Multi-scale characterization of karst media is a fundamental prerequisite for accurate stability evaluation and collapse risk assessment in karst terrains, especially for the safety control of urban metro engineering. Taking the Huaxi South Parking Lot of Guiyang metro line 3 as a case study, this paper proposes an integrated framework for karst collapse risk assessment by coupling multi-scale geological characterization, hydrodynamic-mechanical coupling simulation, and spatial multi-factor analysis. A comprehensive dataset, including 339 borehole records, core CT scanning results, long-term hydrogeological monitoring data, and laboratory test results, was collected to conduct multi-scale characterization of karst media across macro, meso and micro scales, reveal the vertical zonation of karst structures, clarify the hydrodynamic triggering mechanism of karst collapse, determine the critical instability threshold, and reproduce the entire evolution process of collapse. The results show that negative-pressure suffusion induced by rapid groundwater level decline, with a critical pressure difference of ≤ −190 kPa, is the dominant trigger of karst collapse in the study area. The lowest stratum stability and highest collapse risk occur in the strata with an overburden thickness of 2–5 m and a karst cavity diameter of ≥ 3 m. The high-risk zones account for 2.3% of the total study area, and are mainly distributed in the southern part, while the overall site remains stable under normal hydrodynamic conditions. This study can provide theoretical support and technical reference for karst collapse risk prevention and control in urban metro engineering.

In Yuqia Basin, the climate is arid and the ecologic environment is fragile, and shortage of water resources has seriously restricted the sustainable development of local economy. In order to meet the needs of industrial and domestic water in the Yuqia Basin, numerical simulation was used to evaluate the groundwater resources and potential for exploitation. The results showed that the mathematical model and calculation parameters used were mainly in accordance with practical situation. The calculated value of the underground water level is consistent with measured value during the period of identification and validation. The total recharge of groundwater resources was 22.02×10⁴ m³/d, and the total drainage was 21.95×10⁴ m³/d at present. The Yuqia River leakage is the main supply source of groundwater. There is no significant effect on area of wetland when water source place exploited by 2.5×10⁴ m³/d at alluvial-diluvial fan of Yuqia River. After long-term exploitation, the spring flow reduces from 1.42×10⁴ m³/d to 1.01×10⁴ m³/d and wetland area reduces by 32.7% of original area. The calculation of water balance shows that it is safe to the Yuqia Basin, Da Qiadam Lake, the Mahai Basin at downstream of Yuqia River and wetland under the condition of water source place exploited by 2.5×10⁴ m³/d.