Siltation reduces dam storage – vital for water supply and the economy. Managing this is crucial. The Department of Water and Sanitation (DWS) assigned the Water
Research Commission (WRC) to develop a National Siltation Management Strategy (NatSilt). One of the key deliverables is capacity building. read more.
Earlier this year, experts gathered under the umbrella of the National Dam Siltation Management
programme to garner the latest developments in the quest to improve water storage capacity of
South Africa’s dams. Matthew Hattingh reports.
When we non-specialists think of silted-up dams (indeed, when
we think of them at all) we picture in our mind’s eye great
expanses of desiccated mud, cracked and fissured beneath a
baking sun. But scratch the surface, or rather dig down a metre,
and a more promising picture beckons: water. Certainly, that’s
what a recent pre-feasibility study found at the Eastern Cape’s
Nqweba Dam.
When Nqweba (Xhosa for “meeting place”) was first completed
in 1925, known then as the Van Ryneveld’s Pass Dam, it had a full
supply capacity of nearly 79 million cubic metres. Fast-forward
to 2011 and its capacity had shrunk by 43%. Built for irrigation,
today, it cannot meet the domestic and industrial needs of the
nearby Karoo town of Graaff-Reinet.
The problem is not so much an absence of water as a surfeit of
silt. Fine sand and clay – from natural erosion, exacerbated by
overgrazing – carried by the Sundays River and its tributaries are
choking Nqweba. A similar story can be told of many of the 320
state-owned dams managed by the Department of Water and
Sanitation. Although siltation rates vary dramatically, on average
South Africa’s dams are losing capacity at a rate of 0.4% a year
with consequences for water and food security, particularly
during drought.
What’s to be done?
The department has long supported surveys and studies to
better understand a problem that is far from unique to South
Africa: Worldwide dams are losing 0.8% of their capacity a year.
And it underwrites the National Dam Silt Management (NatSilt)
Read More
World Water Day was on 22 March 2022. As we commemorated it, we must continue to reflect on how we have progressed in supplying a basic need of water to all, and what can still be done.
There are strides being made on global access to clean and safe water and sanitation. However, the world is far from reaching its universal access goal by 2030. Sustainable Development Goal 6 aims to achieve equitable access to safe and affordable drinking water for all by 2030. According to Ourworldindata.org, in 2020 only 74% of the global population had access to a safely managed water source, and in 2020 sub-Saharan Africa had 765,780,662 people without access to safe drinking water – rural households often lag on water access. Inadequate access to water is because of poor infrastructure integrity, growing water demands, degraded ecosystems, and insufficient water in storage. This does not paint a pleasant picture, however, there are ways to ensure that this is improved.
South Africa is a water-scarce country and is heavily reliant on water stored in dams for its supply and provision. Siltation is an old problem; however, it has risen to prominence over the last couple of years due to the urgency of South Africa’s water issues. As of 2021, South Africa had 163 dams that were 25% silted, 25 dams with siltation levels between 25% and 50%, and two dams that were 90% silted. A good portion of the national dam’s face siltation because of natural processes and man-made decisions and activities.
This results in loss of storage capacity and reduced useable lifespan of dams. Siltation reaches the dams as it is transported through rivers. Catchment areas are degraded because of poor land-use activities and a lack of coordinated catchment management plans.
There is a need for a systematic and holistic approach to mitigate and manage the effects of dam siltation from its catchment area, which addresses the engineering, ecological, and social aspects. Siltation has been occurring for decades; its effects have been more visible in recent years as we plan to adapt to water and land issues related to population expansion and migration, economic growth, and climate change and weather variability. We cannot build more dams to solve the storage capacity loss, as there are not enough localities for large dams. The country needs a sustainable solution that looks at all sources of water and how we store it.
South Africa does not have a specific policy or legislation that deals with preventing or managing siltation in dams, and it is imperative that this gap be addressed to assist with a systematic approach to siltation management. Institutional fragmentation is currently making it difficult for dam siltation management to be holistically implemented as different institutions have different mandates and priorities. There needs to be a logical approach to preventing, mitigating, and removing siltation build-up in dams. We need to be cognisant that dams are linked to a broader ecosystem in the catchment in which they occur. By treating the dam, catchment activities, and river as one system, this integrated approach to siltation management will ensure healthier catchments and preservation of storage capacity and at the same time create opportunities for jobs and economic development.
Dam engineering has a pivotal role to play in safeguarding water security, however, the design and construction of dams need to consider the impacts they have on the broader ecological systems. Uncoordinated development has resulted in dam siltation not being managed adequately. Ecosystems have been degraded through poor land use and planning. For dam siltation management to be successful, the efforts need to address the state of the existing dams, how they should be operated, and the management of activities within their respective catchments. While addressing the dam engineering components of dam siltation management, it is equally important to address the socio-ecological aspects of it. Poor land-use practices that lead to erosion need to be addressed and revegetation of catchment areas needs to be at the core of the various interventions.
Along with developing a strategy, tools, and models to mitigate against siltation, professionals, students, and civil society need to be capacitated on siltation management through skills development, upskilling, transfer of knowledge, and dissemination of case studies. If we want to develop a new cohort of siltation management professionals, South Africa should start at institutions of learning by offering introductory courses on integrated siltation management to ensure we grow the pool of experts in the field.
Communities in the areas where dams are located need to be capacitated on how they can play a role in preventing land degradation and siltation. We are all affected by the impacts of siltation; raising awareness of the causes, effects, and management of siltation needs to be elevated to move all of our roles into a water stewardship one. Decision-makers need to be empowered with knowledge that will enable them to effect change.
With there not being a specific policy and legislation on siltation management in the country, and a lack of a holistic and pragmatic approach to siltation management, the Water Research Commission has been tasked by the Department of Water and Sanitation to develop a national strategy on dam siltation management. A large focus will be on collaboration between institutions that include civil society, public institutions, and the research and development sector.
This is also a clarion call for all of us to ensure that future generations have adequate water infrastructure, access to clean, safe water, and to protect our water source areas.
South Africa is a semi-arid country which means that the national water infrastructure must be designed to promote and ensure that there is long-term water security. There are multiple threats to water security in South Africa, one of the biggest being the loss of dam storage capacity because of siltation associated with natural processes as well as poor land use planning. According to Dr Shafick Adams, Executive Manager of the Water Resource and Ecosystems impact area at the Water Research Commission, South Africa needs to explore all available water supply options as well as implement water conservation and demand management measures to enable it to adapt to climate change and weather variability, urban and population growth, and ensure equitable access.
Dam siltation is a process where disturbed sediments are transported into the reservoirs where they settle and result in a loss of dam storage capacity. A 2016 study estimated that South African national dam storage capacity loss was 10% due to siltation. This reduction threatens water security which threatens food security, ecosystems, and economic progress in the country.
Dam siltation is a process where disturbed sediments are transported into the reservoirs where they settle and result in a loss of dam storage capacity. A 2016 study estimated that South African national dam storage capacity loss was 10% due to siltation. This reduction threatens water security which threatens food security, ecosystems, and economic progress in the country.
One of the efforts aimed at ensuring that this threat is addressed, is the National Siltation Management Strategy for Large Dams in South Africa Programme (NatSilt Programme) implemented by the Water Research Commission and funded by the Department of Water and Sanitation (DWS). The Programme aims to develop an overall siltation management strategy as well as a myriad of solutions for siltation management and opportunities to beneficiate removed sediment. The programme has a suite of four sub projects focusing on different aspects of dam siltation management interventions and the outcomes of each will be incorporated in the overall strategy.
The programme will equip the DWS with a decision-making mechanism which will inform the department which dams will be classified as exhaustive storage (where siltation rates are too high; silt-prevention operations will be ineffective and dredging not cost effective) or which will be classified as sustainable storage. It is expected that the latter classification which will allow for either of the dam basin management operations model or dredging business model to be implemented.
For dam siltation management to be successful, the efforts need to address the state of the existing dams, how they should be operated and the activities within their respective catchments. While addressing the dam engineering components of dam siltation management, it is equally important to address the socio-ecological systems aspects of it. One of the components of dam siltation that have been highlighted by the programme implemented by the Water Research Commission is the development of a dam classification framework and dam operations model. The dam classification framework aims to classify dams from exhausted to sustainable and subsequently inform the development of the dam operations model. The dam operations model will recommend strategies that will be suitable for operating specific dams.
Dam engineering has an important role to play in safeguarding water security. However, the design and construction of these dams needs to consider the impact of the dams on society and the ecological systems.
The way in which this has been done in South Africa has resulted in dam siltation not being managed adequately. This can be attributed to the inconsistent monitoring efforts and the lack of holistic approaches when dams are being designed and constructed. This negatively affects the lifespan of the dams. In dam engineering, one of the major focuses should be to ensure that the recommended dam siltation mitigation measures do not cause additional adverse effects on the dams. When dealing with the dam classification and operations model, it is vital to assess the structural integrity of the dams that are being categorised. This is to assess whether the dams can withstand the additional loads exerted on them by the accumulated silts. This must consider the types of dams and the materials used to construct them. This is important as it may be found that the operations model will have to consider the vulnerability of the dam walls when the recommended siltation mitigation measures are implemented and whether dam wall reinforcements will be required.
For any project to successfully meet its objectives, it is important to identify the institutions and stakeholders that will be affected by and affect the project based on their legislative mandates. For dam siltation, this can affect how the implementation of the management strategies will be funded. It is also important to identify and engage private and non-governmental stakeholders that will be affected by and affect the dam siltation management strategy developed as the existence of these dams affect them as well. This is dependent on engaging the correct stakeholders so that their identified roles are incorporated into the dam classification framework and operations model while ensuring that the technical requirements of dam engineering are satisfied.
This could enable the siltation management team to identify, in addition to the DWS, which institutions will be keen to fund not only the future research, but the implementation of the tools developed and ease the financial pressure on taxpayers. To ensure sustainability and success of the dam operations model, workshops must prioritise buy-in from surrounding communities as this will affect their level of commitment to participating in the programmes developed. When people have a sense of ownership of the infrastructure in their communities, they tend to participate in ensuring the longevity of that infrastructure.
The success of the NatSilt Programme will hinge on addressing the institutional fragmentation that is currently making it difficult for dam siltation management to be holistically implemented. This involves the availability of relevant real-time data and information that if not managed efficiently, could prove to be a challenge in the development of a dam classification framework, operations model, and the institutional and financial frameworks.
Dam siltation management in South Africa can be successfully implemented if the relevant stakeholders are engaged and there is a collective commitment to address it. These range from the public institutions, private sector and civil society. The integration of responsibilities and interests can ensure a collective interest and commitment to the longevity of dams and knowledge dissemination amongst the stakeholders. If this can be done, the dam classification framework and operations model can guarantee future designs and management of dams will holistically account for more than just the dam structures, but also the socio-ecological systems as well as stewardship and opportunities for job creation and economic growth.
According to Water Research Commission Senior Project Manager Lesego Gaegane, this can be achieved through multi- and transdisciplinary approaches that will be developed by the NatSilt Programme. Capacity development is a core activity of the programme, accredited skills programmes are being developed to support a new cohort of professionals and transfer skills through the programme and its implementation. It is essential that the programme builds technical and institutional capacity to ensure there are skills within the sector to ensure efficient siltation management and implementation of the interventions. For more information.
As a water-scarce country with an extremely variable rainfall, both in space and in time, South Africa is highly dependent on the storage of water in large dams for its water supply. Nationally, the total storage capacity of the major reservoirs in the country amounts to an estimated 33 900 million cubic metres, or about 70% of the mean annual runoff from the land surface of the country. Most of South Africa’s dam infrastructure was constructed before 1980, and thus many of these engineering structures are decades old. In addition, seven of South Africa’s nine provinces rely on inter-basin transfers — where water is transferred from one catchment to another through sophisticated water infrastructure — which provide more than half of their water requirements.
However, these large dams experience various threats to their sustainability, not least of which is siltation. South African rivers, in general, carry large loads of suspended silt, both as a result of natural processes and as a result of human-induced activities such as deforestation, industry activities, improper farming techniques and overgrazing. Silt ends up in the country’s dams, where it reduces the storage capacity. The problem is exacerbated by an increase in high-intensity rainfall events coupled with longer periods of aridity as a result of climate change.
All of South Africa’s dams are affected by siltation to a greater or lesser degree. The most well-known example is the Welbedacht Dam on the Caledon River in the Free State Province. The dam was originally constructed in 1973 with the purpose of supplying water to the city of Bloemfontein. By 1988, just 15 years after construction, the dam had already lost 73% of its original storage capacity. Another example is Hazelmere Dam, located on the Mdloti River in KwaZulu-Natal. This dam, completed in 1975, has lost more than 25% of its original design capacity through siltation.
It is estimated that South Africa is losing about 1% of storage capacity in its dams to siltation every year. The limits to the development of surface water sources have almost been reached and the opportunities for the spatial economic placement of new dams are few. Dam construction is costly, and it is not cost-effective to replace the lost capacity in existing water infrastructure by building more bulk water infrastructure. It is therefore imperative that the country manages its existing bulk water infrastructure as effectively as possible, and extends the storage life of its existing large dams. There are several options for preventing and managing siltation in South Africa’s dams. Siltation management should not be a blanket approach, and should be site specific.
There is thus a requirement for a toolbox of solutions to address the siltation challenge in South Africa. To this end, the Department of Water and Sanitation (DWS) appointed the Water Research Commission (WRC) to develop the National Siltation Management Strategy for Large Dams in South Africa, more commonly known as the NatSilt Programme. The programme represents a collaborative, transdisciplinary approach to tackle the wide spectrum of dam siltation and storage capacity challenges in South Africa.
Leonardo Manus, Acting Deputy Director-General of Regulations, Compliance, and Enforcement at the DWS, said: “We have established our whole economy and livelihoods around these majestic dam structures, but we can so easily lose them if we don’t apply proper management procedures to keep them in that state.
“The NatSilt Programme will provide the department with tools and intelligence to make appropriate, site-specific decisions regarding each dam instead of having a blanket approach,” he added. “Where sedimentation occurs to such an extent that it has to be dealt with, we will create a business model that will not be to the detriment of those who are dependent on the dam. To minimise costs to the downstream users in that specific catchment, we need to find alternatives to expensive methodologies and dredging models deployed to keep any dam operating.”
The NatSilt Programme thus aims to ensure that bulk water resource infrastructure is managed in an efficient, effective and sustainable manner to ensure economic growth, social development and poverty eradication. The programme will provide a package of siltation management solutions as well as an overall strategy. “With this programme we hope to address some of the water challenges the country is facing, but also to establish a collaborative approach to dealing with matters affecting the water sector, rather than organisations and institutions working in silos,” explained WRC Senior Project Manager Lesego Gaegane.
“Siltation of dams is a worldwide problem, which results in the loss of storage capacity and so exacerbates water insecurity. Effective siltation prevention and management will save scarce fiscal resources by extending the life cycle of our existing dams.”
The programme is being undertaken in three phases, the first of which is already underway. The main objective of phase one is the development of the Siltation Management Strategy to prevent and manage the siltation of dams as well as stimulate local economies and recover costs. The strategy will be supported by:
The development of the National Siltation Management Strategy will be designed to enable the project teams to cross-pollinate and share information with each other, as their work is interlinked.
The strategy development process will provide a situational analysis, engage a broad range of stakeholders, map the drivers and challenges linked to potential solutions , and provide an up-to-date state of dam siltation management in South Africa. Further primary data collection will be required to complement that of the DWS databases and modelled to identify siltation prone areas, siltation rates, and load and quality characteristics, among others. This will result in a framework for dam storage design and management. International partners will be included and global practises will be benchmarked to review current management practices
Phase one will also see the investigation of current models utilised to manage siltation in South Africa. The objective is to generate and test tools that will enable the alleviation of dam siltation through optimised catchment management as well as dam engineering methodologies and innovations. An Operations Model will be proposed to optimise and enhance dam management plans, processes, procedures, regulation and compliance. A toolbox will be developed alongside this that will delve into critical decision areas, system indicators and management boundaries in relation to efficient and effective siltation management.
As part of a risk monitoring framework, real-time monitoring indicators and responses will be proposed, including costs to operationalise. For new dams, design considerations will be developed to ensure siltation is minimised as well as considerations of the cost-benefit of dam basin management versus siltation of the dam.
As things stand there has been a development of the framework and operations model which will be implemented as the projected continues. This will not be applied in isolation as the implementation of the developed framework and model will take into consideration the operations and safety manuals of the specific dams. the This will be evident in the pilot phase of the programme. Socio- Ecological aspect affecting dams and catchment areas will also be addressed in implementing the Programme.
Dredging can be a technique to deal with sediment in dams, although it is seen by many as an expensive solution that is highly site specific. There are a number of advantages and disadvantages when it comes to dredging. These factors, together with frequency, cost/benefit and environmental risk will be investigated towards the development of a dredging model that will guide such activities in South Africa. Priority sites will be identified through a consultative process to capture areas requiring intervention. The considerations for the sources for the information that will be used to ensure the sustainability of the dams through the developed model will be vital for the effective implementation of this programme. To effectively implement these interventions, the types of required personnel will need to be identified and the quantity. This has been one of the considerations that have been focused on through the development of the Dredging models.
It has been recognised that all the dam siltation management tools and strategies will not be implementable without a parallel capacity building component to support new skills development and skills transfer through the project and its design. The programme is developing training material, modules and four skills programme’s in the first phase to support a successful and value-adding phase two. The skills programmes that are being developed are occupation based. The aim of the Skills programmes are to offer a building block to full qualifications. The four Skills programmes will be registered as National Skills Programmes with the Quality Council for Trades and Occupation (QCTO).
Phase two
Phase two is expected to start during the second year of the NatSilt Programme later during this year, which will run in parallel with the close out of phase one. Phase two will entail the piloting of the decision-making tools, operations models, dredging models and protocols, capacity building and monitoring and evaluation indicators.
Three sites have been identified where these tools and models will be piloted. They are:
Phase three
Phase three is the culmination of the programme. This phase will involve taking the learnings from Phase 1 and 2 and revising the strategy, adapting and improving the models and tools based on stakeholder engagement and pilots.
The NatSilt Programme will be concluded at the end of 2023.
The need for immediate water security interventions linked to economic competitiveness was discussed during the recent National Dam Siltation Symposium (NatSilt Symposium) on Protecting Our Source Water Systems, a virtual event held over two days in May 2021.
Importantly, the symposium also saw the launch of the National Dam Siltation Management Programme.
Other key outcomes of the symposium included the role municipalities play in the maintenance of the catchment areas and how crucial it is that there is co-operation between the various government departments in ensuring success of the programme.
Due to increasing silt loads in a number of local dams, the pilot projects under the WRC and DWS Siltation Management Strategy for Large State Dams will help to guide wider national initiatives.
The National Dam Siltation Management Programme is essential in aiding the decision- making for which strategies to employ for current and future dams, and is “absolutely critical to the country’s water security” as emphasised by the WRC chief executive officer, Dhesigen Naidoo during the NatSilt Symposium. Department of Water & Sanitation ministerial advisor Jurgen Kogl pointed out at the recent NatSilt virtual symposium that dealing with siltation was sometimes viewed as a grudge purchase, in a similar way to how consumers often viewed buying life insurance.
However, because of the massive cost of building new dams, the problem of siltation has to be tackled swiftly and “head on”, in order to extend the lifespan and capacity of existing infrastructure to be able to supply water for South Africa’s fast developing and growing population.
For more information, visit: https://wrcnatsilt.org.za
Water storage and hydroelectric dams across the world are running out of water as they become increasingly gummed-up with sand and silt. The Water Research Commission (WRC)
has been appointed to develop a new siltation management strategy for South Africa’s large dams, writes Tony Carnie.
More than 60% of the world’s original dam water storage is
likely to be lost within just three decades due to the growing
accumulation of mud, sand and fine silt pouring into dams
across the globe. That was the warning sounded by top
hydrologists during the recent National Siltation (NatSilt)
Symposium hosted by the WRC.
“We currently lose more storage than we build, and climate
change will reduce water yields further due to increased
sediment loads,” said World Bank independent consultant, Dr
Nikolaos Efthymiou, pointing to the threat of more severe storms
and hotter temperatures that are expected to accelerate the
erosion of soils in many parts of the world.
Efthymiou said the heyday of dam building was between 1960
and 1990, with most dams being built in the 1970s. This meant
that the majority of the world’s dams were about 50 years old,
and the building of new dams had slowed significantly because
of economic factors and a shortage of suitable locations.
Though siltation rates vary widely according to local conditions
and land care, dams silt up at the rate of about 0.8% per year at a
Read more…
South Africa is a semi-arid country which means that the national water infrastructure must be designed to promote and ensure that there is long-term water security. There are multiple threats to water security in South Africa, one of the biggest being the loss of dam storage capacity because of siltation associated with natural processes as well as poor land use planning. According to Dr Shafick Adams, Executive Manager of the Water Resource and Ecosystems impact area at the Water Research Commission, South Africa needs to explore all available water supply options as well as implement water conservation and demand management measures to enable it to adapt to climate change and weather variability, urban and population growth, and ensure equitable access.
Dam siltation is a process where disturbed sediments are transported into the reservoirs where they settle and result in a loss of dam storage capacity. A 2016 study estimated that South African national dam storage capacity loss was 10% due to siltation. This reduction threatens water security which threatens food security, ecosystems, and economic progress in the country.
One of the efforts aimed at ensuring that this threat is addressed, is the National Siltation Management Strategy for Large Dams in South Africa Programme (NatSilt Programme) implemented by the Water Research Commission and funded by the Department of Water and Sanitation (DWS). The Programme aims to develop an overall siltation management strategy as well as a myriad of solutions for siltation management and opportunities to beneficiate removed sediment. The programme has a suite of four sub projects focusing on different aspects of dam siltation management interventions and the outcomes of each will be incorporated in the overall strategy.
The programme will equip the DWS with a decision-making mechanism which will inform the department which dams will be classified as exhaustive storage (where siltation rates are too high; silt-prevention operations will be ineffective and dredging not cost effective) or which will be classified as sustainable storage. It is expected that the latter classification which will allow for either of the dam basin management operations model or dredging business model to be implemented.
For dam siltation management to be successful, the efforts need to address the state of the existing dams, how they should be operated and the activities within their respective catchments. While addressing the dam engineering components of dam siltation management, it is equally important to address the socio-ecological systems aspects of it. One of the components of dam siltation that have been highlighted by the programme implemented by the Water Research Commission is the development of a dam classification framework and dam operations model. The dam classification framework aims to classify dams from exhausted to sustainable and subsequently inform the development of the dam operations model. The dam operations model will recommend strategies that will be suitable for operating specific dams.
Dam engineering has an important role to play in safeguarding water security. However, the design and construction of these dams needs to consider the impact of the dams on society and the ecological systems.
The way in which this has been done in South Africa has resulted in dam siltation not being managed adequately. This can be attributed to the inconsistent monitoring efforts and the lack of holistic approaches when dams are being designed and constructed. This negatively affects the lifespan of the dams. In dam engineering, one of the major focuses should be to ensure that the recommended dam siltation mitigation measures do not cause additional adverse effects on the dams. When dealing with the dam classification and operations model, it is vital to assess the structural integrity of the dams that are being categorised. This is to assess whether the dams can withstand the additional loads exerted on them by the accumulated silts. This must consider the types of dams and the materials used to construct them. This is important as it may be found that the operations model will have to consider the vulnerability of the dam walls when the recommended siltation mitigation measures are implemented and whether dam wall reinforcements will be required.
For any project to successfully meet its objectives, it is important to identify the institutions and stakeholders that will be affected by and affect the project based on their legislative mandates. For dam siltation, this can affect how the implementation of the management strategies will be funded. It is also important to identify and engage private and non-governmental stakeholders that will be affected by and affect the dam siltation management strategy developed as the existence of these dams affect them as well. This is dependent on engaging the correct stakeholders so that their identified roles are incorporated into the dam classification framework and operations model while ensuring that the technical requirements of dam engineering are satisfied.
This could enable the siltation management team to identify, in addition to the DWS, which institutions will be keen to fund not only the future research, but the implementation of the tools developed and ease the financial pressure on taxpayers. To ensure sustainability and success of the dam operations model, workshops must prioritise buy-in from surrounding communities as this will affect their level of commitment to participating in the programmes developed. When people have a sense of ownership of the infrastructure in their communities, they tend to participate in ensuring the longevity of that infrastructure.
The success of the NatSilt Programme will hinge on addressing the institutional fragmentation that is currently making it difficult for dam siltation management to be holistically implemented. This involves the availability of relevant real-time data and information that if not managed efficiently, could prove to be a challenge in the development of a dam classification framework, operations model, and the institutional and financial frameworks.
Dam siltation management in South Africa can be successfully implemented if the relevant stakeholders are engaged and there is a collective commitment to address it. These range from the public institutions, private sector and civil society. The integration of responsibilities and interests can ensure a collective interest and commitment to the longevity of dams and knowledge dissemination amongst the stakeholders. If this can be done, the dam classification framework and operations model can guarantee future designs and management of dams will holistically account for more than just the dam structures, but also the socio-ecological systems as well as stewardship and opportunities for job creation and economic growth.
According to Water Research Commission Senior Project Manager Lesego Gaegane, this can be achieved through multi- and transdisciplinary approaches that will be developed by the NatSilt Programme. Capacity development is a core activity of the programme, accredited skills programmes are being developed to support a new cohort of professionals and transfer skills through the programme and its implementation. It is essential that the programme builds technical and institutional capacity to ensure there are skills within the sector to ensure efficient siltation management and implementation of the interventions. For more information,
visit: https://wrcnatsilt.org.za/
The Water Research Commission (WRC) is embarking on an ambitious programme to ensure the effective siltation management and improved storage capacity of 320 State-owned, Department of Water and Sanitation– (DWS-) managed large dams.
The three-year National Dam Siltation Management Strategy in South Africa, or NatSilt, project, was launched during a two-day virtual WRC NatSilt Symposium from May 19 to 20, after the WRC was appointed by the DWS to manage and implement the project.
Funded by the DWS, the programme’s overarching aim is to develop and pilot a strategy that will guide, advise and ensure effective siltation management and related improved storage capacity for dams.
The programme sets out to address reservoir storage losses experienced owing to dam siltation, the accumulation of sediments and silt in dams as a result of soil erosion.
In the last year, some of the country’s dams have experienced up to 90% sedimentation with storage capacity losses ranging between 10% and 30%.
The WRC will be developing a package of siltation management solutions, including the relevant tools, models, frameworks, protocols, guides and plans to assist with the implementation and monitoring of the strategy.
This will assist the DWS in sustaining supply to domestic, industrial, strategic and agricultural bulk water users, as well as save scarce financial resources by extending the lifecycle of existing dams.
The programme will result in the development of a dam basin siltation management operations model, a sustainable dredging business model, a dam basin classification decision-making tool, capacity building, a step-by-step comprehensive implementation plan and the piloting of the draft strategy, models and tools.
Phase 1 comprises research, assessments and the development of a siltation management strategy and related tools for large dams, while the piloting of various models, concepts and the tools will be undertaken in Phase 2.
A review and revision towards a final strategy, with relevant models and tools, will be completed in the final third phase.
The pilot plan will potentially be rolled out in three government water schemes, namely Welbedacht dam in the Free State; Hazelmere dam in KwaZulu-Natal and Darlington Dam/Orange-Fish GWS in the Eastern Cape.
The programme has four sub-projects that will be integrated and managed as one programme to meet the desired objectives.
The strategy development sub-project comprises a situational analysis, the engagement of a broad range of stakeholders, mapping of the drivers and challenges linked to potential solutions and the provision of an up-to-date state of dam siltation management in South Africa.
The development of the relevant tools, models, frameworks, protocols, guides and plans will assist with the implementation and monitoring of the strategy.
Under a sub-project called ‘dam engineering and socioecological systems’, the team will generate and test tools that will enable the alleviation of dam siltation through optimised catchment management as well as dam engineering methodologies and innovations.
The ‘sustainable dredging of dams’ sub-project recognises the importance of dredging and will work to develop sustainable, cost-effective dam dredging model and protocols for a variety of “learning” dams and contexts.
Priority sites will be identified through a consultative process to capture areas requiring intervention and that are representative of a larger set of dams.
The programme will also have a training and capacity development component to develop a new cohort of skilled professionals and citizens to enhance and improve the efficiency of dam siltation management
The three-year National Dam Siltation Management Strategy in South Africa, or NatSilt, project, was launched during a two-day virtual WRC NatSilt Symposium from May 19 to 20, after the WRC was appointed by the DWS to manage and implement the project.
Funded by the DWS, the programme’s overarching aim is to develop and pilot a strategy that will guide, advise and ensure effective siltation management and related improved storage capacity for dams.
The programme sets out to address reservoir storage losses experienced owing to dam siltation, the accumulation of sediments and silt in dams as a result of soil erosion.
In the last year, some of the country’s dams have experienced up to 90% sedimentation with storage capacity losses ranging between 10% and 30%.
The WRC will be developing a package of siltation management solutions, including the relevant tools, models, frameworks, protocols, guides and plans to assist with the implementation and monitoring of the strategy.
This will assist the DWS in sustaining supply to domestic, industrial, strategic and agricultural bulk water users, as well as save scarce financial resources by extending the lifecycle of existing dams.
The programme will result in the development of a dam basin siltation management operations model, a sustainable dredging business model, a dam basin classification decision-making tool, capacity building, a step-by-step comprehensive implementation plan and the piloting of the draft strategy, models and tools.
Phase 1 comprises research, assessments and the development of a siltation management strategy and related tools for large dams, while the piloting of various models, concepts and the tools will be undertaken in Phase 2.
A review and revision towards a final strategy, with relevant models and tools, will be completed in the final third phase.
The pilot plan will potentially be rolled out in three government water schemes, namely Welbedacht dam in the Free State; Hazelmere dam in KwaZulu-Natal and Darlington Dam/Orange-Fish GWS in the Eastern Cape.
The programme has four sub-projects that will be integrated and managed as one programme to meet the desired objectives.
The strategy development sub-project comprises a situational analysis, the engagement of a broad range of stakeholders, mapping of the drivers and challenges linked to potential solutions and the provision of an up-to-date state of dam siltation management in South Africa.
The development of the relevant tools, models, frameworks, protocols, guides and plans will assist with the implementation and monitoring of the strategy.
Under a sub-project called ‘dam engineering and socioecological systems’, the team will generate and test tools that will enable the alleviation of dam siltation through optimised catchment management as well as dam engineering methodologies and innovations.
The ‘sustainable dredging of dams’ sub-project recognises the importance of dredging and will work to develop sustainable, cost-effective dam dredging model and protocols for a variety of “learning” dams and contexts.
Priority sites will be identified through a consultative process to capture areas requiring intervention and that are representative of a larger set of dams.
The programme will also have a training and capacity development component to develop a new cohort of skilled professionals and citizens to enhance and improve the efficiency of dam siltation management