RDA analysis shows the effects of environmental parameters on the occurrence of dragonfly larvae after the dredging. Abbreviations: Aes cya − Aeshna cyanea, Aes mix − Aeshna mixta, Cal spl − Calopteryx splendens, Cal vir − Calopteryx virgo, Ery naj − Erythromma najas, Isc ele − Ischnura elegans, Gom vul − Gomphus vulgatissimus, Pla pen − Platycnemis pennipes, Sym vul − Sympetrum vulgatum.