Decision support system for sustainable rainwater harvesting in South Africa

To reconcile its scarce water resources with the ever increasing demand for fresh water, the South African government continues to explore and investigate various demand management and water supply options such as: effluent reuse, interbasin water transfers, rainwater harvesting (RWH), water conservation as well as sea water desalinisation. RWH is an old but underutilised technology that can play a key role in the improvement of rural livelihoods, thus the need to investigate the potential it holds for South Africa. This thesis presents the Rainwater HArvesting Decision Support System (RHADESS) that was developed to facilitate the integration of three streamlined categories of RWH in the management and development of the country’s water resources at the quaternary catchment scale (± 500 km2). Using biophysical and socioeconomic datasets, RHADESS assesses the RWH footprint of any given area of South Africa. Although physical factors are important parameters in the assessment of the RWH suitability of a given area the non‐consideration of ecological and socioeconomic parameters lead to inappropriate targeting of RWH. Once the footprint is determined, the ecohydrological impact of RWH as reduction in river flow can be established. Despite the increasing adoption of RWH, very little is known about its potential ecohydrological impact. This thesis contributes to understanding these impacts for different levels of adoption of RWH at the quaternary catchment scale. Finally, RHADESS sizes the RWH tank per quaternary catchment, assesses its water security and calculates the area of land needed for a household to achieve food security when RWH is implemented. The decision support system was tested in two quaternary catchments which have contrasting rainfall regimes, the semi‐arid C52A and the humid V13D

Mastitis in Small Ruminants

Bacterial mastitis in small ruminants is a complex disease, with massive economic loss in dairy sheep/goat industry due to poor productivity. The current mastitis prevention strategy relies on culling of infected ewes or does and or the use of antimicrobial agents to eliminate the bacterial infection. This has a potential risk for developing antibiotic resistant bacteria, posing human health risk from consumption of raw sheep or goat dairy products. Existing experimental and licensed vaccines on the market are ineffective against reducing the risk of mastitis in herds or flocks. Raising the needs for development of improved vaccines against mastitis for use in sheep and goats. This review examines, current understanding of the pathological processes and immunological responses against bacterial mastitis, using S. aureus as an example. By highlighting the protective defense mechanism induced in the udder against S. aureus mastitis. Based on evidence from published studies on pathological process and protective immune response mechanism, the need for improved vaccines for prevention of mastitis in small ruminant is highlighted and the development of a vaccine capable of enhancing immune response mechanism, that reduce the establishment of intramammary infection through induction of local IgA, IgG2 and Th17 immune responses is proposed

Rainwater harvesting to enhance water productivity of rainfed agriculture in the semi-arid Zimbabwe

Zimbabwe’s poor are predominantly located in the semi-arid regions and rely on rainfed agriculture for their subsistence. Decline in productivity, scarcity of arable land, irrigation expansion limitations, erratic rainfall and frequent dry spells, among others cause food scarcity. The challenge faced by small-scale farmers is to enhance water productivity of rainfed agriculture by mitigating intra-seasonal dry spells (ISDS) through the adoption of new technologies such as rainwater harvesting (RWH). The paper analyses the agro-hydrological functions of RWH and assesses its impacts (at field scale) on the crop yield gap as well as the Transpirational Water Productivity (WPT). The survey in six districts of the semi-arid Zimbabwe suggests that three parameters (water source, primary use and storage capacity) can help differentiate storage-type-RWH systems from “conventional dams”. The Agricultural Production Simulator Model (APSIM) was used to simulate seven different treatments (Control, RWH, Manure, Manure + RWH, Inorganic Nitrogen and Inorganic Nitrogen + RWH) for 30 years on alfisol deep sand, assuming no fertiliser carry over effect from season to season. The combined use of inorganic fertiliser and RWH is the only treatment that closes the yield gap. Supplemental irrigation alone not only reduces the risks of complete crop failure (from 20% down to 7% on average) for all the treatments but also enhances WPT (from 1.75 kg m−3 up to 2.3 kg m−3 on average) by mitigating ISD

Water for small-scale biogas digesters in sub-Saharan Africa

Acknowledgements This work was part-funded by the UK Natural Environment Research Council funded ESPA project, NE/K010441/1 ‘ALTER – Alternative Carbon Investments in Ecosystems for Poverty Alleviation’. We are also grateful to the AUC for funding part of this work under the Afri-Flame project on ‘Adapta- tion of small-scale biogas digesters for use in rural households in sub-Saharan AfricaPeer reviewedPublisher PD

Apportioning human-induced and climate-induced land degradation : a case of the greater Sekhukhune district municipality

DATA AVAILABILIBITY STATEMENT: Data available upon request from the corresponding author. The data are not available publicly as a result of privacy or ethical considerations.Land degradation (LD) is a global issue that affects sustainability and livelihoods of approximately 1.5 billion people, especially in arid/semi-arid regions. Hence, identifying and assessing LD and its driving forces (natural and anthropogenic) is important in order to design and adopt appropriate sustainable land management interventions. Therefore, using vegetation as a proxy for LD, this study aimed to distinguish anthropogenic from rainfall-driven LD in the Greater Sekhukhune District Municipality from 1990 to 2019. It is widely established that rainfall highly correlates with vegetation productivity. A linear regression was performed between the Normalized Difference Vegetation Index (NDVI) and rainfall. The human-induced LD was then distinguished from that of rainfall using the spatial residual trend (RESTREND) method and the Mann–Kendall (MK) trend. RESTREND results showed that 11.59% of the district was degraded due to human activities such as overgrazing and injudicious rangeland management. While about 41.41% was degraded due to seasonal rainfall variability and an increasing frequency of droughts. Climate variability affected vegetation cover and contributed to different forms of soil erosion and gully formation. These findings provide relevant spatial information on rainfall or human-induced LD, which is useful for policy formulation and the design of LD mitigation measures in semi-arid regions.Global Environment Facility, Department of Science and Innovation of South Africa and UNDP-GEF5 Sustainable Land Management Project, CSIR and the CSIR Parliamentary Grant.https://www.mdpi.com/journal/applsciGeography, Geoinformatics and Meteorolog

Impact of land use and land cover change on land degradation in rural semi-arid South Africa : case of the Greater Sekhukhune District Municipality

DATA AVAILABILITY : The data that support the findings of this study are available on request from the corresponding author. The data are not publicly available due to privacy or ethical restrictions.In semi-arid regions, interactions between biophysical and socio-economic variables are complex. Such interactions and their respective variables significantly alter land use and land cover, degrade landscape’s structure, and impede the efficacy of the adopted land management interventions. This scenario is particularly prevalent in communal land tenure system or areas managed by a hybrid of traditional and state led institutions. Hence, this study sought to investigate the impacts of land use and land cover changes (LULCCs) on land degradation (LD) under communal rural districts, and the key drivers of habitat fragmentation in the Greater Sekhukhune District Municipality (GSDM), South Africa. The study used the wet and dry season multi-temporal remotely sensed image data, key-informant interviews, and workshop with tribal council to determine the major drivers of LULCC and LD. Results revealed that mines and quarries, subsistence and commercial cultivation, and thicket/dense bush LULCs declined significantly during the study period. These LULCs mostly declined in wet season, with loss in vegetation cover highly prevalent. Specifically, the highest conversions were from shrub/grassland to bare soil, thicket/ dense bush to shrub/grassland, and shrub/grassland to residential, respectively. Generally, LULCC affected vegetation productivity within the study area, with increased negative NDVI values observed during the dry season. The findings from key informants and the tribal council workshop emphasized that soil erosion, abandonment of cropland, and injudicious land use (i.e. overgrazing and consequent bush encroachment) have severely degraded the land. The study also established that the degrading land can be attributed to the weakening local communal land management system, particularly the weakening tribal councils. The study recommends an urgent need for collaborative (i.e. government, tribal authorities, and land users) land management through designing relevant multi-stakeholder LD mitigation measures.The Global Environment Facility and the Department of Science and Innovation, Republic of South Africa. Open access funding provided by University of KwaZulu-Natal.http://link.springer.com/journal/10661am2024Geography, Geoinformatics and MeteorologySDG-11:Sustainable cities and communitiesSDG-13:Climate actionSDG-15:Life on lan

Towards The Quantification Of The Historical And Future Water Resources Of The Limpopo River

The complexity of current water resource management poses many challenges. Wa-ter managers must solve a range of interrelated dilemmas – such as balancing quan-tity and quality, mitigating the effects of flooding and drought, and maintaining bio-diversity, ecological functions, and services. Sustainable water resource manage-ment, planning, and development requires reliable quantification of the amount, distribution, and quality of water within river basins. With the demand for water resources rapidly growing across the globe, there is also an urgent need for accu-rate monitoring, forecasting and simulation of hydrologic variables – especially in major (often transboundary) river basins such as the Limpopo – not only for optimal water resources management but more compellingly, also for water security, food security, power generation, and economic development. However, the available data are frequently far from sufficient – in terms of availability, accuracy, and spa-tial/temporal resolution – for the understanding of both natural and anthropogenic processes (and their complex linkages) in a river basin. Such challenges also make it very difficult to use the data for the practical application of estimation of water resources availability

Needs, Rights and Responsibilities in Water Governance: Some Reflections

This article discusses needs, rights and responsibilities with regard to water, drawing on global discourses and cases from South Africa. Taking the New Delhi and Dublin Statements as a point of departure, it describes the prevalent global discourses and sets of dichotomies that have characterised much of the water governance debates, such as human right/economic good, public/private, formal/informal, etc. It explores the boundaries of responsibilities between actors, and argues that, rather than an ‘either/or’ approach, new constellations of governance arrangements need to be sought in urban and rural settings, that acknowledge the differential needs of people and communities. While water is a public, justiciable socioeconomic good, the provision of which should lie ultimately with the government, there are myriad constellations across the spectrum of public to private provision that can meet the challenges. The dichotomies, and in particular the idea of ‘public’ and ‘private’, are only useful to a limited extent, as there are many ‘publics’ and many ‘privates’. The question is not so much who offers the service, but how it is offered or organised, how and by whom needs are defined and contested, to what extent needs are met or not, and how clear lines of accountability are established

Antibiotic-Resistant Pathogenic Escherichia Coli Isolated from Rooftop Rainwater-Harvesting Tanks in the Eastern Cape, South Africa

Although many developing countries use harvested rainwater (HRW) for drinking and other household purposes, its quality is seldom monitored. Continuous assessment of the microbial quality of HRW would ensure the safety of users of such water. The current study investigated the prevalence of pathogenic Escherichia coli strains and their antimicrobial resistance patterns in HRW tanks in the Eastern Cape, South Africa. Rainwater samples were collected weekly between June and September 2016 from 11 tanks in various areas of the province. Enumeration of E. coli was performed using the Colilert®18/Quanti-Tray® 2000 method. E. coli isolates were obtained and screened for their virulence potentials using polymerase chain reaction (PCR), and subsequently tested for antibiotic resistance using the disc-diffusion method against 11 antibiotics. The pathotype most detected was the neonatal meningitis E. coli (NMEC) (ibeA 28%) while pathotype enteroaggregative E. coli (EAEC) was not detected. The highest resistance of the E. coli isolates was observed against Cephalothin (76%). All tested pathotypes were susceptible to Gentamicin, and 52% demonstrated multiple-antibiotic resistance (MAR). The results of the current study are of public health concern since the use of untreated harvested rainwater for potable purposes may pose a risk of transmission of pathogenic and antimicrobial-resistant E. coli