Definition and calculation of hierarchical ecological water requirement in areas with substantial human activity—A case study of the Beijing–Tianjin-Hebei region

Abstract

In areas with high levels of human activity, there is often an imbalance between the supply and demand of water resources. This often means that ecological water requirements (EWRs) cannot be met in the long term, which leads to a deterioration in the ecological environment. To protect the ecological environment in areas with considerable human activity, research into hierarchical EWRs is essential. This paper first defined the hierarchical EWR concept (the minimum, suitable and ideal EWR) in areas with substantial human activity, and then developed a method to calculate this requirement over a large-scale area, taking the Beijing–Tianjin–Hebei region in China as a case study. Results showed that the minimum EWR in the Beijing–Tianjin–Hebei region was 42.81 × 108 m3, the suitable EWR was 54.37 × 108 m3, and the ideal EWR was 70.01 × 108 m3. The EWR of 13 cities in the region was calculated. The water requirement in the central area of Beijing–Tianjin–Hebei was significantly higher than that of the southern or northern areas. The EWR rate was used to characterize the EWR as a proportion of the surface water resources. The results showed that the minimum, suitable and ideal EWRs for Beijing–Tianjin–Hebei were 39%, 49%, and 63%, respectively. It was calculated that the annual average ecological water supply guarantee rate of Beijing–Tianjin–Hebei from 2015 to 2019 was 46%, which generally met the minimum EWR. This paper provides technical methods and a reference for calculating the EWR over large-scale areas with considerable human activity.