Author(s): Ban Xuan; S. Panayiotis; Shi Wu-Rong
Linked Author(s):
Keywords: Spawning condition; Range of variability approach; Spearman correlation; Indicators of Hydrology; Hydrologic regime alteration
Abstract: The Spearman correlation method, together with the traditional range of variability approach (RVA), were used to identify the Indicators of Hydrology (HIs) that are highly correlated with the biomass of four major Chinese carps (FMCC). These were selected from a group of 32 initially considered HIs. These highly correlated HIs decreased greatly from the High or Middle RVA categories to the Low RVA category after the impoundment of Three Gorges Dam (TGD), except for the base flow. The alterations of the fall rate, 7-day max, 30-day max of discharge and the fall rate of water level have positive impacts, while high pulse duration and rise rate, monthly water level in July, and other max-relevant water level have negative impacts on the spawning success of FMCC. This study suggests that the FMCC biomass can be enhanced by decreasing the base flow and allowing for high pulse releases during the spawning period that have sufficiently long duration, rapidly rising and gradually falling discharge rates. More specifically, the water volume released by TGD should result in a flood having duration longer than one day and discharge exceeding 20,000 m3/s at Yichang station. The rise rate for this high pulse should be more than 730 m3/s/day, and the fall rate should be less than 1,600 m3/s/day. The present results provide additional guidance for improving the ecological conditions for FMCC through appropriate adjustments in the current TGD operation.
Year: 2018