Scielo RSS <![CDATA[Water SA]]> http://www.scielo.org.za/rss.php?pid=1816-795020120003&lang=pt vol. 38 num. 3 lang. pt <![CDATA[SciELO Logo]]> http://www.scielo.org.za/img/en/fbpelogp.gif http://www.scielo.org.za <![CDATA[<b>Groundwater</b>: <b>our source of security in an uncertain future</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1816-79502012000300001&lng=pt&nrm=iso&tlng=pt <![CDATA[<b>Managed groundwater development for water-supply security in Sub-Saharan Africa</b>: <b>investment priorities</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1816-79502012000300002&lng=pt&nrm=iso&tlng=pt In numerous countries of Sub-Saharan Africa the strategic agenda of the water-sector is undergoing substantial change because of demographic pressure, climate change and economic transformation. Two new policy questions are arising from the need to make better use of available groundwater storage to improve water-supply security: <![CDATA[<b>Sand, salt and water in the Stampriet Basin, Namibia</b>: <b>calculating unsaturated zone (Kalahari dunefield) recharge using the chloride mass balance approach</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1816-79502012000300003&lng=pt&nrm=iso&tlng=pt Estimating groundwater recharge rates in the Stampriet Basin is important for assessing the sustainability of the groundwater resource both within south-east Namibia, and across the borders of this transboundary resource into Botswana and South Africa. The 65 000 km² basin contains a multi-layered aquifer system, of up to 9 superimposed aquifers, with a major upper unconfined and 2 major artesian levels. The majority of water abstraction (66%) is from the unconfined Kalahari Aquifer. This research investigates the direct recharge pathway through the dune-sand cover of the southern Kalahari dunefield which overlies ~80% of the basin. This is undertaken using established chloride mass balance methods within 4 unsaturated zone profiles (9 m to 11.5 m depth) from 2 regions of the basin. The results indicate that recent recharge rates are between 7 mmy-1 to 46 mmy-1, with profiles representing between 10 years and 30 years of rainfall infiltration. This is the first time that substantial direct (diffuse) recharge has been quantified for the Stampriet Basin, and this part of the southern Kalahari. These 4 profiles indicate potentially similar levels of spatial variability as seen in many other semi-arid, sand-rich unsaturated zones across the world. Further studies using the unsaturated zone should be employed in this region, to better inform our understanding of recharge mechanisms across the basin. The chloride mass balance technique provides information about the unsaturated zone, and important insights about recharge in various sand-covered regions of the basin for which very little is known, or is possible to determine using conventional water balance approaches. Direct recharge rates estimated in this way constitute a vital part of constraining the water balance of the basin, and particularly of the Kalahari Aquifer from which the majority of groundwater abstraction occurs. <![CDATA[<b>Evaluation of factors influencing transmissivity in fractured hard-rock aquifers of the Limpopo Province</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1816-79502012000300004&lng=pt&nrm=iso&tlng=pt Geologically-complex fractured aquifers underlie large parts of the semi-arid Limpopo Province where some of the greatest groundwater needs in South Africa occur. It is important to identify potentially high-yielding zones that can be targeted for water supply. The study covered 7 distinct groundwater regions within Limpopo Province, together covering about 63 500 km². Results from over 4 000 pumping-test analyses indicated that geological setting (e.g. aureole of granitoids), proximity and orientation of dykes and lineaments and proximity of surface-water drainages may exert an influence on borehole productivity. Although dykes are poor groundwater targets, drilling dykes composed of dolerite may prove to be more successful. Lineaments striking perpendicular to the current maximum horizontal stress seem to be more favourable targets, which is inconsistent with the predicted regime. Due to the complex geological history, it is difficult to link open discontinuities to a distinct recent or past tectonic event. Regional stress-field data, as in this case, may not account for local, possibly highly significant, stress-field variations. The hydrogeological importance of several factors related to groundwater occurrence, can be used as a working reference for future groundwater-development programmes. <![CDATA[<b>Can groundwater be successfully implemented as a bulk water resource within rural Limpopo Province? Analysis based on GRIP datasets</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1816-79502012000300005&lng=pt&nrm=iso&tlng=pt Groundwater is a strategic water resource in rural Limpopo Province and it accounts for almost 70% of rural domestic water supply. The resource is available throughout the Province in varying quantities and qualities depending on the hydrogeological properties of the underlying aquifer. These properties are mostly secondary in nature and are constrained by the processes of weathering, faulting, fracturing and the influence of intrusive rocks. These properties define typical fractured aquifers in which the selection of drilling sites requires a thorough scientific approach to locate a successful productive borehole. While most water service authorities in the Province have been randomly developing new boreholes with limited success rates, the analysis of datasets in the newly established groundwater data repository, the Limpopo Groundwater Resource Information Project (GRIP) demonstrates that large quantities of groundwater can be obtained and used for bulk supply if the drilling sites are scientifically selected. The GRIP dataset contains 24 922 entries of which 4 000 were tested. The pumping test results indicate that an estimated 576 000 m³/d (210 Mm³/a) can be sustainably abstracted from boreholes in approximately 2 500 villages that are dispersed throughout the Province. However, more than 50% of these boreholes are unequipped of which 3 000 can provide a combined yield of 109 Mm³/a based on a 24 h abstraction rate. These results show that groundwater can be developed as a potential viable bulk-water supply source. This paper attempts to demonstrate, using the existing GRIP dataset, that groundwater is an underutilised resource that can be viably and cost-effectively developed as an alternative bulk water source or conjunctively with surface water. <![CDATA[<b>Water-balance approach for assessing potential for smallholder groundwater irrigation in Sub-Saharan Africa</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1816-79502012000300006&lng=pt&nrm=iso&tlng=pt Strategies for increasing the development and use of groundwater for agriculture over much of Sub-Saharan Africa (SSA) are urgently needed. Expansion of small-scale groundwater irrigation offers an attractive option to smallholder farmers to overcome unreliable wet-season rainfall and enhance dry-season production. This paper presents a simple, generic groundwater-balance-based methodology that uses a set of type-curves to assist with decision making on the scope for developing sustainable groundwater irrigation supplies, and to help understand how cropping choices influence the potential areal extent of irrigation. Guidance to avoid over-exploitation of the resource is also provided. The methodology is applied to 2 sites in West Africa with contrasting climatic and subsurface conditions. At both sites the analysis reveals that there is significant potential for further groundwater development for irrigation whilst allowing provisions for other sectoral uses, including basic human needs and the environment. <![CDATA[<b>A groundwater-planning toolkit for the main Karoo basin</b>: <b>identifying and quantifying groundwater-development options incorporating the concept of wellfield yields and aquifer firm yields</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1816-79502012000300007&lng=pt&nrm=iso&tlng=pt This paper provides an overview of groundwater-planning tools that were developed during a Water Research Commission project that was initiated due to the need to place the significant knowledge on groundwater of the Karoo Basin within the realms of water resource planning. In essence, the project aimed to identify favourable areas of groundwater potential for bulk municipal water supplies, to provide a method to quantify them, and to package the information so that it is assessable for planning purposes. In identifying favourable groundwater areas, the focus turned to developing a detailed transmissivity map of the Main Karoo Basin. In order to present yields in an accessible manner to water-supply planners, the same concept used in surface-water resource assessments and dam or reservoir design were adapted and applied to groundwater. Two methods were developed, namely the Aquifer Assured Yield Model and the Aquifer Firm Yield Model (the latter of which was developed into a software package together with the other products). The Aquifer Firm Yield Model provides the historical firm yield and uses historical monthly rainfall data together with recharge, evapotranspiration and baseflow to determine aquifer storage in any given month. The firm yield can be considered to define the upper limit of the groundwater resource. In order to establish possible wellfield yields, the C-J Wellfield Model (based on the Cooper-Jacob approximation of the Theis groundwater-flow equation) was developed whereby borehole spacing can be optimised after inputting estimated transmissivity values from the transmissivity map. To aid the planning process, groundwater-quality maps were produced together with the Wellfield Cost Model which provides an easy way to obtain first-order cost estimates of the wellfield options. This paper briefly describes these 'tools' that were produced and provides slightly more detail on how the transmissivity maps were developed <![CDATA[<b>Climate change vulnerability index for South African aquifers</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1816-79502012000300008&lng=pt&nrm=iso&tlng=pt South Africa is viewed as a water-stressed country with an average annual rainfall of 500 mm and any climatic change could have adverse impacts on water resources of the country. The potential impacts of climate change on water resources and surface hydrology for Africa and Southern Africa have received considerable attention from hydrologists during the past decade. Very little research has been conducted on the future impact of climate change on groundwater resources in South Africa. Climate change can affect groundwater levels, recharge and groundwater contribution to baseflow. To assess these impacts a climate change vulnerability index was developed. This vulnerability-index method is known as the DART index. The parameters considered in the DART method are as follows: depth to water-level change, aquifer type (storativity), recharge and transmissivity. The DART index is used as a regional screening tool to identify areas that could experience possible changes in their groundwater resources as a result of climate change. The current DART index does not account for adaptation and migration occurrences. <![CDATA[<b>Community-groundwater compatibility assessments</b>: <b>an approach towards sustainable groundwater development</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1816-79502012000300009&lng=pt&nrm=iso&tlng=pt To address water availability problems in a semi-arid country like South Africa, the National Water Act (RSA, 1998) proposes that specialists adopt an approach that is strategic, deliberate and dictated by socio-political reforms and socioeconomic development needs on a programmatic basis for long-term sustainability. To achieve this goal an approach is developed to determine community-groundwater compatibility as part of the initial stages of regional rural groundwater-development projects in the Eastern Cape Province, South Africa. The steps followed in the community-groundwater compatibility assessment include: A desktop study where available literature is collected and reviewed. From this information and history, the sociopolitical challenges that will have to be faced for the successful completion of the groundwater-development project in the study area can often be established. This is valuable information to assist the hydrogeological team in planning the community-groundwater compatibility assessment, taking note of pitfalls and lessons learnt from previous approaches that might not always have been successful. A socio-economic characterisation includes setting up a contact database for the community authorities and technical managers within the study. The contact database includes all contact details of the ward councillors/technical managers as well as any relevant information or comments made by the ward councillor/technical manager during the conversation. All identified stakeholders must also be contacted, informing them of the project and study. The data obtained from the role-players are used to develop a social-character map. Site surveys and sampling are based on the social-character map. The study team assesses the knowledge communities carry concerning groundwater as well as their general attitude towards the use of groundwater. Data processing and analyses include the statistical processing of the collected data to assess the comprehensive measure of groundwater compatibility per area, and the individual indicators of the groundwater-compatibility index are given a relative score. This enables the different indicators for groundwater compatibility per area to be combined to give a single composite score for each spatial area. Target areas are finally characterised in terms of their 'community-groundwater compatibility index'. Maps showing the social and basic hydrogeological character of target areas are valuable tools towards assisting local authorities in decision-making. <![CDATA[<b>Ensuring water supply for all towns and villages in the Eastern Cape and Western Cape Provinces of South Africa</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1816-79502012000300010&lng=pt&nrm=iso&tlng=pt The Department of Water Affairs (DWA) has embarked on a nationwide programme to develop water-reconciliation strategies for all towns across the country. Reconciliation strategies for the major metropolitan areas and systems (e.g. Johannesburg/Pretoria, East London, Cape Town and Durban) were developed next. The implementation of these strategies is monitored by strategy steering committees. The approach has now been extended to all other metropolitan areas as well as all towns and villages or clusters of villages. In order to prepare the actual strategies, regardless of the size of the town, thorough documentation, research and analysis of the available information was required, as well as evaluation of projected growth scenarios to assess water requirements over the next 25 years and identification of potential additional sources to meet this growing requirement. It has emerged that the poor operation and maintenance of water supply, treatment and reticulation infrastructure are resulting in significant losses, which, if corrected, can reverse the current water shortages being experienced. Similarly, the generally poor management of effluent remains a threat to surface water and groundwater quality downstream. It appears that many municipalities perceive groundwater as an unreliable resource; however, in general, the issue of staff and skills shortages to manage the resource effectively is the actual problem. This is an operational issue rather than a groundwater-resource-specific issue. This aspect requires special attention for existing groundwater schemes and proposed groundwater development. In most instances water conservation and water-demand management and the development of local surface and groundwater resources are the most feasible options to meet any current or projected future water-supply shortfalls. Any intervention must be combined with a skills-development programme at the operational level to ensure the sustainability of the proposed supply options. This paper is based on the experience gained in the development of reconciliation strategies for the towns and villages in the DWA Southern Planning Region (i.e. surface water drainage areas in the Eastern Cape and Western Cape Provinces), which was carried out by Umvoto Africa in association with engineering consulting practice Aurecon. <![CDATA[<b>A proposed groundwater management framework for municipalities in South Africa</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1816-79502012000300011&lng=pt&nrm=iso&tlng=pt Groundwater is not being perceived as an important water resource and therefore has been given limited attention in South Africa. This is reflected in general statistics showing that only 13% of the nation's total water supply originates from groundwater. In contrast, most towns in arid areas depend on groundwater either as a sole supply or as an essential supply for drought management. The perception remains that groundwater is not a sustainable resource for bulk domestic supply and cannot be managed properly. Despite this, a growing number of municipalities utilise groundwater on a regular basis, and provide examples of successful management of this resource. Various guidelines for groundwater management in South Africa have been developed. These are valuable sources of information in terms of requirements and steps to protect and manage aquifers. However, an overarching groundwater management framework was still lacking. Hence, the Water Research Commission (WRC) has commissioned a project to develop a Groundwater Management Framework that incorporates all aspects of groundwater management at municipal level. The proposed Groundwater Management Framework aims to improve on the management of groundwater resources by equipping the responsible authorities with the required tools and capacity. This goes beyond data collection and monitoring, and requires human and capital resources. The framework includes a detailed description of the different functions and the relevant responsibilities, the required skills, the optimal position within the municipal structure and required communication lines. Hence, the assigned responsibilities and available tools to achieve sustainable groundwater management reflect the local level of water institutions, i.e. Water Services Authority (WSA), Water Services Provider (WSP) and Water User Associations (WUAs). However, the principles of the framework can be applied at all levels and all scales. It is recommended that this framework be rolled out and promoted at the local government level, in combination with requisite skills development at operational level, and training of municipal officials, as well as providing incentives for successful implementation and integration of groundwater management in municipal planning. <![CDATA[<b>Groundwater governance in South Africa</b>: <b>a status assessment</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1816-79502012000300012&lng=pt&nrm=iso&tlng=pt Groundwater governance provisions and arrangements in South Africa were studied at national level and at local level for a highly productive aquifer, the Botleng Dolomite Aquifer. Technical, legal, institutional and operational governance provisions were found to be reasonable at the national level but weak with regards to cross-sector policy coordination. At the local level, basic technical provisions such as hydrogeological maps and aquifer delineation with classified typology are in place but other governance provisions such as institutional capacity, provisions to control groundwater abstraction and pollution, cross-sector policy coordination and the implementation of a groundwater management action plan are weak or non-existent. Adaptation measures to climate change are not yet fully considered in planning. Only at the national level a groundwater strategy and artificial-recharge strategy has been developed but awaits implementation. Most critical management measures are considered, namely: The integration of the National Groundwater Strategy (NGS) into the various water-related strategies Strengthening of the groundwater regulatory environment Strengthening of the institutional capacity <![CDATA[<b>Valuing groundwater</b>: <b>a practical approach for integrating groundwater economic values into decision making - A case study in Namibia, Southern Africa</b>]]> http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1816-79502012000300013&lng=pt&nrm=iso&tlng=pt Groundwater provides a range of services to people in Southern Africa; however, the benefits provided by these services are often not fully appreciated and factored into decisions about groundwater management and use. After outlining briefly the importance of groundwater in the region and the pressures facing groundwater, this paper discusses how economic valuation can help improve its management. The main focus of the paper is the presentation of the practical 5-step economic valuation methodology that has been developed as part of the Southern African Development Community (SADC) Groundwater and Drought Management Project. This methodology can be generally applied to groundwater management issues across the SADC region. The methodology is based upon an ecosystem services approach which considers all the potential services that groundwater provides, which can result in improvements in human welfare. These services include provisioning services such as water for domestic use, agriculture and industry; regulating services such as the recharge of surface waters and carbon storage benefits; and cultural services such as the tourism associated with wildlife at groundwater-fed watering holes. The methodology incorporates a 2-tiered valuation approach. The Tier 1 valuation is based on market pricing and value-transfer approaches and can provide an initial view of the economic value of a resource in a particular use. A value-transfer tool has been developed, which allows the user to select from a menu of the currently available transfer values for use in an assessment. A Tier 2 valuation requires more detailed primary studies and may be required following a Tier 1 assessment where more certainty in decision-making is required. The methodology has been tested at 4 pilot sites in the region. An example of the application of the SADC groundwater-valuation methodology in Namibia is presented in this paper. The paper concludes with recommendations for the development of groundwater valuation in the region. Emphasis is placed on training, the commissioning of more groundwater-valuation studies and the need for more scientific research to facilitate the valuation of groundwater-regulating services.