A factorial inexact copula stochastic programming (FICSP) approach for water-energy- food nexus system management

Abstract

In this study, a factorial inexact copula stochastic programming (FICSP) method is developed for planning the regional-scale water-energy-food nexus (WEFN) system. The FICSP cannot only deal with uncertainties expressed as interval and random parameters, but also handle the interdependence among correlated random variables. Moreover, the multilevel factorial analysis embedded in FICSP is able to reflect the main and interactive effects among uncertain parameters. The IFCCP approach was then applied to planning the WEFN system for the City of Jinan, Shandong Province, China. A FICSP-WEFN model has been established under consideration of various restrictions related to water and land availability, food and vegetable demands and other environmental constraints. The obtained results indicated that the surface water and groundwater availabilities would be highly correlated with their marginals fitted through the Gaussian distribution and their dependence described by the Gaussian copula. Under limited water resources, the corn cultivation would be prioritized but the increase of water resources tends to increase the wheat cultivation and reduce corn planting. Under the advantageous conditions where sufficient water resources are available, the additional water resources tend to be allocated to wheat and vegetables whilst corn cultivation would not be changed. Moreover, the surface and recycled water would be first utilized for crop production, with the remaining water requirements satisfied by groundwater. The results from factorial analysis indicated that the system benefits would be increased under the demanding conditions through increasing the joint risk level and also the violation risk for surface water availability or decreasing the violation risk of groundwater availability. Nevertheless, the increase in the violation risks under the advantageous conditions would not necessarily lead to increased system benefit, implying that the crop cultivation patterns may be influenced by other restrictions rather than the water availability. In general, the developed FICSP method cannot only generate desired management strategies for WEFN system under consideration of joint risks, but also help track the factors that make dominant impacts on the WEFN management practices.