwater without considerable adverse impacts on the river base flow and groundwater storage. Abstraction simulations for different scenarios of extremely severe droughts reveal that it is possible to use groundwater to cope with the droughts in the catchment. However, local groundwater exploitation in Nelspruit and White River sub-catchment will cause large drawdowns (> 10 m) and high base flow reduction (> 20%). This case study shows that conjunctive water management of groundwater and surface water resources is necessary to mitigate the impacts of droughts.

Abstract. Global climate change has received much attention worldwide in the scientific as well as in the political community, indicating that changes in precipitation, extreme droughts and floods may threaten increasingly many regions. Drought is a natural phenomenon that may cause social, economical and environmental damages to the society. In this study, we assess the drought intensity and severity and the groundwater potential to be used as a supplement source of water to mitigate drought impacts in the Crocodile River catchment, a water-stressed sub-catchment of the Incomati River catchment in South Africa. The research methodology consists mainly of three parts. First, the spatial and temporal variation of the meteorological and hydrological drought severity and intensity over the catchment were evaluated. The Standardized Precipitation Index (SPI) was used to analyse the meteorological drought and the Standardized Runoff Index (SRI) was used for the hydrological drought. Second, the water deficit in the catchment during the drought period was computed using a simple water balance method. Finally, a groundwater model was constructed in order to assess the feasibility of using groundwater as an emergency source for drought impact mitigation. Results show that the meteorological drought severity varies accordingly with the precipitation; the low rainfall areas are more vulnerable to severe meteorological droughts (lower and upper crocodile). Moreover, the most water stressed sub-catchments with high level of water uses but limited storage, such as the Kaap located in the middle catchment and the Lower Crocodile sub-catchments are those which are more vulnerable to severe hydrological droughts. The analysis of the potential groundwater use during droughts showed that a deficit of 97 Mm3 yr−1 could be supplied from groundwater without considerable adverse impacts on the river base flow and groundwater storage. Abstraction simulations for different scenarios of extremely severe droughts reveal that it is possible to use groundwater to cope with the droughts in the catchment. However, local groundwater exploitation in Nelspruit and White River sub-catchment will cause large drawdowns (> 10 m) and high base flow reduction (> 20%). This case study shows that conjunctive water management of groundwater and surface water resources is the necessary to mitigate the impacts of droughts.

Abstract. The Incomati is a semi-arid trans-boundary river basin in southern Africa, with a high variability of streamflow and competing water demands from irrigated agriculture, energy, forestry and industries. These sectors compete with environmental flows and basic human water needs, resulting in a "stressed" water resource system. The impacts of these demands, relative to the natural flow regime, appear significant. However, despite being a relatively well-gauged basin in South Africa, the natural flow regime and its spatial and temporal variability are poorly understood and remain poorly described, resulting in a limited knowledge base for water resource planning and management decisions. Thus, there is an opportunity to improve water management, if it can be underpinned by a better scientific understanding of the drivers of streamflow availability and variability in the catchment. In this study, long-term rainfall and streamflow records were analysed. Statistical analysis, using annual anomalies, was conducted on 20 rainfall stations, for the period 1950–2011. The Spearman test was used to identify trends in the records on annual and monthly timescales. The variability of rainfall across the basin was confirmed to be high, both intra- and inter-annually. The statistical analysis of rainfall data revealed no significant trend of increase or decrease. Observed flow data from 33 gauges were screened and analysed, using the Indicators of Hydrologic Alteration (IHA) approach. Temporal variability was high, with the coefficient of variation of annual flows in the range of 1 to 3.6. Significant declining trends in October flows, and low flow indicators, were also identified at most gauging stations of the Komati and Crocodile sub-catchments; however, no trends were evident in the other parameters, including high flows. The trends were mapped using GIS and were compared with historical and current land use. These results suggest that land use and flow regulation are larger drivers of temporal changes in streamflow than climatic forces. Indeed, over the past 40 years, the areas under commercial forestry and irrigated agriculture have increased over 4 times.

Abstract. The Incomati is a semi-arid trans-boundary river basin in southern Africa, with a high variability of streamflow and competing water demands from irrigated agriculture, energy, forestry and industries. These sectors compete with environmental flows and basic human water needs, resulting in a "stressed" water resources system. The impacts of these demands, relative to the natural flow regime, appear significant. However, despite being a relatively well-gauged basin in South Africa, the natural flow regime and its spatial and temporal variability are poorly understood and remain poorly described, resulting in a limited knowledge base for water resources planning and management decisions. Thus, there is an opportunity to improve water management, if it can be underpinned by a better scientific understanding of the drivers of streamflow availability and variability in the catchment. In this study, long-term rainfall and streamflow records were analysed. Statistical analysis, using annual anomalies, was conducted on 20 rainfall stations, for the period of 1950 to 2011. The Spearman Test was used to identify any trends in the records at annual and monthly time scales. The variability of rainfall across the basin was confirmed to be high, both intra- and inter-annually. The statistical analysis of rainfall data revealed no significant trend of increase or decrease for the studied period. Observed flow data from 33 gauges was screened and analyzed, using the Indicators of Hydrologic Alteration (IHA) approach. Long-term analyses were conducted to identify temporal/spatial variability and trends in streamflow records. Temporal variability was high, with the coefficient of variation of annual flows in the range of 1 to 3.6. Significant declining trends in October flows, and low flows indicators were also identified at most gauging stations of the Komati and Crocodile sub-catchments, however no trends were evident on the other parameters, including high flows. The trends were mapped, using GIS and were compared to historical and current land use. These results suggest that land use and flow regulation are larger drivers of temporal changes in the streamflow than climatic forces. Indeed, over the past 40 years, the areas under commercial forestry and irrigated agriculture have increased over four times.

<em>Biological indicators such as macro-invertebrates and water quality parameters can give an overalln overview of what is happening in a river catchment. The aim of the study was to determine the influence of anthropogenic activities on macro-invertebrates assemblage and water quality using multivariate analysis and to determine the present ecological state of the river using the Macro-Invertebrates Response Assessment index. The South African Scoring System Version 5 (SASS 5) was used to collect macro invertebrates. Water quality samples were collected using a polyethylene bottle and analysed by Mpumamanzi Laboratory in Nelspruit and Water lab in Pretoria. From the results obtained it was evident that anthropogenic activities along the Crocodile River play a role in water quality deterioration and the subsequent distribution of macro-invertebrates during high and low flow conditions. The main anthropogenic activities contribute to the influence of macro-invertebrates community and water quality are agricultural activities in the upper reaches and a combination of industrial, domestic, mining and agricultural activities in the middle and lower reaches of the Crocodile River.</em>

Increasing competition for water in South Africa is changing the management emphasis from one of supply to that of controlling demand. There are many possible alternative uses of water. The Catchment Resource Assessment Model (CRAM) is a tool which can help evaluate these alternative uses. CRAM has been designed to: - be objective; - be fair to all parties; - balance social, environmental and economic benefits and costs, and - be understandable to the educated non-specialist user. Using water as a “currency”, CRAM simulates the impacts of land uses on hydrological, economic, environmental and social conditions in a catchment. The Crocodile River catchment is modelled in the current implementation of CRAM. Users have indicated their preference for familiar and well-tried submodels in CRAM, rather than new, unknown models.

Brominated flame retardants (BFRs) are considered to be environmental pollutants due to their toxicity, persistence and ubiquity in the environment. Little information is known about the presence of brominated flame retardants in South Africa's water systems. Therefore, this study examined and compared different extraction methods (liquid–liquid (LL) vs. solid phase (SP) for water, Soxhlet extraction (SE) vs. ultrasonic for sediment) for extraction efficiencies in the determination of polybrominated diphenyl ethers (PBDEs) and polybrominated biphenyls (PBBs) in water and sediment from Jukskei River. Clean-up of sample extracts was performed using disposable Pasteur pipettes containing neutral, acidified and basic silica gel. Final extracts, after concentration and dilution to 200 μL were analyzed by injecting 1 μL in the GC-ECD and GC-MS. Results obtained showed good recoveries for most of the tested analytes in water; for LLE, values ranged between 80.5 ± 10.22% and 126.6 ± 1.94%; SPE, 70.41 ± 2.01%–124.78 ± 3.78% (n = 3) and for sediment (73–114%, with an RSD &lt;17%) using SE. The ultrasonic extraction method gave less than 50% recovery for most of the congeners. The concentrations of the BFRs in water samples were less than the detection limit while the concentrations in sediment ranged from 1.95 to 36.61 ng g−1 dry weight for Σ11 BFRs. Dichloromethane and n-hexane : acetone (2 : 1, v/v) gave optimum value of recovery for water and sediment respectively.

This paper describes a 2-year pilot project undertaken in an urban catchment in Cape Town, South Africa. The impermeable area of the Lotus River catchment has doubled over 15 years, from 17% in 1983 to 34% in 1997. Following the abolition of urban influx control in 1990, informal settlements in the catchment grew rapidly and now house about 90,000 out of the catchment's total population of 380,000 people. The informal areas are still largely unserviced, despite a commitment from local government to speed up service delivery to the poorest areas of the city. Within the Lotus River project, hydrological and ecological assessments of the urban watercourses were undertaken, through physico-chemical and microbiological sampling programmes, macro-invertebrate counts, and vegetation sampling. All available information regarding the catchment was integrated within a GIS platform, including demographic and socio-economic data on the various communities, and hydrogeological information on the underlying aquifer obtained from earlier studies. The integrated nature of the project allows a number of conclusions and recommendations to be drawn, regarding the management of this particular catchment. However, important general lessons have also been learned which can be applied by local authorities responsible for urban catchments in developing countries. The necessity of providing the required institutional structures cannot be overemphasised.

In South Africa, precipitation is extremely variable and water is scarce. South Africa is also a country with great welfare needs. Challenging economic development targets and plans therefore need to be implemented successfully within the constraints of limited water supply and unreliable water availability. These economic development plans are underpinned by the development and growth of economic activities such as agriculture, mining, energy production and many types of small, medium and micro enterprises, which are some of the largest water using sectors in the economy. Within these activities, increased competition places pressure on water users to keep supplying their markets with competitively priced goods, while rising costs of new water supplies puts pressure on water users to allocate sufficient water to their production processes. These market forces and the relative scarcity of water as an economic production factor, impact on financial viability and imply that the economic efficiency of water use becomes increasingly important. The National Water Act of 1998 (NWA) is a legislative response to this situation, and promotes a radical shift towards efficiency and equity goals in water allocation. Water users who require water as an input to economic activities are consequently seriously revising their water use patterns in response to one of the major implications of the NWA and its related principal strategy: water demand management. Water demand management strives to adhere to the principles of equity, social justice, economic efficiency and environmental sustainability, which are central to the NWA. This study evaluates the costs and benefits of water use in order to simulate the effects of water demand management activities on a catchment economy. The results of a number of studies were combined to generate an economy-wide model: a Social Accounting Matrix (SAM), for the case study area and to simulate the direct and indirect effects of water demand management on the people, the economy and the natural environment in the area. Water demand management (WDM) is defined as consisting of two phases. In the first phase, goals of full cost recovery, improving water use efficiency and allocating water optimally are targeted. The second phase of WDM arrives when a situation of absolute water scarcity is reached within a catchment. In this phase water demand outweighs water supply and water has to be allocated according to its scarcity value. Water markets play a large role here. The SAM was used to simulate the direct and indirect impacts on the economy and the environment of a number of WDM related scenarios. Water e-allocation decisions and the effects of various WDM policy instruments, such as reduction of water use subsidies and increases in water tariffs were simulated. Unintended consequences of other environmental policies on water use, in this case, carbon tax, were explored. Water scarcity predictions were done, and some of the transaction costs involved in water trading was quantified. The study concludes with a discussion on the indirect effects on the economy, the environment and people of changes affecting the agricultural (including forestry) activities. The direct and indirect impacts of WDM policies on the economy and the environment, and the importance of environmental-economic models in water cost benefit modeling are also discussed. Implications for policy and management are highlighted. This study shows specifically how, through modelling various scenarios, policy decisions aimed at managing specific variables (e.g. water use, carbon emissions) have an economic and environmental impact much wider than the sector in which the policy was targeted for. Each scenario shows how a water transaction, or a change in subsidy in the agricultural (including forestry) sector, could impact on the output of other economic sectors, and therefore the economy as a whole. It is therefore evident that policy decisions, which are implemented at a macro level, and could have a major direct impact on a wider range of economic sectors, should be carefully considered as they could have large, undesirable, unintended consequences.
Dissertation (MSc (Agricultural Economics))--University of Pretoria, 2004.
Agricultural Economics, Extension and Rural Development
MSc (Agric)
unrestricted

Internationally, water resources are facing increasing pressure due to over-exploitation and pollution. Integrated Water Resource Management (IWRM) has been accepted internationally as a paradigm for integrative and sustainable management of water resources. However, in practice, the implementation and success of IWRM policies has been hampered by the lack of availability of integrative decision support tools, especially within the context of limited resources and observed data. This is true for the Crocodile River Catchment (CRC), located within the Mpumalanga Province of South Africa. The catchment has been experiencing a decline in water quality as a result of the point source input of a cocktail of pollutants, which are discharged from industrial and municipal wastewater treatment plants, as well as diffuse source runoff and return flows from the extensive areas of irrigated agriculture and mining sites. The decline in water quality has profound implications for a range of stakeholders across the catchment including increased treatment costs and reduced crop yields. The combination of deteriorating water quality and the lack of understanding of the relationships between water quantity and quality for determining compliance/non-compliance in the CRC have resulted in collaboration between stakeholders, willing to work in a participatory and transparent manner to create an Integrated Water Quality Management Plan (IWQMP). This project aimed to model water quality, (combined water quality and quantity), to facilitate the IWQMP aiding in the understanding of the relationship between water quantity and quality in the CRC. A relatively simple water quality model (WQSAM) was used that receives inputs from established water quantity systems models, and was designed to be a water quality decision support tool for South African catchments. The model was applied to the CRC, achieving acceptable simulations of total dissolved solids (used as a surrogate for salinity) and nutrients (including orthophosphates, nitrates +nitrites and ammonium) for historical conditions. Validation results revealed that there is little consistency within the catchment, attributed to the non-stationary nature of water quality at many of the sites in the CRC. The analyses of the results using a number of representations including, seasonal load distributions, load duration curves and load flow plots, confirmed that the WQSAM model was able to capture the variability of relationships between water quantity and quality, provided that simulated hydrology was sufficiently accurate. The outputs produced by WQSAM was seen as useful for the CRC, with the Inkomati-Usuthu Catchment Management Agency (IUCMA) planning to operationalise the model in 2015. The ability of WQSAM to simulate water quality in data scarce catchments, with constituents that are appropriate for the needs of water resource management within South Africa, is highly beneficial.

Water quality deterioration is reaching crisis proportions in South Africa. Many South African catchments are over-allocated, and decreasing volumes of source water mean increasing concentrations of pollutants. The Crocodile River Catchment in the Mpumalanga province in South Africa was identified through previous research, as a catchment faced with deteriorating source water quality for water users in the catchment. Poor source water quality has become a sufficiently acute concern for the stakeholders in this catchment to co-operate in developing a process that assists with compliance control of their water use and waste disposal to reduce costs, decrease industrial risks as water quality compliance increases, and improve source water quality. The sugar industry is downstream within the Crocodile River Catchment, and is affected by the activities of all upstream water users; the industry is thus dependent on the stakeholders upstream participating in the effective management of the resource. However, the sugar industry is also located just before the confluence of the Crocodile River and Komati River upstream of the Mozambique border, and thus the water quality of the sugar industry effluent will affect the quality of the water that flows into Mozambique. The sugar industry is on the opposite river bank to the Kruger National Park, which has high water resource protection goals. Therefore, the sugar industry has a national role to play in the management of water resources in the Crocodile River Catchment. This study provides a focused view of the role of the sugar industry in the development of a co-operative, integrated water quality management process (IWQMP) in the Crocodile River Catchment. In order to address the objectives of this study, this research drew from an understanding of the social processes that influence water management practices within the sugar industry as well as social processes that influence the role of the Inkomati-Usuthu Catchment Management Agency as the main governing institution in water resource management in the Inkomati Water Management Area. The study also drew from an understanding of scientific knowledge in terms of a water chemistry which describes the upstream and downstream water quality impacts related to the sugar industry. The water quality analysis for the Lower Crocodile River Catchment shows a decline in water quality in terms of Total Dissolved Solids (TDS) loads when moving from below Mbombela to the Mozambique border. The major sources of TDS in the Lower Crocodile River are point source dominated, which may be attributed to the extensive mining, industrial and municipal activities that occur across the catchment. When observing Total Alkalinity (TAL) and pH values from below Mbombela to the furthest monitoring point, there is deterioration in the quality of the water in the Lower Crocodile River, with the Kaap River contributing a negative effect that is diluted by the Crocodile main stem. The Hectorspruit Waste Water Treatment Works (WWTWs) (located in the Lower Crocodile River Catchment) contributes high concentrations of TDS and TAL into the Crocodile River. Total Inorganic Nitrogen and Soluble Reactive Phosphorus concentrations decrease in the lower reaches of the Crocodile River compared with the river below Mbombela, which can be attributed to the extensive sugar cane plantations located in the Lower Crocodile River Catchment acting as an “agricultural wetland” that serves a function of bioremediation resulting in large scale absorption of nutrients. This is an interesting result as earlier assumptions were that fertiliser application would result in an overall increase in nutrient loads and concentrations. Biomonitoring data show no substantial change in aquatic health in the LowerCrocodile River Catchment. For a catchment that has an extensive agricultural land use in terms of sugarcane and citrus production, the Crocodile River is unexpectedly not in a toxic state in terms of aquatic health. This is a positive result and it suggests that pesticide use is strictly controlled in the sugar and citrus industry in the Crocodile River Catchment. For long term sustainability, it is essential for the sugar industry to maintain (and possibly improve) this pesticide management. The social component of this study aimed to provide an analysis of the management practices of the sugar mill as well as examining agricultural practices in the sugar cane fields in relation to water quality management through the use of Cultural Historical Activity System Theory (CHAT). This component showed that there are contradictions within the sugar industry activity system that are considered to be areas of “tension” that can be loosened or focused on to improve the contribution the sugar industry can make to the IWQMP. Surfacing contradictions within the sugar industry activity system and the Inkomati-Usuthu Catchment Management Agency activity systems highlighted areas of potential for learning and change. While an understanding of biophysical processes through scientific knowledge is critical in water management decision making, it is evident that an understanding of other actors, institutions and networks that inform water quality management decision-making also plays a significant role. The notion of improving the role of scientific or biophysical knowledge in contributing to socio-ecologically robust knowledge co-creation, decisions and actions towards resolving water quality problems is emphasised. Specifically, moving towards improving interactions between scientists and other actors (water users in the Crocodile Catchment in this case), so that scientific practices become more orientated towards societal platforms where water quality management is tackled to enable improved water quality management practices. Therefore, linking the social and biophysical components in this study provides a holistic understanding of how the sugar industry can contribute to the development of an IWQMP for the Crocodile River catchment.

Irrigation policy from 1870 is examined in detail. History shows that water allocation was made on political grounds, the preferred solution being supply augmentation with economic demand management playing a secondary role. Failure to conduct any proper cost-benefit, or other economic, studies of water use efficiency, led to water abundance for some users and no supply for others. As water resources became economically scarce, and supply augmentation prohibitively expensive and environmentally damaging, water markets evolved in the 1980s in response to demands for more flexible allocation. These markets, which were initially illegal, have improved efficiency. A case study of the Crocodile River catchment explains the history of institutional development since the Second World War and how local institutions allocated water. Much of this institutional change was driven by the racist policy of apartheid. Recent institutional changes, driven by misallocation and droughts, are examined in detail because they enabled a market in tradeable use rights to flourish. The efficiency gains from this market are estimated. The final section of the research examines recent changes in water institutions in South Africa following the end of apartheid and the 1994 elections. The research concludes with a discussion of the likely path that allocation will take given the post-1994 institutions, and possible future research on the catchment, and water use in South Africa.

A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of requirements for the degree of Master of Science. Johannesburg, 2017.
A study on groundwater recharge and processes controlling recharge was conducted in the Upper Crocodile catchment, located in the Johannesburg region. The catchment extends from the water divide south of Johannesburg, to the Hartbeespoort Dam in the North-West Province. The study area is predominantly underlain by the crystalline basement and meta-sedimentary rocks. The Upper Crocodile catchment is classified as a semi-arid region, receiving a mean annual rainfall of 699.3 mm/yr. Groundwater recharge was quantitatively and qualitatively assessed using the water balance, baseflow separation, water table fluctuation and environmental isotope methods. The water balance and the baseflow separation methods resulted in recharge amounts of 4 and 5.8% of mean annual rainfall, respectively. The water table fluctuation method was only applied to the dolomitic aquifer and yielded a mean annual recharge estimate of 14% of the mean annual rainfall. Application of the isotopic shift method, which makes use of isotopically enriched water samples, resulted in a recharge amount of 10.19 to 23.90 mm/month obtained for the quartzites of the Witwatersrand Supergroup, south of the study area. Tritium was used to determine the residence time of stream water samples, collected during winter to represent baseflow. Additionally, it was used to understand the range of groundwater contribution to streams. The tritium values revealed that there are three types of water; i) relatively old water with lower tritium values, ii) intermediate tritium values indicating the possibility of mixing of older groundwater with more recent recharge and iii) high tritium values suggesting contamination from a local source/recent rainwater. The results of groundwater recharge from the quantitative methods showed a temporal and spatial variability of recharge; this was attributed to the different processes that govern groundwater recharge. Climate appeared to have the most influence on potential groundwater recharge, with rainfall controlling the temporal variability of recharge while land cover, soil characteristics and geology influenced the spatial distribution of groundwater recharge. Approximately 153 x 106 m3/yr of wastewater was discharged into streamflow from wastewater treatment works as of 2008. The wastewater flow into streams overshadowed the baseflow contribution. The consequence of the presence of wastewater was reflected in the overestimation of groundwater recharge.
LG2017

Ph.D.
The Crocodile River catchment, in Mpumalanga, is one the most intensively used catchments in South Africa. The large number of intensively cultivated crops grown in the middle and lower subcatchments; industrial discharges; highly intensive irrigation; and extensive areas of exotic afforestation in the upper and middle sub-catchments has dramatically changed land use patterns within the catchment. The Middle Crocodile River sub-catchment is also impacted by intensive urbanisation; around Nelspruit, KaNyamazane and Matsulu. The Kaap River sub-catchment has been intensively mined for minerals and the impacts of these mining operations are still reflected in the water quality of streams and rivers in this sub-catchment. The downstream uses of the Crocodile River's water quality are the aquatic ecosystem, the Kruger National Park (as the river is the southern boundary of the park) and Mozambique (international obligations). The Crocodile River catchment supports one of the richest fish species diversities in South Africa. It is therefore important to determine the impacts of these land use activities on the fish populations and the potential human health risks if fish are consumed. In the present study data from five gauging stations for each of the main tributaries draining the five sub-catchments (the Upper, Middle and Lower Crocodile River, Kaap and Elands Rivers) were used. The water quality and quantity was determined from Department of Water Affairs and Forestry's (DWAF) National Hydrological Chemical Data Bank. Assessments of water quality (chemical, physical), sediment characteristics, and fish biological characteristics were undertaken at each of the chosen sampling sites. Water and fish samples were collected seasonally on ten sampling trips during the study period, June 1989 to September 1992. Eleven species of fish were collected, by means of gill and seine nets, at eight sites. The biological characteristics of the larger fish captured were measured and tissue (gills, liver, muscle, intestine, ovaries, testes and abdominal fat) samples were collected. These samples were analysed for eleven metals and Pyrethroid, Carbamate, Organochlorine, Organophosphate and Triazine pesticides. Sediment core samples were collected and determinations made of particle size, percentage organics, metals and pesticides. Standard methods were used for the determination of .the metal and pesticide concentrations in the water, sediment and fish tissues. The pesticide use per crop for South Africa was determined from a data-base. This data was used to determine the potential pesticide runoff from the different crops in the sub-catchments and to compare with the sediment and fish tissue levels recorded. The water quality status of the Crocodile River catchment is impacted by a variety of diffuse and point sources of pollution. The water quality indicated that diffuse sources of pollution originated from afforestation in the Upper, Middle and Kaap River sub-catchments; current and abandoned mining activities in the Kaap River sub-catchment; runoff from irrigated lands in the Middle, Lower and Kaap River sub-catchments; and wastes from industrial activities in the Elands and Middle sub-catchments. Point sources of pollution in the Crocodile River include ndustrial and waste water treatment works discharges mainly in the Middle sub-catchment.

M.Sc.
A comparative study was undertaken in the Olifants River catchment, to determine the water quality at two dam sites, namely, Bronkhorstspruit Dam (control) and Loskop Dam (polluted) in the upper Olifants River system and two river point, namely, at Mamba and Balule in the Kruger National Park, in the lower Olifants River system. Data was obtained during the physical and chemical analysis of water and sediment samples, and during bioaccumulation studies using Atomic Absorption spectrometry, testing for aluminium, chromium, copper, iron, lead, manganese, nickel, strontium and zinc. These tests were conducted on the liver, skin, muscle and gills of Clarias gariepinus. The information collected from Mamba and Balule, was compared with a previous study carried out primarily in the Kruger National Park by Marx, (1996). The study undertaken by Marx (1996) was carried out during a drought period, which allowed for the comparison with results recorded after flooding during the present study. This current research project therefore allowed for the comparison between two different water sources, namely, that of dams and rivers, and under varying environmental conditions. The Aquatic Toxicity index (ATI) developed by Wepener et al. (1992) was employed to facilitate the comparison between the water physical and chemical parameters that were measured, at each sample site, with a single variable being calculated for each sample site per survey. The water quality (ATI values) at the two control sites namely, Bronkhorstspruit Dam and Balule deteriorated substantially after the floods. High water levels due to the floods had a dilution effect on the concentration of pollutants however, toxicants were washed in from upstream and due to surface runoff. The removal of the purifying reed beds upstream of Balule and at the inflow to Bronkhorstspruit Dam, resulted in the release of latent sludge containing metals and organic pollutants into the water column. The ATI value's obtained for the two control points were similar or even higher than those obtained for the two polluted sites namely at, Loskop Dam and Mamba for the autumn and winter sampling periods. During following surveys the water quality at all four sample sites improved, returning to pre flood values by the last survey in summer, namely reflecting similar values as those recorded by Marx (1996) at Balule, Mamba and Loskop Dam for the same period. Sediment concentrations recorded a similar trend to that for water at all four sample sites throughout the study. The bioaccumulation study indicated that the gill concentrations recorded were generally the highest, followed by the liver concentrations. From this one may deduce that gills were the dominant site for metal absorption by the fish, with the excretion of metals also taking place via this route. Liver concentrations are an indication of the activation of protective _mechanisms in the fish sampled, the high concentrations recorded indicate the high physiological response the fish have had to the various levels of exposure. The low concentrations recorded in the muscle indicates the effectiveness of the liver in the detoxification of the fish, indicating that only limited storage of the various metals tested for took place at this site. Skin concentrations were quite high, these concentrations represent the products of an excretory process, which takes place via the skin. The order of concentrations recorded during the present study, were similar to the orders recorded by Marx, (1996) and other authors, however, the order of the skin and muscle concentrations were often reversed. This may be due to the increased excretion of these metals via the skin, resulting from increased exposure to these metals after the floods. Thus the increased exposure

Ph.D.
The current study evaluated a bio-monitoring technique developed in the USA by Adams, Brown and Goede, 1993. This project was sponsored by the Department of Water Affairs and Forestry (DWAF), to enable testing of the Health Assessment Index (HAI) under South African conditions. Testing took place in the Olifants River system, one of the most polluted river systems . in South Africa. Initially two river points were tested using Oreochromis mossambicus (Robinson, 1996), Clarias gariepinus (Marx, 1996) and Labeo rosae (Luus-Powell, 1997). The current study re-tested the HAI at the same two sample sites, namely Mamba and Balule in the Kruger National Park, using 0. mossambicus and C. gariepinus respectively. Two additional sites were tested in the upper catchment area, namely Loskop Dam and Bronkhorstspruit Dam. The current study further enabled the comparison of HAI results collected during drought and flood conditions. Results obtained after deployment of the HAI were corroborated using chemical analysis of water, sediment and biota. Water and sediment analysis was carried out by the Institute for Water Quality Studies using standard techniques. Bio-accumulation of aluminium, copper, iron, lead, manganese, nickel, strontium and zinc was assessed in the gills, liver, skin and muscle tissue of sample fish using standard Atomic Absorption Spectrometry techniques. Modifications made to the original HAI involved the inclusion of variable ranking in the assessment of fish parasites, with endo- and ectoparasites evaluated separately. Testing of this parasite hypothesis lead to the development of a Parasite Index component to the HAI. Assessment of water, sediment and fish tissue determined that the Olifants River system is indeed exposed to macro and heavy metal pollutants, which negatively affect aquatic health. Constituents posing the greatest threat are chlorides, fluorides, phosphates, total dissolved solids, copper and iron concentrations. Testing the HAI and parasite hypothesis using C. gariepinus, provided the most meaningful results. During testing of the parasite hypothesis both endo- and ectoparasite numbers conformed to the suggested idea that higher endoparasite numbers will occur at highly impacted areas, whereby ectoparasite numbers will be low. This was particularly evident in the lower catchment area, whereby comparisons between drought and flood conditions were carried out. Subsequent decreases in water quality directly after the flood were noted using water and sediment analysis. This observation reflects the results gathered using the HAT and during testing of the parasite hypothesis at all four sample sites. During statistical analysis of the HAI, using logistic regression analysis, parasite numbers, more specifically endoparasite numbers, were the most indicative of fish health. Environmental stressors (flood conditions) result in immunological responses observed in fish, and are reflected statistically using the HAI as changes in WBC %. It is suggested that endoparasites and WBC % provide the best overall assessment of fish condition. These variables should thus not be eliminated, in order to streamline the HAI evaluation procedures. Testing of this bio-monitoring technique under South African conditions provided meaningful results. This indicates that the HAI can be used to assess water quality, with existing water monitoring programmes further benefiting from its incorporation.

M. Tech. (Biotechnology) Vaal University of Technology
One of the major problems encountered in qualitative and quantitative determination of residual pesticides by gas chromatography is the matrix effects. Matrix components have a considerable effect on the way analysis is conducted and the quality of results obtained, introducing problems such as inaccurate quantification, low analyte delectability and reporting of false positive or even false negative results. It was aimed to develop and validate a suitable method for counteracting the matrix effects so as to improve the detection and quantification of selected organochlorine pesticide residues from real water samples. The real water samples used were sampled from three points along the Jukskei River catchment area in Gauteng, South Africa for a period of 7 months from January to July 201 0 so as to create a representative sample. An automated solid phase extraction (SPE) method coupled to Gas ChromatographyMass Spectrometry (GC-MS) method for the analysis of 20 selected organochlorine pesticides was developed and validated for the purposes of studying the matrix effects. The analytical method showed a significant degree of validity when tested against parameters such as linearity, repeatability and sensitivity. Endosulphan beta, 4,4' Dichlorodiphenyldichloroethane, and Heptachlor-epoxide had the broadest linear calibration ranges of 1 ppm- 0.0156 ppm. Benzene hexachloride (BHC) delta and Lindane had the lowest statistical limits of detection of 0.018 ppm. Statistical hypothesis testing indicated that there was significant linearity in all selected organochlorine calibration curves. Four different reversed sorbent phases, including LC18, SC18- E and Strata-X (styrene divinyl benzene) were tested for organochlorine retention efficiency. The LC-18 200 mg cartridge proved to be the most robust and effective sorbent phase as it produced better recoveries varying from 90-130% for most analytes. A breakthrough volume of 100 ml for the LC-18 200 mg cartridge was determined using an optimum matrix load curve. It was then concluded that the method developed was suitable for further research towards the influence of the matrix on selective determination of the selected organochlorine pesticides. Four different calibration methods, namely matrix-free external standard, matrixmatched external standard, matrix-free internal standard and matrix-matched internal standard were applied to test the efficiency of computing recoveries. All calibration curves for the 20 organochlorine pesticides showed significant linearity > 0.99 when plotted on both Chemstation and Excel. The calibration methods were tested on three different matrices composed of a high sample matrix (synthetic matrix), a low sample matrix (real sample matrix) and a no sample matrix (ultrapure water). Statistical hypothesis testing led to the decision that there are significant differences between the mean recoveries of the three water sample matrices and also that the differences in the mean recoveries of the three sample matrices are independent of the both the two calibration techniques (internal standard and external standard) and calibration types (matrix-matched and matrix-free) applied. This led to the overall conclusion that the matrix effects have an overwhelming influence on the selective determination of the selected organochlorine pesticides.

In comparison to the rest of Europe, Africa, and Asia, most rivers arising and flowing within the Mediterranean watershed typically drain small catchments with mountainous headwaters. The hydrology of Mediterranean catchments is strongly influenced by the seasonal distribution of precipitation, catchment geology, vegetation type and extent, and the geomorphology of the slope and channel systems. It is important to appreciate, as the preceding chapters have shown, that the area draining to the Mediterranean Sea is large and enormously variable in terms of the key controls on catchment hydrology outlined above, and it is therefore not possible to define, in hydrological terms, a strict single Mediterranean river type. However, river regimes across the basin do have a marked seasonality that is largely controlled by the climate system (Chapter 3) and, in most basins, the dominant flows occur in winter—but autumn and spring runoff is also important in many areas. These patterns reflect the general water balance of the basin as a whole, but there are key geographical patterns in catchment hydrology and sediment yield and a marked contrast is evident between the more humid north and the semi-arid south and east (Struglia et al. 2004; Chapter 21). Also, because of the long history of vegetation and hillslope modification by human activity and the more recent and widespread implementation of water resource management projects, there are almost no natural river regimes in the Mediterranean region, especially in the middle and lower reaches of river catchments (Cudennec et al. 2007). Runoff generation on hillslopes in the Mediterranean is very closely related to rainfall intensities and land surface properties as discussed in Chapter 6. While this is probably true of most catchments, runoff generation in the Mediterranean is very sensitive to vegetation cover because of the seasonal dynamics of rainfall and the role played by extreme events. The cumulative effect of these characteristics is a specific set of management problems and restoration issues and, although these are rather different in the various socio-political regimes of the region, it can be argued that they are in many ways unique to Mediterranean catchments.