Limited capacity currently exists to control long-term impacts of aquifer overabstraction and pollution in many locations (established but incomplete). Monitoring, modelling and managing aquifer systems are essential to implement sound aquifer and integrated water resources management. Salinization of aquifers resulting from subsidence in river deltas is a complex catchment and coastal urbanization issue (SDG 11), but saline intrusion into coastal aquifers can be controlled by managed aquifer recharge (well established). {9.9}
Efficient water use requires water-sensitive urban design of water infrastructure, including conjunctive surface and groundwater development and the promotion of managed aquifer recharge (well established). Together with investment in wastewater treatment and recycling, these approaches support water quantity and quality management, and promote drought risk reduction and resilient urban water supplies. At the same time, the provision of drinking water supply and sanitation services to all, as well as leakage control from bulk water supplies, are still challenges in many cities worldwide. {9.9}