Abstract: Based on the data collected from 67 zoobenthos sampling sites (13 reference sites and 54 impaired sites) in the Huai River Basin (Henan section) from April to May of 2015, we analyzed twenty candidate biological index values for distribution range, correlations and discriminability, and screened out total number of taxa, proportion of sensitive groups, biotic index, number of amphipods and mollusks, percentage of amphipods and mollusks, and percentage of dominant species to form a B-IBI index system for the Huai River Basin (Henan section). Methods of 3-score system, 4-score system, and ratio technique were separately used to uniformize dimensions of various parameters. We compared the accuracy of the three methods for their function in evaluation. Results showed that the health evaluation criteria established on the B-IBI values of all the sampling sites and dimensions of various parameters uniformized with the 4score system were superior to that based on the ratio method and 3score system. A health assessment standard of river ecosystem suitable for the Huai River Basin (Henan section) was established based on the calculated B-IBI value: >24, healthy; 18-24, sub-healthy; 12-18, fair; 6-12, poor; ≤6, extremely poor. 19.40% of the total 67 sampling sites were in healthy state, 26.87% in sub-healthy state, 32.84% in fair state, 10.45% in poor state, and 10.45% in extremely poor state. In Huai River Basin (Henan section), the B-IBI was significantly positively correlated with the redox potential, and negatively correlated with NH₄⁺-N. There was no significant correlationbetween the other water quality indicators and B-IBI. The correlation between B-IBI and water quality indices varied greatly among different rivers.

Key words: time lag, sap flow, diameter class, Robinia pseudoacacia, Quercus liaotungensis, soil water content