Read the passage below carefully:
Rapid urban expansion across coastal West Africa has severely degraded natural wetland ecosystems that historically served as crucial buffers against municipal flooding. In response to increasing seasonal inundation, urban planners initially prioritized hard engineering solutions, such as concrete drainage channels and seawalls. However, these artificial conduits often accelerated runoff velocity and transferred flood risks downstream to vulnerable peri-urban settlements. Contemporary ecological assessment demonstrates that restoring degraded wetland vegetation offers a far more resilient and cost-effective flood mitigation strategy. By slowing surface runoff and facilitating natural groundwater recharge, restored wetlands effectively attenuate peak flood discharges. Furthermore, integrating green infrastructure with existing municipal drainage networks provides auxiliary socio-environmental benefits, including biodiversity preservation and urban microclimate regulation. Consequently, urban water policy must transition from defensive infrastructure toward holistic ecological restoration.
Based on the passage, arrange the following central arguments in the logical sequence that reflects the author's overall line of reasoning from beginning to end.
- 1Urban expansion degraded natural wetlands that previously mitigated coastal flooding.
- 2Conventional engineering interventions failed by shifting flood vulnerabilities downstream.
- 3Ecological assessments revealed green infrastructure as a superior method for regulating water flow.
- 4Municipal water governance should pivot toward holistic ecological restoration for long-term urban resilience.