Water–Energy–Carbon Nexus Modeling for Urban Water Systems: System Dynamics Approach

A comprehensive water-energy-carbon (WEC) nexus model for an urban water system (UWS) using system dynamics is proposed to assist municipalities, urban developers, and policy makers for neighborhood water planning and management. The proposed model and decision support tool was developed for the operational phase of UWSs. The model was validated using historical water and energy consumption data (2005–2014) of Penticton (British Columbia, Canada). Spearman's correlation coefficients between water and energy, water and carbon, and energy and carbon were 0.94, 0.89, and 0.83, respectively, revealing highly significant interconnections. The energy for water was 11.1 MWh/ML, water for energy was 6,512 L/MWh, and carbon emissions were 124.4 kg CO2e/MWh from energy use and 120.8 kg CO2e/ML from wastewater processes. A Monte Carlo–based sensitivity analysis showed residential outdoor irrigation and water heating energy for showers and dishwashers have higher contribution to model variability. The intervention analysis reveals significant differences in savings in water, energy, and carbon for various water and energy-based interventions in UWSs and the developed tool is well capable for analyzing these dynamic savings.