Study on the ecological flow and its guarantee degree considering hydrological variation

Abstract

Human activities have altered the natural flow regime and exacerbated the consumption of water resources, leading to increasingly acute conflict between domestic and production water demands and ecological water demands. Scientific quantification of ecological flow and its guarantee degree under hydrological variation is an important topic for water resources allocation research. A comprehensive study of ecological flow and its guarantee degree is currently lacking. Thus, the improved monthly runoff frequency method (IMRF) and the guarantee degree of ecological flow based on the ecological requirements of fish (EFG) were proposed in this study. The quantity, timing, and quality of water required by fish during the migration period, spawning and feeding period, and overwintering period were considered in EFG. Taking the Jinsha River Basin as the study area, the results demonstrated that the annual runoff series was mutated in 1986, the overall hydrological alteration degree was 32.7 % and the ecological risk based on DHRAM was moderate in the basin. The suitable and basic ecological flows for each month were reliable and could serve as reasonable water quantity standards for the quantification of EFG. EFG of typical years (wet, normal, dry, and withered years) for the pre-change period were 86 %, 82 %, 67 %, and 63 %, respectively; and 79 %, 81 %, 73 %, and 71 % for typical years during the post-change period, respectively. The differences in EFG for the pre- and post-change periods were closely related to the variations in the hydrological regime of the river. The findings can provide a valuable reference for ecological protection and water resource management in the Jinsha River Basin, and may also be instructive for similar studies in other cases.

Keywords

• Suitable ecological flow
• Basic ecological flow
• Guarantee degree
• Ecological requirements
• Hydrological variation