This definition better captures the complexity of cities today and in particular their interconnectedness with their hinterland and other administrative units. In the case of water policy, the functional approach relates to the catchment area where cities are located, which can help map centres of water demand (urban areas where most people live) and water supply (the surrounding environments where point sources are located). Overcoming the mismatch between administrative perimeters and hydrographic boundaries is a question of governance.