Public Service Facility Configuration in Less-Developed Counties Based on an Optimal Supply–Demand Accessibility Method

Global demographic shifts and rising population mobility have created a profound decoupling between dynamic population distributions and static public service facility configurations. This socio-spatial mismatch is particularly acute in less-developed counties, where the widespread “multi-local living” practices among rural residents have rendered traditional planning models based on static administrative quotas ineffective. This study uses Pucheng County, China, as a case study; we integrate mobile phone signaling data with complex network analysis to construct population flow networks that capture actual service demand and usage preferences. A demand-driven improvement of the traditional Optimal Supply–Demand Accessibility (OSD) model is proposed through flow-based supply adjustment coefficients and determines the coverage and accessibility of public service facilities at the county level to achieve optimization of their layout. The findings reveal: (1) Villages are classified into five types (high-inflow, inflow, balanced, outflow, high-outflow). (2) Within a 30 min walking radius, the service coverage rates of the three facility types improved by an average of 25 percentage points, with medical and elderly care facilities showing significantly greater improvements. (3) Accordingly, a “precise gap-filling + medical-care integration + mobile services” allocation model is proposed. The study provides a transferable framework for improving public service accessibility in regions characterized by high population mobility and service underprovision.