Spatial matching and flow in supply and demand of water provision services: A case study in Xiangjiang River Basin

Global climate change and increased human consumption have aggravated the uneven spatiotemporal distribution of watershed water resources, affecting the water provision supply and demand state. However, this problem has often been ignored. The present study used the Xiangjiang River basin(XRB) as the study area, and the Integrated Valuation of Ecosystem Services and Trade-offs(InVEST) model, demand quantification model,supply–demand ratio, and water flow formula were applied to explore the spatial heterogeneity, flow, and equilibrium between water supply and demand. The results demonstrated significant spatial heterogeneity in the upstream, midstream, and downstream regions.The areas of water shortage were mainly located the downstream of the Changsha–Zhuzhou–Xiangtan urban agglomeration, and the Hengyang basin was the most scarcity area. Affected by terrain gradients and human needs, water flow varied from-16.33 × 10^(8) m^(3) to 13.69 × 10^(8) m^(3)from the upstream to the downstream area, which provided a possibility to reduce spatial heterogeneity. In the future, measures such as strengthening water resource system control,sponge city construction, and dynamic monitoring technology should be taken to balance the supply and demand of water in different river sections of the basin. This study can provide references for regulating water resources allocation in different reaches of the basin.

Spatio-temporal Evolution and Flow of Water Provision Service Balance in Jinghe River Basin

Quantifying the whole process of ecosystem services from generation through transfer to use,and analyzing the balance between the supply and demand of regional ecosystem services are of great significance for formulating regional sustainable development strategies,realizing regional ecosystem management,and effective resource allocation.Based on the SWAT model,InVEST model,ArcGIS,and other software,this study analyzed the supply-demand balance of water provision services in Jinghe River Basin,a typical region located in the Loess Plateau,using multi-source data.This research then analyzed the spatial-temporal distribution pattern and spatial matching characteristics of the supply and demand of water provision services in Jinghe River Basin from 2000 to 2015.On this basis,a spatial flow model of water provision service was constructed,the flow rules(flow paths)of the water provision service were explored at the subwatershed scale,and the spatial scope of the supply area and benefit area were depicted.The results show that:(1)Water resource supply and demand in the Jinghe River basin both showed increasing trends from 2000 to 2015.(2)The supply-demand balance of water resources was generally up to the standard,however,there were significant differences between urban and rural areas.The supply-demand balances of the central urban areas of each county were relatively low,and even exceeded the supply in the lower reaches of the Jingyang River,such as Gaoling County,Qindu District,and Jingyang County.In rural areas,due to the small population and industrial distribution,coupled with a better ecological environmental base,the supply-demand balance was relatively high,such as Pengyang County,Lingtai County,Huachi County,Huanxian County,Ningxian County,and Zhenyuan County.(3)From 2000 to 2015,the spatial matching pattern of supply and demand in the Jinghe River Basin showed a trend of decline with fluctuations.In 2015,the supply-demand ratios of more than 60%of the subwatersheds showed trends of decline,and the proportion of under-supply area increased by 55.7%in 2015 compared with that in 2000.(4)The supply areas of water provision service in Jinghe River Basin are distributed in the upper reaches of the basin,and the benefit areas are Huating County,Chongxin County,Yongshou County,Chunhua County,Ganxian County,Liquan County,Qindu District,and others in the middle and lower reaches.