Project No: 26201721

Title: Integrating Agent-based Exploratory Modeling and Spatial Optimization for Sustainable Promotion of Decentralized Water Systems

Prof. Zhongming LU


This project aims to advance the understanding and management of the sustainable promotion of in-building decentralized water conservation systems such as rainwater harvesting and greywater recycling. Decentralized water (DW) systems provide alternative water sources to supplement centralized water systems (i.e., centralized water supply system for delivering drinking water and centralized wastewater treatment system for collecting wastewater). In Hong Kong, the annual mean rainfall is 2,400 mm. Moreover, around 50% domestic freshwater used for bath and laundry can be collected for greywater recycling. The large-scale implementation of DW systems could facilitate the utilization of these plentiful greywater and rainwater resources, which reduce the total water demand, improve the reliability of water supply, and mitigate the environmental impacts of urban water consumption. The promotion of DW systems involves a complex and dynamic process, including 1) The decision of adopting a DW system is controlled by individual buildings as opposed to the water utility. Therefore, the number of buildings adopting the decentralization determines the scale of implementation; 2) On urban scale, geographical locations can affect whether DW systems are more environmentally sustainable and economically viable to supplement the services from existing centralized water systems. The potential negative impact of DW systems on the operation of existing water systems should be considered, as it decreases the flow of the entire system. These critical decisions or issues have not been well examined in managing the sustainable promotion of DW systems. Our research objectives include: 1) Examination of how decisions of buildings affect the market demand and spatial distribution of DW systems; 2) Identification of optimal selections of buildings to install DW systems; and 3) Evaluation of financial incentives that may effectively promote sustainable adoption. We will develop a new integrated approach through (1) studying the spatial patterns of adoption (i.e., which buildings will adopt DW systems) and diffusion (i.e., when buildings will adopt DW systems) using a spatial agent-based model (ABM) that simulates the decisions of buildings; (2) applying spatial optimization techniques to identify the optimal distribution (i.e., which buildings should use DW systems); (3) leveraging ABM and spatial optimization to design and evaluate financial incentives. A U.S. city and a Hong Kong New Town using freshwater for toilet flushing will be used to develop and verify our integrated approach. Ultimately, this proposed research will improve the decision-making process and support know-how of the sustainable promotion of DW systems in cities.