Quantification and classification of supply-flow-demand in the water supply services

The Yangtze River Basin (YRB), China. The supply-flow-demand process of water supply services (WSSs) directly affects the sustainable development of regional water resources. In this study, a large basin soil and water assessment tool (SWAT) model was constructed to simulate the supply of WSSs. The competitive and non-competitive water demands were evaluated, and the primary factors influencing water demand were identified. On the basis of the service path distribution network (SPAN) model, a new standard for classifying WSSs flows was introduced, five flow types were clearly defined, and the flow characteristics of WSSs were explored. The constructed WSSs supply and demand assessment model has good applicability in the YRB. Emphasizing non-competitive demand can help provide a more comprehensive assessment of the water supply and demand status. Both supply and demand clearly exhibit spatiotemporal heterogeneity. The total amounts of supply, competitive demand and non-competitive demand have increased by 36.88 %, 2.11 % and 11.5 % respectively. The flow order of the five flow types was: protection > gain > attenuation > non-loss > jam, and the flow rate of all types increased. The proposed classification and identification method for WSSs flow can be used to analyze the water resource status of a basin effectively and provide a scientific basis for the sustainable development of water resources in the YRB. • Water demands of socio-economic and natural-ecological systems were assessed. • The types of water supply services flow were classified based on flow paths. • A water supply services flow model at the basin scale was constructed. • Analyzed the various types of water demands and flow types of causes. • Classification of water supply services are essential for water security.