With the increasing population and accelerated urbanization, demands for water are rising for different sectors around the world, including in South Asia. Integrated water resource management (IWRM) offers a promising potential to address multifaceted water demands. This study therefore aimed to address this issue by (i) reviewing key issues related to water, land, and food in South Asian countries, (ii) exploring the prevalent irrigation management strategies in those countries, and (iii) examining the IWRM situation based on a Nepalese case study, and it proposes some options to support effective implementation of IWRM. South Asia, the home to 24% of the world's population with only 15% and 7% of the world's arable and permanent crop land and water resources, respectively, is the worst-affected region in the world from undernourishment. Surface irrigation is the dominant irrigation application method in the region, which incurs high water losses due to the lack of flexible water control structures in canal networks. The Nepalese case study revealed a lack of clear institutional arrangements to implement IWRM and disparate and conflicting views about IWRM. Creation and strengthening of basin-level water user organizations, technological improvements, and awareness-raising activities are some potential ways forward to implement IWRM.

Introduction: Implementing Integrated Water Resources Management requires balancing conflicting goals, and the effects on developing countries, which have a poor institutional capacity for change, and suggests a slower pace of integrated water resources management. The growing population of the world, especially in developing countries on one hand, and the need to provide food for this population, on the other hand, have not been the result of overreaching of resources. In this manner, the continuation of an untapped harvest of resources will endanger the sustainability of the region in the near future. Food production is largely depending on the water so that 70 to 80 percent of the water extracted from resources is consumed for irrigation, which is the reason why irrigated cultivation is regarded as inefficient consumers. Understanding how to extract, manage and consume water is the key to solve this problem. On the other hand, the health and safety of communities and agricultural production require energy. Principally in irrigation, it is not possible to extract water without consuming energy. Seeking to establish the goals of the third millennium of the United Nations, researchers have presented a variety of interdisciplinary approaches to achieve a dynamic balance in the food production and consumption of resources, most notably the approach of Water, Energy and Food (WEF) Nexus. Considering the limitation of the resources which is increasing day by day. This approach causes productivity increase by integrating water, energy and food cycles. Managing water, energy and food, despite the inherent systemic differences, are very similar, due to the close relationship between the system perspective and their interaction with each other, a new concept is now called a Nexus approach. This viewpoint describes the interconnected nature and the interplay of the three sectors.Materials and Methods: This research was carried out in Sefid-Rud dam Irrigation and Drainage Network. Sefid-Rud basin is located in the Guilan province, which is benefits from high precipitation, but factors such as dams construction in the upper reaches of the Sefid-Rud dam, the timely inconvenient precipitation and the lack of infrastructure to harvest the runoff, causes water shortages in the area. It is worth mentioning that 50% of the Guilan households have engaged in rice cultivation and more than 70% of the lands are located in the irrigation and drainage network of the Sefid-Rud dam. Hence, reducing rice cultivation in this region will have a great impact on economic and social life. Managing a Nexus approach to provide WEF security requires integrated and analytical approaches that can identify cross-sectoral exchanges, cost-effective planning, policy, and strategy management. Therefore, in this study, WEAP and LEAP software were used for managing water and food resources and managing the energy sector in Sefid-Rud irrigation and drainage network, respectively. Then, the integrated water resources management in the area was addressed by establishing a linkage between these two applications. In the first part of this study, the parameters output such as net water demand, water resources share for each demand node, unmet demand and the coverage regardless of the energy sector were compared.Results and Discussion: The results reveal that the annual water requirement of the Sefid-Rud irrigation and drainage network in 2016 with the NEXUS approach estimated about 8 million cubic meters more than the non-NEXUS approach. Agriculture is the most water-consuming node in the region and there are lots of dependencies on rice cultivation as the most water-consuming crop in the Guilan region. The next step aims to balance the supply and demand, the unmet demand at the agricultural section in the Foomanat, Central and East areas under various management scenarios. These scenarios are including dredging, increase the efficiency of transmission and distribution channels of irrigation and drainage networks, and eliminating unauthorized wells were evaluated.Conclusion: By examining the results of the applied management scenarios mentioned above, the 30% increase in the efficiency of transmission and distribution channels of irrigation and drainage networks in Sefid-Rud has the greatest impact on meeting the demand and reducing the unmet demands of triple areas. As a result of the 30% efficiency improvement scenario, decrease the agricultural demands of the Foomanat area, the central area, and the east (about 29.1, 84.5 and 62.1 million cubic meters, respectively) more than the reference scenario.

The water, energy and food nexus (WEF nexus) is currently quite popular in environmental management. The concept found a fertile ground in science and policymaking, but there is no consistent view on the meaning of integration within the nexus. Here, a wealth of publications is reviewed in an endeavour to: (1) reveal the lines of justification for the need of the WEF nexus debate and (2) identify the range of tools for analysing the interdependent resource issues of the nexus using an integrated framework of science and policy. There are three drivers behind the emergence of the nexus thinking. These are a) increasing resource interlinks due to growing scarcities, b) recent resource supply crises, and c) failures of sector-driven management strategies. Evaluation of the WEF nexus integrative debate can be carried out using four key criteria, namely ability to change current policy debates, issue and thinking novelty, practicability and measurability, and clearness and implementation roadmap. It is clear that, although the nexus has been quite successful in changing policy debates, issue prioritization is missing and seems to be left to specific case studies and policymakers' choices. There is a high need for ‘incorporation’ and ‘cross-linking’ of issues between the three resources. In this regard, nexus governance is the missing link in the nexus debate.

In this study, we focus on water quality as a vehicle to illustrate the role that the water, energy, and food (WEF) Nexus perspective may have in promoting ecosystem services in agriculture. The mediation of water quality by terrestrial systems is a key ecosystem service for a range of actors (municipalities, fishers, industries, and energy providers) and is reshaped radically by agricultural activity. To address these impacts, many programs exist to promote improved land-use practices in agriculture; however, where these practices incur a cost or other burden to the farmer, adoption can be low unless some form of incentive is provided (as in a payment for ecosystem services (PES) program). Provision of such incentives can be a challenge to sustain in the long term, if there is not a clear beneficiary or other actor willing to provide them. Successfully closing the loop between impacts and incentives often requires identifying a measurable and valuable service with a clear central beneficiary that is impacted by the summative effects of the diffuse agricultural practices across the landscape. Drawing on cases from our own research, we demonstrate how the WEF Nexus perspective—by integrating non-point-source agricultural problems under well-defined energy issues—can highlight central beneficiaries of improved agricultural practice, where none may have existed otherwise.

In this study, we focus on water quality as a vehicle to illustrate the role that the water, energy, and food (WEF) Nexus perspective may have in promoting ecosystem services in agriculture. The mediation of water quality by terrestrial systems is a key ecosystem service for a range of actors (municipalities, fishers, industries, and energy providers) and is reshaped radically by agricultural activity. To address these impacts, many programs exist to promote improved land-use practices in agriculture; however, where these practices incur a cost or other burden to the farmer, adoption can be low unless some form of incentive is provided (as in a payment for ecosystem services (PES) program). Provision of such incentives can be a challenge to sustain in the long term, if there is not a clear beneficiary or other actor willing to provide them. Successfully closing the loop between impacts and incentives often requires identifying a measurable and valuable service with a clear central beneficiary that is impacted by the summative effects of the diffuse agricultural practices across the landscape. Drawing on cases from our own research, we demonstrate how the WEF Nexus perspective—by integrating non-point-source agricultural problems under well-defined energy issues—can highlight central beneficiaries of improved agricultural practice, where none may have existed otherwise.

Sustainable agricultural intensification requires irrigation methods and strategies to minimize yield penalties while optimizing water, land and energy use efficiencies. We assessed, from a silo-based and integrated water-energy-food (WEF) nexus perspective, the performance of irrigation technologies in different agro-climatic regions. Secondary to this, we assessed the impact of adopting systematic approaches such as the WEF nexus on improving efficiency in irrigated agriculture through irrigation modernization. The evidence-based perspectives of silo-based performances individually considered the metrics of yield (Y), water use efficiency (WUE), and energy productivity (EP). The WEF nexus approach applied sustainability polygons to integrate the three metrics into a nexus index representing the holistic performance of the irrigation technologies. Silo-based performance in temperate regions suggests net gains for WUE (+1.10 kg m-3 ) and Y (+6.29 ton ha-1 ) when transitioning from furrow to sprinkler irrigation, with a net loss in EP (-3.82 ton MJ-1 ). There is potential for a net loss on EP (-3.33 ton MJ-1 ) when transitioning from furrow to drip system in temperate regions. The best performance of irrigation technologies in dry regions in water, energy and food silos was achieved by sprinkler, drip and furrow irrigation systems, respectively. Thus, appraising irrigation technologies from a silos perspective promotes individual silos, which renders an unsustainable picture of the performance of irrigation systems. The integrative WEF nexus approach successfully highlighted the trade-offs and synergies in the nexus of water, energy and food in irrigated agriculture. Drip irrigation led all irrigation technologies in WEF nexus performance in dry (21.44 unit2 ), tropical (23.98 unit2 ), and temperate regions (47.28 unit2 ). Overall, the irrigation modernization pathway to drip technology from either furrow or sprinkler systems improves irrigated agriculture’s WEF nexus performance in all three regions for more crop per drop per joule per hectare under climate change. This can promote inclusive and sustainable irrigation development within the planetary boundaries.