Michele Warburton

Adaptation to climate change and other stressors among commercial and small-scale South African farmers

Commercial and small-scale farmers in South Africa are exposed to many challenges. Interviews with 44 farmers in the upper Thukela basin, KwaZulu-Natal, were conducted to identify common and specific challenges for the two groups and adaptive strategies for dealing with the effects of climate and other stressors. This work was conducted as part of a larger participatory project with local stakeholders to develop a local adaptation plan for coping with climate variability and change. Although many challenges related to exposure to climate variability and change, weak agricultural policies, limited governmental support, and theft were common to both farming communities, their adaptive capacities were vastly different. Small-scale farmers were more vulnerable due to difficulties to finance the high input costs of improved seed varieties and implements, limited access to knowledge and agricultural techniques for water and soil conservation and limited customs of long-term planning. In addition to temperature and drought-related challenges, small-scale farmers were concerned about soil erosion, water logging and livestock diseases, challenges for which the commercial farmers already had efficient adaptation strategies in place. The major obstacle hindering commercial farmers with future planning was the lack of clear directives from the government, for example, with regard to issuing of water licences and land reform. Enabling agricultural communities to procure sustainable livelihoods requires implementation of strategies that address the common and specific challenges and strengthen the adaptive capacity of both commercial and small-scale farmers. Identified ways forward include knowledge transfer within and across farming communities, clear governmental directives and targeted locally adapted finance programmes.

Design and test of a model-assisted participatory process for the formulation of a local climate adaptation plan

This article presents the design and testing of a model-assisted participatory process for the formulation of a local adaptation plan to climate change. The pilot study focused on small-scale and commercial agriculture, water supply, housing, wildlife, livestock and biodiversity in the Thukela River basin, KwaZulu-Natal, South Africa. The methodology was based on stakeholders identifying and ranking the severity of climate-related challenges, and downscaled stakeholder-identified information provided by modellers, with the aim of addressing possible changes of exposure in the future. The methodology enables the integration of model-based information with experience and visions based on local realities. It includes stakeholders’ own assessments of their vulnerability to prevailing climate variability and the severity, if specified, of climate-related problems that may occur more often in the future. The methodology made it possible to identify the main issues to focus on in the adaptation plan, including barriers to adaptation. We make recommendations for how to design a model-assisted participatory process, emphasizing the need for transparency, to recognize the interests of the stakeholders, good advance planning, local relevance, involvement of local champions, and adaptation of Information material to each groups previous experience and understanding.

Mapping areas of future urban growth in the Mgeni catchment

Due to increases in population and migration to cities, the areas of urban land use are increasing. This study models the plausible future urban growth in the Mgeni catchment in KwaZulu-Natal, South Africa, using the SLEUTH Urban Growth Model (SLEUTH). The SLEUTH acronym stands for the input layers required for the model viz. Slope, Land use, Excluded areas, Urban Extent, Transport routes and Hillshade. The purpose of this study is to predict the scale and location of future urban growth, for use in hydrological impact assessment studies. SLEUTH was calibrated and applied to the Mgeni catchment to project future urban areas. The results revealed, when assessing the 95–100% probability class, that the Henley, Pietermaritzburg and Durban areas would experience the highest urban growth in the Mgeni catchment by the year 2050. It was concluded that the SLEUTH Model is suitable to account for the scale and location of future urban growth in the Mgeni catchment.

Use of ACRU, a distributed hydrological model, to evaluate how errors from downscaled rainfall are propagated in simulated runoff in uMngeni catchment, South Africa

ABSTRACT The hypothesis of no significant difference in errors between observed (historical) and downscaled global circulation model (GCM) rainfall and corresponding errors in simulated runoff was tested. The percentage difference in mean and standard deviation, normalized errors and normalized bias metrics were used. The ACRU hydrological model was used to simulate runoff. Results indicated that errors in rainfall lead to amplified errors in simulated runoff. A 10% error magnitude in mean rainfall was amplified three times in mean runoff. Rainfall variability was amplified by twice as much from rainfall to simulated runoff. These findings indicate that uncertainty in input downscaled rainfall is amplified in simulated runoff, hence the quality of input rainfall is a strong determining factor of the simulated runoff. Ultimately, there is a need for continuous improvement in the GCM downscaling process, particularly model process description, so as to minimize uncertainties due to GCM model description. EDITOR A. Castellarin; ASSOCIATE EDITOR S. Kanae