Assessment and Influencing Factors of Water Supply Capacity and Water Resource Utilization Efficiency in Southwest China

China has been facing serious water scarcity, and improving the supply and utilization of water resources from the perspective of resource endowment, economic development and water infrastructure is of great significance toward sustainable water development. In this work, two index systems for evaluating the water supply capacity (WSC) and the water infrastructure construction level (WICL) were constructed; the water resource utilization efficiency (WRUE) was measured by applying a super slack-based measure model; the ordinary least squares and geographically weighted regression models were used to explore the heterogeneity of spatial relationships. The results showed that both WSC (0.15~0.67) and WRUE (0.25~1.18) had spatial heterogeneity. WSC was positively correlated with water resource accessibility and GDP per capita (R² = 0.406, p < 0.01), which represented water resource endowment and economic development, respectively. WRUE was positively correlated with GDP per capita but was negatively correlated with accessibility (R² = 0.654, p < 0.01). The relationship of WICL with accessibility and GDP per capita varied over the study’s area. We found that the WSC in the southeast, WRUE in the north and WICL in the south were mainly associated with water resource endowments. The WSC in the north, WRUE in the southwest and WICL in the north were mainly associated with the economic development level. Noteworthily, strengthening the construction of water conservancy is one of the effective ways to improve water supply. Suggestions on improving WSC and WRUE were provided based on different accessibility and economic conditions, to promote the sustainable development of water resources.