In the context of global energy transition, concentrated solar power systems, particularly solar power towers, offer critical advantages in thermal energy storage and dispatchable electricity generation. However, their deployment in arid regions requires cooling solutions with minimal water consumption, where natural draft dry cooling towers face challenges of high capital costs and structural shadow effects in SPT plants. This study proposes a coupled cooling system that integrates finned-tube heat exchangers into the base of the solar power tower, leveraging the tower's structural height to generate buoyant airflow while eliminating standalone cooling infrastructure. A validated 1D model was developed for the coupled cooling system, incorporating a 0.5 m insulation layer at the tower top to minimize heat losses of the receiver. Comparative analyses under design and off-design conditions revealed that, despite the high-aspect-ratio structure introducing a trade-off between enhanced natural draft and elevated flow resistance, the 262 m coupled cooling system achieves 180.03 MW heat rejection, comparable to a conventional 120 m natural draft dry cooling tower with minimal terminal temperature differences. Further integration with a 100 MW recompression sCO2 power cycle achieved a cycle efficiency of 45.76 % through multi-objective optimization. Economic evaluation confirms 15.16 % lower levelized cooling cost versus mechanical draft system. The results confirm the technical viability of coupled cooling system as a water-efficient solution for arid-region CSP plants, addressing critical challenges in sustainable power generation.