SDG 17 underscores the pivotal and interconnected role of water, including its energy implications, in addressing challenges related to human well-being and sustainable development. Solar water pumps (SWPs) offer an important technological innovation exemplifying this water–energy–food–society nexus. As a comparatively new and eco-friendly approach to irrigation, SWPs have the potential to substantially benefit millions of smallholder farmers in sub-Saharan Africa (SSA). With costs for solar products steadily reducing, the small-scale SWP market is expected to grow in sales and expand into new territories. Overall, the region’s groundwater resources are known to be greatly underutilized and hence enable greater SWP adoption. This study assesses the possible risks to groundwater resources from SWP expansion to the year 2030. The current market environment is extremely heterogeneous across regions and countries. It is conservatively estimated that up to 10,000 units are sold each year, with the strongest markets found in East Africa. Around 100,000 SWP units are estimated to be in operation. For projected rates of annual growth spanning from 6% to 18%, along with intentionally high estimates of groundwater pumping, the upper limit on the quantity of available groundwater pumped by small SWP development to 2030 would vary from 0.4% to 0.6% at the SSA scale. Values in the regions vary from a low of <0.1% for Central Africa through to a high of 1.6%–2.1% for Southern Africa. Specific countries may generally support additional SWPs ranging from tens of thousands up to millions of units without negatively impacting on groundwater availability. Countries characterized by greater recharge and lower current groundwater use can accommodate greater numbers of SWP systems. Short-term threats to the availability of groundwater are assessed to be low over the short and medium terms. Over the long term, risks to groundwater may be greater than evaluated in this study should SWP growth rates exceed the projected range or if improvements in technology allow for stronger, small-capacity pumps to flood the market. To address long-term groundwater management challenges, key action areas have been defined that recognize the diverse conditions across the regions.

The objective of this study is to describe a target water&ndash;energy&ndash;food (WEF) nexus domain world including causal linkages and trade-off relationships between WEF resources and their stakeholders, and to develop a WEF nexus system map as an interdisciplinary tool used for understanding the subsequent complexity of WEF nexus systems. An ontology engineering method, which is a qualitative method, was applied for the replicability of the WEF nexus domain ontology and the map, because ontology engineering is a method of semantic web development for enhancing the compatibility of qualitative descriptions logically or objectively. The WEF nexus system map has three underlying concepts: (1) systems thinking, (2) holistic thinking, and (3) an integrated approach at an operational level, according to the hypothesis that the chains of changes in linkages between water, energy, and food resources holistically and systemically affect the WEF nexus system, including natural and social systems, both temporally and spatially. This study is significant because it allows us to (1) develop the WEF nexus domain ontology database, including defining the concepts and sub-concepts of trade-offs relating to WEF for the replicability of this study; (2) integrate the qualitative ontology method and quantitative network analysis method to identify key concepts serving as linkage hubs in the WEF nexus domain ontology; and (3) visualize human&ndash;nature interactions such as linkages between water, energy, and food resources and their stakeholders in social and natural systems. This paper also discusses future challenges in the application of the map for a science&ndash;policy&ndash;society interface.

The resolution adopted by the General Assembly of the United Nations on 25 September 2015 is symptomatic of the water-energy-food (WEF) nexus. It postulates goals and related targets for 2030 that include (1) End hunger, achieve food security and improved nutrition, and promote sustainable agriculture (SDG2); (2) Ensure availability and sustainable management of water and sanitation for all (SDG6); and (3) Ensure access to affordable, reliable, sustainable, and modern energy for all (SDG7). There will be tradeoffs between achieving these goals particularly in the wake of changing consumption patterns and rising demands from a growing population expected to reach more than nine billion by 2050. This paper uses global economic analysis tools to assess the impacts of long-term changes in fossil fuel prices, for example, as a result of a carbon tax under the UNFCCC or in response to new, large findings of fossil energy sources, on water and food outcomes. We find that a fossil fuel tax would not adversely affect food security and could be a boon to global food security if it reduces adverse climate change impacts.

Many countries are exposed to malnutrition within their population, either in the form of undernutrition or obesity leading to dire affects for human health. As a consequence, a ‘Decade of Action’ was certified by the UN in 2016 to promote the need to end all types of malnutrition. Within food security objectives, this study evaluates the possibility to maximise the nutritional value of agricultural output through the optimal allocation of water and energy resources. Using a hypothetical case study in Qatar, two complementary multi-objective mathematical models are developed to solve various scenarios. Firstly, the goal programming minimises the expected value of negative deviation from the desired target in food groups and nutrients. Secondly, the linear programming model increases the expected value of self-sufficiency percentage in food groups and nutrients. The results indicate the specific dependency of increasing the self-sufficiency of different nutrients on the increased production of dates group and fish group, implying that dates and fish can be considered strategic crops in terms of their contribution towards food security, owing to the fact that they require the least quantity of water and energy resources for production. As poultry and meat groups require the largest quantities of water and energy resources, optimal results do not favour their production. The optimal production mix that increases the satisfaction of nutrients at 40% of the food groups self-sufficiency satisfaction with the same amount of energy and water are as follows: 52378, 47085, 111303 tonnes of dates, milk and dairy products and fish groups respectively. This production mix will achieve 29.18%, 100%, 90.8%, and 2.5% satisfaction percentage of carbohydrates, protein, fats, and fibres respectively.

The resolution adopted by the General Assembly of the United Nations on 25 September 2015 is symptomatic of the water-energy-food (WEF) nexus. It postulates goals and related targets for 2030 that include (1) End hunger, achieve food security and improved nutrition, and promote sustainable agriculture (SDG2); (2) Ensure availability and sustainable management of water and sanitation for all (SDG6); and (3) Ensure access to affordable, reliable, sustainable, and modern energy for all (SDG7). There will be tradeoffs between achieving these goals particularly in the wake of changing consumption patterns and rising demands from a growing population expected to reach more than nine billion by 2050. This paper uses global economic analysis tools to assess the impacts of long-term changes in fossil fuel prices, for example, as a result of a carbon tax under the UNFCCC or in response to new, large findings of fossil energy sources, on water and food outcomes. We find that a fossil fuel tax would not adversely affect food security and could be a boon to global food security if it reduces adverse climate change impacts.

This paper attempts to understand and explore the problem of eutrophication in the context of agriculture with the help of a nexus perspective. Eutrophication is significantly linked to water and energy resources with theoretically well-defined trade-offs and threshold levels. While looking at the linkages between water and land resources comprehensively, our paper questions the present approach to designing and implementing watershed management, and analyses the effects of agricultural intensification, especially in dry regions. Eutrophication is the process by which excessive nutrient loads in water bodies lead to undesirable water-quality problems and the degradation of the overall aquatic ecosystem. Due to limited information and knowledge on water and soil quality in most countries, farmers continue to use fertilizers at an increasing rate and agricultural run-off has been carrying ever more nitrogen and phosphorus into water bodies. This is likely to become a vicious cycle of eutrophication affecting food and water security. Of late, soil- and water-conservation interventions, like watershed development, are further reducing run-off. It is argued that there is a need to rethink the assumptions under which watershed interventions are designed and implemented.