Abstract: Water security affects the healthy and sustainable development of regional social economy. Global climate change and human activities have put great pressure on water resources security. A system dynamics (SD) model involving water resources, water environment, and socio-economic systems was built to assess and predict the water resources vulnerability of Nandu River basin in 2010-2035, and the causes and mechanism of water resources vulnerability were expounded. The assessment index system and evaluation standard were constructed by using the analytic hierarchy process. Four scenarios, namely, conventional, technological innovation, economic priority, and comprehensive development scenarios were set in the model. Results unveiled that industrial water consumption, urban/rural water consumption, and GDP growth rate were positively related to water resources vulnerability, while sewage treatment rate and the tertiary industry/industrial ratio were negatively related to water resources vulnerability. The water resources in all the four scenarios went through three stages: moderately vulnerable, slightly vulnerable, and not vulnerable, displaying a downward trend in vulnerability. Such downward amplitude in scenario 4 was the largest, followed by scenarios 2, 1 and 3 in sequence. The overall vulnerability was the largest in scenario 3, with an average of 43.81, and the smallest in scenario 4, averaging 33.48. In conclusion, scenario 4, namely, the comprehensive development mode is the most suitable for the healthy development of Nandu River Basin.

Key words: water resource vulnerability, system dynamics, system flow, scenarios, assessment system, Nandu River Basin