Early warning systems (EWS) facilitate societies’ preparedness and effective response capabilities to climate risks. Climate risks embody hazards, exposure, and vulnerability associated with a particular geographical area. Building an effective EWS requires consideration of the factors above to help people with coping mechanisms. The objective of this paper is to propose an approach that can enhance EWSs and ensure an effective climate risk resilience development. The paper focuses on the Southern African Development Community (SADC) region and highlights the issues with EWS, identifying weaknesses and characteristics of EWS to help in climate risk adaptation strategies. The SADC region was chosen as the context because it is a climate variability and change hotspot with many vulnerable populations residing in rural communities. Trending themes on building climate risk resilience were uncovered through scientific mapping and network analysis of published articles from 2008 to 2022. This paper contributes to on-going research on building climate risks resilience through early warning systems to identify hidden trends and emerging technologies from articles in order to enhance the operationalization and design of EWS. This review provides insight into technological interventions for assessing climate risks to build preparedness and resilience. From the review analysis, it is determined that there exists a plethora of evidence to support the argument that involving communities in the co-designing of EWS would improve risk knowledge, anticipation, and preparedness. Additionally, Fourth Industrial Revolution (4IR) technologies provide effective tools to address existing EWS’ weaknesses, such as lack of real-time data collection and automation. However, 4IR technology is still at a nascent stage in EWS applications in Africa. Furthermore, policy across societies, institutions, and technology industries ought to be coordinated and integrated to develop a strategy toward implementing climate resilient-based EWS to facilitate the operations of disaster risk managers. The Social, Institutional, and Technology model can potentially increase communities’ resilience; therefore, it is recommended to develop EWS.

Given the many users in South Africa of the SCS (Soil Conservation Service) hydrograph-generating technique, which requires key soils information, this paper presents a methodology to develop a detailed map (at the spatial resolution of South Africa's 27 491 terrain units) of the SCS runoff-related soil groups. In order to achieve this objective, background is first provided on the soils context within the SCS technique, as well as on the approaches to defining SCS hydrological soil groups, by assigning SCS soil groups to South African soil series. Steps when mapping SCS soil groups across South Africa at terrain unit spatial resolution are then outlined. This is followed by the presentation and interpretation of the detailed terrain unit level map of SCS soil groups for South Africa. The detailed new map illustrates the finer detail across contributing catchments countrywide now obtained from the terrain unit approach, compared to the previous map of SCS soil groups based only on the coarser soil land types.

Soil organic carbon (SOC) content and the water holding capacity of soils are two properties which link the carbon and hydrological cycles. Hydrological model inputs seldom include soil carbon as a parameter even though soil carbon content is known to influence soil water retention capacities. This study is a sensitivity analysis of changes in hydrological responses when the model inputs include different soil carbon percentages for the topsoil horizon. Sensitivities of hydrological responses such as transpiration, runoff volumes, the stormflow component of runoff and extreme runoff events to SOC content were quantified under various climatic conditions in South Africa. The soil water holding capacities at the drained upper limit (i.e. field capacity), permanent wilting point and saturation were calculated for the topsoil horizon, using SOC dependent pedo (soil)-transfer functions for different soil carbon scenarios and locations in South Africa. These variables, together with other pre-determined soil- and locationrelated inputs, as well as 50 years of daily climate, were then used as inputs in a process-based hydrological model. Overall, it was found that increased SOC content in the topsoil horizon leads to an increase in transpiration, a reduction in runoff, especially in its stormflow component, and a reduction of extreme runoff events. However, these changes are relatively small compared to the influence of climate, particularly of rainfall amount and distribution.Significance: Organic carbon content of the soil and the water holding capacity of soils link the carbon and hydrological cycles. Management interventions that increase SOC lead to win-win situations because, in addition to climate change mitigation, plant water availability improves, and overall surface runoff ‘flashiness’ becomes more regulated. While rainfall amount and distribution over space and time remain the most critical determinants of hydrological responses, increased SOC in the topsoil horizon leads to increases in transpiration and thus plant growth, and to a reduction in runoff, especially in its stormflow component, and hence to a small reduction of severe flooding events.

Water quality in South Africa’s river systems is declining, driven in part by changes in land use and management. Diffuse pollution significantly contributes to river degradation, requiring identification of critical source areas of diffuse pollutants, including nutrients and suspended solids. This study assesses diffuse pollution risks in two contrasting catchments: the Thukela and the Breede. A risk-based assessment was undertaken using the Sensitive Catchment Integrated Modelling Analysis Platform (SCIMAP). SCIMAP integrates a digital elevation model (to determine hydrological connectivity), land use based diffuse pollution potential, here assessed from national land cover classes using the Automated Land-based Activity Risk Assessment Method (ALARM), and rainfall information (representing runoff dilution potential). Results are presented as (i) risk generation of diffuse nutrients based on land use attributes, (ii) the connectivity risk of the movement of pollutants to the river channel, (iii) nutrient risk from the landscape component’s critical source areas, (iv) nutrient concentration risk in the channel component of the catchment, and (v) suspended solid risks from the landscape component. In the Thukela Catchment, landscape-scale nutrient risk patterns were relatively uniform at catchment scale, with distinctions only emerging at finer spatial scales, where elevated risks were associated with some commercial and subsistence agricultural areas. The Breede Catchment exhibited distinct nutrient risk patterns even at catchment scale, with high-risk areas closely linked to some commercial agriculture areas. Channel segments of high nutrient risk for both catchments became evident only at detailed spatial scales. Landscape-based diffuse suspended solids risk areas within the Thukela Catchment range from lows under undisturbed natural vegetation or areas of low connectivity, to highs dominated by degradation and subsistence farming, combined with a high connectivity risk. The Breede Catchment was more muted. This approach is useful to backtrack from polluted river sections to areas with high risk of generating and mobilising pollutants.

South Africa (SA) is projected to become warmer and drier, with increasing frequency and intensity of extreme climatological and hydrometeorological events. The changing climate affects the agri-food systems, compounds water insecurity, and impacts socio-economic and environmental systems. This study analyses climate risks on water and agri-food systems in three provinces, representing three Hydro-Climatic Zones (HCZs) of SA. The study used the Climate Moisture Index (CMI) to assess water stress and the Thermal Heat Index (THI) to identify heat stress across different HCZs and time periods. Past and projected rainfall and air temperatures, described as historical (1960–1990), present (2015–2044), and distant future (2070–2099) time horizons, were used to compute the CMI and THI. More severe changes in the CMI and THI, indicative of drier, hotter climates, are observed in HCZ 1. The results indicate a heterogeneous decrease in rainfall across the study sites alongside distinct increases in temperatures. These conditions indicate an increasing likelihood of water and heat stress, which will exceed the optimal thresholds for crops. Understanding the severity of climate risks is critical to mitigating their impact on socio-ecological and agri-food systems. The study’s results highlight the need for context-specific, transformative adaptive strategies. Simplifying crop stress indices and prioritising the adoption of crops with high thresholds to water and heat stress will support sustainable natural resource management and strengthen the resilience of agri-food systems, particularly in marginalised environments.