Abstract: Eight metrics for quantifying current velocity gradients along horizontal or vertical directions were proposed, and water velocity and depth data of 285 transects were collected during December 2-10, 2005, in the reach from Gezhouba Dam to Honghuatao of Yangtze River byAcoustic Doppler Current Profiler (ADCP), to study the habitat diversity of this reach. The result showed that the major water depth in the reach between Gezhouba Dam and onghuatao was 4.71-12.04 m. The analysis on Kmean algorithm of transectaveraged velocity and eight metrics showed that the areas of types 7, 8 and 2 predominated over the other, together occupying 8866% of total area of the whole reach. The reach between Gezhouba Dam and Miaozui had the most diversified hydraulic environment. Rtype cluster showed that the eight metrics had no close relationships with the average current velocity of the transect, indicating that the areas with similar current velocity were not necessary to have similar spatial velocity gradients. Therefore, it was necessary to use these metrics to portray the character of the water current. ADCP has great potential for studying diversity of river current habitats and riverine ecosystem rehabilitation. However, data collecting criterion and data processing should be discussed further.

Key words: Photoinhibition, Thermal dissipation, P_max, Photosynthetic pigment, Eupatorium adenophorum