Developing countries face a difficult challenge in meeting the growing demands for food, water, and energy, which is further compounded by climate change. Effective adaptation to change requires the efficient use of land, water, energy, and other vital resources, and coordinated efforts to minimize trade-offs and maximize synergies. However, as in many developing countries, the policy process in South Asia generally follows a sectoral approach that does not take into account the interconnections and interdependence among the three sectors. Although the concept of a water–energy–food nexus is gaining currency, and adaptation to climate change has become an urgent need, little effort has been made so far to understand the linkages between the nexus perspective and adaptation to climate change. Using the Hindu Kush Himalayan region as an example, this article seeks to increase understanding of the interlinkages in the water, energy, and food nexus, explains why it is important to consider this nexus in the context of adaptation responses, and argues that focusing on trade-offs and synergies using a nexus approach could facilitate greater climate change adaptation and help ensure food, water, and energy security by enhancing resource use efficiency and encouraging greater policy coherence. It concludes that a nexus-based adaption approach – which integrates a nexus perspective into climate change adaptation plans and an adaptation perspective into development plans – is crucial for effective adaptation. The article provides a conceptual framework for considering the nexus approach in relation to climate change adaptation, discusses the potential synergies, trade-offs, and offers a broader framework for making adaptation responses more effective. Policy relevance This article draws attention to the importance of the interlinkages in the water, energy, and food nexus, and the implications for sustainable development and adaptation. The potential synergies and complementarities among the sectors should be used to guide formulation of effective adaptation options. The issues highlight the need for a shift in policy approaches from a sectoral focus, which can result in competing and counterproductive actions, to an integrated approach with policy coherence among the sectors that uses knowledge of the interlinkages to maximize gain, optimize trade-offs, and avoid negative impacts.

A compromise programming based model has been developed for maximizing food production with minimum allocation of available water at watershed scale after meeting human, livestock and environmental needs under different scenarios. Agricultural water allocation in conjunction with available land resources under a set of constraints has been examined. The formulated model has the potential to analyze the implications of water availability on agricultural water allocation plans, and consequently food production. A case study in Indian Himalayan region, where despite abundant availability of water, rainfed agriculture is mostly practiced by majority of farmers with a primary objective of self-sufficiency in food production, well demonstrates the applicability of the developed model. Three distinct scenarios affecting water availability were considered. Analysis of imposition of fixed mandatory outflows of 20 to 70 % (as per water source) for satisfying environmental needs with present production mix revealed water scarcity within the study watershed ranging from 4 to 66 % across various quarters of an year, which necessitates optimum utilization of rainfed fallow land by allocating it to high value crops ginger and lentil (6 to 32 times more than existing allocation) on one hand, and drastic reduction (76 to 100 %) of area under all irrigated crops (except onion with 4–6 times increase) on the other, to achieve the conflicting objectives. The compromise plans also suggested increase (by 14 % in environmental watershed scenario) or decrease (by 29 % in degraded watershed scenario) in size of livestock population as per scenario based water availability. Overall, the compromise plans were successful in achieving a high percentage (>93 %) of ideal values of the objective functions, which were 155 to 170 % of existing food production and 71 to 85 % of existing water utilization across the scenarios. The proposed optimization model has the potential for application in identical agro-climatic settings to enhance food production in an environmental friendly manner.