Sensitivity and uncertainty propagation in coupled models for assessing smallholder farmer food security in the Olifants River Basins, South Africa

Using family balance (i.e., combined net farm and non-farm incomes less family expenses), an output from an integrated model, which couples water resource, agronomic and socio-economic models, its sensitivity and uncertainty are evaluated for five smallholder farming groups (AeE) in the Olifants Basin. The crop management practiced included conventional rainfed, untied ridges, planting basins and supplemental irrigation. Scatter plots inferred the most sensitive variables affecting family balance, while the Monte Carlo method, using random sampling, was used to propagate the uncertainty in the model inputs to produce family balance probability distributions. A non-linear correlation between in-season rainfall and family balance arises from several factors that affect crop yield, indicating the complexity of farm family finance resource-base in relation to climate, crop management practices and environ- mental resources of soil and water. Stronger relationships between family balance and evapotranspira- tion than with in-season rainfall were obtained. Sensitivity analysis results suggest more targeted investment effort in data monitoring of yield, in-season rainfall, supplemental irrigation and maize price to reduce family balance uncertainty that varied from 42% to 54% at 90% confidence level. While sup- plemental irrigation offers the most marginal increase in yields, its wide adoption is limited by avail- ability of water and infrastructure cost

Innovative coupling of hydrological modelling for IWRM: linking catchment functioning with socio-economic conditions in the Olifants

Computerised integrated models from science contribute to better informed and holistic exante integrated assessments of multifaceted policies and technologies. This view has lead to considerable effort being devoted to developing integrated models to support decisionmaking under Integrated Water Resources Management (IWRM). Nevertheless, an appraisal of previous and ongoing efforts to develop such decision support systems shows that attempts to address the hydro-socio-economic effects on livelihoods have been deficient and fragmented. To date, no universal standard integration method or framework is in use. Existing integrated models application failures have pointed to the lack of stakeholder participation. In an endeavour to close this gap, this thesis focuses on an integrated model development with prediction capability, ICHSEA, developed in Avenues script language in ArcView 3.3, to take advantage of the mapping capability of ArcView. This model couples existing hydrology (SWAT), agronomy (PARCHED-THIRST) and socio-economic (OLYMPE) models to link livelihoods of resource-constrained smallholder farmers to water resources availability at catchment level in the semi-arid Olifants subbasin, South Africa. These three models were calibrated and validated using observed data and local stakeholder participation, prior to coupling in the integrated model. All the models performed well in representing the study conditions, as indicated by the statistical performance. The integrated model is generally applicable to any catchment. The study methodology was inspired by the need to enhance rural livelihoods and to close the gap of stakeholder involvement in building and applying integrated models to ensure acceptability and application in decision-making. Over 20 years, the predicted impacts of untied ridges and planting basins versus conventional rainfed tillage on surface runoff reduction were 14.3 % and 19.8 %, respectively, and about 41─46 % sediment yield reduction in the catchment. At 90 % confidence interval, family savings improved from US$4─US$ 270 under conventional rainfed to US$233─US$ 1 140 under supplemental irrigation. These results underscore the economic and environmental benefits that could be achieved by adopting the new crop management practices. A relationship between maize crop evapotranspiration and family savings under different crop management strategies was also derived for five farm typologies in the catchment

Rural poverty and Food insecurity mapping at district level for improved agricultural water management in the Limpopo River Basin

The Challenge Program on Water and Food (CPWF) Phase II for the Limpopo Basin Development Challenge (LBDC) project aims to develop methods, processes, and technologies to help resource- constrained smallholder farmers mitigate poverty and food insecurity through improved agricultural water management (AWM) strategies. The purposes of this paper are to: 1) Identify areas in the Limpopo River Basin with high levels of rural poverty and food insecurity; 2) Identify areas where AWM interventions are taking place; and 3) Check whether current activities of the CPWF in the Limpopo Basin are located in areas of need as per poverty profiles and geographical location of smallholder farms. The generated poverty and food insecurity maps were based on food security surveys and estimates of consumption or income-based welfare outcomes at the district level from 2003–2013. Based on existing district level poverty and other relevant data in the basin, the study shows that the LBDC study sites are located in poor areas in the Limpopo Basin, and poverty reduction efforts should prioritize vulnerable female and child-headed households as they are the most negatively impacted by poverty and food insecurity in the four countries. Hence, with the overall aim of CPWF under LBDC to reduce poverty and food insecurity, and improve livelihoods, poverty indices should rank highly as one of the factors for project site selection. Poverty and food insecurity mapping plays an important role in identifying areas lagging behind in social and economic development, and also in facilitating targeted developmental programs such as education, health, access to credit, agricultural production support and food aid. However, it should be recognized that using district-level information often masks the existence of poverty pockets in otherwise relatively well-off districts, which could lead to poorly targeted AWM schemes. In addition, the poverty index is limited by the subjective nature of community-level and household-level factors that influence it, and this is reflected by the responses from research participants. Whereas a common poverty line for a particular time frame enables poverty comparisons across countries, local level poverty assessments, however, usually require more in-depth and diverse information that can be used in designing cost-effective and efficient anti-poverty programs and livelihoods enhancement opportunities. In order to achieve the research project’s goals of poverty and food insecurity reduction, and livelihood enhancement of smallholder farmers in the Limpopo Basin, it is of greater significance to understand trends in poverty rates rather than 1-year values at CPWF-LBDC study sites. Poverty maps that highlight areas marginalized by resource constraints help in setting priorities for developing technologies and in deploying resources where they are most needed and likely to alleviate poverty and food insecurity. This work provides background information on the Limpopo Basin

The challenge of integrated water resource management for improved rural livelihoods: Managing risk, mitigating drought and improving water productivity in the water scarce Limpopo Basin

The Challenge of Integrated Water Resource Management for Improved Rural Livelihoods: Managing Risk, Mitigating Drought and Improving Water Productivity in the Water Scarce Limpopo Basin: Integrated Water Resources Management (IWRM) is a systems approach to water management, based on the principle of managing the full water cycle. It is required, not only to balance water for food and nature, but also to unlock paths to sustainable development. A global hotspot area in terms of water for food and improved livelihoods is in the poverty stricken rural areas of water scarce semi-arid tropics, such as in the Limpopo basin. The improvement in resilience that the IWRM approach can impart to rural livelihood systems has been shown by a series of case studies in the Limpopo Basin

Effectiveness of agricultural water management technologies on rainfed cereals crop yield and runoff in semi-arid catchment: a meta-analysis

Multiple agricultural water management (AWM) technologies are being promoted worldwide in rainfed agro-ecological production systems, such as the Limpopo River Basin, to close the yield gap, enhance food security and reduce poverty, but evidences on yield gains and environmental impacts are varied. This paper conducts a review of the performance of AWM technologies against conventional farmer practices to produce adequate evidence on cereal yield and field runoff changes. With the interrogation of literature from 1980 to 2013 using seven AWM groupings, enough evidence was found that AWM technologies can deliver substantial benefits of increased crop yield and water productivity with reduced environmental impacts. Using random effects model, the standardized mean difference (SMD) of yield between AWM and control was 0.27, while SMD of water productivity was 0.46, indicating the effectiveness of the technologies (SMD > 0). Subgroup analyses showed greatest yield responses on silty-clay-loam, clay-loam and sandy soils compared to clay and loam-sandy soils, and higher yield increase under low rainfall regime (200–500 mm) than under high rainfall regime (500–800 mm). Large yield change variations for different AWM technologies present a huge opportunity for meeting the existing yield gaps and enhancing coping capacity in dry years and under climate change