Assessment of Water Resources Carrying Capacity for Sustainable Development Based on a System Dynamics Model: A Case Study of Tieling City, China

Studies of water resources carrying capacity (WRCC) can provide helpful information about how the socio-economic system is both supported and restrained by the water resources system. As such, there is a need to develop better quantitative assessment methods to determine the potential maximum socio-economic growth within a catchment subjected to a given amount of water resource. An improved WRCC assessment method based on a system dynamics model (WRCC-SDM) is proposed in this paper. WRCC-SDM is built on synthesis simulations of coupling effects and feedback mechanisms within the society-economy-water compound system. The results can integrally represent system behaviors and states, and the evaluation of WRCC is achieved using this model. Moreover, an integrated indicator (Population-GDP-GDP per capita) is proposed to express the threshold value of WRCC. Based on the natural water resources supply capacity and associated socio-economic development potential, the concepts of critical WRCC and extreme WRCC are put forward. Critical WRCC represents the socio-economic scale that will cause total water demand to reach the maximum natural water resources supply capacity, while extreme WRCC reflects the socio-economic scale when the GDP growth rate constrained by limited water resources is zero. The methodology was applied to assess the water resources situation in Tieling City, China under different scenarios. The results indicate that: (1) Given the constraints represented by water resources, projected GDP growth tends to follow an S-curve growth pattern; and (2) Rapid population growth may lead to earlier and more severe water resources constraints.