Informing Equitable Water and Food Policies through Accurate Spatial Information on Irrigated Areas in Smallholder Farming Systems

Abstract

Accurate information on irrigated areas’ spatial distribution and extent are crucial in enhancing agricultural water productivity, water resources management, and formulating strategic policies that enhance water and food security and ecologically sustainable development. However, data are typically limited for smallholder irrigated areas, which is key to achieving social equity and equal distribution of financial resources. This study addressed this gap by delineating disaggregated smallholder and commercial irrigated areas through the random forest algorithm, a non-parametric machine learning classifier. Location within or outside former apartheid “homelands” was taken as a proxy for smallholder, and commercial irrigation. Being in a medium rainfall area, the huge irrigation potential of the Inkomati-Usuthu Water Management Area (UWMA) is already well developed for commercial crop production outside former homelands. However, information about the spatial distribution and extent of irrigated areas within former homelands, which is largely informal, was missing. Therefore, we first classified cultivated lands in 2019 and 2020 as a baseline, from where the Normalised Difference Vegetation Index (NDVI) was used to distinguish irrigated from rainfed, focusing on the dry winter period when crops are predominately irrigated. The mapping accuracy of 84.9% improved the efficacy in defining the actual spatial extent of current irrigated areas at both smallholder and commercial spatial scales. The proportion of irrigated areas was high for both commercial (92.5%) and smallholder (96.2%) irrigation. Moreover, smallholder irrigation increased by over 19% between 2019 and 2020, compared to slightly over 7% in the commercial sector. Such information is critical for policy formulation regarding equitable and inclusive water allocation, irrigation expansion, land reform, and food and water security in smallholder farming systems.

Optimal production areas of underutilized indigenous crops and their role under climate change: Focus on Bambara groundnut

“…Delineating accurate suitability areas for the cultivation of crops is essential under climate change as it improves decisions on crop production and irrigation development to promote food and water security (Magidi et al, 2021b;Hagos et al, 2022). However, the main drawback in achieving accurate statistics on cropped area and the most suitable areas for specific crops has been the lack of reliable input data at reasonably high spatial resolution.…”

“…Still, the extent to which they can bring relief to the stressed water resources is yet unknown (Mabhaudhi et al, 2018b). Tapping into groundwater also requires reliable energy resources, which brings to the fore the need for a water-energy nexus planning to enhance agricultural and water productivity (Magidi et al, 2021b).…”

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

“…In the case of South Africa, over 60% of the available freshwater resources are used in agriculture and mostly on 1.3 million hectares of irrigated area (Phakathi & Wale, 2018). This is happening when almost 98% of the available freshwater resources are already allocated, leaving little room for irrigation expansion (Magidi et al, 2021b). Yet, agriculture is under pressure to meet the food requirements of a growing population, and the country is the 30th driest country in the world with an average rainfall of between 460 mm and 840 mm per annum (Mahlalela, Blamey, Hart, Reason 2020).…”

“…Projections indicate that agricultural productivity will need to double from current production levels by 2050 to feed a projected population of about 80 million people in South Africa in the same period (Masipa, 2017). The challenges are exacerbated by climate change and scarce energy resources as rising temperatures result in increased evapotranspiration rates (Magidi et al, 2021b;Mpandeli et al, 2018). At the same time, climate change results in increasing rainfall variability, droughts, and floods, making the need to better manage water use in agriculture an urgent priority (Nhemachena et al, 2020).…”

“…Huge quantities of freshwater resources are already being used in irrigated agriculture, and the demand from the sector will only increase to continue producing enough food for the growing population (Magidi et al, 2021b). To counter the triple challenges of water scarcity, land degradation, and food insecurity, agriculture must become more crop-water productive, efficient, and environmentally friendly.…”