Integrated risk analysis of water-energy nexus systems based on systems dynamics, orthogonal design and copula analysis

Within specific cities or regions, water and energy are intimately and highly interwoven, forming water-energy nexus (WEN) systems. Such a nexus system is complicated, leading to the generation of coupled risks of water and energy resources. In this research, an integrated approach of systems dynamics, orthogonal design and copula analysis (IA-SOC) was developed for supporting risk analysis of WEN systems. Innovations of this approach includes: 1) the development of a method through coupling system dynamics and orthogonal design, and 2) the combination of Copula analysis for supporting interactive risk assessment of both water and energy resources. The proposed approach was applied in Jing-Jin-Ji (J-J-J) region to deal with risk analysis of WEN and promote coordinated development. The results showed that: 1) the established system dynamics models can be employed to predict the water and energy demands; 2) the orthogonal table L27(313) can be adopted to obtain the representative scenario combinations, which could be introduced into system dynamic models to obtain the water and energy demands over the planning period; 3) it was appropriate to employ Lognormal distribution to establish the marginal distribution function of water and energy resources, meanwhile the Bivariate Frank Copula function was adopted to construct the joint distribution function of WEN to quantify the inherent relationship between water and energy resources; 4) the demands for water and energy resources in J-J-J region over the planning period were [252.06, 290.7] billion m3 and [433.67, 477.02] million tons of standard coal equivalent (S.C.E.), respectively. Correspondingly, the shortage risks of water and energy resources were [0.938, 0.981] and [0.835, 0.936]; and 5) different scenario combinations were set to identify the controlled amount of water and energy demands. The results could provide reasonable policy recommendations on the risk analysis of water and energy resources to promote regional coordinated development.