Abstract:

Taking Linjiang River，a branch of the Yangtze River，as the research objects to study eutrophication problem in branch backwater region.Based on the monitoring data of chlorophylla concentration and water quality in the middle reach of Linjiang River backwater region from Oct.2007 to Sept.2008，chlorophylla concentration trend were analyzed，the correlation analysis between chlorophylla concentration and its influencing factors was made.According to the results of correlation analysis，a multiple stepwise regression model between chlorophylla concentration and its influencing factors was constructed.The chlorophylla concentration in Lingjiang River backwater region had a high level from the first ten days of May to the last ten days of September，the variation range was 227～661 mg/m3.Chlorophylla concentration was affected by some influencing factors together.The relationship between the chlorophylla concentration and water temperature，velocity of flow，diaphaneity，COD，TP displayed significant positive linear correlations，but not significantly related with TN.The multiple stepwise regression model which used water temperature，velocity of flow，TP as independent variable and chlorophylla concentration as dependent variable was constructed.The result of model initial validation indicated that the model can be used to describe the change of chlorophylla concentration in Linjiang River backwater region.The research result showed that decreasing phosphorus content would be the key work for preventing and controlling the eutrophication of Linjiang River backwater regions in May and June.

Key words: branch/ backwater region/ chlorophylla/multiple stepwise regression model