Exploring circular water options for a water-stressed city: Water metabolism analysis for Paju City, South Korea

For urban areas with limited water supplies, circular water strategies must be pursued to achieve water security goals. By tracking and balancing all water flows and their potential changes city-wide, urban water metabolism is a useful framework for exploring the effect of circular water strategies on performance. This study focused on a water-stressed city in South Korea, Paju. We first analyzed Paju's current and future water metabolism. We then explored the effects of 10 alternative water management options (implementing four circular water strategies separately or combined, in both conservative and maximum potential cases) on three aspects of water security (water resource efficiency, self-sufficiency, and supply diversification). In 2018, Paju had lower efficiency of water use than our benchmarking case, Seoul, despite Paju's higher level of supply self-sufficiency and diversity. By 2040, the expected growth and increasing water demand of the city would further increase its reliance on water imports, requiring expansion of water infrastructure. However, if Paju employs large-scale wastewater recycling and rainwater harvesting, and reduces its water loss and demand, the combined effect could offset the expected water supply increase between 2018 and 2040, as well as the associated need for additional infrastructure.