This paper focuses on a collection of methods that can be used to analyze the water-energy-food (WEF) nexus. We classify these methods as qualitative or quantitative for interdisciplinary and transdisciplinary research approaches. The methods for interdisciplinary research approaches can be used to unify a collection of related variables, visualize the research problem, evaluate the issue, and simulate the system of interest. Qualitative methods are generally used to describe the nexus in the region of interest, and include primary research methods such as Questionnaire Surveys, as well as secondary research methods such as Ontology Engineering and Integrated Maps. Quantitative methods for examining the nexus include Physical Models, Benefit-Cost Analysis (BCA), Integrated Indices, and Optimization Management Models. The authors discuss each of these methods in the following sections, along with accompanying case studies from research sites in Japan and the Philippines. Although the case studies are specific to two regions, these methods could be applicable to other areas, with appropriate calibration.

Security measures of three resources; water, energy and food are analyzed for thirty two countries in the Asia Pacific region which are faced to Pacific Ocean, in terms of amounts of the resource, self-production, and diversity of sources of each resource. Diversity for all the three resources is also analyzed using surface water and groundwater for water sources; hydro power, geothermal power, solar, and biomass for energy; and cereals, vegetable, fruit, meat, and fish for food. We see high diversity of sources of water in the US and the Philippines, and a low diversity of sources of food in the US, Canada, and Indonesia. These security measures including water security show new hydrological insight for Asia-Pacific region.

Urbanisation will be one of the 21st century's most transformative trends. By 2050, it will increase from 55% to 68%, more than doubling the urban population in South Asia and Sub-Saharan Africa. Urbanisation has multifarious (positive as well as negative) impacts on the wellbeing of humans and the environment. The 17 UN Sustainable Development Goals (SDGs) form the blueprint to achieve a sustainable future for all. Clean Water and Sanitation is a specific goal (SDG 6) within the suite of 17 interconnected goals. Here we provide an overview of some of the challenges that urbanisation poses in relation to SDG 6, especially in developing economies. Worldwide, several cities are on the verge of water crisis. Water distribution to informal settlements or slums in megacities (e.g. >50% population in the megacities of India) is essentially non-existent and limits access to adequate safe water supply. Besides due to poor sewer connectivity in the emerging economies, there is a heavy reliance on septic tanks, and other on-site sanitation (OSS) system and by 2030, 4.9 billion people are expected to rely on OSS. About 62–93% of the urban population in Vietnam, Sri Lanka, the Philippines and Indonesia rely on septic tanks, where septage treatment is rare. Globally, over 80% of wastewater is released to the environment without adequate treatment. About 11% of all irrigated croplands is irrigated with such untreated or poorly treated wastewater. In addition to acute and chronic health effects, this also results in significant pollution of often-limited surface and groundwater resources in Sub-Saharan Africa and Asia. Direct and indirect water reuse plays a key role in global water and food security. Here we offer several suggestions to mitigate water and food insecurity in emerging economies.

Urbanisation will be one of the 21st century's most transformative trends. By 2050, it will increase from 55% to 68%, more than doubling the urban population in South Asia and Sub-Saharan Africa. Urbanisation has multifarious (positive as well as negative) impacts on the wellbeing of humans and the environment. The 17 UN Sustainable Development Goals (SDGs) form the blueprint to achieve a sustainable future for all. Clean Water and Sanitation is a specific goal (SDG 6) within the suite of 17 interconnected goals. Here we provide an overview of some of the challenges that urbanisation poses in relation to SDG 6, especially in developing economies. Worldwide, several cities are on the verge of water crisis. Water distribution to informal settlements or slums in megacities (e.g. N50% population in the megacities of India) is essentially non-existent and limits access to adequate safe water supply. Besides due to poor sewer connectivity in the emerging economies, there is a heavy reliance on septic tanks, and other on-site sanitation (OSS) system and by 2030, 4.9 billion people are expected to rely on OSS. About 62–93% of the urban population in Vietnam, Sri Lanka, the Philippines and Indonesia rely on septic tanks, where septage treatment is rare. Globally, over 80% of wastewater is released to the environment without adequate treatment. About 11% of all irrigated croplands is irrigated with such untreated or poorly treated wastewater. In addition to acute and chronic health effects, this also results in significant pollution of often-limited surface and groundwater resources in Sub-Saharan Africa and Asia. Direct and indirect water reuse plays a key role in global water and food security. Here we offer several suggestions to mitigate water and food insecurity in emerging economies.

This study explores the connectivity of upland farmers and downstream fishers through interlinkages of water, energy and food within the Dampalit sub-watershed of Laguna Lake, Philippines.The aim of the study is to yield policy relevant results to improve the status of the water resources and food products and to reduce possible user conflicts. Surveying 176 households mainly in the mid- and downstream areas elements and interlinkages of the local Water-Energy-Food Nexus (WEF-Nexus) were identified by the five capitals of the sustainable livelihood approach through a socio-ecological network analysis.Besides the innovative methodology, this research adds to the underserved local perspective in the WEF-Nexus research. The survey shows different livelihood profiles for the two groups and a lack of direct social links between them in the WEF-Nexus context. Also indirect links through consumption of the other group’s food products could not be identified. However, a large fraction of the population share the use of char coal for cooking, the Makiling groundwater for drinking and various household purposes and the Central Market in Los Banos for their food supply.

The Philippines currently relies largely on fossil-fuel based power generation (about 77 percent) and is expected to increase power generation from coal-based (fossil) plants to meet future energy demand, which would negatively affect environmental outcomes. Primary energy supply is expected to double between 2011 and 2030. The renewable energy potential is relatively high in the Philippines and could contribute to supply modern reliable energy services and improve energy security. The government’s energy reform agenda highlights the importance of access to more reliable energy using indigenous energy resources while minimizing imported fossil-fuel use in an optimal and cost-effective way. The feasibility of this type of diversification from fossil-fuel to renewable energy based power generation can be assessed by applying energy optimization models, such as MARKAL1/TIMES2. Application of a bottom-up energy optimization model can provide important insights into the implications of prospective conversion technologies that can be pursued by the Philippine government in a cost-efficient and effective way to ensure energy security and develop a low-carbon society. | Non-PR | CRP5; Phil-EWF; IFPRI2 | EPTD | CGIAR Research Program on Water, Land and Ecosystems (WLE)

The usual vulnerability assessment is often sectoral and hazard-specific. With the nexus approach on water, energy and food (WEF), it is recognized that these three sectors have interactions and synergies and tradeoffs in their activities. Security has five dimensions, namely: availability, accessibility, affordability, accessibility, quality and sustainability. This study involved developing and implementing an integrated vulnerability assessment (IVA) methodology and framework of WEF security nexus applied to a watershed. The framework considered the watershed with three sub-systems of ecological, energy and food interacting with water as the common element. The same concept of vulnerability assessment was used for IVA as a function of exposure, sensitivity and adaptive capacity. IVA was operationalized by identifying variables or parameters pertaining to relationships among WEF and inclusion of sectoral variables related to the various dimensions of security. Based on the study, IVA of WEF nexus is a more holistic approach in assessing vulnerability. IVA account for the relationships among the sectors, in contrast to the sectoral approach. Using the combined climate risks due to different hazards (intense typhoons, erratic rainfall, severe drought, and temperature rise) gives a broader coverage unlike the hazard-specific approach. Parameters used were applicable for IVA of the watershed area. Additional relevant variables can be included if data are available.

Feeding experiments were conducted to test the nutritional value of five marine phytoplankton species namely: Chaetoceros calcitrans, Tetrasemis sp., Dunaliella sp., Nannochloris sp. and Chlorella sp. isolated from panay , Philippines to the larvae of Penaeus monodon from nauplius to Mysis. Proximate analyses and determination fatty acid composition were made on the larvae were directly related to the level of Polyunsaturated fatty acids in the legal diets. Best results were obtained with Chaetoceros calcitrans, Tetraselmis sp. and Dunaliella sp as food.