Papers by Sukhmani Mantel
Abstract: Water law in South Africa subscribes to the Integrated Water Resources Management (IWRM... more Abstract: Water law in South Africa subscribes to the Integrated Water Resources Management (IWRM) paradigm by seeking to provide equitable access of water to all users including the ecosystem. The management of water resources to be in line with IWRM policies is seen to be a major challenge in South Africa due to increasing demands, problematic water quality impacts and concerns over future climate change and development impacts. Because of limited resources within water resources management, simple models may be more useful than complex models (Young et al. 1996). An existing yield model, the Water Resources Modelling Platform (WReMP) is well established within water resource management in South Africa, and this study outlines the development of a Water Quality Systems Assessment Model (WQSAM) that is specifically designed to interface with the water quantity inputs and outputs of WReMP. WQSAM has been designed to give useful predictions of water quality using the available observ...
IntechOpen eBooks, Dec 7, 2023
<jats:p>&lt;p&gt;Maps can be many things: colourful, or dull; complex, or very simp... more <jats:p>&lt;p&gt;Maps can be many things: colourful, or dull; complex, or very simple; helpful, or very difficult to read. They also have the potential to support the public's knowledge of environmental and social issues, and to lay out paths towards behavioural changes and conservation consciousness.&lt;/p&gt; &lt;p&gt;This potential is already being explored in some parts of the world. For example, the &lt;a href="https://greatlakesconnectivity.org/fishApp"&gt;FishWerks App&lt;/a&gt; uses maps to highlight the barriers to fish movement in the Great Lakes region of the United States. Based on the ongoing work with &lt;a href="https://theconversation.com/what-we-learned-when-our-map-of-southern-africas-rivers-went-viral-110735"&gt;a map of southern African rivers&lt;/a&gt; that went viral two years ago, the same potential exists to drive conservation awareness and action in the southern African region.&lt;/p&gt;</jats:p>
Digital Storytelling is a means of making research personal and accessible to communities. This v... more Digital Storytelling is a means of making research personal and accessible to communities. This video was created in a course offered by the Rhodes University Community Engagement Division in March 2021. This is an updated video which shows the links to SDGs and it builds on the South African Rivers map that went viral a couple of years ago and the feedback received on the map is described in The Conversation, May 20, 2021 https://theconversation.com/maps-can-bridge-gaps-between-citizens-scientists-and-policymakers-160374
Digital Storytelling is a means of making research personal and accessible to communities. This v... more Digital Storytelling is a means of making research personal and accessible to communities. This video was created in a course offered by the Rhodes University Community Engagement Division in March 2021. This is an updated video which shows the links to SDGs and it builds on the South African Rivers map that went viral a couple of years ago and the feedback received on the map is described in The Conversation, May 20, 2021 https://theconversation.com/maps-can-bridge-gaps-between-citizens-scientists-and-policymakers-160374
Wetlands, May 25, 2019
Limited knowledge of wetland geomorphic processes often results in poor wetland management. This ... more Limited knowledge of wetland geomorphic processes often results in poor wetland management. This study aims to illustrate the importance of incorporating geomorphic knowledge of wetland origin in their management. The geomorphic origin and dynamics of the Kafue wetland were determined from the analysis of remotely sensed and geological data. The wetland is a remnant of a paleo-lake that was captured by the tributary of the middle Zambezi River. At the point of capture, resistant Muva Group metavolcanic rocks dominate narrow valleys characterised by straight channels. The resistant lithology prevents the lower Kafue River to cut into the wetland thus maintaining wetland conditions upstream. Sedimentation regime through overbank and bed deposits shaped the wetland's structure, ecological diversity, and hydrological functioning. The operation of the Itezhitezhi dam has negatively impacted the wetland's hydrological and sedimentological regime. The dam starves the system of sediment needed for promoting levee and channel bed aggradation. Regulated discharge with reduced sediment load can lead to channel incision and therefore reduce flood frequency, which may ultimately lead to wetland desiccation. The study recommends the incorporation of geomorphic knowledge into wetland management since the understanding of wetlands from a geomorphic perspective can complement natural processes occurring within wetlands.
African Journal of Range & Forage Science, Nov 1, 2016
Australian Acacias have spread to many parts of the world. In South Africa, species such as A. me... more Australian Acacias have spread to many parts of the world. In South Africa, species such as A. mearnsii and A. dealbata are invasive. Consequently, more effort has focused on their clearing. In a context of increasing clearing costs, it is crucial to develop innovative ways of managing invasions. Our aim was to understand the biophysical properties of A. mearnsii in grasslands as they relate to grass production and to explore management implications. Aboveground biomass (AGB) of A. mearnsii was determined using a published allometric equation in invaded grasslands of the north Eastern Cape, South Africa. The relationships among the A. mearnsii leaf area index (LAI), Normalized Difference Vegetation Index (NDVI) and AGB were investigated. The influence of A. mearnsii LAI and terrain slope on grass cover was also investigated. Strong linear relationships between NDVI, LAI and AGB were developed. Acacia mearnsii canopy adversely impacted grass production more than terrain slope (p < 0.05) and when LAI approached 2.1, grass cover dropped to below 10% in infested areas. Reducing A. mearnsii canopy could promote grass production while encouraging carbon sequestration. Given the high AGB and clearing costs, it may be prudent to adopt the 'novel ecosystems' approach in managing infested landscapes.
Environmental Modelling and Software, Nov 1, 2017
Due to the degeneration of water quality globally, water quality models could increasingly be uti... more Due to the degeneration of water quality globally, water quality models could increasingly be utilised within water resource management. However, a lack of observed data as well as financial resources often constrain the number of potential water quality models that could practically be utilised. This study presents the Water Quality Systems Assessment Model (WQSAM). WQSAM directly utilises flow data generated by systems models to drive water quality simulations. The model subscribes to requisite simplicity by constraining the number of variables simulated as well as the processes represented to only those most important to water quality management, in this case, nutrients and salinity. The model application to the upper Olifants River catchment in South Africa is described. WQSAM was able to use the limited observed data to simulate representative frequency distributions of water quality, and the approach used within WQSAM was shown to be suitable for application to data scarce catchments.
Journal of Hydrology: Regional Studies, Dec 1, 2020
Africa from both a water supply and hydro-power generation perspective. Study focus: : Calibratio... more Africa from both a water supply and hydro-power generation perspective. Study focus: : Calibration of two hydrological models (Pitman and WEAP) that have been established for 76 sub-basins covering the total basin area of about 1 350 000 km 2. The longer-term purpose of establishing the models is to facilitate scenario analyses of future conditions related to changes in water use and management as well as climate change. New hydrological insights for the region: : While there are many (inevitable) uncertainties in the data used, as well as the models and calibrated parameter sets themselves, the results suggest that the models are generally fit for purpose in terms of evaluating future changes. There are, however, some parts of the basin where the reduction of identified uncertainties would lead to improved models and greater confidence in their future use. One of sources of uncertainty relates to the existence of several large wetland areas that have impacts on downstream flows, but are difficult to simulate due to the relatively poor existing understanding of the dynamics of water exchange between the river channels and the wetland storage areas.
Water law in South Africa subscribes to the Integrated Water Resources Management (IWRM) paradigm... more Water law in South Africa subscribes to the Integrated Water Resources Management (IWRM) paradigm by seeking to provide equitable access of water to all users including the ecosystem. The management of water resources to be in line with IWRM policies is seen to be a major challenge in South Africa due to increasing demands, problematic water quality impacts and concerns over future climate change and development impacts. Because of limited resources within water resources management, simple models may be more useful than complex models (Young et al. 1996). An existing yield model, the Water Resources Modelling Platform (WReMP) is well established within water resource management in South Africa, and this study outlines the development of a Water Quality Systems Assessment Model (WQSAM) that is specifically designed to interface with the water quantity inputs and outputs of WReMP. WQSAM has been designed to give useful predictions of water quality using the available observed data, and uses an approach that is oriented to risk management. WQSAM includes modules for simulating water quality variable inputs from diffuse source and point sources as well as the fate of water quality variables in-stream and within reservoirs. Future developments include the application of WQSAM to the Amatola system in the Eastern Cape, South Africa. WQSAM will include Thresholds of Potential Concern (TPCs), as well as a Decision Support System (DSS) specific to the Amatola system.
Water SA, Aug 2, 2017
WQSAM is a practical water quality model for use in guiding southern African water quality manage... more 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 estimating non-point source loads, this study describes a formal model to link the nutrient signatures of incremental flow to land cover. Study catchments 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 regressions 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 approach 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.
South African Geographical Journal, Jul 2, 2019
ABSTRACT Satellite imagery has been widely used to delineate, map and monitor different wetland t... more ABSTRACT Satellite imagery has been widely used to delineate, map and monitor different wetland types. However, the influence of clouds and spectral confusion between wetlands and other land cover types has a negative effect on classification accuracies across nearly all methods. Most wetlands are topographic lowlands surrounded by uplands, and this study explores the possibilities of delineating wetlands from Digital Elevation Models (DEMs) using the cut-and-fill method. The objectives were: (1) to examine the possible use of the cut-and-fill method, which is commonly used in construction, to delineate different types of large floodplain wetlands, and (2) to compare the accuracy of the cut-and-fill method with wetness indices commonly used for delineating wetlands from satellite images. Comparison between the cut-and-fill method, the Normalised Difference Water Index (NDWI) and the Modified Normalised Water Difference Index (MNDWI) showed that the cut-and-fill method was superior in terms of overall accuracy and kappa statistics while the NDWI was the poorest of the three methods. The study concluded that the cut-and-fill method can be useful in delineating wetland areas, especially for wetlands in confined valley settings and where cloud-free images are not available.
The water quality degradation of fresh water resources has become an increasingly urgent global p... more The water quality degradation of fresh water resources has become an increasingly urgent global problem which is predicted to be exacerbated by future development and climate change. Since water quality is to a large extent driven by water quantity, it is useful for a model to incorporate a rainfall-runoff component (natural hydrology), reservoir storage, return flows and abstractions (systems modelling), and a water quality component. One such model that meets these requirements is the Water Evaluation and Planning (WEAP) Model. During 2012, WEAP was applied to the Buffalo River within the Eastern Cape, South Africa, to investigate the effect on water availability of future development impacts, as well as potential climate change for the near future (2046-2065) under the A2 emission scenario. It was found that WEAP does not simulate water quality within reservoirs and water quality simulation facilities within WEAP are too simple. A new model was developed: the Water Quality Systems Assessment Model (WQSAM). WQSAM accepts water quantity data from a routinely used systems model, simulates water quality in a simplified manner, and also simulates water quality for reservoirs. WQSAM was applied to the Buffalo River to investigate climate change and development impacts on water quality, using the same Global Climate Model output and development data as were used within the WEAP study. The water quality results provided by the two models are compared, with the suitability of use of both WEAP and WQSAM to investigate future water quality discussed. WQSAM demonstrated the following advantages to water quality modelling compared to WEAP: 1) modelling of water quality in reservoirs; 2) consideration of water temperature effects on water quality; 3) consideration of transient events by modelling on a daily time step; 4) a more comprehensive and realistic conceptual model of water quality processes. Water quality modelling; WEAP; WQSAM; Buffalo River; South Africa Globally, the water quality of fresh water resources is deteriorating. In some countries, such as South Africa, water quality has deteriorated to such an extent within some regions that some water is no longer usable, for example, acid mine drainage within the northern parts of the country, and irrigation water within many parts of the country that has been shown to be contaminated with faecal bacteria to dangerous levels.
South African Geographical Journal, Feb 16, 2022
Journal of Water and Climate Change, Apr 25, 2016
Globally, water resources are being over-utilised; a situation exacerbated by degenerating water ... more Globally, water resources are being over-utilised; a situation exacerbated by degenerating water quality of rivers. To achieve sustainable management of water resources, uncertainty under climate change and development must be considered. A companion study was the first to incorporate uncertainty within water resources development scenario modelling for a catchment in South Africa using the Water Evaluation and Planning (WEAP) model. That study is extended in the current study by considering water quality in the form of nutrients and salinity. The WEAP model was calibrated against available observed data for the period 1999-2005. Using the calibrated WEAP model, driven by flow predicted using downscaled climate change models and projected future development, water quality was simulated for the years 2046-2065. Future simulations indicated marginally increased dilution capacity as well as increased nutrient inputs. It is evident that WEAP suffers major limitations in its water quality simulation capacity. Adaptive management along with continual monitoring as a strategy to cope with uncertainty associated with climate change and development is recommended. The shortcomings identified within WEAP in the current study were the motivation for the development of a new water quality decision support system specific to the requirements of water management in southern Africa.
Modeling Earth Systems and Environment, Feb 10, 2023
are exacerbated" (Lötter, 2017). Changes in the patterns of climate, e.g. precipitation and tempe... more are exacerbated" (Lötter, 2017). Changes in the patterns of climate, e.g. precipitation and temperature, can significantly and permanently impact catchment erosion and sedimentation processes (Li and Fang 2016), which may impact rural livelihoods and the formal and informal agricultural sectors. Although not prioritised as an acute environmental hazard, accelerated soil erosion has affected almost 2 billion hectares of fertile land (Arekhi et al. 2012), more than 50% of pasturelands and 80% of agricultural lands globally (Pimentel et al., 1995). Cultivation and degradation are both leading drivers of soil loss (Lötter, 2017), posing a risk to water resources (Blignaut et al. 2010). With food supply systems already under pressure from climate change and a growing population, ecosystem degradation adds to the looming long-term food security problem (Masipa 2017; Mugambiwa and Tirivangasi 2017; Pimentel and Burgess 2013). The problem of soil erosion is further compounded by the fact that much of the eroded soil is transported through river systems into reservoirs (Vanmaercke et al. 2014). Thus, sedimentation has significantly threatened reservoir lifespans
Water
The main objective of this study was to examine the implications of watershed management (WSM) on... more The main objective of this study was to examine the implications of watershed management (WSM) on hydrological parameters in the Aba Gerima watershed in the Upper Blue Nile Basin. The Hydrus 1D model simulations were conducted in control sites and sites under WSM to estimate various components of the hydrologic cycle, using different soil physical & hydrological data under each category of experimental sites. Results were calibrated with measured soil moisture data through inverse solutions. Thus, Hydrus 1D model was found to be effective in predicting results, with R2 values of 0.73 to 0.853 and RMSE values ranging from 0.015 to 0.04. The cumulative evaporation estimated for 365 days for control sites was 37.6% higher than that of sites under WSM. Surface and bottom fluxes in the sites under WSM were 4.6% and 12.5%, respectively, higher than the control sites. This could be attributed to the increased soil water availability resulting from the implemented WSM practices in Aba Gerim...
Water Research Commission, WRC Report No. 2018/1/14; ISBN 978-1-4312-0520-2, 2018
EXECUTIVE SUMMARY
This report has been generated by the Water Research Commission (WRC) funded... more EXECUTIVE SUMMARY
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). Introduction Reports by the Intergovernmental Panel on Climate Change have placed emphasis on freshwater resources, in particular their vulnerability, and the development of management and adaptation measures, in recognition that water resources are fundamental to basic human needs in addition to facilitating present and future planned development projects. Few projects have recognised that climate change adds an additional dimension of concern to the range of issues (such as development, mismanagement and pollution) that are already causing the deterioration of South African water resources. The climate in South Africa is naturally highly variable, and this, along with compromised governance, results in South Africa being very vulnerable. The WRC-funded project aimed to quantify changes associated with near future (2046-2065) climate change (using the Special Report on Emissions Scenarios (SRES) A2 emission scenario) and socio-economic development, with inclusion of the uncertainty linked to these changes, in order to develop a decision support system that incorporates these uncertainties. The aims for the project were:
1. To identify potential impacts and threats to sustainable water services delivery posed by climate change, as well as the uncertainties associated with these, with regards to changes in water quantity, water quality and socio-economic developments. This will be done through application of existing or newly developed estimation tools that can be used to convert downscaled Global Climate Models (GCM) output data to likely changes (including uncertainties) in the variables that impact directly on the operations of water boards (water quantity and quality). Part of the estimation process will include timescales of the expected changes.
2. Develop a methodology for assessing risks and vulnerabilities (including uncertainties in predictions) to climate change for Water Boards and their capacity to fulfil their mandate on water services delivery.
3. Develop a strategy and monitoring network for water audits in order to monitor indicators of change.
4. Derive Thresholds of Potential Concerns (TPCs) for water quality and quantity issues for Water Boards related to raw and potable water, discharges, pricing effects, etc. based on the outputs of the climate models.
5. Develop a decision-support framework for an adaptive management strategy to assess and modify water services delivery and development plans of the Water Boards in terms of infrastructure repair and developments, water conservation and demand management, water pricing changes and other associated issues.
Water law in South Africa subscribes to the Integrated Water Resources Management (IWRM) paradigm... more Water law in South Africa subscribes to the Integrated Water Resources Management (IWRM) paradigm by seeking to provide equitable access of water to all users including the ecosystem. The management of water resources to be in line with IWRM policies is seen to be a major challenge in South Africa due to increasing demands, problematic water quality impacts and concerns over future climate change and development impacts. Because of limited resources within water resources management, simple models may be more useful than complex models (Young et al. 1996). An existing yield model, the Water Resources Modelling Platform (WReMP) is well established within water resource management in South Africa, and this study outlines the development of a Water Quality Systems Assessment Model (WQSAM) that is specifically designed to interface with the water quantity inputs and outputs of WReMP. WQSAM has been designed to give useful predictions of water quality using the available observed data, a...
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Papers by Sukhmani Mantel
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). Introduction Reports by the Intergovernmental Panel on Climate Change have placed emphasis on freshwater resources, in particular their vulnerability, and the development of management and adaptation measures, in recognition that water resources are fundamental to basic human needs in addition to facilitating present and future planned development projects. Few projects have recognised that climate change adds an additional dimension of concern to the range of issues (such as development, mismanagement and pollution) that are already causing the deterioration of South African water resources. The climate in South Africa is naturally highly variable, and this, along with compromised governance, results in South Africa being very vulnerable. The WRC-funded project aimed to quantify changes associated with near future (2046-2065) climate change (using the Special Report on Emissions Scenarios (SRES) A2 emission scenario) and socio-economic development, with inclusion of the uncertainty linked to these changes, in order to develop a decision support system that incorporates these uncertainties. The aims for the project were:
1. To identify potential impacts and threats to sustainable water services delivery posed by climate change, as well as the uncertainties associated with these, with regards to changes in water quantity, water quality and socio-economic developments. This will be done through application of existing or newly developed estimation tools that can be used to convert downscaled Global Climate Models (GCM) output data to likely changes (including uncertainties) in the variables that impact directly on the operations of water boards (water quantity and quality). Part of the estimation process will include timescales of the expected changes.
2. Develop a methodology for assessing risks and vulnerabilities (including uncertainties in predictions) to climate change for Water Boards and their capacity to fulfil their mandate on water services delivery.
3. Develop a strategy and monitoring network for water audits in order to monitor indicators of change.
4. Derive Thresholds of Potential Concerns (TPCs) for water quality and quantity issues for Water Boards related to raw and potable water, discharges, pricing effects, etc. based on the outputs of the climate models.
5. Develop a decision-support framework for an adaptive management strategy to assess and modify water services delivery and development plans of the Water Boards in terms of infrastructure repair and developments, water conservation and demand management, water pricing changes and other associated issues.
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). Introduction Reports by the Intergovernmental Panel on Climate Change have placed emphasis on freshwater resources, in particular their vulnerability, and the development of management and adaptation measures, in recognition that water resources are fundamental to basic human needs in addition to facilitating present and future planned development projects. Few projects have recognised that climate change adds an additional dimension of concern to the range of issues (such as development, mismanagement and pollution) that are already causing the deterioration of South African water resources. The climate in South Africa is naturally highly variable, and this, along with compromised governance, results in South Africa being very vulnerable. The WRC-funded project aimed to quantify changes associated with near future (2046-2065) climate change (using the Special Report on Emissions Scenarios (SRES) A2 emission scenario) and socio-economic development, with inclusion of the uncertainty linked to these changes, in order to develop a decision support system that incorporates these uncertainties. The aims for the project were:
1. To identify potential impacts and threats to sustainable water services delivery posed by climate change, as well as the uncertainties associated with these, with regards to changes in water quantity, water quality and socio-economic developments. This will be done through application of existing or newly developed estimation tools that can be used to convert downscaled Global Climate Models (GCM) output data to likely changes (including uncertainties) in the variables that impact directly on the operations of water boards (water quantity and quality). Part of the estimation process will include timescales of the expected changes.
2. Develop a methodology for assessing risks and vulnerabilities (including uncertainties in predictions) to climate change for Water Boards and their capacity to fulfil their mandate on water services delivery.
3. Develop a strategy and monitoring network for water audits in order to monitor indicators of change.
4. Derive Thresholds of Potential Concerns (TPCs) for water quality and quantity issues for Water Boards related to raw and potable water, discharges, pricing effects, etc. based on the outputs of the climate models.
5. Develop a decision-support framework for an adaptive management strategy to assess and modify water services delivery and development plans of the Water Boards in terms of infrastructure repair and developments, water conservation and demand management, water pricing changes and other associated issues.