Temporal-Spatial Variations in the Economic Value Produced by Environmental Flows in a Water Shortage Area in Northwest China

Scientific and accurate assessments of the economic value produced by environmental flows are an important basis for the protection of environmental flows by means of economics. Because of the temporal and spatial variation characteristics of environmental flows, it is more appropriate to study the economic value produced by environmental flows using a temporal-spatial scale rather than static calculations. In the present study, we combine the major influencing factors to establish the temporal-spatial calculation methods of the economic value produced by environmental flows using the assessment techniques of resources and environmental economics. The results obtained for the Wei River show that the annual variation range of the total economic value is CNY 0.30-0.42 billion, and the unit economic value is 0.86-6.40 CNY/m(3) during the non-flood season ranging from the years 1980 to 2017. In general, the monthly variation in the total economic value ranges from CNY 0.04 to 0.08 billion, and the unit economic value is 0.94-14.34 CNY/m(3). Based on this result, the variation tendency of the total economic value is consistent with the changing trend of the environmental flows occurring in the river; however, the unit economic value presents a reverse pattern. Furthermore, the deficiency of environmental flows can lead to a significant increase in its unit economic value. This method presents a dynamic, small temporal-spatial scale assessment of the economic value produced by environmental flows. It can also provide theoretical support for the ecological compensation of environmental flow protection in rivers present in water shortage areas.