This research study shows that ‘business-as-usual’ scenarios will have substantial production surpluses of rice, which dominates water use patterns in the country at present. However, the surpluses come at a considerable environmental cost, due to high levels of groundwater depletion. Bangladesh can mitigate potential groundwater crises by limiting rice production to meet the requirements of self-sufficiency. Increases in water productivity of both Aman (wet season) and Boro (dry season) rice production can help too. A carefully designed deficit irrigation regime for Boro rice can also increase transpiration, yield, water productivity and production, and reduce the pressure on scarce groundwater resources.

This research study shows that ‘business-as-usual’ scenarios will have substantial production surpluses of rice, which dominates water use patterns in the country at present. However, the surpluses come at a considerable environmental cost, due to high levels of groundwater depletion. Bangladesh can mitigate potential groundwater crises by limiting rice production to meet the requirements of self-sufficiency. Increases in water productivity of both Aman (wet season) and Boro (dry season) rice production can help too. A carefully designed deficit irrigation regime for Boro rice can also increase transpiration, yield, water productivity and production, and reduce the pressure on scarce groundwater resources.

Most of the world irrigation systems were developed on a step-by-step basis, over the centuries, and were designed for a long life (50 years or more), on the assumption that climatic conditions would not change in the future. This will not be so in the years to come due to the global warming and greenhouse effect. Therefore, engineers and decision makers need to systematically review planning principles, design criteria, operating rules, contingency plans and management policies for new infrastructures. In relation to these issues and based on available information, the report gives an overview of current and future (time horizon 2025) irrigation development around the world. Moreover, the paper analyses the results of the most recent and advanced General Circulation Models for assessing the hydrological impacts of climate variability on crop requirements, water availability, food security and the planning and design process of irrigation systems. Finally, a five-step planning and design procedure is proposed able to integrate, within the development process, the hydrological consequences of climate change | [A livello mondiale, la maggior parte dei sistemi di irrigazione è stata sviluppata gradualmente, nel corso dei secoli ed è stata progettata per lunghi periodi (50 anni o più) in base al presupposto che le condizioni climatiche non sarebbero cambiate in futuro. Questo non sarà più vero per i prossimi anni, per effetto del riscaldamento globale e dell'effetto serra. Perciò, i tecnici e i politici devono rivedere sistematicamente i principi di programmazione, i criteri di progettazione, le norme operative, i pianti di emergenza e le politiche di gestione per le nuove infrastrutture. In relazione a queste questioni e in base alle informazioni disponibili, il contributo fornisce una panoramica dello sviluppo presente e futuro (orizzonte temporale al 2025) dello sviluppo dell'irrigazione a livello mondiale. Inoltre, il lavoro analizza i risultati dei Modelli di Circolazione Generale più recenti e avanzati per determinare gli impatti idrologici della variabilità climatica sulle esigenze delle coltivazioni, la disponibilità di acqua, la sicurezza alimentare e il processo di programmazione e progettazione dei sistemi di irrigazione. Infine, viene proposta una procedura di programmazione e progettazione a cinque fasi, in grado di incorporare nel processo di sviluppo le conseguenze idrologiche del cambiamento climatico]

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.

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.

This report derives from the importance of water for irrigation to the question, how will additional food be produced as competition for scarce land and water resources increases? The International Water Management Institute (IWMI), Food and Agriculture Organization of the United Nations (FAO), and International Food Policy Research Institute (IFPRI) provide a partial picture of supply and demand for food supply and irrigation-water by 2025 and 2030. The World Bank initiated a validation exercise in cooperation with these agencies to ensure that the models: consider a balanced range of assumptions and scenarios; introduce additional assumptions and scenarios; and replace, or fine-tune, some of them. It attempts to introduce into the forecasts the possible impacts of additional policy interventions and to evaluate their likely effects on the global projections of agriculture-water supply and demand. The validation exercise provides a review of the existing model structure and components, the assumptions made, the scenarios, and scenario results. Model assumptions, scenarios, and results of the revised response from the IWMI, FAO, and IFPRI are given as a part of the validation exercise as well as assumptions made and scenarios developed under different criteria and issues as raised by the group of experts.

This report derives from the importance of water for irrigation to the question, how will additional food be produced as competition for scarce land and water resources increases? The International Water Management Institute (IWMI), Food and Agriculture Organization of the United Nations (FAO), and International Food Policy Research Institute (IFPRI) provide a partial picture of supply and demand for food supply and irrigation-water by 2025 and 2030. The World Bank initiated a validation exercise in cooperation with these agencies to ensure that the models: consider a balanced range of assumptions and scenarios; introduce additional assumptions and scenarios; and replace, or fine-tune, some of them. It attempts to introduce into the forecasts the possible impacts of additional policy interventions and to evaluate their likely effects on the global projections of agriculture-water supply and demand. The validation exercise provides a review of the existing model structure and components, the assumptions made, the scenarios, and scenario results. Model assumptions, scenarios, and results of the revised response from the IWMI, FAO, and IFPRI are given as a part of the validation exercise as well as assumptions made and scenarios developed under different criteria and issues as raised by the group of experts.

The attainment of food and water security rank high on the agendas of governments in the Middle East and North Africa (MENA) region and sub-Saharan Africa (SSA). Although the objectives are similar, the underlying drivers, resource endowments and opportunities for achieving them are different. Differences between two regions in natural resource endowment and investment capital stock can, in theory, lead to mutually beneficial trade to achieve desired objectives. Concerns about the recent food crises coupled with the disparity in land and water endowment and investable capital between MENA and SSA have led in recent years to investment in agricultural land in the latter by a number of MENA countries with the aim of producing food. At the same time, many SSA countries seek these investments to infuse capital, technology and know-how into their agricultural sector to improve productivity, food security and rural livelihoods. However, these recent foreign direct agricultural investments have to date performed poorly or have been abandoned without achieving the initial objectives of setting them up. Based on research conducted in selected sub-Saharan countries, this paper analyses the reasons for the failure of these investments. It then reviews a few successful agricultural investments by private sector companies with a long history of operation in SSA. Juxtaposing lessons distilled from failed and successful case studies, the paper argues that large-scale agricultural investments that take advantage of this accumulated knowledge are needed and do have a critical role to play. Such investments, when they also incorporate ecosystems management practices and smallholder inclusive business models in their operations, can serve as appropriate instruments to reconcile the food and water security objectives of both the MENA region and SSA, while promoting sustainable intensification of agriculture and improved rural livelihoods in SSA.