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Ashton, P. J., F. C. van Zyl, and R. G. Heath. "Water quality management in the Crocodile River catchment, Eastern Transvaal, South Africa." Water Science and Technology 32, no. 5-6 (September 1, 1995): 201–8. http://dx.doi.org/10.2166/wst.1995.0603.
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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.
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Mussá, F. E. F., Y. Zhou, S. Maskey, I. Masih, and S. Uhlenbrook. "Groundwater as an emergency source for drought mitigation in the Crocodile River catchment, South Africa." Hydrology and Earth System Sciences 19, no. 2 (February 26, 2015): 1093–106. http://dx.doi.org/10.5194/hess-19-1093-2015.
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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.
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Mussá, F. E. F., Y. Zhou, S. Maskey, I. Masih, and S. Uhlenbrook. "Groundwater as an emergency source for drought mitigation in the Crocodile River catchment, South Africa." Hydrology and Earth System Sciences Discussions 11, no. 3 (March 6, 2014): 2719–57. http://dx.doi.org/10.5194/hessd-11-2719-2014.
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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.
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Saraiva Okello, A. M. L., I. Masih, S. Uhlenbrook, G. P. W. Jewitt, P. van der Zaag, and E. Riddell. "Drivers of spatial and temporal variability of streamflow in the Incomati River basin." Hydrology and Earth System Sciences 19, no. 2 (February 2, 2015): 657–73. http://dx.doi.org/10.5194/hess-19-657-2015.
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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.
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Saraiva Okello, A. M. L., I. Masih, S. Uhlenbrook, G. W. P. Jewitt, P. van der Zaag, and E. Riddell. "Drivers of spatial and temporal variability of streamflow in the Incomati River Basin." Hydrology and Earth System Sciences Discussions 11, no. 7 (July 29, 2014): 8879–921. http://dx.doi.org/10.5194/hessd-11-8879-2014.
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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.
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MI, Soko, and Gyedu-Ababio T. "The Influence of Anthropogenic Activities on Macro-Invertearates Assemblage and Water Quality in the Crocodile River (East) Mpumalanga, South Africa." Sustainability in Environment 2, no. 2 (March 10, 2017): 124. http://dx.doi.org/10.22158/se.v2n2p124.
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<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>
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Chapman, R. A., P. T. Manders, R. J. Scholes, and J. M. Bosch. "Who should get the water? Decision support for water resource management." Water Science and Technology 32, no. 5-6 (September 1, 1995): 37–43. http://dx.doi.org/10.2166/wst.1995.0554.
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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.
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Olukunle, O. I., O. J. Okonkwo, K. K. Kefeni, and M. Lupankwa. "Determination of brominated flame retardants in Jukskei River catchment area in Gauteng, South Africa." Water Science and Technology 65, no. 4 (February 1, 2012): 743–49. http://dx.doi.org/10.2166/wst.2012.894.
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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 <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.
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Grobicki, A. M. W. "Urban catchment management in a developing country: the Lotus River project, Cape Town, South Africa." Water Science and Technology 44, no. 2-3 (July 1, 2001): 313–19. http://dx.doi.org/10.2166/wst.2001.0784.
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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.
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Ngcaba, Pelisa, and Alfred Maroyi. "Floristic Composition and Diversity in Tsitsa River Catchment Area, the Eastern Cape Province, South Africa." Journal of Biological Sciences 17, no. 6 (August 1, 2017): 288–97. http://dx.doi.org/10.3923/jbs.2017.288.297.
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Venter, S. N., M. C. Steynberg, C. M. E. de Wet, D. Hohls, G. du Plessis, and R. Kfir. "A situational analysis of the microbial water quality in a peri-urban catchment in South Africa." Water Science and Technology 35, no. 11-12 (June 1, 1997): 119–24. http://dx.doi.org/10.2166/wst.1997.0720.
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A situational analysis of a peri-urban catchment experiencing microbial water quality problems was carried out using data collected over two and a half years. The water and land use in the area was determined. The main sources of pollution were identified and the effects of dilution and bacterial die-off on water quality were evaluated by modelling the level of faecal coliforms along the length of the river using the QUAL2E model. As a result of the assessment, water quality goals were set for the catchment and suggestions were made for the improvement of microbial quality. Certain areas of the catchment are densely populated and both developed and informal settlements exist. Water is mainly used for domestic and recreational purposes. The river receives diffuse source discharges as well as point source discharges from four wastewater treatment plants and an industrial site. Assessment of indicator organism and pathogen analyses indicated that the main factors affecting the microbial quality were discharges from the sewage plants and runoff from informal settlement areas. The industrial activities in the catchment did not have a major effect. Modelling runs predicting faecal coliform levels demonstrated that bacterial die-off did not result in a significant improvement to the microbial water quality in the catchment.
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Masupha, Teboho Elisa, and Mokhele Edmond Moeletsi. "Analysis of potential future droughts limiting maize production, in the Luvuvhu River catchment area, South Africa." Physics and Chemistry of the Earth, Parts A/B/C 105 (June 2018): 44–51. http://dx.doi.org/10.1016/j.pce.2018.03.009.
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Selebalo, Itumeleng M., Mary C. Scholes, and Jai K. Clifford-Holmes. "A Systemic Analysis of the Environmental Impacts of Gold Mining within the Blyde River Catchment, a Strategic Water Area of South Africa." Water 13, no. 3 (January 26, 2021): 301. http://dx.doi.org/10.3390/w13030301.
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Exploratory modelling of the impact of gold mining on groundwater in a strategic water area of South Africa was undertaken. A systems dynamics (SD) model was developed to simulate the impact of gold mining on water quality, focusing on groundwater contamination risk, within the context of competing developmental priorities around water resource development and the socio-economic gains from gold mining. The model also identified interventions to minimise the impacts by the year 2040. The study area was the Blyde River Catchment (BRC), which is part of the Olifants Water Management Area in South Africa. This area is an important contributor, currently and in the future, to freshwater flows and groundwater in the Olifants River Catchment, which is one of South Africa’s most economically important catchments. The model development process included a causal loop diagram–based problem conceptualisation, followed by the drawing of stock-flow diagrams and the determining of model parameters based on a combination of background literature, data from environmental impact assessments, and from the national Department of Water and Sanitation. The model showed the potential environmental risks of gold mine wastewater production and interventions to minimise these risks. The most effective intervention identified to reduce the risk of groundwater contamination was the development and use of synthetic-lined tailings dams. The baseline simulation result of sulphate loading of 5430 t/year can be reduced by 3070 t/year to give a simulated sulphate load of 2270 t/year in 2040 using this intervention. In comparison, the simulated wastewater recycling intervention only reduced the sulphate load to 4630 t/year and the wastewater treatment interventions to 3420 t/year. This project contributes to the exploratory modelling of an understudied region of the Olifants River Catchment that is a crucial provider of freshwater flows to the Olifants, which is threatened by increasing gold mining in the upper BRC. The SD model highlighted the importance of protecting the dolomitic aquifers in the BRC for the long term sustainability of the catchment, which is particularly important if groundwater development occurs.
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Sibali, Linda L., Jonathan O. Okwonkwo, and Rob I. McCrindle. "Determination of selected organochlorine pesticide (OCP) compounds from the Jukskei River catchment area in Gauteng, South Africa." Water SA 34, no. 5 (December 7, 2018): 611. http://dx.doi.org/10.4314/wsa.v34i5.180659.
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Nde, Samuel, and Manny Mathuthu. "Assessment of Potentially Toxic Elements as Non-Point Sources of Contamination in the Upper Crocodile Catchment Area, North-West Province, South Africa." International Journal of Environmental Research and Public Health 15, no. 4 (March 23, 2018): 576. http://dx.doi.org/10.3390/ijerph15040576.
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Entwistle, N., G. Heritage, S. Tooth, and D. Milan. "Anastomosing reach control on hydraulics and sediment distribution on the Sabie River, South Africa." Proceedings of the International Association of Hydrological Sciences 367 (March 3, 2015): 215–19. http://dx.doi.org/10.5194/piahs-367-215-2015.
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Abstract. Rivers in the Kruger National Park, South Africa, have variable degrees of bedrock and alluvial influence. Pre-2000 aerial imagery for the Sabie River (catchment area 6320 km2) reveals downstream alternations from alluvial single thread or braided, to bedrock anastomosed or mixed anastomosed channel types, with pool-rapids also present locally. In 2000 and 2012, extreme floods resulted in significant alluvial erosion, widely exposing the underlying bedrock. Since the 2012 flood, aerial LiDAR surveys reveal the strong gradient control exerted by the bedrock and mixed anastomosed channel types, which influences hydraulic conditions and sediment dynamics. Two dimensional hydraulic modelling of moderate floods (<1500 m3 s−1) reveals reduced velocities upstream of bedrock or mixed anastomosed channel types, which promotes deposition. During more extreme floods (>3500 m3 s−1), the bedrock or mixed anastomosed channel types are drowned out, resulting in dramatically increased velocities along the entire river and widespread alluvial stripping regardless of initial channel type or location.
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Welderufael, W. A., Y. E. Woyessa, and D. C. Edossa. "Hydrological impact of rainwater harvesting in the Modder river basin of central South Africa." Hydrology and Earth System Sciences Discussions 8, no. 3 (May 23, 2011): 5051–81. http://dx.doi.org/10.5194/hessd-8-5051-2011.
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Abstract. Along the path of water flowing in a river basin are many water-related human interventions that modify the natural systems. Rainwater harvesting is one such intervention that involves harnessing of water in the upstream catchment. Increased water usage at upstream level is an issue of concern for downstream water availability to sustain ecosystem services. The upstream Modder River basin, located in a semi arid region in the central South Africa, is experiencing intermittent meteorological droughts causing water shortages for agriculture, livestock and domestic purpose. To address this problem a technique was developed for small scale farmers with the objective of harnessing rainwater for crop production. However, the hydrological impact of a wider adoption of this technique by farmers has not been well quantified. In this regard, the SWAT hydrological model was used to simulate the hydrological impact of such practices. The scenarios studied were: (1) Baseline scenario, based on the actual land use of 2000, which is dominated by pasture (combination of natural and some improved grass lands) (PAST); (2) Partial conversion of Land use 2000 (PAST) to conventional agriculture (Agri-CON); and (3) Partial conversion of Land use 2000 (PAST) to in-field rainwater harvesting which was aimed at improving the precipitation use efficiency (Agri-IRWH). SWAT was calibrated using observed daily mean stream flow data of a sub-catchment (419 km2) in the study area. SWAT performed well in simulating the stream flow giving Nash and Sutcliffe (1970) efficiency index of 0.57 for the monthly stream flow calibration. The simulated water balance results showed that the highest peak mean monthly direct flow was obtained on Agri-CON land use (18 mm), followed by PAST (12 mm) and Agri-IRWH land use (9 mm). These were 19 %, 13 % and 11 % of the mean annual rainfall, respectively. The Agri-IRWH scenario reduced direct flow by 38 % compared to Agri-CON. On the other hand it was found that the Agri-IRWH contributed to more groundwater flow (40 mm) compared to PAST (32 mm) and Agri-CON (19 mm) scenarios. These results are in line with the intended purpose of Agri-IRWH. Although there was a visible impact of the rainwater harvesting technique on the water yield when considered on a monthly time frame, the overall result suggests that the water yield of one of the upper Modder River Basin quaternary catchment may not be adversely affected by the Agri-IRWH land use scenario despite its surface runoff abstraction design.
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Watson, Sara, Marika Low, Natasha Phillips, Corey O’Driscoll, Matthew Shaw, Chris Ames, Zenobia Jacobs, and Alex Mackay. "Robberg Material Procurement and Transport in the Doring River Catchment: Evidence from the Open-Air Locality of Uitspankraal 9, Western Cape, South Africa." Journal of African Archaeology 18, no. 2 (December 17, 2020): 209–28. http://dx.doi.org/10.1163/21915784-20200013.
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Abstract Decisions related to the production of lithic technology involve landscape-scale patterns of resource acquisition and transport that are not observable in assemblages from any one single site. In this study, we describe the stone artifacts from a discrete cluster of stone artifacts assigned to the Robberg technocomplex (22-16 ka) at the open-air locality of Uitspankraal 9 (UPK9), which is located near two major sources of toolstone in the Doring River catchment of Western Cape, South Africa. OSL dating of the underlying sediment unit provides a terminus post quem age of 27.5 ± 2.1 ka for the assemblage. Comparison of near-source artifact reduction at UPK9 with data from three rock shelter assemblages within the Doring watershed – Putslaagte 8 (PL8), Klipfonteinrand Rock Shelter (KFR), and Mertenhof Rock Shelter (MRS) – suggests that “gearing-up” with cores and blanks occurred along the river in anticipation of transport into the wider catchment area. The results reveal an integrated system of technological supply in which raw materials from different sources were acquired, reduced, and transported in different ways throughout the Doring River region.
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Howard, J. R., M. E. Ligthelm, and A. Tanner. "The development of a water quality management plan for the Mgeni River catchment." Water Science and Technology 32, no. 5-6 (September 1, 1995): 217–26. http://dx.doi.org/10.2166/wst.1995.0608.
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Located in the province of KwaZulu-Natal, South Africa, the Mgeni River catchment provides the potable water resources for nearly two million people, in an area of approximately 4 400 km2. The river system is well developed and impounded, but increasing population pressures in the catchment are placing greater demands on this critical water resource resulting in increasing loads of nutrients, faecal bacteria and suspended solids. Umgeni Water and the Department of Water Affairs and Forestry are developing an affordable and practically implementable plan to manage the water quality on an integrated catchment basis, encompassing demographic, land-use and management considerations. The development of the plan is discussed and information on the water management related issues provided. A multidisciplinary approach has proved essential, facilitated by the development of a GIS-based system to manage and utilize the information from the study. Establishment of communication links with interested and affected parties has been critical, as has the clarification of their roles and responsibilities in dealing with identified pollution issues. Future development within the catchment is considered and the implementation of the management plan is discussed against the background of the Reconstruction and Development Programme.
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Nde, Samuel Che, Manny Mathuthu, Rodrigue Yves Mpika Massoukou, Sammy Kipyego Bett, Guiem Richard, and Olagbaju Peter Oluwadamilare. "Modelling the dynamics of the cancer risk due to potentially toxic elements in agricultural soils, in the upper Crocodile River catchment, North-West province, South Africa." Ecotoxicology and Environmental Safety 211 (March 2021): 111961. http://dx.doi.org/10.1016/j.ecoenv.2021.111961.
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Dunham, Kevin M., Andrea Ghiurghi, Rezia Cumbi, and Ferdinando Urbano. "Human–wildlife conflict in Mozambique: a national perspective, with emphasis on wildlife attacks on humans." Oryx 44, no. 2 (April 2010): 185–93. http://dx.doi.org/10.1017/s003060530999086x.
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AbstractHuman–wildlife conflicts are common across Africa. In Mozambique, official records show that wildlife killed 265 people during 27 months (July 2006 to September 2008). Crocodile Crocodylus niloticus, lion Panthera leo, elephant Loxodonta africana and hippopotamus Hippopotamus amphibius caused most deaths but crocodiles were responsible for 66%. Crocodile attacks occurred across Mozambique but 53% of deaths occurred in districts bordering Lake Cabora Bassa and the Zambezi River. Hippopotamus attacks were also concentrated here. Lion attacks occurred mainly in northern Mozambique and, while people were attacked by elephants across the country, 67% of deaths occurred in northern Mozambique. Attacks by lions, elephants or hippopotamuses were relatively rare but additional data will probably show that attacks by these species are more widespread than the preliminary records suggest. Buffalo Syncerus caffer, hyaena Crocuta crocuta and leopard Panthera pardus were minor conflict species. Good land-use planning, a long-term solution to many conflicts, is particularly relevant in Mozambique, where the crocodile and hippopotamus populations of protected areas are often in rivers that border these areas, and cause conflicts outside them, and where people commonly live within protected areas. Poverty may prompt fishermen to risk crocodile attack by entering rivers or lakes. The high incidence of conflicts near Limpopo and South Africa’s Kruger National Parks (both within the Great Limpopo Transfrontier Conservation Area) highlights the problems created for people by facilitating the unrestricted movement of wildlife between protected areas across their land.
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Masupha, Teboho Elisa, and Mokhele Edmond Moeletsi. "Use of standardized precipitation evapotranspiration index to investigate drought relative to maize, in the Luvuvhu River catchment area, South Africa." Physics and Chemistry of the Earth, Parts A/B/C 102 (December 2017): 1–9. http://dx.doi.org/10.1016/j.pce.2017.08.002.
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Nyathi, N. A., W. Zhao, and W. Musakwa. "LAND USE LAND COVER CHANGES AND THEIR IMPACTS ON ECOSYSTEM SERVICES IN THE NZHELELE RIVER CATCHMENT, SOUTH AFRICA." ISPRS Annals of Photogrammetry, Remote Sensing and Spatial Information Sciences V-3-2020 (August 3, 2020): 809–16. http://dx.doi.org/10.5194/isprs-annals-v-3-2020-809-2020.
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Abstract. Land use change can result in variations in ecosystem services (ESS) and their relationships. Studying the temporal dynamics of ESS and their relationships can support scenario analyses that provide the theoretical basis for policy decisions and regional ecosystem management in any context. Understanding the spatiotemporal changes in land use and land cover change helps understand ESS management. In this study, the InVEST model was applied to assess carbon sequestration from 1999 to 2018 and to construct two simulated scenarios that represented different land use strategies. The results showed a spatial increase in the cropland class from the stipulated years with a corresponding increase in carbon within the area. It is assumed that the relationship between these two phenomena can affect agricultural policies as a large portion of South Africa depends on it for livelihood betterment. The Spearman’s Correlation Coefficient was used to assess the relationship between the two ESS. The result showed a highly significant correlation that means a change in policy from a governmental level is required. This paper subtly aims to provide data towards the South African context and more scenarios and research is needed to fully deduce effective land use management policies and decisions.
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Hahn, Annette, Enno Schefuß, Sergio Andò, Hayley C. Cawthra, Peter Frenzel, Martin Kugel, Stephanie Meschner, Gesine Mollenhauer, and Matthias Zabel. "Southern Hemisphere anticyclonic circulation drives oceanic and climatic conditions in late Holocene southernmost Africa." Climate of the Past 13, no. 6 (June 9, 2017): 649–65. http://dx.doi.org/10.5194/cp-13-649-2017.
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Abstract. Due to the high sensitivity of southern Africa to climate change, a reliable understanding of its hydrological system is crucial. Recent studies of the regional climatic system have revealed a highly complex interplay of forcing factors on precipitation regimes. This includes the influence of the tropical easterlies, the strength of the southern hemispheric westerlies as well as sea surface temperatures along the coast of the subcontinent. However, very few marine records have been available in order to study the coupling of marine and atmospheric circulation systems. Here we present results from a marine sediment core, recovered in shallow waters off the Gouritz River mouth on the south coast of South Africa. Core GeoB18308-1 allows a closer view of the last ∼ 4 kyr. Climate sensitive organic proxies, like the distribution and isotopic composition of plant-wax lipids as well as indicators for sea surface temperatures and soil input, give information on oceanographic and hydrologic changes during the recorded time period. Moreover, the micropaleontology, mineralogical and elemental composition of the sediments reflect the variability of the terrigenous input to the core site. The combination of down-core sediment signatures and a catchment-wide provenance study indicate that the Little Ice Age ( ∼ 300–650 cal yr BP) was characterized by climatic conditions favorable to torrential flood events. The Medieval Climate Anomaly ( ∼ 950–650 cal yr BP) is expressed by lower sea surface temperatures in the Mossel Bay area and humid conditions in the Gouritz River catchment. These new results suggest that the coincidence of humid conditions and cooler sea surface temperatures along the south coast of South Africa resulted from a strengthened and more southerly anticyclonic circulation. Most probably, the transport of moisture from the Indian Ocean by strong subtropical easterlies was coupled with Agulhas Bank upwelling pulses, which were initiated by an increase in Agulhas Current strength.
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Pool, E. J., C. Jagals, J. H. van Wyk, and P. Jagals. "The use of IL-6 induction as a human biomarker for inflammatory agents in water." Water Science and Technology 47, no. 3 (February 1, 2003): 71–75. http://dx.doi.org/10.2166/wst.2003.0164.
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A rapid whole blood culture (WBC) assay system was developed to monitor the inflammatory potential of water samples collected in the Manguang Municipal area, South Africa. Several systems associated with the Modder River catchment area were investigated in this preliminary study to find out whether there were potential problems in this catchment area. Three focus areas were investigated: (a) the impact of the Klein Modder River, which passes through a densely populated residential area, on the inflammatory activity of the Modder River; (b) the efficiency of the treatment plants in eliminating inflammatory activity; and (c) the efficiency of chlorination of treated water in eliminating inflammatory activity that was not eliminated by the treatment system. Water contaminated with inflammatory substances induced the pro-inflammatory hormone interleukin 6 (IL-6). All water samples collected from the Modder River induced IL-6 secretion, and the quantity of IL-6 secreted was dependent on the concentration and origin of the sample. The lowest IL-6 inducing activity for river water was obtained for samples collected near the origin of the river (Rustfontein). Samples at subsequent points downstream from confluence with the Klein Modder River showed a major increase in IL-6 inducing activity. The two treatment plants along the Modder River also received water of different inflammatory activity. Both treatment plants eliminated some of the inflammatory activity during processing, however inflammatory residues remained after processing which might have been potentially harmful for infants and people with suppressed immune systems. Chlorination eliminated most of the inflammatory activity, indicating that chlorination of water was a necessary process in ensuring water of low inflammatory content.
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Swart, Nelius, and Edmund Pool. "Rapid Detection of Selected Steroid Hormones from Sewage Effluents using an ELISA in the Kuils River Water Catchment Area, South Africa." Journal of Immunoassay and Immunochemistry 28, no. 4 (September 2007): 395–408. http://dx.doi.org/10.1080/15321810701603799.
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Hassan, Rashid M. "Economy-wide benefits from water-intensive industries in South Africa: Quasi-input-output analysis of the contribution of irrigation agriculture and cultivated plantations in the Crocodile River catchment." Development Southern Africa 20, no. 2 (June 2003): 171–95. http://dx.doi.org/10.1080/03768350302953.
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Mamera, Matthew, and Johan J. van Tol. "Application of Hydropedological Information to Conceptualize Pollution Migration From Dry Sanitation Systems in the Ntabelanga Catchment Area, South Africa." Air, Soil and Water Research 11 (January 2018): 117862211879548. http://dx.doi.org/10.1177/1178622118795485.
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The hydrological response of catchments is determined by the combined hydropedological response of hillslopes. In the Ntabelanga area, 56% of the households use pit latrines and untreated drinking groundwater supplies. Soil morphological properties and their spatial distribution were used to conceptualize hillslope hydropedological behaviour to determine the fate of Escherichia coli and faecal coliform from 4 pit latrines. Four hillslopes below the pit latrines (MT1, MT2, MT3, and MT4) occur above first-order tributaries to the Tsitsa River, South Africa, were studied. The studied sites are adjacent to the proposed footprint of a planned multi-purpose storage dam, Ntabelanga. Apedal soils, without morphological evidence of saturation, dominated the upper slopes of MT1 and the lower slopes of MT2, thus promoting vertical drainage. Hydromorphic properties were observed at the soil/bedrock interface in the lower parts of MT1 and the entire slope of MT4. This signifies slowly permeable bedrock and the occurrence of lateral flow. High clay contents and strong structured soils were dominant in MT3, indicating slow internal drainage with a large adsorption capacity. The conceptual models derived from morphological properties were verified using soil physical and organic pollutant measurements. In general, hydraulic conductivity values support the interpretations made from soil morphological measurements. Faecal coliforms and E coli bacteria counts were mostly <1 CFU/g soil in MT1, MT2, and MT4; hillslope migrations were detected in MT3 posing pollution risks.
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Nyam, Y. S., J. H. Kotir, A. J. Jordaan, and A. A. Ogundeji. "Developing a Conceptual Model for Sustainable water Resource Management and Agricultural Development: the Case of the Breede River Catchment Area, South Africa." Environmental Management 67, no. 4 (January 11, 2021): 632–47. http://dx.doi.org/10.1007/s00267-020-01399-x.
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Muruven, D. N., and M. Tekere. "An Evaluation of the Cumulative Surface Water Pollution on Selected Areas within the Consolidated Main Reef Area, Roodepoort, South Africa." Air, Soil and Water Research 6 (January 2013): ASWR.S12997. http://dx.doi.org/10.4137/aswr.s12997.
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Mining has long been at the center of the South African economy and has contributed to significant developments within the country. However, despite the large economic impact, surface water pollution due to mining is prevalent in most of the country's water catchments. Surface water in many areas of the central Roodepoort area in Johannesburg, South Africa, has also been impacted primarily by mining activities. The surface water quality for the Bosmontspruit, Russell's Stream, and the New Canada Dam was assessed in this study from October 2010 to March 2011. Physicochemical and biological characteristics of the water were determined for eight monitoring points, and the results obtained were compared with the in-stream water quality guidelines for the Klip River catchment and the South African Water Quality Guidelines. A trend noticed throughout the sampling period was the noncompliance to the set target water quality ranges (TWQRs) in the levels of total dissolved solids (TDS) and dissolved oxygen (DO). The results indicate that concentrations of iron, aluminum, nickel, manganese, and potassium were above the permissible limits across the Bosmontspruit and Russell's Stream. Excessive fecal coliforms and ammonium pollution were also detected in the Bosmontspruit. Additionally, during the monitoring period, it was noted that the water was being utilized for domestic purposes, and may pose health hazards due to poor water quality.
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Hollingworth, B., and D. Mullins. "Economic analysis of water resource development proposals in the Sabie River Basin." Water Science and Technology 32, no. 5-6 (September 1, 1995): 71–78. http://dx.doi.org/10.2166/wst.1995.0564.
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The Sabie River is an important river catchment in South Africa because of its ecodiversity, importance to the Kruger National Park, agricultural and afforestation potential and relatively undeveloped water resources. These resources are under stress from increasing irrigation and a burgeoning population. In the mid-eighties an intensive river basin study was undertaken to guide and promote sustained development. The studies described in this paper were undertaken in order to include economic criteria in development investment decision making. These studies were firstly, a macro-economic view which extended to sector analysis and secondly, a cost-benefit analysis of the proposals. The first found that the balance between economic growth and the demand for water takes place in an area which exhibits a dualistic and interdependent nature, between the Sabie River subregion with dynamic economic growth sectors, and the Sand River subregion with a small economic base but high population concentration. The study introduces the concept of investment absorption capacity which uses Gross Geographic Product as a proxy in a methodology that indicates the maximum capital that can, technically, be invested in water resource development in the area. The second part uses traditional cost-benefit analysis to determine the economically preferred proposals for development.
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Dabrowski, J. M. "Applying SWAT to predict orthophosphate loads and trophic status in four reservoirs in the upper Olifants catchment, South Africa." Hydrology and Earth System Sciences Discussions 10, no. 11 (November 12, 2013): 13635–70. http://dx.doi.org/10.5194/hessd-10-13635-2013.
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Abstract. Excessive phosphate loading in the upper Olifants River, South Africa has resulted in widespread eutrophication and associated ecosystem health impacts. The majority of sewage treatment works (STWs) are operating poorly and are likely an important source of bioavailable orthophosphate (OP) in the catchment. The Soil Water Assessment Tool (SWAT), was used to identify important sources of OP loading in the catchment and predict changes in the trophic status of four reservoirs associated with three STWs effluent OP standards; (current average of 4 mg L−1 and standards of 1 and 0.1 mg L−1). Naish-Sutcliffe and PBIAS statistics showed good model performance for simulations of flow and OP loading using a multi-site calibration and validation approach. Key sub-catchments responsible for high OP loading were identified. Three of the four reservoirs are heavily impacted by OP loading originating from STWs. Two reservoirs show mean annual OP concentrations indicative of eutrophic conditions and a 1 mg L−1 effluent standard would reduce concentrations to well within the mesotrophic range. There was little difference in OP loads and concentrations associated with the 1 and 0.1 mg L−1 effluent standard, indicating that attention to nonpoint sources would be required to realise any benefit associated with the strictest effluent standard. Regression analyses and associated 95% prediction limits between simulated OP loads and concentrations for all effluent treatment scenarios from 2002 to 2010 allowed for the quantification of OP loading that would ensure a specific trophic status in each reservoir. This study is one of the first to apply SWAT in simulating OP loading and concentrations in large reservoirs and its application in South Africa provides further support for its utility throughout a wide a geographical area.
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Jordaan, K., A. M. Comeau, D. P. Khasa, and C. C. Bezuidenhout. "An integrated insight into the response of bacterial communities to anthropogenic contaminants in a river: A case study of the Wonderfonteinspruit catchment area, South Africa." PLOS ONE 14, no. 5 (May 21, 2019): e0216758. http://dx.doi.org/10.1371/journal.pone.0216758.
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Revilla-Romero, B., J. Thielen, P. Salamon, T. De Groeve, and G. R. Brakenridge. "Evaluation of the satellite-based Global Flood Detection System for measuring river discharge: influence of local factors." Hydrology and Earth System Sciences 18, no. 11 (November 7, 2014): 4467–84. http://dx.doi.org/10.5194/hess-18-4467-2014.
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Abstract. One of the main challenges for global hydrological modelling is the limited availability of observational data for calibration and model verification. This is particularly the case for real-time applications. This problem could potentially be overcome if discharge measurements based on satellite data were sufficiently accurate to substitute for ground-based measurements. The aim of this study is to test the potentials and constraints of the remote sensing signal of the Global Flood Detection System for converting the flood detection signal into river discharge values. The study uses data for 322 river measurement locations in Africa, Asia, Europe, North America and South America. Satellite discharge measurements were calibrated for these sites and a validation analysis with in situ discharge was performed. The locations with very good performance will be used in a future project where satellite discharge measurements are obtained on a daily basis to fill the gaps where real-time ground observations are not available. These include several international river locations in Africa: the Niger, Volta and Zambezi rivers. Analysis of the potential factors affecting the satellite signal was based on a classification decision tree (random forest) and showed that mean discharge, climatic region, land cover and upstream catchment area are the dominant variables which determine good or poor performance of the measure\\-ment sites. In general terms, higher skill scores were obtained for locations with one or more of the following characteristics: a river width higher than 1km; a large floodplain area and in flooded forest, a potential flooded area greater than 40%; sparse vegetation, croplands or grasslands and closed to open and open forest; leaf area index > 2; tropical climatic area; and without hydraulic infrastructures. Also, locations where river ice cover is seasonally present obtained higher skill scores. This work provides guidance on the best locations and limitations for estimating discharge values from these daily satellite signals.
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Revilla-Romero, B., J. Thielen, P. Salamon, T. De Groeve, and G. R. Brakenridge. "Evaluation of the satellite-based Global Flood Detection System for measuring river discharge: influence of local factors." Hydrology and Earth System Sciences Discussions 11, no. 7 (July 3, 2014): 7331–74. http://dx.doi.org/10.5194/hessd-11-7331-2014.
Full textAbstract:
Abstract. One of the main challenges for global hydrological modelling is the limited availability of observational data for calibration and model verification. This is particularly the case for real time applications. This problem could potentially be overcome if discharge measurements based on satellite data were sufficiently accurate to substitute for ground-based measurements. The aim of this study is to test the potentials and constraints of the remote sensing signal of the Global Flood Detection System for converting the flood detection signal into river discharge values. The study uses data for 322 river measurement locations in Africa, Asia, Europe, North America and South America. Satellite discharge measurements were calibrated for these sites and a validation analysis with in situ discharge was performed. The locations with very good performance will be used in a future project where satellite discharge measurements are obtained on a daily basis to fill the gaps where real time ground observations are not available. These include several international river locations in Africa: Niger, Volta and Zambezi rivers. Analysis of the potential factors affecting the satellite signal was based on a classification decision tree (Random Forest) and showed that mean discharge, climatic region, land cover and upstream catchment area are the dominant variables which determine good or poor performance of the measurement sites. In general terms, higher skill scores were obtained for locations with one or more of the following characteristics: a river width higher than 1 km; a large floodplain area and in flooded forest; with a potential flooded area greater than 40%; sparse vegetation, croplands or grasslands and closed to open and open forest; Leaf Area Index > 2; tropical climatic area; and without hydraulic infrastructures. Also, locations where river ice cover is seasonally present obtained higher skill scores. The work provides guidance on the best locations and limitations for estimating discharge values from these daily satellite signals.
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Dabrowski, J. M. "Applying SWAT to predict ortho-phosphate loads and trophic status in four reservoirs in the upper Olifants catchment, South Africa." Hydrology and Earth System Sciences 18, no. 7 (July 16, 2014): 2629–43. http://dx.doi.org/10.5194/hess-18-2629-2014.
Full textAbstract:
Abstract. Excessive phosphate loading in the upper Olifants River, South Africa has resulted in widespread eutrophication and associated ecosystem health impacts. The majority of sewage treatment works (STWs) are operating poorly and are likely an important source of bioavailable ortho-phosphate (OP) in the catchment. The Soil Water Assessment Tool (SWAT) was used to identify important sources of OP loading in the catchment and to predict changes in the trophic status of four reservoirs associated with three STW effluent OP standards (the current average of 4 mg L−1 and standards of 1 and 0.1 mg L−1). Nash–Sutcliffe and PBIAS statistics showed good model performance for simulations of flow and OP loading using a multi-site calibration and validation approach. Key sub-catchments responsible for high OP loading were identified. Three of the four reservoirs are heavily impacted by OP loading originating from STWs. Two reservoirs show mean annual OP concentrations indicative of eutrophic conditions and a 1 mg L−1 effluent standard would reduce concentrations to well within the mesotrophic range. There was little difference in OP loads and concentrations associated with the 1 and 0.1 mg L−1 effluent standards, indicating that attention to nonpoint sources would be required to realise any benefit associated with the strictest effluent standard. Regression analyses and associated 95% prediction limits between simulated OP loads and concentrations for all effluent treatment scenarios from 2002 to 2010 allowed for the quantification of OP loading that would ensure a specific trophic status in each reservoir. This study is one of the first to apply SWAT in simulating OP loading and concentrations in large reservoirs, and its application in South Africa provides further support for its utility throughout a wide geographical area.
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Gebel, Micha, Stephan Bürger, Michael Wallace, Hanlie Malherbe, Hannah Vogt, and Carsten Lorz. "Simulation of land use impacts on sediment and nutrient transfer in coastal areas of Western Cape, South Africa." Change and Adaptation in Socio-Ecological Systems 3, no. 1 (January 1, 2017): 1–17. http://dx.doi.org/10.1515/cass-2017-0001.
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AbstractA major challenge for water resource management in Western Cape, South Africa, is the reduction of the growing sediment and nutrient loads in coastal areas, which belong to the areas most affected by land use change. We used the WebGIS based software STOFFBILANZ to simulate runoff, soil loss, sediment, phosphorus, and nitrogen input in the surface water and groundwater of study area (ca. 6,450 km²). The simulated runoff shows a large regional variability caused by the heterogeneous distribution of rainfall. For the reference catchment Klein River simulated total daily runoff fit the observed values of the reference year 2012. The calculation of potential input of sediment, phosphorus, and nitrogen into waters is based on aggregated or generalized information on climate data, land use types, crop and fruit types, yields, mineral fertilizers, farm manure, nitrogen fixing by leguminous plants, atmospheric nitrogen deposition, and soil denitrification. Critical source areas for potential sediment input, particulate P input and diffuse N input are mainly agricultural areas. Additionally, point sources of high relevance for N and P are found in urban areas. Based on the potential input of sediment and nutrients the impacts of current land use change on water resources were estimated. We used the web-based information system WebLand for the simulation aiming at the provision of stakeholders with information for decision making in water resource management.
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Mathivha, Fhumulani, Caston Sigauke, Hector Chikoore, and John Odiyo. "Short-Term and Medium-Term Drought Forecasting Using Generalized Additive Models." Sustainability 12, no. 10 (May 14, 2020): 4006. http://dx.doi.org/10.3390/su12104006.
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Forecasting extreme hydrological events is critical for drought risk and efficient water resource management in semi-arid environments that are prone to natural hazards. This study aimed at forecasting drought conditions in a semi-arid region in north-eastern South Africa. The Standardized Precipitation Evaporation Index (SPEI) was used as a drought-quantifying parameter. Data for SPEI formulation for eight weather stations were obtained from South Africa Weather Services. Forecasting of the SPEI was achieved by using Generalized Additive Models (GAMs) at 1, 6, and 12 month timescales. Time series decomposition was done to reduce time series complexities, and variable selection was done using Lasso. Mild drought conditions were found to be more prevalent in the study area compared to other drought categories. Four models were developed to forecast drought in the Luvuvhu River Catchment (i.e., GAM, Ensemble Empirical Mode Decomposition (EEMD)-GAM, EEMD-Autoregressive Integrated Moving Average (ARIMA)-GAM, and Forecast Quantile Regression Averaging (fQRA)). At the first two timescales, fQRA forecasted the test data better than the other models, while GAMs were best at the 12 month timescale. Root Mean Square Error values of 0.0599, 0.2609, and 0.1809 were shown by fQRA and GAM at the 1, 6, and 12 month timescales, respectively. The study findings demonstrated the strength of GAMs in short- and medium-term drought forecasting.
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Dupont, Lydie M., Thibaut Caley, and Isla S. Castañeda. "Effects of atmospheric CO<sub>2</sub> variability of the past 800 kyr on the biomes of southeast Africa." Climate of the Past 15, no. 3 (June 19, 2019): 1083–97. http://dx.doi.org/10.5194/cp-15-1083-2019.
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Abstract. Very little is known about the impact of atmospheric carbon dioxide pressure (pCO2) on the shaping of biomes. The development of pCO2 throughout the Brunhes Chron may be considered a natural experiment to elucidate relationships between vegetation and pCO2. While the glacial periods show low to very low values (∼220 to ∼190 ppmv, respectively), the pCO2 levels of the interglacial periods vary from intermediate to relatively high (∼250 to more than 270 ppmv, respectively). To study the influence of pCO2 on the Pleistocene development of SE African vegetation, we used the pollen record of a marine core (MD96-2048) retrieved from Delagoa Bight south of the Limpopo River mouth in combination with stable isotopes and geochemical proxies. Applying endmember analysis, four pollen assemblages could be distinguished representing different biomes: heathland, mountain forest, shrubland and woodland. We find that the vegetation of the Limpopo River catchment and the coastal region of southern Mozambique is influenced not only by hydroclimate but also by temperature and atmospheric pCO2. Our results suggest that the extension of mountain forest occurred during those parts of the glacials when pCO2 and temperatures were moderate and that only during the colder periods when atmospheric pCO2 was low (less than 220 ppmv) open ericaceous vegetation including C4 sedges extended. The main development of woodlands in the area took place after the Mid-Brunhes Event (∼430 ka) when interglacial pCO2 levels regularly rose over 270 ppmv.
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DOMULLODZHANOV, D. H., and R. RAHMATILLOEV. "REZULTS OF INVESTIGATIONS ON COLLECTION AND USAGE OF PRECIPITATION FOR DIFFERENT NEEDS OF THE POPULATION IN AGRO L ANDSCAPED OF THE RIVER KYZYLSU-SOUTHERN." Prirodoobustrojstvo, no. 4 (2020): 111–16. http://dx.doi.org/10.26897/1997-6011-2020-4-111-116.
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The technologies of precipitation collection and usage are widely developed and used in the countries of South Asia, Eastern Africa, the Caribbean basin and in other countries. The collected water resources are used to meet the household needs of the population, cattle watering and the surplus for irrigation of agricultural crops on farm lands. In Tajikistan there are also used simple rainwater collecting systems, however, their parameters are not linked to the precipitation regularities and water use norms for various purposes, the systems are not scientifically substantiated, they do not have water balance calculations and their cost is high. Therefore, it is very relevant to develop and install low-cost systems for collecting, storing and using precipitation for household needs and irrigation of agricultural crops in household plots with applying water-saving technologies. According to results of investigations carried out in the hilly, foothill and low-mountain agro-landscapes of the Kyzylsu-southern river basin of Tajikistan there was found an average water catchment area in households based on field experiments and proposed a low-cost system for collecting and storing precipitation from rooftops of buildings and outbuildings of households with a volume up to 10 m3, cost about 332 US dollars and coefficient of efficiency of rainfall collection 90.5…93.3%.
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Salau, Wahab, and Paul Ifatokun Ifabiyi. "HYDRO-GEOMORPHIC FACTORS AND THE POTENTIAL OF HYDROKINETIC POWER PRODUCTION UPSTREAM OF IKERE GORGE DAM, NIGERIA." Geosfera Indonesia 4, no. 1 (April 29, 2019): 25. http://dx.doi.org/10.19184/geosi.v4i1.9511.
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The operation of hydrokinetic turbine depends on river flow and pressure head (∆H) which are of high potential in many parts of Nigeria. This study attempts the analysis of the potential of the area upstream of Ikere Gorge dam for hydrokinetic potential. Soil and Water Assessment Tool (SWAT) was used to determine the hydrological parameters of the sub-basins. Pearson Moment Correlation and linear regression methods were used to find the relationships between morphometric properties and the discharge parameters. Hydrological modeling and statistical computations were done to estimate the theoretical potential of the catchment. The result shows that River Oshe has 9.542 MW, which is the highest potential while River Konsun with 1.161 MW has the lowest potential Pearson Moment Correlation shows that there is strong positive relation of 0.7 between slope and pressure head (∆H) at 0.05 significant levels. The result of the multiple regression show that hydro-geomorphic factors explained 59.1% of the variance in the explanation of hydrokinetic power potential upstream of Ikere gorge dam.
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Levin, Jonathan C., Darragh J. Woodford, and Gavin C. Snow. "Evaluating the effectiveness of freshwater fishes as bio-indicators for urban impacts in the Crocodile (West) catchment, South Africa." Water SA 45, no. 3 July (July 31, 2019). http://dx.doi.org/10.17159/wsa/2019.v45.i3.6745.
Full textAbstract:
Urbanisation in South Africa has resulted in the degradation of aquatic ecosystems across a rural-to-urban gradient; impacting the availability of clean water. Biological organisms, including fish assemblages, have been used as indicators of environmental change, as part of monitoring programmes designed to protect and improve aquatic ecosystem conditions. However, the effectiveness of individual freshwater fish species as bio-indicators for urban impacts has not yet been evaluated. This study investigated the occurrence of freshwater fish species across three urban gradients within the upper Crocodile River sub-management area as potential bio-indicators. Having collected presence and absence data, five native fish species were determined to be widespread. Their effectiveness as bio-indicators for six environmental drivers, identified through principle component analysis, was assessed using species stressor-response curves derived from logistic regression analysis. Of the five species, the largescale yellowfish (Labeobarbus marequensis) and stargazer catfish (Amphilius uranoscopus) showed potential to be effective bio-indicators for urban impacts on aquatic water quality and instream habitat. These taxa, as effective urban bio-indicators, have the potential to improve the efficiency of urban river health assessments through reducing data gathering and staff training requirements.
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ASD Carroll and CJ Curtis. "Increasing nutrient influx trends and remediation options at Hartbeespoort Dam, South Africa: a mass-balance approach." Water SA 47, no. 2 April (April 29, 2021). http://dx.doi.org/10.17159/wsa/2021.v47.i2.10917.
Full textAbstract:
The Hartbeespoort Dam, located 40 km west of Tshwane on the Crocodile River, is an extremely eutrophic water body. Situated in one of the most economically active areas of South Africa, it receives a high nutrient input from wastewater treatment works (WWTW), leaking sewers, as well as urban and agricultural runoff. The Metsi a Me programme, which ran from 2006 to 2016, aimed to mitigate in-lake nutrient stocks using biomanipulation, including the physical removal of Eichhornia crassipes (water hyacinth) and Microcystis aeruginosa (blue-green algae). Using Department of Water and Sanitation water quality and flow data, the annual influxes and outfluxes of total nitrogen (TN) and total phosphorus (TP) to the Hartbeespoort Dam were calculated. Through literature review and comparison with previous studies, the relative importance of nutrient removal from biomass harvesting in relation to retained nutrients was assessed. The average nutrient influx from rivers during hydrological years 2010/11 to 2016/17 was 582 t∙a−1 TP and 4 687 t∙a−1 TN, with trends for both TN and TP being significantly positive over this period. TP influx increased by 77.8 t∙a−1 every year and TN influx increased by 456 t∙a−1, reversing a long-term negative trend. Average annual dam retention + removal (calculated as the difference between river inputs and outputs, i.e., including sedimentation, biomass removal and denitrification losses) was 358 t P and 2 195 t N. A best estimation of nutrient removal from water hyacinth and algal harvesting was 2.1 t∙a−1 P and 11.5 t∙a−1 N, and 3.9 t∙a−1 P and 40 t∙a−1 N, respectively. An estimated 341 t∙a−1 P and 674–1 288 t∙a−1 N was sedimented. Denitrification losses are poorly quantified but are possibly comparable to sedimentation. River outfluxes increased by 28.4 t∙a−1 TP and 110 t∙a−1 TN, smaller rates than the influxes, suggesting increasing retention per annum. Upgrading WWTWs in the catchment and refurbishing leaking and overflowing sewers is the most appropriate long-term solution.
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"Water quality management in the Crocodile River catchment, Eastern Transvaal, South Africa." Water Science and Technology 32, no. 5-6 (1995). http://dx.doi.org/10.1016/0273-1223(95)00664-8.
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Petersen, Robin M., Andries C. Hoffman, Pieter Kotze, and Sean M. Marr. "First record of the invasive Australian redclaw crayfish Cherax quadricarinatus (von Martens, 1868) in the Crocodile River, Kruger National Park, South Africa." Koedoe 59, no. 1 (March 31, 2017). http://dx.doi.org/10.4102/koedoe.v59i1.1435.
Full textAbstract:
The redclaw crayfish Cherax quadricarinatus (von Martens, 1868), a robust freshwater crayfish native to Australia and Papua New Guinea, has now been recorded from the Kruger National Park (KNP). Previously absent from the Crocodile River, SAN Parks received a report in February 2016 of redclaw crayfish below the Van Graan Dam on the border of the KNP. Here, we provide evidence of the presence of redclaw crayfish in the Crocodile River. A better understanding of the redclaw crayfish distribution, habitat preferences, rate of spread and impacts on the local aquatic ecosystems in the Crocodile River is urgently required to develop mitigation strategies that minimise the spread of this invasive crayfish in the KNP and the Komati Catchment. The negative impacts of global crayfish introductions justify efforts to discourage further introductions and prevent their secondary spread.Conservation implications: A better understanding of the redclaw crayfish distribution, habitat preferences, rate of spread and impacts on the local aquatic ecosystems in the Crocodile River is urgently required to develop mitigation strategies that minimise the spread of this invasive crayfish in the Kruger National Park and the Komati Catchment.
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Stone-Jovicich, Samantha S., Timothy Lynam, Anne Leitch, and Natalie A. Jones. "Using Consensus Analysis to Assess Mental Models about Water Use and Management in the Crocodile River Catchment, South Africa." Ecology and Society 16, no. 1 (2011). http://dx.doi.org/10.5751/es-03755-160145.
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SM Mazibuko, G Mukwada, and ME Moeletsi. "Assessing the frequency of drought/flood severity in the Luvuvhu River catchment, Limpopo Province, South Africa." Water SA 47, no. 2 April (April 29, 2021). http://dx.doi.org/10.17159/wsa/2021.v47.i2.10913.
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The Luvuvhu River catchment experiences rainfall variability with a high frequency of extremely dry and wet conditions. Understanding the frequency of drought and floods in this catchment area is important to the agriculture sector for managing the negative impacts of these natural hazards. This study was undertaken to investigate the frequency and severity of drought/floods and linkages with the El Niño Southern Oscillation (ENSO) phenomenon. Poor and resource-limited small-scale farmers in the Luvuvhu River catchment area struggle to adjust due to decreasing crop yields and livestock mortality caused by drought and floods. Monthly rainfall data from 15 grid points (0.5° × 0.5°) was used to compute the Standardised Precipitation Index (SPI) for the period between 1979 and 2016. The 3-month SPI was calculated for the December–January–February (DJF) period. The second half of the agricultural season was selected because the influence of ENSO is high during the late summer season (DJF) in the catchment. The SPI results indicate that the agricultural seasons 1982/83, 1991/92 and 2015/16 were characterised by extreme drought. Conversely, the SPI values also show that the wettest seasons were recorded in 1998/99 and 1999/00. The catchment experiences a high frequency of moderate to severe drought in the north and north-eastern parts. Spatially, the occurrence of moderate to severe dry conditions covers large areas in the north and south-western parts. Severe to extreme wet conditions cover large areas in the north and south-eastern parts of the catchment. The SST index (Niño 3.4) shows a strong influence on rainfall variability in the catchment, resulting in either dry or wet conditions. Therefore, this study recommends further research focusing on more climatic modes that influence rainfall variability, as well as further development of drought and flood forecasting to improve farmers’ adaptations options and reliability of weather forecasts used as a tool to manage crop production.
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Mark R Jury. "Climate trends in the Cape Town area, South Africa." Water SA 46, no. 3 July (July 28, 2020). http://dx.doi.org/10.17159/wsa/2020.v46.i3.8654.
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Climatic conditions near Cape Town, South Africa (34°S, 19°E) are analysed for historical trends in station measurements in the 20th century and in modern satellite-blended datasets. Despite the variety of datasets and record lengths, all show a steady drying trend. Faster rates of warming, 0.1°C∙yr-1, are found in land surface temperatures during the period 2000–2017. Drying trends are most acute to the northwest of the Hottentots Holland mountains. Hydrology station measurements in the Upper Berg River catchment since 1956 reveal a decline in streamflow of −0.012 m3∙s-1∙month-1, and an upward slope in potential evaporation of +0.020 W∙m-2∙month-1. Rainfall has declined most in May and September, indicating a shorter winter wet season. Features supporting the drying trend include an increase of easterly winds and low-level subsidence during summer. The clockwise circulation trend around Cape Town entrains dry air from the Karoo interior and the south coast upwelling zone, leading to negative sensible heat flux, a capping inversion and diminished orographic rainfall.
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Seeliger, Leanne, Willem P. de Clercq, Willem Hoffman, James D. S. Cullis, Annabel M. Horn, and Marlene de Witt. "Applying the water-energy-food nexus to farm profitability in the Middle Breede Catchment, South Africa." South African Journal of Science 114, no. 11/12 (November 27, 2018). http://dx.doi.org/10.17159/sajs.2018/5062.
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The water-energy-food nexus has emerged as a useful concept to understand the multiple interdependencies that exist between the water, energy and food sectors. The nexus is an ambitious attempt to work across disciplines and scales to understand the workings of these complex systems. It is, however, criticised for being more of a general framework than a practical methodology because of the vast amount of data it would need to make real-life contributions to sustainable development. We show how the nexus approach, when used within a farm budget model, can transform the problem focus in water governance. By changing the relationship among water, energy and food production of a farm, profitability is significantly changed. The water-energy-food nexus debate is discussed within the context of the South African water sector, particularly the Breede River Catchment. Working from within the farm budget model, we demonstrate the impact of moving from an irrigation canal system that requires electricity for pumping, to a gravity-fed piped irrigation system in the Middle Breede River. The finding is that the water-energy-food nexus has the potential to unlock groundbreaking solutions to complex problems in agricultural water management when used in appropriate modelling systems. Significance: The water-energy-food nexus approach can lead to an entirely new framing of water governance problems and therefore solutions to these problems. The water-energy-food nexus when used in farm budget models can identify ways of altering farm profitability. By addressing the energy cost of farming through an irrigation pipeline system in parts of the Breede Catchment Area, farm profitability could significantly increase. A gravity-fed closed pipeline system in parts of the Breede River can improve water availability and reduce farm and management costs.
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Heritage, G. L., and A. W. Van Niekerk. "Drought conditions and sediment transport in the Sabie River." Koedoe 38, no. 2 (September 25, 1995). http://dx.doi.org/10.4102/koedoe.v38i2.311.
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Drought conditions in the Sabie catchment in the eastern Transvaal (now called Mpumalanga), South Africa, has had an observable effect on the sediment dynamics of the river. Sediment production within the catchment is largely unaffected by a reduction in the frequency and magnitude of rainfall events, although the rate of translocation of the weathered material from the catchment into the river channel is noticeably altered. The infrequent storm events during drought conditions generate a greater sed- iment input to the river from the catchment than a similar-magnitude event under average conditions. This sediment is also less likely to be transported through the system due to the reduced frequency of intermediate flows which act to rework in-channel sed- iment accumulations. Thus, significant accumulations of alluvial material are likely to form at specific locations, particularly where the local sediment transport capacity of the channel is low. Studies of the transport dynamics of the Sabie River, under both nor- mal and drought conditions, reveal that there are major depositional zones between Kruger Weir and Skukuza, and in the area around Lower Sabie. The 1992 drought resulted in a significant build-up of sediment in these areas, with a consequent reduc- tion in geomorphic diversity. This sediment is becoming stabilised due to the lower and less variable flows of the recent drought and associated vegetative colonisation. An increase in the magnitude and frequency of high and intermediate flows is needed to mobilise this accumulated sediment and to prevent its stabilisation by riparian vegetation.