Research On Quantitative Methods To Ecological Instream Flow Requirements Of River

The quantitative research on ecological instream flow requirements of river is a key problem of water resource allocation, because it is a basic basis of limiting the greatest exploitation and utilization degree of water resource. On the basis of summarizing and analyzing former research results, comparatively deep researches to river ecological instream flow requirements theories and methods have been carried on in this paper.Firstly, the components, structure and function of river ecosystem under the scale of spatial and temporal have been analyzed. From five respects of Magnitude, frequency, timing, duration and the rate of change of element of hydrology, the ecological function of river regime has been discussed. The concepts of ecological instream flow requirements are given on the basis of summarizing the definition of domestic and foreign researches. According to river ecosystem integrity and continuum theory, the characteristic that the ecological instream flow requirements should possess have been analyzed.Secondly, in summarizing the quantitative methods of ecological instream flow requirements used extensively, and according to the theory of suitable habitats for aquatic organisms, a method based on ecological objectives has been discussed. In the studies of the section of Heyuan gauged station of Dongjiang in Guangdong province, common carp, the most important economic species, is regarded as indicating organism, and the results indicate that the suitable flow range for the critical period of common carp are from 105cms to 374cms. Finally, the ecological instream flow recommendations of the whole year in Heyuan station has been developed.Based on aquatic ecosystem integrity and restoration of flow regime characterization with important ecological functions, a method referred to as "Range of Variability Approach" to develop the rational ecological instream flow has been applied. The RVA identifies the statistical characterization of Indicators of Hydrologic Alteration(IHA) and Environmental Flow Components(EFC) of less altered flow regime as the dominating parameter.Lastly, a study is carried on upper river reaches of Dongjiang, and minimum and suitable ecological instream flow recommendations of different water years have been developed for Heyuan section. The results indicate that the ecological instream flow recommendations developed by RVA method could be better reflect the change characteristic among wet, average and dry water years and in a year.