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6 results on '"School of Bioresources Engineering and Environmental Hydrology University of KwaZulu-Natal"'

1. Spatial scale impact on daily surface water and sediment fluxes in Thukela river, South Africa

Author

Macdex Mutema, Samuel Kusangaya, Vincent Chaplot, Graham Jewitt, Pauline Chivenge, School of Agricultural, Earth & Environmental Sciences, Centre for Water Resources Research (CWRR), University of KwaZulu-Natal (UKZN), School of Bioresources Engineering and Environmental Hydrology University of KwaZulu-Natal, PB X01, International Crops Research Institute for the Semi-Arid Tropics [Inde] (ICRISAT), Consultative Group on International Agricultural Research [CGIAR] (CGIAR), Biogéochimie-Traceurs-Paléoclimat (BTP), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), University of KwaZulu-Natal [Durban, Afrique du Sud] (UKZN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636))

Subjects
010504 meteorology & atmospheric sciences, Erosion control, 0208 environmental biotechnology, Drainage basin, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], 02 engineering and technology, Structural basin, 01 natural sciences, Geochemistry and Petrology, Erosion mechanisms, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Hydrology, geography, geography.geographical_feature_category, 15. Life on land, 6. Clean water, 020801 environmental engineering, Infiltration (hydrology), Geophysics, Water quality, Multiple nested catchments, Erosion, Environmental science, Surface runoff, Surface water, Sediment fluxes
Abstract

The on- and off-site effects of soil erosion in many environments are well known, but there is still limited understanding of the soil loss fluxes in downstream direction due, among other factors, to scarce and poor quality. A four year study to (i) evaluate water and sediment fluxes at different spatio-temporal scales and (ii) interpret the results in terms of processes involved and the controlling factors, was conducted in Thukela basin, South Africa. Five hierarchically nested catchments; namely microcatchment (0.23 km 2 ), subcatchment (1.20 km 2 ), catchment (9.75 km 2 ), sub-basin (253 km 2 ) and basin (29,038 km 2 ), were used in addition to fifteen (1 m 2 ) microplots and ten (10 m 2 ) plots on five locations within the microcatchment. The results showed 19% decrease of unit-area runoff (q) from 3.1 L m −2 day −1 at microplot to 2.5 L m −2 day −1 at plot scale followed by steeper (56%) decrease at microcatchment scale. The q decreased in downstream direction to very low level (q ≤ 0.26 L m −2 day −1 ). The changes in q were accompanied by initial 1% increase of soil loss (SL) from 18.8 g m −2 day −1 at microplot to 19.1 g m −2 day −1 at plot scale. The SL also decreased sharply (by 39 fold) to 0.50 g m −2 day −1 at microcatchment scale, followed by further decrease in downstream direction. The decrease of q with spatial scale was attributed to infiltration losses, while initial increase of SL signified greater competence of sheet than splash erosion. The decrease of SL beyond the plot scale was attributed to redistribution of the soil on the hillslope and deposition on the stream channel upstream of the microcatchment outlet. Therefore, erosion control strategies focussing on the recovery of vegetation on the slope and stabilisation of gullies are recommended.

Published
2016
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2. Annual water, sediment, nutrient, and organic carbon fluxes in river basins: A global meta-analysis as a function of scale

Author

Vincent Chaplot, Günter Blöschl, Macdex Mutema, Graham Jewitt, Pauline Chivenge, School of Agricultural, Earth & Environmental Sciences, Centre for Water Resources Research (CWRR), University of KwaZulu-Natal (UKZN), Biogéochimie-Traceurs-Paléoclimat (BTP), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), School of Bioresources Engineering and Environmental Hydrology University of KwaZulu-Natal, PB X01, Institute of Hydraulic Engineering and Water Resources Management, Vienna University of Technology (TU Wien), University of KwaZulu-Natal [Durban, Afrique du Sud] (UKZN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636))

Subjects
Total organic carbon, Hydrology, geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, 0207 environmental engineering, Drainage basin, Sediment, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], 02 engineering and technology, 15. Life on land, 01 natural sciences, 6. Clean water, Carbon cycle, 13. Climate action, Erosion, Environmental science, Spatial variability, Ecosystem, 020701 environmental engineering, Surface runoff, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Water Science and Technology
Abstract

Process controls on water, sediment, nutrient, and organic carbon exports from the landscape through runoff are not fully understood. This paper provides analyses from 446 sites worldwide to evaluate the impact of environmental factors (MAP and MAT: mean annual precipitation and temperature; CLAY and BD: soil clay content and bulk density; S: slope gradient; LU: land use) on annual exports (RC: runoff coefficients; SL: sediment loads; TOCL: organic carbon losses; TNL: nitrogen losses; TPL: phosphorus losses) from different spatial scales. R-C was found to increase, on average, from 18% at local scale (in headwaters), 25% at microcatchment and subcatchment scale (midreaches) to 41% at catchment scale (lower reaches of river basins) in response to multiple factors. SL increased from microplots (468 g m(-2) yr(-1)) to plots (901 g m(-2) yr(-1)), accompanied by decreasing TOCL and TNL. Climate was a major control masking the effects of other factors. For example, R-C, SL, TOCL, TNL, and TPL tended to increase with MAP at all spatial scales. These variables, however, decreased with MAT. The impact of CLAY, BD, LU, and S on erosion variables was largely confined to the hillslope scale, where R-C, SL, and TOCL decreased with CLAY, while TNL and TPL increased. The results contribute to better understanding of water, nutrient, and carbon cycles in terrestrial ecosystems and should inform river basin modeling and ecosystem management. The important role of spatial climate variability points to a need for comparative research in specific environments at nested spatiotemporal scales.

Published
2015
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3. Influence of grass soil cover on water runoff and soil detachment under rainfall simulation in a sub-humid South African degraded rangeland

Author

Séraphine Grellier, Jean-Louis Janeau, Pascal Podwojewski, Christian Valentin, Simon Lorentz, Vincent Chaplot, Biogéochimie et écologie des milieux continentaux (Bioemco), Centre National de la Recherche Scientifique (CNRS)-AgroParisTech-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut National de la Recherche Agronomique (INRA)-École normale supérieure - Paris (ENS Paris), University of KwaZulu-Natal (UKZN), School of Bioresources Engineering and Environmental Hydrology University of KwaZulu-Natal, PB X01, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut de Recherche pour le Développement (IRD)-Institut National de la Recherche Agronomique (INRA)-Université Pierre et Marie Curie - Paris 6 (UPMC)-AgroParisTech-Centre National de la Recherche Scientifique (CNRS), and University of KwaZulu-Natal [Durban, Afrique du Sud] (UKZN)

Subjects
010504 meteorology & atmospheric sciences, Geography, Planning and Development, interrill erosion, runoff, infiltration, 01 natural sciences, soil degradation, Soil retrogression and degradation, Earth and Planetary Sciences (miscellaneous), Overgrazing, 0105 earth and related environmental sciences, Earth-Surface Processes, 2. Zero hunger, Hydrology, 04 agricultural and veterinary sciences, rainfall simulation, 15. Life on land, Infiltration (hydrology), [SDE]Environmental Sciences, 040103 agronomy & agriculture, Land degradation, Erosion, 0401 agriculture, forestry, and fisheries, Soil horizon, Environmental science, Rangeland, soil cover, Surface runoff
Abstract

In most regions of the world overgrazing plays a major role in land degradation and thus creates a major threat to natural ecosystems. Several feedbacks exist between overgrazing, vegetation, soil infiltration by water and soil erosion that need to be better understood. In this study of a sub-humid overgrazed rangeland in South Africa, the main objective was to evaluate the impact of grass cover on soil infiltration by water and soil detachment. Artificial rains of 30 and 60 mm h−1 were applied for 30 min on 1 m2 micro-plots showing similar sandy-loam Acrisols with different proportions of soil surface coverage by grass (Class A: 75–100%; B: 75–50%; C: 50–25%; D: 25–5%; E: 5–0% with an outcropping A horizon; F: 0% with an outcropping B horizon) to evaluate pre-runoff rainfall (Pr), steady state water infiltration (I), sediment concentration (SC) and soil losses (SL). Whatever the class of vegetal cover and the rainfall intensity, with the exception of two plots probably affected by biological activity, I decreased regularly to a steady rate

Published
2010
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4. Dung beetles (Coleoptera: Scarabaeidae) can improve soil hydrological properties

Author

Clarke H. Scholtz, Séraphine Grellier, Jacqueline Brown, Jean-Louis Janeau, Pascal Podwojewski, DEPARTMENT OF ZOOLOGY AND ENTOMOLOGY, University of Pretoria [South Africa], Biogéochimie et écologie des milieux continentaux (Bioemco), Centre National de la Recherche Scientifique (CNRS)-AgroParisTech-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut National de la Recherche Agronomique (INRA)-École normale supérieure - Paris (ENS Paris), School of Bioresources Engineering and Environmental Hydrology University of KwaZulu-Natal, PB X01, Department of Zoology and Entomology [Pretoria], École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut de Recherche pour le Développement (IRD)-Institut National de la Recherche Agronomique (INRA)-Université Pierre et Marie Curie - Paris 6 (UPMC)-AgroParisTech-Centre National de la Recherche Scientifique (CNRS), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)

Subjects
0106 biological sciences, Runoff, Soil biology, Soil Science, 010603 evolutionary biology, 01 natural sciences, Paracoprid, Animal science, Water content, 2. Zero hunger, Scarabaeidae, Ecology, biology, Moisture, Infiltration, 04 agricultural and veterinary sciences, 15. Life on land, biology.organism_classification, beetles, Agricultural and Biological Sciences (miscellaneous), Bulk density, Infiltration (hydrology), Erosion, Soil water, [SDE]Environmental Sciences, 040103 agronomy & agriculture, 0401 agriculture, forestry, and fisheries, Environmental science, Land degradation, Surface runoff
Abstract

Although dung beetles are known to perform a multitude of ecosystem services, their effects on water infiltration, runoff, porosity, moisture and erosion of soil have never been thoroughly researched. Maintenance of these hydrological properties is important in agro-ecosystem functioning where overgrazing results in negative impacts on the soil. The study site was located in the Potshini catchment in Kwazulu-Natal (South Africa), an area heavily grazed by livestock. We conducted two rainfall simulations on three 1 m(-2) control (no dung) and six dung-treated plots in December 2008, and repeated the study in June 2009 on the same plots. Natural populations of dung beetles were allowed to colonise the dung. Simulations were conducted for 30 min at an intensity of 30 mm h(-1). Key variables calculated were pre-runoff amounts (Pi), infiltration ratios (Ki), and soil losses. Samples were collected for bulk density determination during the same time periods in order to measure differences in porosity and moisture in control and dung-treated plots at different depths. Using multivariate statistics we found significant differences between dung-treated and control plots in three of four simulations. After 48 h of beetle activity, Pi and Ki values were significantly increased and remained at elevated levels six months later. Soil losses were initially higher in dung-treated plots than controls, but had declined to less than control values after six months. Bulk density in the A-horizon (0-10 cm) was significantly reduced after 48 h of beetle activity and remained so for six months. No difference in bulk density was observed at greater depths. Soil moisture initially increased significantly in the A-horizon, as well as at 20 and 30 cm depths after six months of activity. We conclude that dung beetles positively influence hydrological properties of the soil by increasing water infiltration and soil porosity, and reducing surface water runoff. Contrasting effects on soil losses are problematic to reconcile from this study. High losses initially observed may be offset in the long-term by reductions associated with the increased infiltration ratios, though this remains to be confirmed.

Published
2010
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5. Establishment of a catchment monitoring network through a participatory approach in a small rural catchment in South Africa

Author

Kongo, V. M., Kosgei, J. R., Jewitt, G. P. W., Lorentz, S. A., School of Bioresources Engineering and Environmental Hydrology University of KwaZulu-Natal, PB X01, and EGU, Publication

Subjects
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, 010504 meteorology & atmospheric sciences, [SDU.OCEAN] Sciences of the Universe [physics]/Ocean, Atmosphere, [SDU.STU] Sciences of the Universe [physics]/Earth Sciences, 0207 environmental engineering, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, 02 engineering and technology, 020701 environmental engineering, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, 01 natural sciences, [SDU.ENVI] Sciences of the Universe [physics]/Continental interfaces, environment, 6. Clean water, 0105 earth and related environmental sciences
Abstract

The establishment of a catchment monitoring network is a process, from the inception of the idea to its implementation, the latter being the construction of relevant gauging structures and installation of the various instruments. It is useful that the local communities and other stakeholders are involved and participate in such a process as was realised during the establishment of the hydrological monitoring network in the Potshini catchment in the Bergville district in the KwaZulu-Natal Province in South Africa. The paper illustrates the participatory application of various methods and techniques for establishing a hydrological monitoring network, in a small rural inhabited catchment, to monitor hydrological processes at both field and catchment scale for research purposes in water resources management. The authors conclude that the participation of the local community and other stakeholders in catchment monitoring and instilling the sense of ownership and management of natural resources to the local communities needs to be encouraged at all times. Success stories in water resources management by local communities can be realized if such a process is integrated with other development plans in the catchment at all forums with due recognition of the social dynamics of the communities living in the catchment.

Published
2007

6. Adaptive management and water temperature variability within a South African river system: what are the management options?

Author

Rivers-Moore NA and Jewitt GP

Subjects
Animals, Models, Theoretical, Organizational Policy, Policy Making, South Africa, Temperature, Time Factors, Vertebrates growth & development, Water Movements, Water Supply, Conservation of Natural Resources, Environmental Monitoring, Meteorological Concepts, Rivers, Water Pollution prevention & control
Abstract

Water temperatures, and in particular daily maximum water temperatures, are a critical water quality parameter. An understanding of associated resource management issues, including links between water temperature variability and aquatic diversity values, should be part of any management programme that considers river systems. Simple rule-based models have been shown to be appropriate tools within an adaptive management approach, both because of their heuristic value and in their application for scenario generation. Such a model was developed to simulate changes in the condition factor of Chiloglanis anoterus [Crass, R.S., 1960. Notes on the freshwater fishes of Natal with descriptions of 4 new species. Annals of the Natal Museum 14, 405-458] (Pisces: Mochokidae) in response to annual frequency of exceedance of a threshold temperature under three broad environmental scenarios for part of the Sabie River falling within South Africa's Kruger National Park. This model has potential for application within the adaptive management programme being implemented by the Kruger National Park. Results show that under broad scenarios of a 10% reduction in mean daily flow rates, or a 2 degrees C increase in mean daily air temperatures, system variability is likely to increase relative to reference conditions . It is suggested that so-called "thresholds of probable concern" (TPCs), which are based on current levels of "natural" system variability, are useful as management targets for achieving a "desired future state" for the river system. The model, recognised as a preliminary hypothesis, highlights a lack of knowledge regarding the nature of system variability, and the correspondingly wide confidence limits of the proposed TPC restricts its utility in a short-term management context. Thus, it is now recognised that its value lies more in its use as a long-term modelling tool to reflect water temperature responses to flow variability. This highlights the fact that research outcomes may not always be those intended at the beginning of a project and that opportunities to implement these may be lost as lags in understanding relative to project lifetimes often exist.

Published
2007
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