System dynamics modelling to simulate regional water-energy-food nexus combined with the society-economy-environment system in Hunan Province, China

Nexus approaches provide an efficient way to analyze the dynamic evolution of the water-energy-food nexus (WEFN), yet there is a need to close the science-policy divide by making simulation models more practically relevant. This study incorporates society, economy and environment systems (SEE) into the WEFN, simulating a broad environmental sys-tem. A system dynamics model is constructed to simulate and dynamically track the development of the WEF-SEE sys-tem in Hunan Province, China. The developed model is applied to assess WEF-SEE system trajectories from 2021 to 2035 against nine policy goals formulated by the Hunan Provincial Government. Baseline results suggest that Hunan Province will have a surplus of grain production and will be in a state of self-sufficiency in water resources. The energy security situation is notas optimistic, with imports being required to meet demand. The sustainable devel-opment of the WEF Nexus will be constrained by resource shortages. As the future development of Hunan Province outpaces environmental protection policies, water pollution and CO2 emissions and are expected to increase. Intra-system trade-offs and synergies under the impacts of different policies indicate that the implementation of an indica-tive policy has the intended impact within its particular subsystem, but may lead to trade-offs in other subsystems. Due to system interconnectedness, the simultaneous implementation of multiple policies may increase or hinder progress towards certain goals. For example, expanding planting area increases food production, but increase agricultural water demand and water pollutant discharge, counter to water security goal and environmental protection goals. Cross-system impacts must be considered when choosing policies. This study advances environmental system analysis and evaluation, and contributes to practical policy recommendations, providing useful insights for Hunan Province, espe-cially considering potential trade-offs and synergies. Such information could lead to more effective, holistic environ -mental policy formulation.

Automated summary

This study incorporates society, economy and environment systems into the water-energy-food nexu,s and constructs a system dynamics model to simulate the development of the system in Hunan Province, China. The study finds that Hunan Province will have surplus of grain production and water resources, but imports will be needed to meet energy demand. As the development of the province outpaces environmental protection policies, water pollution and CO2 emissions are expected to increase. Trade-offs and synergies between different policy impacts indicate that the simultaneous implementation of multiple policies may affect progress towards certain goals.