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Design flood estimation (DFE) is essential in the planning and design of hydraulic structures. In South Africa, outdated methods are widely applied for DFE. In this paper the potential of a continuous simulation modelling (CSM) approach to DFE in South Africa, using the daily time-step ACRU agrohydrological model, is investigated. The paper focuses on the links and similarities between the SCS-SA and ACRU models and the subsequent preliminary investigations that were undertaken to account for and incorporate the land cover classes, including land management practices and hydrological condition, of the SCS-SA model into the ACRU CSM approach. The approach to this study was to investigate how design volumes simulated by the SCS-SA model for various land management practices or conditions could be simulated by the ACRU model. Since peak discharge estimation in both models is directly dependent on simulated volumes, this preliminary study focused only on design runoff volumes, with subsequent investigations on peak discharge required in future research. In the absence of observed data, design runoff volumes and changes in design runoff volumes, as simulated by the SCS-SA model, were used as a substitute for observed data, i.e., as a reference, to achieve similar design runoff volumes and changes in design volumes in the ACRU model. This was achieved by adjusting relevant input parameters in the ACRU model to represent the change in management practice or hydrological condition, as represented in the SCS-SA model. Following a sensitivity analysis of relevant ACRU parameters, calibration of 2 selected parameters against SCS-SA CN values for selected land cover classes was performed. A strong linear relationship (R2 = 0.94) between these ACRU parameters and SCS-SA CNs for selected land cover classes was found and consequently specific rules and equations were developed to represent SCS-SA land cover classes in ACRU. Recommendations are made to further validate and verify the approach and to further the development of a CSM system for DFE in South Africa. [ABSTRACT FROM AUTHOR]

Southern Africa is likely to experience higher evapotranspiration and altered rainfall characteristics due to global warming and climate change. Climate-driven water use may potentially stress water supply facilities due to increased demand and reduced surface water yield. This paper presents a conceptual theoretical framework for assessing impacts of climate change on domestic irrigation water use. The prediction of climatic conditions that may potentially influence future water use is reviewed together with regional capacity for downscaling global climate projections. The impact assessment of water use is based on the modification and adaptation of an existing end-use model for water demand to include parameters for climate change. The Penman-Monteith equation and the soil water balance equation are incorporated for the estimation of daily water needs of vegetated areas in residential properties. The paper also discusses data requirements and a calibration procedure to improve model fit to the observed domestic irrigation water use. The proposed approach could form a basis for constructing a detailed model for planning various adaption measures relating to climate-driven domestic irrigation water use. [ABSTRACT FROM AUTHOR]

Planning for current and future climate risks depends on more than early warning signals and technical climate information. The management and enabling of effective risk approaches, we argue, is shaped by complex contextual settings. These contexts are shaped by decisions including: What climate risks are prioritised? Who makes decisions about risk response interventions and how do they make these decisions? This preliminary study uses observed changes in storm events in the City of Johannesburg (CoJ) and the City's Climate Change Adaptation Plan as a lens through which the scope of such contexts and decisions can be interrogated. The study is used as a springboard from which to begin a dialogue on interactive approaches to adaptation and response planning for current and future climate change. We suggest that this dialogue may be required for a more proactive disaster-risk approach in the city. The major focus of the paper includes a statistical analysis of historical weather data from the OR Tambo Weather Station, located in close proximity to the city. Significant trends are identified in the frequency and intensity of thunderstorms for the period 1960-2009. This preliminary assessment shows some similarities with emerging climate change projections that suggest that heavy rainfall events may become more frequent and intense. The preliminary results presented here also concur with the recent findings contained in the CoJ's Climate Change Adaptation Plan (2009). While the study is in no way substantive and few wider generalisations and strong conclusions can be drawn from it, the study does provide a useful starting point for considering possible planning interventions. The potential value of using science and information from studies, such as this, is highlighted along with the possible ways in which such science can interact with and help inform a comprehensive planning agenda in the City. Finally, the paper calls for more attention to be paid to the contributions and perceptions of community awareness and understanding of climate risks. [ABSTRACT FROM AUTHOR]

A number of severe flooding events have occurred both in South Africa and internationally in recent years. Furthermore, changes in both the intensity and frequency of extreme rainfall events have been documented, both locally and internationally, associated with climate change. The recent loss of life, destruction of infrastructure, and associated economic losses caused by flooding, compounded by the probability of increased rainfall variability in the future, highlight that design flood estimation (DFE) techniques within South Africa are outdated and in need of revision. A National Flood Studies Programme (NFSP) has recently been initiated to overhaul DFE procedures in South Africa. One of the recommendations in the NFSP is the further development of a continuous simulation modelling (CSM) system for DFE in South Africa. The focus of this paper is a review of CSM techniques for DFE, to guide further development for application in South Africa. An introduction to DFE, and particularly the CSM approach, is presented, followed by a brief overview of DFE techniques used in South Africa, leading into a more detailed summary of CSM for DFE within South Africa to date. This is followed by a review of the development and application of CSM methods for DFE internationally, with a focus on the United Kingdom and Australia, where methods have been developed with the intention of national scale implementation. It is important to highlight that there is a plethora of CSM methods available internationally and this review is not exhaustive; it focuses on and identifies some of the strengths and weaknesses of several popular methods, particularly those intended for national scale application, as the intended outcome from this review is to identify a path towards the development of a usable national scale CSM system for DFE in South Africa. Emphasis on a usable method is important, considering the reality that, despite promising results, numerous benefits, and national scale methods being developed, it appears that the CSM method for DFE is rarely used in practice. [ABSTRACT FROM AUTHOR]

South Africa, being a semi-arid country, faces water resource constraints. The projected impacts of climate change in the Keiskamma River Catchment, Eastern Cape Province, are, for example, changes in rainfall with effects on streamflow, salt water intrusion, decreasing water quality due to runoff and erosion, and droughts. This paper uses an existing framework, the Adaptive Capacity Wheel (ACW), complemented by two additional dimensions: adaptation motivation and adaptation belief. The objectives were, first, to assess the adaptive capacity of water governance in the study region, and, second, to show how the ACW can be used as an approach and a communication tool with stakeholders to identify strengths and weaknesses. Based on this, recommendations can be drawn that could help water experts and stakeholders in the future. The results depict a 'medium' score for adaptive capacity. However, it is important to look closely at each dimension assessed by the ACW. The key recommendations are: to overcome the implementation gap, to ensure better coordination across and within governmental levels; to raise awareness, capacity and skill among decision makers and the public; and to increase the political will to overcome adaptation barriers. [ABSTRACT FROM AUTHOR]

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: What is the scope for promoting much increased groundwater use for irrigated agriculture, and how might the investment risks be reduced and sustainable outcomes ensured? How can the demand to expand urban groundwater use, for both further supplementing municipal water-supply systems and for direct in situ water supply, be best channelled to maximise the benefits whilst minimising the risks? This 'new agenda' poses very different challenges from the long-standing requirement to provide rural water supplies of adequate coverage, reliability and quality (which, while still not yet fully addressed, is outside the scope of this paper). Balanced answers to these new questions are needed to provide a sound basis for appropriate investment policies on managed groundwater development and adequate institutional provisions for their implementation. They are discussed here from the standpoint of the GW-MATE experience in some World Bank-supported projects in eastern Africa during 2001-2010, together with a review of some developments in western Africa and insights from parts of Asia and Latin America. [ABSTRACT FROM AUTHOR]

This paper reviews the progress made in the assessment of water resources in South Africa over the past 60 years by examining 5 major studies that were undertaken in this period. These studies illustrate how the exponential growth in computer power and the concomitant development of highly sophisticated tools have changed the manner in which our water resources have been appraised, allowing us to deal with more and more complex issues, including: water quality, surface water/groundwater interaction and the reduction in runoff due to afforestation and alien vegetation. However, the main concern today is the serious decline in hydrological monitoring in recent times. It is imperative that this decline be addressed, especially if we are to deal effectively with problems related to climate cycles and climate change, together with the deterioration in water quality. [ABSTRACT FROM AUTHOR]

As a point of departure, the South African water-related sector is placed within the broader climate change context. Following on brief explanations of the terms adaptation, adaptive management and adaptive capacity, a summary of recent (2011) findings on projections of climate change effects on hydrological responses over South Africa is presented as the scientific cornerstone to practical adaptive management options. These options are based on the identification of major categories and subcategories in which adaptive capacity can be enhanced, the identification of 17 sectors within the broader South African water-related community which are likely to be impacted by climate change and the identification of the range of foreseen changes that these various sectors are likely to have to cope with, and adapt to, as a consequence of projected changes in climate drivers and hydrological responses. Five sectors are then selected for detailed case studies on adaptive management options, viz. national water planners, municipalities, rain-fed (dryland) agriculture, the insurance industry and aquatic ecosystems. The paper concludes by stressing the importance of adaptation to climate change and briefly outlines further plans of action in this field. [ABSTRACT FROM AUTHOR]

Long-term population growth and economic development are placing ever-increasing pressure on South Africa's freshwater supply. On the basis of the current climate change predictions, which often entail uncertain consequences for aquifer systems and the associated groundwater goods and services, it is expected that the stress on water will increase even further. Currently, South Africa's groundwater governance regime does not provide the capacity to assure effective and sustainable resource regulation and allocation. To date, the management of groundwater is hampered by a variety of uncertainties, such as global climate change and socio-economic growth, as well as ineffective governance structures affecting resource use, regulation, protection and the implementation of alternative strategies needed to achieve sustainable management. This paper presents the results of a qualitative assessment of interviews conducted with experts in South Africa. Four key challenges are identified to the development of adaptive and sustainable groundwater management and the successful implementation of current water legislation in South Africa. These are: the undervaluation of groundwater importance and significance; the need for expertise and information at all scales; the centralisation of power; and the disregard of ecosystems and the associated goods and services. As a means to tackle these challenges, it has been assumed that the concept of adaptive water management represents a suitable approach to governing groundwater resources, by taking into account complex system linkages between hydrogeological, political, socio-economic and environmental domains. Supporting principles, such as tools for cooperation, participation and information networks, have been developed to facilitate the implementation of adaptive water management approaches and hence to achieve institutional change in the political arena of groundwater management. [ABSTRACT FROM AUTHOR]

South Africa's unallocated water resources have dwindled to precariously low levels. Furthermore, it is generally recognised by the authorities and specialists alike that it is likely that water demand will outstrip water supply within the next decade. Macro-economically and strategically speaking, the question therefore is how to make best use of the country's available water resources? We ask this question since South Africa is a country classified as having chronic water shortages, a condition exacerbated by climate change and the presence of invasive alien plant species. In this paper we address the question of sectoral water allocation by applying a macro-economic comparative static Computable General Equilibrium (CGE) Model using an integrated database comprising South Africa's Social Accounting Matrix (SAM) and sectoral water use balances. We refer to AsgiSA, the South African Government's Accelerated and Shared Growth Initiative for South Africa, and conclude that introducing the proposed programmes in a business-as-usual and water-intensive manner will strengthen the current growth in the demand for water. This will bring forward, or accelerate, the need for introducing water rationing among sectors. The importance of this conclusion cannot be emphasised enough. Water is essential, and recognised in as much in the preamble to the National Water Act of 1998, with regards to livelihoods, health and from a socio-economic development perspective since there are no substitutes for it. While water rationing is imminent, the reality thereof has not yet led to a rethink of macro-economic policies. This delayed effect can create a degree of comfort and ill-founded complacency leading to non-action, whereas there is an urgent need for proactive measures towards water conservation. [ABSTRACT FROM AUTHOR]

The natural resources of the Okavango Delta, a large wetland in semi-arid Botswana, form the basis of livelihoods of the local population and support economically important high-end tourism. The hydro-ecological system is dynamic at various time scales, responding to climate variability, and both flood and drought conditions have in the past put pressure on the system's users. Human-induced climate change can potentially exacerbate the effects of existing climate variability. In this paper, we present simulated future hydro-ecological conditions in the Okavango Delta generated by a step-wise modelling procedure. The outputs of three different global climate models are used to drive a suite of hydrological models. Lastly, a rule-based dynamic model relates hydroperiod conditions to vegetation assemblages. The simulated future conditions vary from much drier to much wetter than those recorded in the past. Models indicate that climatic change would result in change in both extent and distribution of the major ecotopes of the Okavango Delta. Importantly, the different ecotopes will be affected to varying degrees. The projected changes will have consequences for the wildlife-based management of the system. They will affect, for example, available grazing and migration/movement patterns of large herbivores, as well as fish. Such consequences can have rapid up-trophic level effects, ultimately leading to potentially substantial impacts on the economy. The main conclusion to be drawn is that management planning and land-use systems should be as flexible as possible. [ABSTRACT FROM AUTHOR]