ABSTRACT This paper presents essential concept of reconstruction of integrated regional water resources systems (IRWRS), basic status of urban water supply in China, and a case study of solving urban water issues induced by unitary water source through reconstructing IRWRS. Integrated regional water resources systems are defined as water resources systems that consist of water source subsystems, water project subsystems, water utilization subsystems, water management subsystems and the environment of the systems. Lack of enough water sources with sufficient quantity and proper quality is recognized to be one of the most crucial stresses to urban water security. Integrated regional water resources systems with multiple water sources are regarded as an important solution to unitary water source induced urban water scarcity and pertinent issues. The results from the Xi'an Water Resources System show that urban water supply capacity and reliability is capable of being significantly improved through reconstructing IRWRS. KEYWORDS Integrated regional water resources system (IRWRS); multiple water sources; water scarcity; water supply capacity and reliability; unitary water source, urbanization
