Study On The Impact Of Dam Construction On River Ecosystem

Rivers are an important carrier of freshwater resources.For many years,humans have built water conservancy projects on rivers for economic benefits,which have caused serious damage to river ecosystems.However,due to insufficient research on river ecology itself and improper management,the research on damaged river ecosystem has not received much attention.In this paper,the impact of dam construction on the spatial distribution and temporal dynamics of river benthic animals was studied with the small dams in Xiangxi River Basin,and the health status of river ecosystems was evaluated by the benthic integrity index.The main research contents and results are as follows:(1)Analysis of benthos data collected for dam construction shows that the community structure is from upstream to downstream,and the relative abundance of Thysanoptera is gradually reduced,while the number of eyes is gradually increasing.The S1 sample of the dominant species is Nemoura sp.,S2 and S3 are Epeorus sp.,and S4 and S5 are Baetiella sp.The biodiversity of each plot showed a trend of decreasing from upstream to downstream.According to analysis of variance,there was a difference between the source region and the area affected by the dam(P<0.05).The functional feeding groups has obvious changes in the seasons.The source of the spring is the scraper(SC)as the main dominant group in the spring,and the tearer(SH)is the main in summer,autumn and winter.In the downstream areas affected by the dam,the four seasons are dominated by scrapers(SC).(2)Through the analysis of the results of drifting benthic community structure,the research shows that the vertical connectivity of the river is damaged by the construction of the dam,and the community structure of each sample is different.The number of species,the number of individuals,and dominant species all showed a trend of decreasing from upstream to downstream.The biomass and drift density in the source area are significantly higher than in the downstream area.The number of species and the Margalef richness index showed a gradual decrease.(3)For the analysis of benthos data collected by fixed collection and drifting,it is found that there are differences between the dominant groups of the two.Affected by dam construction,groups suitable for drifting migrate downstream of the dam,while those with poor ability do not.Using the Biological Integrity Index B-IBI to evaluate the health of river ecosystems,the results show that the river ecosystem in the source region is the best,with a B-IBI score of 24.The area affected by the dam was significantly lower in scores,with a BIBI score of 14.Analysis of variance showed that the overall difference in the biological integrity index of benthic animals between the various samples was significant(P<0.05),and the difference between the four seasons was extremely significant(P<0.01).Through the analysis of the evaluation results,it is found that the dam has a continuous barrier effect on the river ecosystem.The research results of this thesis have enriched the research content of dam construction on river ecosystem.It is hoped that this study can provide a useful reference for the development of river ecology in China,and to rationally develop and utilize hydropower resources,protect river ecological environment,and make sustainable The development path provides certain theoretical guidance.