Towards SDG 15.3: The biome context as the appropriate degradation monitoring dimension
- Xoxo, Sinetemba, Mantel, Sukhmani K, de Vos, Alta, Mahlaba, Bawinile, le Maître, David, Tanner, Jane L
- Authors: Xoxo, Sinetemba , Mantel, Sukhmani K , de Vos, Alta , Mahlaba, Bawinile , le Maître, David , Tanner, Jane L
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/415961 , vital:71304 , xlink:href="https://doi.org/10.1016/j.envsci.2022.07.008"
- Description: Accurate and reliable estimation of terrestrial ecosystem degradation is critical to meeting the challenge of reversing land degradation. Remote sensing data (especially land productivity dynamics) is commonly used to estimate land degradation, and this study uses the TRENDS.EARTH toolbox for the period covering 2000–2018, demonstrating the benefit of tracking the degradation process (SDG 15.3.1) at a biophysical unit. Contributing to the country’s SDG 15.3.1 monitoring, anthropogenic degradation was estimated based on RESTREND land productivity, biome-specific land cover trends, and soil organic carbon (SOC) stocks. Underlying degradation was evaluated by reclassifying a 28-year national land cover change dataset to match the UNCCD land cover legend. Analysis results indicate that land productivity changes (especially in stable grasslands, afforested, and cropland areas) mainly influenced the degradation status of the biome (19.9% degraded and 25.6% improvement). Global datasets also suggest that land cover and SOC had a minimal contribution (more than 2%) to anthropogenic degradation dynamics in the biome between 2000 and 2018. The GIS analysis showed that long-term, the major contributors to the biome’s underlying 9% anthropogenic degradation were woody proliferation into the Grassland Biome, urban expansion, and wetland drainage.
- Full Text:
- Authors: Xoxo, Sinetemba , Mantel, Sukhmani K , de Vos, Alta , Mahlaba, Bawinile , le Maître, David , Tanner, Jane L
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/415961 , vital:71304 , xlink:href="https://doi.org/10.1016/j.envsci.2022.07.008"
- Description: Accurate and reliable estimation of terrestrial ecosystem degradation is critical to meeting the challenge of reversing land degradation. Remote sensing data (especially land productivity dynamics) is commonly used to estimate land degradation, and this study uses the TRENDS.EARTH toolbox for the period covering 2000–2018, demonstrating the benefit of tracking the degradation process (SDG 15.3.1) at a biophysical unit. Contributing to the country’s SDG 15.3.1 monitoring, anthropogenic degradation was estimated based on RESTREND land productivity, biome-specific land cover trends, and soil organic carbon (SOC) stocks. Underlying degradation was evaluated by reclassifying a 28-year national land cover change dataset to match the UNCCD land cover legend. Analysis results indicate that land productivity changes (especially in stable grasslands, afforested, and cropland areas) mainly influenced the degradation status of the biome (19.9% degraded and 25.6% improvement). Global datasets also suggest that land cover and SOC had a minimal contribution (more than 2%) to anthropogenic degradation dynamics in the biome between 2000 and 2018. The GIS analysis showed that long-term, the major contributors to the biome’s underlying 9% anthropogenic degradation were woody proliferation into the Grassland Biome, urban expansion, and wetland drainage.
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The Role of Ecological Infrastructure (EI) in Mitigating the Impacts of Droughts
- Mantel, Sukhmani K, Xoxo, Sinetemba, Mahlaba, Bawinile, Tanner, Jane L, Le Maître, David
- Authors: Mantel, Sukhmani K , Xoxo, Sinetemba , Mahlaba, Bawinile , Tanner, Jane L , Le Maître, David
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , report
- Identifier: http://hdl.handle.net/10962/438209 , vital:73443 , ISBN 978-0-6392-0304-1 , https://wrcwebsite.azurewebsites.net/wp-content/uploads/mdocs/2928_web.pdf
- Description: To explain how well-managed ecological infrastructure can help to miti-gate the impacts of droughts on human livelihoods and well-being and to propose strategic responses that will maintain and enhance the value of this service that people will embrace and implement.
- Full Text:
- Authors: Mantel, Sukhmani K , Xoxo, Sinetemba , Mahlaba, Bawinile , Tanner, Jane L , Le Maître, David
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , report
- Identifier: http://hdl.handle.net/10962/438209 , vital:73443 , ISBN 978-0-6392-0304-1 , https://wrcwebsite.azurewebsites.net/wp-content/uploads/mdocs/2928_web.pdf
- Description: To explain how well-managed ecological infrastructure can help to miti-gate the impacts of droughts on human livelihoods and well-being and to propose strategic responses that will maintain and enhance the value of this service that people will embrace and implement.
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A comparison of three models used to determine water fluxes over the Albany Thicket, Eastern Cape, South Africa:
- Palmer, Anthony R, Ezenne, G I, Choruma, D J, Gwate, O, Mantel, Sukhmani K, Tanner, Jane L
- Authors: Palmer, Anthony R , Ezenne, G I , Choruma, D J , Gwate, O , Mantel, Sukhmani K , Tanner, Jane L
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/150047 , vital:38934 , https://doi.org/10.1016/j.agrformet.2020.107984
- Description: The Albany Thicket (AT) biome contains outstanding global biodiversity as well as the potential to achieve carbon credits associated with water-efficient Crasslucean acid metabolism (CAM). Understanding the water fluxes in the AT is crucial to determining carbon (C) sequestration rates and water-use efficiency. Despite large variation in water fluxes across the AT, only a few studies have been conducted in this region with their results validated against short periods of observed data. This study aims to evaluate three models of water fluxes over AT against data from an eddy covariance (EC) system active from October 2015 to May 2018. ET was modelled using the BioGeoChemistry Management (BGC-MAN) model, a biophysical model (Penman-Monteith-Leuning (PML)) and a remotely-sensed product (MOD16), and their results compared with that from the EC system.
- Full Text:
- Authors: Palmer, Anthony R , Ezenne, G I , Choruma, D J , Gwate, O , Mantel, Sukhmani K , Tanner, Jane L
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/150047 , vital:38934 , https://doi.org/10.1016/j.agrformet.2020.107984
- Description: The Albany Thicket (AT) biome contains outstanding global biodiversity as well as the potential to achieve carbon credits associated with water-efficient Crasslucean acid metabolism (CAM). Understanding the water fluxes in the AT is crucial to determining carbon (C) sequestration rates and water-use efficiency. Despite large variation in water fluxes across the AT, only a few studies have been conducted in this region with their results validated against short periods of observed data. This study aims to evaluate three models of water fluxes over AT against data from an eddy covariance (EC) system active from October 2015 to May 2018. ET was modelled using the BioGeoChemistry Management (BGC-MAN) model, a biophysical model (Penman-Monteith-Leuning (PML)) and a remotely-sensed product (MOD16), and their results compared with that from the EC system.
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Impacts of Climate Change in Determining the Ecological Reserve
- Tanner, Jane L, Griffin, Neil J, Slaughter, Andrew R, Mantel, Sukhmani K, Dabula, Pumza, Hughes, Denis A, Wolff, Margaret G
- Authors: Tanner, Jane L , Griffin, Neil J , Slaughter, Andrew R , Mantel, Sukhmani K , Dabula, Pumza , Hughes, Denis A , Wolff, Margaret G
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , report
- Identifier: http://hdl.handle.net/10962/438128 , vital:73437 , ISBN 978-0-6392-0124-5 , https://wrcwebsite.azurewebsites.net/wp-content/uploads/mdocs/2834 final.pdf
- Description: The intermediate and long-term impacts of climate change require evaluation of the adaptive capacity of the riverine ecosystems to pro-mote sustainability. The predicted climate change impacts are the moti-vation behind the current research which targets the knowledge gap of the impacts of climate change on the ecological Reserve (or Ecological Water Requirements [EWR]). In order for the Department of Water and Sanitation (DWS) to meet their mandate to protect aquatic ecosystems, given the constraints of climate change, it is necessary to take cogni-sance of the implications of climate change and to make the necessary adjustments and changes to the ecological Reserve determination methodology. These adjustments will help ensure that sufficient water, at the right time, distributed in the right flow pattern and of adequate quality is provided, so that key ecological processes are sustained, and that biotic communities maintain their health and integrity.
- Full Text:
- Authors: Tanner, Jane L , Griffin, Neil J , Slaughter, Andrew R , Mantel, Sukhmani K , Dabula, Pumza , Hughes, Denis A , Wolff, Margaret G
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , report
- Identifier: http://hdl.handle.net/10962/438128 , vital:73437 , ISBN 978-0-6392-0124-5 , https://wrcwebsite.azurewebsites.net/wp-content/uploads/mdocs/2834 final.pdf
- Description: The intermediate and long-term impacts of climate change require evaluation of the adaptive capacity of the riverine ecosystems to pro-mote sustainability. The predicted climate change impacts are the moti-vation behind the current research which targets the knowledge gap of the impacts of climate change on the ecological Reserve (or Ecological Water Requirements [EWR]). In order for the Department of Water and Sanitation (DWS) to meet their mandate to protect aquatic ecosystems, given the constraints of climate change, it is necessary to take cogni-sance of the implications of climate change and to make the necessary adjustments and changes to the ecological Reserve determination methodology. These adjustments will help ensure that sufficient water, at the right time, distributed in the right flow pattern and of adequate quality is provided, so that key ecological processes are sustained, and that biotic communities maintain their health and integrity.
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Measuring and modelling evapotranspiration in a South African grassland: Comparison of two improved Penman-Monteith formulations
- Gwate, Onalenna, Mantel, Sukhmani K, Palmer, Anthony R, Gibson, Lesley A, Munch, Zahn
- Authors: Gwate, Onalenna , Mantel, Sukhmani K , Palmer, Anthony R , Gibson, Lesley A , Munch, Zahn
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , report
- Identifier: http://hdl.handle.net/10962/438167 , vital:73440 , ISBN 1816-7950 , https://wrcwebsite.azurewebsites.net/wp-content/uploads/mdocs/44_03_16_3530.pdf
- Description: Accurately measuring evapotranspiration (ET) is important in the con-text of global atmospheric changes and for use with climate models. Direct ET measurement is costly to apply widely and local calibration and validation of ET models developed elsewhere improves confidence in ET derived from such models. is study sought to compare the per-formance of the Penman-Monteith-Leuning (PML) and Penman-Monteith-Palmer (PMP) ET models, over mesic grasslands in two study sites in South Africa. The study used routine meteorological data from a scientific-grade automatic weather station (AWS) to apply the PML and PMP models. The PML model was calibrated at one site and validated in both sites. On the other hand, the PMP model does not require cali-bration and hence it was validated in both sites.
- Full Text:
- Authors: Gwate, Onalenna , Mantel, Sukhmani K , Palmer, Anthony R , Gibson, Lesley A , Munch, Zahn
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , report
- Identifier: http://hdl.handle.net/10962/438167 , vital:73440 , ISBN 1816-7950 , https://wrcwebsite.azurewebsites.net/wp-content/uploads/mdocs/44_03_16_3530.pdf
- Description: Accurately measuring evapotranspiration (ET) is important in the con-text of global atmospheric changes and for use with climate models. Direct ET measurement is costly to apply widely and local calibration and validation of ET models developed elsewhere improves confidence in ET derived from such models. is study sought to compare the per-formance of the Penman-Monteith-Leuning (PML) and Penman-Monteith-Palmer (PMP) ET models, over mesic grasslands in two study sites in South Africa. The study used routine meteorological data from a scientific-grade automatic weather station (AWS) to apply the PML and PMP models. The PML model was calibrated at one site and validated in both sites. On the other hand, the PMP model does not require cali-bration and hence it was validated in both sites.
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Rehabilitation of grasslands after eradication of alien invasive trees
- Palmer, Anthony R, Gwate, Onalenna, Gushaa, Bukho, Gibson, Lesley A, Münch, Zahn, Mantel, Sukhmani K, Murata, Chenai, de Wet, Chris, Zondani, Thantaswa, Perry, Adam
- Authors: Palmer, Anthony R , Gwate, Onalenna , Gushaa, Bukho , Gibson, Lesley A , Münch, Zahn , Mantel, Sukhmani K , Murata, Chenai , de Wet, Chris , Zondani, Thantaswa , Perry, Adam
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , report
- Identifier: http://hdl.handle.net/10962/438195 , vital:73442 , ISBN 978-0-6392-0098-9 , https://wrcwebsite.azurewebsites.net/wp-content/uploads/mdocs/TT 786_final web.pdf
- Description: Invasive alien plants (IAPs) remain a serious threat to the water supply and to stor-age reservoirs throughout South Africa. IAPs are known to use a large quantity of water through evapotranspiration, and the clearing and control of IAPs has been a major activity of the Working for Water (WfW) programme. Successful clearing of these often aggressive woody trees and shrubs requires careful regeneration of ef-fective indigenous vegetation cover after the physical clear-felling and removal of the IAPs. Application of effective post-clearing management regimes is required in order to improve the grass cover within catchments and this can ensure that there is controlled runoff and groundwater re-charge. South Africa's water catchment areas receive insufficient rainfall (Blignaut and De Wit 2004). In addition, limited options for the construction of new reservoirs and water schemes has stimulated the need to explore other options for increasing and conserving water supplies (Ashton and Seetal 2002) and improved demand management.
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- Authors: Palmer, Anthony R , Gwate, Onalenna , Gushaa, Bukho , Gibson, Lesley A , Münch, Zahn , Mantel, Sukhmani K , Murata, Chenai , de Wet, Chris , Zondani, Thantaswa , Perry, Adam
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , report
- Identifier: http://hdl.handle.net/10962/438195 , vital:73442 , ISBN 978-0-6392-0098-9 , https://wrcwebsite.azurewebsites.net/wp-content/uploads/mdocs/TT 786_final web.pdf
- Description: Invasive alien plants (IAPs) remain a serious threat to the water supply and to stor-age reservoirs throughout South Africa. IAPs are known to use a large quantity of water through evapotranspiration, and the clearing and control of IAPs has been a major activity of the Working for Water (WfW) programme. Successful clearing of these often aggressive woody trees and shrubs requires careful regeneration of ef-fective indigenous vegetation cover after the physical clear-felling and removal of the IAPs. Application of effective post-clearing management regimes is required in order to improve the grass cover within catchments and this can ensure that there is controlled runoff and groundwater re-charge. South Africa's water catchment areas receive insufficient rainfall (Blignaut and De Wit 2004). In addition, limited options for the construction of new reservoirs and water schemes has stimulated the need to explore other options for increasing and conserving water supplies (Ashton and Seetal 2002) and improved demand management.
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Extending functionality and knowledge transfer of the Water Quality Systems Assessment Model
- Slaughter, Andrew R, Gwapedza, David, Mantel, Sukhmani K, Hughes, Denis A, Griffin, Neil J
- Authors: Slaughter, Andrew R , Gwapedza, David , Mantel, Sukhmani K , Hughes, Denis A , Griffin, Neil J
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , report
- Identifier: http://hdl.handle.net/10962/438115 , vital:73436 , ISBN 978-0-6392-0059-0 , https://wrcwebsite.azurewebsites.net/wp-content/uploads/mdocs/2448_final.pdf
- Description: This report has been generated by the Water Research Commission (WRC) funded project Developing Climate Change Adaptation Measures and Decision-Support System for Selected South African Water Boards (Project No. K5/2018).
- Full Text:
- Authors: Slaughter, Andrew R , Gwapedza, David , Mantel, Sukhmani K , Hughes, Denis A , Griffin, Neil J
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , report
- Identifier: http://hdl.handle.net/10962/438115 , vital:73436 , ISBN 978-0-6392-0059-0 , https://wrcwebsite.azurewebsites.net/wp-content/uploads/mdocs/2448_final.pdf
- Description: This report has been generated by the Water Research Commission (WRC) funded project Developing Climate Change Adaptation Measures and Decision-Support System for Selected South African Water Boards (Project No. K5/2018).
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Land cover models to predict non-point nutrient inputs for selected biomes in South Africa
- Slaughter, Andrew R, Mantel, Sukhmani K
- Authors: Slaughter, Andrew R , Mantel, Sukhmani K
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , report
- Identifier: http://hdl.handle.net/10962/438152 , vital:73439 , ISBN 1816-7950 , https://wrcwebsite.azurewebsites.net/wp-content/uploads/mdocs/3390.pdf
- Description: WQSAM is a practical water quality model for use in guiding southern African water quality management. However, the estimation of non-point nutrient inputs within WQSAM is uncertain, as it is achieved through a combination of calibration and expert knowledge. Non-point source loads can be correlated to particular land cover types. Although observed water quality data through which non-point source loads can be estimated are scarce, land cover databases exist covering the entire area of South Africa. To reduce the uncertainty associated with estimat-ing non-point source loads, this study describes a formal model to link the nutrient signatures of incremental flow to land cover. Study catch-ments incorporating the fynbos, grassland, savanna and thicket biomes were identified. Instream nutrients of 25 sites were modelled using WQSAM and calibrated against observed data. Multiple regression was used to investigate the relationships between the calibrated nutrient signatures of incremental flow from WQSAM and land cover within study sites. The regression models reflected greater non-point loads from cultivation-and urban-related land cover categories. The nutrient signatures of incremental flow obtained through the multiple regres-sions were consistent with those obtained through calibration of the WQSAM model at higher signature values, whereas discrepancies were evident at lower values. It is argued that this formal modelling ap-proach for linking land cover to nutrient signatures of incremental flow can be implemented for situations where it is known that there are strong non-point inputs of nutrients into a river reach. The statistical model presented in the current study could potentially be applied as an alternative to the water quality model as a relatively simple method to estimate non-point source loads of nutrients from tributary catchments in South Africa.
- Full Text:
- Authors: Slaughter, Andrew R , Mantel, Sukhmani K
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , report
- Identifier: http://hdl.handle.net/10962/438152 , vital:73439 , ISBN 1816-7950 , https://wrcwebsite.azurewebsites.net/wp-content/uploads/mdocs/3390.pdf
- Description: WQSAM is a practical water quality model for use in guiding southern African water quality management. However, the estimation of non-point nutrient inputs within WQSAM is uncertain, as it is achieved through a combination of calibration and expert knowledge. Non-point source loads can be correlated to particular land cover types. Although observed water quality data through which non-point source loads can be estimated are scarce, land cover databases exist covering the entire area of South Africa. To reduce the uncertainty associated with estimat-ing non-point source loads, this study describes a formal model to link the nutrient signatures of incremental flow to land cover. Study catch-ments incorporating the fynbos, grassland, savanna and thicket biomes were identified. Instream nutrients of 25 sites were modelled using WQSAM and calibrated against observed data. Multiple regression was used to investigate the relationships between the calibrated nutrient signatures of incremental flow from WQSAM and land cover within study sites. The regression models reflected greater non-point loads from cultivation-and urban-related land cover categories. The nutrient signatures of incremental flow obtained through the multiple regres-sions were consistent with those obtained through calibration of the WQSAM model at higher signature values, whereas discrepancies were evident at lower values. It is argued that this formal modelling ap-proach for linking land cover to nutrient signatures of incremental flow can be implemented for situations where it is known that there are strong non-point inputs of nutrients into a river reach. The statistical model presented in the current study could potentially be applied as an alternative to the water quality model as a relatively simple method to estimate non-point source loads of nutrients from tributary catchments in South Africa.
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Informing the Responses of Water Service Delivery Institutions to Climate and Development Changes: A Case Study in the Amatole Region, Eastern Cape
- Hughes, Denis A, Mantel, Sukhmani K, Slaughter, Andrew R
- Authors: Hughes, Denis A , Mantel, Sukhmani K , Slaughter, Andrew R
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , report
- Identifier: http://hdl.handle.net/10962/438140 , vital:73438 , ISBN 978-1-4312-0520-2 , https://wrcwebsite.azurewebsites.net/wp-content/uploads/mdocs/2018-1-14.pdf
- Description: This report has been generated by the Water Research Commission (WRC) funded project Developing Climate Change Adaptation Measures and Decision-Support System for Selected South African Water Boards (Project No. K5/2018).
- Full Text:
- Authors: Hughes, Denis A , Mantel, Sukhmani K , Slaughter, Andrew R
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , report
- Identifier: http://hdl.handle.net/10962/438140 , vital:73438 , ISBN 978-1-4312-0520-2 , https://wrcwebsite.azurewebsites.net/wp-content/uploads/mdocs/2018-1-14.pdf
- Description: This report has been generated by the Water Research Commission (WRC) funded project Developing Climate Change Adaptation Measures and Decision-Support System for Selected South African Water Boards (Project No. K5/2018).
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Prediction of water temperature metrics using spatial modelling in the Eastern and Western Cape, South Africa
- Rivers-Moore, Nick A, Mantel, Sukhmani K, Dallas, Helen F
- Authors: Rivers-Moore, Nick A , Mantel, Sukhmani K , Dallas, Helen F
- Date: 2012
- Language: English
- Type: text , Article
- Identifier: vital:7071 , http://hdl.handle.net/10962/d1003947 , http://www.scielo.org.za/scielo.php?pid=S1816-79502012000200002&script=sci_arttext
- Description: Key aspects of a river's temperature regime are described by magnitudes, timing and durations of thermal events, and frequencies of extreme exceedance events. To understand alterations to thermal regimes, it is necessary to describe thermal time series based on these statistics. Classification of sites based on their thermal metrics, and understanding of spatial patterns of these thermal statistics, provides a powerful approach for comparing study sites against reference sites. Water temperature regime dynamics should be viewed regionally, where regional divisions have an inherent underpinning by an understanding of natural thermal variability. The aim of this research was to link key water temperature metrics to readily-mapped environmental surrogates, and to produce spatial images of temperature metrics: 37 temperature metrics were derived for 12 months of sub-daily water temperatures at 90 sites in the Eastern Cape and Western Cape provinces, South Africa. These metrics were correlated with 16 environmental variables. Correlations enabled development of multiple regression models which facilitated mapping of temperature metrics over the study area. This approach has the potential to be applied at a national scale as more thermal time series are collected nationally. It is argued that the appropriateness of management decisions in rivers can be improved by including guidelines for thermal metrics at a regional scale. Such maps could facilitate incorporation of a temperature component into management guidelines for water resources.
- Full Text:
- Authors: Rivers-Moore, Nick A , Mantel, Sukhmani K , Dallas, Helen F
- Date: 2012
- Language: English
- Type: text , Article
- Identifier: vital:7071 , http://hdl.handle.net/10962/d1003947 , http://www.scielo.org.za/scielo.php?pid=S1816-79502012000200002&script=sci_arttext
- Description: Key aspects of a river's temperature regime are described by magnitudes, timing and durations of thermal events, and frequencies of extreme exceedance events. To understand alterations to thermal regimes, it is necessary to describe thermal time series based on these statistics. Classification of sites based on their thermal metrics, and understanding of spatial patterns of these thermal statistics, provides a powerful approach for comparing study sites against reference sites. Water temperature regime dynamics should be viewed regionally, where regional divisions have an inherent underpinning by an understanding of natural thermal variability. The aim of this research was to link key water temperature metrics to readily-mapped environmental surrogates, and to produce spatial images of temperature metrics: 37 temperature metrics were derived for 12 months of sub-daily water temperatures at 90 sites in the Eastern Cape and Western Cape provinces, South Africa. These metrics were correlated with 16 environmental variables. Correlations enabled development of multiple regression models which facilitated mapping of temperature metrics over the study area. This approach has the potential to be applied at a national scale as more thermal time series are collected nationally. It is argued that the appropriateness of management decisions in rivers can be improved by including guidelines for thermal metrics at a regional scale. Such maps could facilitate incorporation of a temperature component into management guidelines for water resources.
- Full Text:
Prediction of water temperature metrics using spatial modelling in the Eastern and Western Cape, South Africa
- Rivers-Moore, Nick A, Mantel, Sukhmani K, Dallas, Helen F
- Authors: Rivers-Moore, Nick A , Mantel, Sukhmani K , Dallas, Helen F
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , report
- Identifier: http://hdl.handle.net/10962/438180 , vital:73441 , ISBN 1816-7950 , https://wrcwebsite.azurewebsites.net/wp-content/uploads/mdocs/2651.pdf
- Description: Key aspects of a river’s temperature regime are described by magnitudes, timing and durations of thermal events, and frequencies of extreme exceedance events. To understand alterations to thermal regimes, it is necessary to describe thermal time series based on these statistics. Classification of sites based on their thermal met-rics, and understanding of spatial patterns of these thermal statistics, provides a powerful approach for comparing study sites against reference sites. Water tem-perature regime dynamics should be viewed regionally, where regional divisions have an inherent underpinning by an understanding of natural thermal variability. The aim of this research was to link key water temperature metrics to readi-lymapped environmental surrogates, and to produce spatial images of temperature metrics: 37 temperature metrics were derived for 12 months of sub-daily water temperatures at 90 sites in the Eastern Cape and Western Cape provinces, South Africa.
- Full Text:
- Authors: Rivers-Moore, Nick A , Mantel, Sukhmani K , Dallas, Helen F
- Date: 2012
- Subjects: To be catalogued
- Language: English
- Type: text , report
- Identifier: http://hdl.handle.net/10962/438180 , vital:73441 , ISBN 1816-7950 , https://wrcwebsite.azurewebsites.net/wp-content/uploads/mdocs/2651.pdf
- Description: Key aspects of a river’s temperature regime are described by magnitudes, timing and durations of thermal events, and frequencies of extreme exceedance events. To understand alterations to thermal regimes, it is necessary to describe thermal time series based on these statistics. Classification of sites based on their thermal met-rics, and understanding of spatial patterns of these thermal statistics, provides a powerful approach for comparing study sites against reference sites. Water tem-perature regime dynamics should be viewed regionally, where regional divisions have an inherent underpinning by an understanding of natural thermal variability. The aim of this research was to link key water temperature metrics to readi-lymapped environmental surrogates, and to produce spatial images of temperature metrics: 37 temperature metrics were derived for 12 months of sub-daily water temperatures at 90 sites in the Eastern Cape and Western Cape provinces, South Africa.
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Evaluating The Potential Contribution Of Episodic Toxicity Data To Environmental Water Quality Management In South Africa
- Gordon, Andrew K, Mantel, Sukhmani K, Muller, Nikite W J
- Authors: Gordon, Andrew K , Mantel, Sukhmani K , Muller, Nikite W J
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , report
- Identifier: http://hdl.handle.net/10962/438310 , vital:73450 , ISBN 978-1-4312-0070-2 , https://wrcwebsite.azurewebsites.net/wp-content/uploads/mdocs/KV259-10.pdf
- Description: An important aspect of the dynamics of nutrients and pollutants in natural systems is captured in the concept of allochthony, founded on the observation that nutrients and energy in a variety of forms are transferred between adjacent habitats, com-munities and ecosystems that are not routinely considered as connected. Different forms of nutrients and energy move across the conceptual boundaries of habitats via organisms’ activities or physical processes such as wind or water currents, and these transfers can represent important food subsidies. Such cross-partition ecolog-ical subsidies can augment the nutritional condition, biomass and biodiversity of communities, particularly where local production (or autochthony) alone may be inadequate to support local food webs. Furthermore, organic subsidies can influ-ence population dynamics, community interactions and ecosystem processes, and can represent dominant flux inputs in ecosystem budgets. Our intention was to explore organic nutrient fluxes in relation to a primarily lotic (i.e. flowing) aquatic sys-tem at the scale of a hydrological catchment.
- Full Text:
- Authors: Gordon, Andrew K , Mantel, Sukhmani K , Muller, Nikite W J
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , report
- Identifier: http://hdl.handle.net/10962/438310 , vital:73450 , ISBN 978-1-4312-0070-2 , https://wrcwebsite.azurewebsites.net/wp-content/uploads/mdocs/KV259-10.pdf
- Description: An important aspect of the dynamics of nutrients and pollutants in natural systems is captured in the concept of allochthony, founded on the observation that nutrients and energy in a variety of forms are transferred between adjacent habitats, com-munities and ecosystems that are not routinely considered as connected. Different forms of nutrients and energy move across the conceptual boundaries of habitats via organisms’ activities or physical processes such as wind or water currents, and these transfers can represent important food subsidies. Such cross-partition ecolog-ical subsidies can augment the nutritional condition, biomass and biodiversity of communities, particularly where local production (or autochthony) alone may be inadequate to support local food webs. Furthermore, organic subsidies can influ-ence population dynamics, community interactions and ecosystem processes, and can represent dominant flux inputs in ecosystem budgets. Our intention was to explore organic nutrient fluxes in relation to a primarily lotic (i.e. flowing) aquatic sys-tem at the scale of a hydrological catchment.
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Ecological impacts of small dams on South African rivers Part 1: Drivers of change–water quantity and quality
- Mantel, Sukhmani K, Hughes, Denis A, Muller, Nikite W J
- Authors: Mantel, Sukhmani K , Hughes, Denis A , Muller, Nikite W J
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , report
- Identifier: http://hdl.handle.net/10962/438099 , vital:73435 , ISBN 1816-7950 , https://wrcwebsite.azurewebsites.net/wp-content/uploads/mdocs/2398.pdf
- Description: Impacts of large dams are well-known and quantifiable, while small dams have generally been perceived as benign, both socially and envi-ronmentally. The present study quantifies the cumulative impacts of small dams on the water quality (physico-chemistry and invertebrate biotic indices) and quantity (discharge) of downstream rivers in 2 South African regions. The information from 2 South African national data-bases was used for evaluating the cumulative impacts on water quality and quantity. Physico-chemistry and biological data were obtained from the River Health Programme, and discharge data at stream flow gauges was obtained from the Hydrological Information System. Multivariate analyses were conducted to establish broad patterns for cumulative impacts of small dams across the 2 regions–Western Cape (winter rain-fall, temperate, south-western coast) and Mpumalanga (summer rain-fall, tropical, eastern coast). Multivariate analyses found that the chang-es in macroinvertebrate indices and the stream’s physico-chemistry were more strongly correlated with the density of small dams in the catchment (as a measure of cumulative impact potential) relative to the storage capacity of large dams. T-tests on the data, not including sam-ples with upstream large dams, indicated that the high density of small dams significantly reduced low flows and increased certain physico-chemistry variables (particularly total dissolved salts) in both the re-gions, along with associated significant reductions in a macroinverte-brate index (SASS4 average score per taxon). Regional differences were apparent in the results for discharge reductions and the macroin-vertebrate index. The results suggest that the cumulative effect of a high number of small dams is impacting the quality and quantity of wa-ters in South African rivers and that these impacts need to be systemat-ically incorporated into the monitoring protocol of the environmental wa-ter requirements.
- Full Text:
- Authors: Mantel, Sukhmani K , Hughes, Denis A , Muller, Nikite W J
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , report
- Identifier: http://hdl.handle.net/10962/438099 , vital:73435 , ISBN 1816-7950 , https://wrcwebsite.azurewebsites.net/wp-content/uploads/mdocs/2398.pdf
- Description: Impacts of large dams are well-known and quantifiable, while small dams have generally been perceived as benign, both socially and envi-ronmentally. The present study quantifies the cumulative impacts of small dams on the water quality (physico-chemistry and invertebrate biotic indices) and quantity (discharge) of downstream rivers in 2 South African regions. The information from 2 South African national data-bases was used for evaluating the cumulative impacts on water quality and quantity. Physico-chemistry and biological data were obtained from the River Health Programme, and discharge data at stream flow gauges was obtained from the Hydrological Information System. Multivariate analyses were conducted to establish broad patterns for cumulative impacts of small dams across the 2 regions–Western Cape (winter rain-fall, temperate, south-western coast) and Mpumalanga (summer rain-fall, tropical, eastern coast). Multivariate analyses found that the chang-es in macroinvertebrate indices and the stream’s physico-chemistry were more strongly correlated with the density of small dams in the catchment (as a measure of cumulative impact potential) relative to the storage capacity of large dams. T-tests on the data, not including sam-ples with upstream large dams, indicated that the high density of small dams significantly reduced low flows and increased certain physico-chemistry variables (particularly total dissolved salts) in both the re-gions, along with associated significant reductions in a macroinverte-brate index (SASS4 average score per taxon). Regional differences were apparent in the results for discharge reductions and the macroin-vertebrate index. The results suggest that the cumulative effect of a high number of small dams is impacting the quality and quantity of wa-ters in South African rivers and that these impacts need to be systemat-ically incorporated into the monitoring protocol of the environmental wa-ter requirements.
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Ecological impacts of small dams on South African rivers Part 2: Biotic response – abundance and composition of macroinvertebrate communities
- Mantel, Sukhmani K, Muller, Nikite W J, Hughes, Denis A
- Authors: Mantel, Sukhmani K , Muller, Nikite W J , Hughes, Denis A
- Date: 2010
- Language: English
- Type: text , Article
- Identifier: vital:7095 , http://hdl.handle.net/10962/d1012437
- Description: This paper investigates the cumulative impacts of small dams on invertebrate communities in 2 regions of South Africa – the Western Cape and Mpumalanga. Previous research found reduced discharge, increased total dissolved salts, and a decrease in average score per taxon (ASPT; collected using SASS4 methods) at sites with high density of small dams in their catchment. These changes in ASPT are investigated using the invertebrate abundance data available in the River Health Programme. Multivariate analyses found differences in invertebrate communities in rivers with high densities of small dams in their catchment in foothill-gravel streams (in both Western Cape and Mpumalanga) and in foothill-cobble streams (in Western Cape only). Opportunistic taxa that are tolerant of pollution, and capable of exploiting various habitats, and those that prefer slower currents increased in numbers, while other taxa that are sensitive to pollution and disturbance declined in numbers. Some regional differences were noted possibly reflecting climatic differences between the regions. Since the results of this study are correlative, it highlights the need for a systematic (by sites and seasons) and detailed (at species level) collection of data to verify the results of cumulative effects of small dams. This can further the development of a framework for small-dam construction and management that will limit their impact on river catchments.
- Full Text:
- Authors: Mantel, Sukhmani K , Muller, Nikite W J , Hughes, Denis A
- Date: 2010
- Language: English
- Type: text , Article
- Identifier: vital:7095 , http://hdl.handle.net/10962/d1012437
- Description: This paper investigates the cumulative impacts of small dams on invertebrate communities in 2 regions of South Africa – the Western Cape and Mpumalanga. Previous research found reduced discharge, increased total dissolved salts, and a decrease in average score per taxon (ASPT; collected using SASS4 methods) at sites with high density of small dams in their catchment. These changes in ASPT are investigated using the invertebrate abundance data available in the River Health Programme. Multivariate analyses found differences in invertebrate communities in rivers with high densities of small dams in their catchment in foothill-gravel streams (in both Western Cape and Mpumalanga) and in foothill-cobble streams (in Western Cape only). Opportunistic taxa that are tolerant of pollution, and capable of exploiting various habitats, and those that prefer slower currents increased in numbers, while other taxa that are sensitive to pollution and disturbance declined in numbers. Some regional differences were noted possibly reflecting climatic differences between the regions. Since the results of this study are correlative, it highlights the need for a systematic (by sites and seasons) and detailed (at species level) collection of data to verify the results of cumulative effects of small dams. This can further the development of a framework for small-dam construction and management that will limit their impact on river catchments.
- Full Text:
Ecological impacts of small dams on South African rivers Part 2: Biotic response–abundance and composition of macroinvertebrate communities
- Mantel, Sukhmani K, Muller, Nikite W J, Hughes, Denis A
- Authors: Mantel, Sukhmani K , Muller, Nikite W J , Hughes, Denis A
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , report
- Identifier: http://hdl.handle.net/10962/438087 , vital:73434 , ISBN 1816-7950 , https://wrcwebsite.azurewebsites.net/wp-content/uploads/mdocs/2354.pdf
- Description: This paper investigates the cumulative impacts of small dams on inver-tebrate communities in 2 regions of South Africa–the Western Cape and Mpumalanga. Previous research found reduced discharge, in-creased total dissolved salts, and a decrease in average score per tax-on (ASPT; collected using SASS4 methods) at sites with high density of small dams in their catchment. These changes in ASPT are investigat-ed using the invertebrate abundance data available in the River Health Programme. Multivariate analyses found differences in invertebrate communities in rivers with high densities of small dams in their catch-ment in foothill-gravel streams (in both Western Cape and Mpuma-langa) and in foothill-cobble streams (in Western Cape only). Opportun-istic taxa that are tolerant of pollution, and capable of exploiting various habitats, and those that prefer slower currents increased in numbers, while other taxa that are sensitive to pollution and disturbance declined in numbers. Some regional differences were noted possibly reflecting climatic differences between the regions. Since the results of this study are correlative, it highlights the need for a systematic (by sites and sea-sons) and detailed (at species level) collection of data to verify the re-sults of cumulative effects of small dams. This can further the devel-opment of a framework for small-dam construction and management that will limit their impact on river catchments.
- Full Text:
- Authors: Mantel, Sukhmani K , Muller, Nikite W J , Hughes, Denis A
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , report
- Identifier: http://hdl.handle.net/10962/438087 , vital:73434 , ISBN 1816-7950 , https://wrcwebsite.azurewebsites.net/wp-content/uploads/mdocs/2354.pdf
- Description: This paper investigates the cumulative impacts of small dams on inver-tebrate communities in 2 regions of South Africa–the Western Cape and Mpumalanga. Previous research found reduced discharge, in-creased total dissolved salts, and a decrease in average score per tax-on (ASPT; collected using SASS4 methods) at sites with high density of small dams in their catchment. These changes in ASPT are investigat-ed using the invertebrate abundance data available in the River Health Programme. Multivariate analyses found differences in invertebrate communities in rivers with high densities of small dams in their catch-ment in foothill-gravel streams (in both Western Cape and Mpuma-langa) and in foothill-cobble streams (in Western Cape only). Opportun-istic taxa that are tolerant of pollution, and capable of exploiting various habitats, and those that prefer slower currents increased in numbers, while other taxa that are sensitive to pollution and disturbance declined in numbers. Some regional differences were noted possibly reflecting climatic differences between the regions. Since the results of this study are correlative, it highlights the need for a systematic (by sites and sea-sons) and detailed (at species level) collection of data to verify the re-sults of cumulative effects of small dams. This can further the devel-opment of a framework for small-dam construction and management that will limit their impact on river catchments.
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First steps in the development of a water temperature model framework for refining the ecological Reserve in South African rivers
- Rivers-Moore, Nick A, Hughes, Denis A, Mantel, Sukhmani K, Hill, Trevor R
- Authors: Rivers-Moore, Nick A , Hughes, Denis A , Mantel, Sukhmani K , Hill, Trevor R
- Date: 2008-10-05
- Language: English
- Type: text , Article
- Identifier: vital:7092 , http://hdl.handle.net/10962/d1012425
- Description: Ecological Reserve determination for rivers in South Africa presently does not include a water temperature component, in spite of its importance in determining species distribution patterns. To achieve this requires an understanding of how lotic thermographs from South African rivers differ from northern hemisphere rivers, to avoid mismanaging rivers based on incorrect regional assumptions. Hourly water temperatures from 20 sites in four river systems, representing a range of latitudes, altitudes and stream orders, were assessed using a range of metrics. These data were analysed using principal component analyses and multiple linear regressions to understand what variables a water temperature model for use in ecoregions within South Africa should include. While temperature data are generally lacking in low- and higher-order South African rivers, data suggest that South African rivers are warmer than northern hemisphere rivers. Water temperatures could be grouped into cool, warm and intermediate types. Based on temperature time series analyses, this paper argues that a suitable water-temperature model for use in ecological Reserve determinations should be dynamic, include flow and air temperature variables, and be adaptive through a heat exchange coefficient term. The inclusion of water temperature in the determination and management of river ecological Reserves would allow for more holistic application of the National Water Act's ecological management provisions. Water temperature guidelines added to the ecological Reserve could be integrated into heuristic aquatic monitoring programmes within priority areas identified in regional conservation plans.
- Full Text:
- Authors: Rivers-Moore, Nick A , Hughes, Denis A , Mantel, Sukhmani K , Hill, Trevor R
- Date: 2008-10-05
- Language: English
- Type: text , Article
- Identifier: vital:7092 , http://hdl.handle.net/10962/d1012425
- Description: Ecological Reserve determination for rivers in South Africa presently does not include a water temperature component, in spite of its importance in determining species distribution patterns. To achieve this requires an understanding of how lotic thermographs from South African rivers differ from northern hemisphere rivers, to avoid mismanaging rivers based on incorrect regional assumptions. Hourly water temperatures from 20 sites in four river systems, representing a range of latitudes, altitudes and stream orders, were assessed using a range of metrics. These data were analysed using principal component analyses and multiple linear regressions to understand what variables a water temperature model for use in ecoregions within South Africa should include. While temperature data are generally lacking in low- and higher-order South African rivers, data suggest that South African rivers are warmer than northern hemisphere rivers. Water temperatures could be grouped into cool, warm and intermediate types. Based on temperature time series analyses, this paper argues that a suitable water-temperature model for use in ecological Reserve determinations should be dynamic, include flow and air temperature variables, and be adaptive through a heat exchange coefficient term. The inclusion of water temperature in the determination and management of river ecological Reserves would allow for more holistic application of the National Water Act's ecological management provisions. Water temperature guidelines added to the ecological Reserve could be integrated into heuristic aquatic monitoring programmes within priority areas identified in regional conservation plans.
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Links between water temperatures, ecological responses and flow rates: a framework for establishing water temperature guidelines for the ecological reserve
- Rivers-Moore, Nick A, Hughes, Denis A, Mantel, Sukhmani K
- Authors: Rivers-Moore, Nick A , Hughes, Denis A , Mantel, Sukhmani K
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , report
- Identifier: http://hdl.handle.net/10962/438295 , vital:73449 , ISBN 978-1-77005-738-8 , https://wrcwebsite.azurewebsites.net/wp-content/uploads/mdocs/KV214-CONSERVATION.pdf
- Description: Global ecosystems face unprecedented crises in habitat fragmentation, destruction and ultimately extinction (Groves, 2003), and of all the vary-ing ecological systems rivers are the most neglected and endangered (Groves, 2003; Driver, et al., 2005; Roux et al., 2005). The greatest threat to these systems is the loss or degradation of natural habitat and processes (Driver et al., 2005), and water temperatures, after flow vol-umes, are a primary abiotic driver of species patterns within river sys-tems. Stuckenberg (1969) highlighted the links between temperature, topography and faunal assemblages, while Rivers-Moore et al.(2004) highlights the major impacts of water temperatures on organisms, and illustrate how water temperatures are one of the primary environmental drivers structuring fish communities in the Sabie River, arguably the most icthyologically species-rich river in South Africa.
- Full Text:
- Authors: Rivers-Moore, Nick A , Hughes, Denis A , Mantel, Sukhmani K
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , report
- Identifier: http://hdl.handle.net/10962/438295 , vital:73449 , ISBN 978-1-77005-738-8 , https://wrcwebsite.azurewebsites.net/wp-content/uploads/mdocs/KV214-CONSERVATION.pdf
- Description: Global ecosystems face unprecedented crises in habitat fragmentation, destruction and ultimately extinction (Groves, 2003), and of all the vary-ing ecological systems rivers are the most neglected and endangered (Groves, 2003; Driver, et al., 2005; Roux et al., 2005). The greatest threat to these systems is the loss or degradation of natural habitat and processes (Driver et al., 2005), and water temperatures, after flow vol-umes, are a primary abiotic driver of species patterns within river sys-tems. Stuckenberg (1969) highlighted the links between temperature, topography and faunal assemblages, while Rivers-Moore et al.(2004) highlights the major impacts of water temperatures on organisms, and illustrate how water temperatures are one of the primary environmental drivers structuring fish communities in the Sabie River, arguably the most icthyologically species-rich river in South Africa.
- Full Text:
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