Using sap flow data to assess variations in water use and water status of apple orchards of varying age groups in the Western Cape Province of South Africa

No accurate quantitative information currently exists on how water use of apple (Malus domestica) orchards varies from planting to full-bearing age, leading to poor irrigation and water allocation decision making. This study sought to address this knowledge gap by investigating how the water use and tree water status vary with canopy cover, cultivar, and climatic conditions in 12 orchards growing in prime apple-producing regions in South Africa. The orchards were planted to the Golden Delicious/Golden Delicious Reinders cultivars which are widely planted in South Africa and the Cripps’ Pink/Cripps’ Red/Rosy Glow which are high-value lateseason cultivars. The performance of two transpiration reduction coefficients, one based on sap flow (Ksf) and the other based on soil water depletion (Ks) (FAO approach) were evaluated against the midday stem water potential (MSWP) in all the orchards. While canopy cover had a clear effect on the whole-tree sap flow rates, there were no significant differences in the transpiration per unit leaf area among the cultivars. The daily average sap flux density under unstressed conditions was highest (~284 cm3∙cm–2) in the medium canopy cover orchards (30–44% fractional cover), followed by the mature orchards (~226 cm3∙cm–2), and was lowest in the young orchards (~137 cm3∙cm–2). Canopy cover rather than growing season length had a greater effect on seasonal total water use. Peak daily orchard transpiration ranged from 1.7 mm for young Golden Delicious Reinders trees to 5.0 mm in mature Golden Delicious trees that were maintained with  large canopies to reduce sunburn damage to the fruit. For the red cultivars, the peak daily transpiration ranged from 2.0 to 3.9 mm, and the mature trees were maintained with less dense canopies to facilitate the development of the red fruit colour. The less dense canopies on the red cultivars had water-saving benefits since the seasonal total transpiration was lower relative to the Golden Delicious cultivar. The sap flow derived stress  coefficient was strongly correlated to the MSWP (R2 ~ 0.60–0.97) in all the orchards while Ks was not able to detect plant stress due to over-irrigation. Keywords: cultivar canopy cover transpiration reduction xylem water potentia

Tea Value Chains Viability in Limpopo Province of South Africa: A Cost–benefit Analysis

The research was conducted to investigate the production of value-added tea as part of the resuscitation of Tshivhase-Mukumbani Tea Estate. Data were mainly obtained from records kept at the Tshivhase-Mukumbani Tea Estate, through a review of literature and interviews of the selected respondents. Evaluation of economic viability of the value-adding initiative was based on Net Present Value (NPC) and the Benefit-Cost Ratio (BCR) calculated from time-series data obtained for the period 2005–2012. The quantity of value-added tea produced varied across years, geographical locations, and seasons, with production higher for wetter seasons. The NPV was consistently negative, while the BCR was below unity throughout the study period, implying that the value-adding initiative was economically not feasible. Initiatives for achieving economic sustainability of the value addition were (1) Improve the marketing of the made tea brand Midi Tea as organic and longer shelf life. (2) Good labor contracting management practices to deal with labor disputes and unrest. (3) Good supply chain and procurement management practices to reduce the cost of production (4) Monitoring the impact of climate variability and mitigate by providing irrigation (5) Intercropping tea with a suitable winter yielding crops such as avocadoes or Macadamia

Resilience and sustainability through nexus planning

Rapid urbanization is placing unprecedented strain on the life-critical resources of water, energy, and food. We need rapid take-up of coordinated (or “nexus”) approaches to urban development and resource management if we’re to make sustainable cities a reality

Resilience and sustainability through nexus planning

Rapid urbanization is placing unprecedented strain on the life-critical resources of water, energy, and food. We need rapid take-up of coordinated (or “nexus”) approaches to urban development and resource management if we’re to make sustainable cities a reality

A model to integrate and assess water-energy-food nexus performance: South Africa case study

The main limiting factor impeding the operationalisation of the WEF nexus has been lack of metrics and tools to translate the concept into a fully-fledged operational framework to support policy and decision-making. This study developed a WEF nexus model by (i) defining WEF nexus sustainability indicators, and (ii) calculating composite indices for those indicators to establish numerical relationships among WEF nexus resources using South Africa as a case study. The composite indices show WEF nexus performance as well as monitoring and evaluation of WEF resources management. The indicators were integrated through the Analytic Hierarchy Process (AHP) in a multicriteria decision-making (MCDM). The established quantitative relationships indicate resource utilisation, management and performance through a spider graph to illustrate WEF nexus performance, providing a general overview of the level of interactions, interrelationships and inter-connectedness of resources. The shape of the spider graph is determined by the level of the interdependencies and interactions among the WEF nexus sectors, whose management is viewed either as sustainable or unsustainable depending on the classification of the developed integrated index. The spider graph for South Africa showed an over-emphasis on food self-sufficiency and water productivity at the expense of other sectors. The deformed shape of the spider graph is a demonstration of the sectoral or “silo” approach in resource management. The calculated integrated WEF nexus index of 0.203 for South Africa classified the country under the low sustainability category. The developed model is a decision support tool that provides evidence for interventions in priority areas. The model demonstrates the capabilities of the WEF nexus to evaluate synergies and trade-offs in a systematic and integrated way to increases efficiency and productivity in resource management for sustainable development

Securing land and water for food production through sustainable land reform: a nexus planning perspective

Land and water are vital resources for sustaining rural livelihoods and are critical for rural development as they form the basis of agriculture, the main economic activity for rural communities. Nevertheless, in most developing countries, land and water resources are unevenly distributed due to historical and socio-economic imbalances, hence the need for land reform policies to address these disparities. However, redistributing land without considering the interconnectedness of land and socio-ecological systems can compound existing food and water insecurity challenges. This study used a mixed research method, integrating both quantitative and qualitative data, to develop a framework to guide policy and decision-makers to formulate coherent strategies towards sustainable land redistribution programmes and achieve the desired outcomes. The approach was vital for integrating the broad and intricate interlinkages between water, land, and environmental resources. Therefore, the framework is based on transformative and circular models for informing strategic policy decisions towards sustainable land redistribution. The focus was on South Africa’s land redistribution plans and the implications on water and food security and rural development. The developed framework is designed to ensure the sustainability of agrarian reform and rural economic development. It is framed to address land and water accessibility inequalities, promote water and food security, and enhance rural development. A sustainable land redistribution increases the adaptive capacity of rural communities to climate change, enhances their resilience, and provides pathways towards Sustainable Development Goals (SDGs)

Enhancing sustainable human and environmental health through nexus planning

In Mabhaudhi, Tafadzwanashe; Senzanje, A.; Modi, A.; Jewitt, G.; Massawe, F. (Eds.). Water - energy - food nexus narratives and resource securities: a global south perspective. Amsterdam, Netherlands: ElsevierA combination of climate change and accelerated population growth is instigating some of the worst challenges that humankind faces today that include resource depletion and degradation. Both built environment and ecological infrastructure have been modified and are creating novel socioecological interactions posing the risk of novel infectious diseases transmission to humans. The experiences of the COVID-19 exposed the vulnerability of human health from wildlife and the risk of novel socioecological interactions on livelihoods. This chapter enhances the preparedness and improves the resilience against novel pathogens by assessing vulnerability and the available options to reduce risk through the water–health–ecosystem–nutrition nexus. As a transformative, nexus planning provides integrated pathways toward resilience and preparedness to reduce health risks on humans posed by novel pathogens. A systematic review of literature facilitated an understanding of the trends of novel infectious diseases and the available options to improve sanitation, nutrition, and adaptative capacity in the advent of novel socioecological interactions. The aim is to guide policy formulations to achieve Sustainable Development Goals such as 3 (good health and wellbeing), 6 (clean water and sanitation), and 13 (climate action). Risk reduction framing in the health sector through nexus planning provides pathways toward healthy environments and mutual socioecological interactions

Advances in water research: enhancing sustainable water use in irrigated agriculture in South Africa

Water scarcity has become one of the greatest challenges facing humankind today. Its scarcity is compounded by climate change and increasing demand from a growing population. In South Africa, over 60% of the available freshwater resources are used in agriculture, mainly in irrigated agriculture. There is an urgent need to promote sustainable irrigation technologies that optimize food production without increasing water applied and with positive environmental spinoffs. Sustainable irrigation technologies and practices could enhance water use efficiency (WUE) and productivity in agriculture and reduce environmental burdens, including energy use. This chapter highlights some of the innovative irrigation practices and technologies that enhance food production and, at the same time, reduce water use in agriculture. The chapter broadly discusses WUE and water productivity (WP) in irrigated agriculture from engineering and agronomic perspectives. The chapter further highlights some of the environmental impacts of irrigation expansion and the possible solutions. We further provide the importance of accurate spatial information on irrigated areas to inform policy on irrigation expansion. The Water Research Commission (WRC) of South Africa has been spearheading research on the sustainable use of water for the past 50 years as part of its research agenda

Climate change adaptation through the water-energy-food nexus in southern Africa

Climate change is a complex and cross-cutting problem that needs an integrated and transformative systems approach to respond to the challenge. Current sectoral approaches to climate change adaptation initiatives often create imbalances and retard sustainable development. Regional and international literature on climate change adaptation opportunities and challenges applicable to southern Africa from a water-energy-food (WEF) nexus perspective was reviewed. Specifically, this review highlights climate change impacts on water, energy, and food resources in southern Africa, while exploring mitigation and adaptation opportunities. The review further recommends strategies to develop cross-sectoral sustainable measures aimed at building resilient communities. Regional WEF nexus related institutions and legal frameworks were also reviewed to relate the WEF nexus to policy. Southern Africa is witnessing an increased frequency and intensity in climate change-associated extreme weather events, causing water, food, and energy insecurity. A projected reduction of 20% in annual rainfall by 2080 in southern Africa will only increase the regional socio-economic challenges. This is exacerbating regional resource scarcities and vulnerabilities. It will also have direct and indirect impacts on nutrition, human well-being, and health. Reduced agricultural production, lack of access to clean water, sanitation, and clean, sustainable energy are the major areas of concern. The region is already experiencing an upsurge of vector borne diseases (malaria and dengue fever), and water and food-borne diseases (cholera and diarrhoea). What is clear is that climate change impacts are cross-sectoral and multidimensional, and therefore require cross-sectoral mitigation and adaptation approaches. In this regard, a wellcoordinated and integrated WEF nexus approach offers opportunities to build resilient systems, harmonise interventions, and mitigate trade-offs and hence improve sustainability. This would be achieved through greater resource mobilisation and coordination, policy convergence across sectors, and targeting nexus points in the landscape. The WEF nexus approach has potential to increase the resilience of marginalised communities in southern Africa by contributing towards attaining the Sustainable Development Goals (SDGs 1, 2, 3, 6, 7, and 13)