Present day, 1.1 billion people face the lack of water; 1.3 billion people cannot access modern energy and 1.02 billion people are still starving. Meanwhile, the number of human population keeps increasing and this will induce the water, energy, and food scarcity in the future even worse. Increasing the stock or finding new alternative resources of water, energy and food individually is the most practical way to avoid the scarcity. Behind this improvement, it must be realized that these resources are connected each other. Water needs energy to be treated and distributed; in opposite way energy production requires water for cooling system or as the sources in hydropower plant. Food is in needed water and energy for growing, producing and delivering. Food can also become new energy source from biofuel but the food intensification will deteriorate water quality. Therefore, the integrated development and management, known as Water-Energy-Food (WEF) Nexus, is needed to reach the balance and optimal development.
Fulfilling the human need faces another challenge when the climate change influences the availability of these resources. Many researchers report that climate change causes increase in the earth temperature alters the rainfall pattern and magnitude which affect the safe water availability. Further, it can affect the food and energy production. Taking an inappropriate use of water, energy and food will threaten the amount of resources itself. As it is a complex and complicated interconnection, it is difficult to determine the appropriate uses solely based on human judgment. Many researchers have developed computer models to simulate the correlation between each element and aid the decision maker. Due to its complexity, most of models only focus on one or two elements such as water-energy or water-food and put other element as the secondary parameter. This study provides overview of the WEF Nexus and inter-connections among the three elements. Furthermore, we will envision a development of an evaluation model that can simulate and optimize the use of water, energy and food efficiently under the climate change condition. If succeed, this model could be a decision support system for government or stakeholder to implement a regulation related to efficient use of water, energy and food.