平原河网地区闸控型河道生态修复效果评价

To confront the problem of repeated bloom after urban river control, the Xiaolaigang reach in Qingpu District of Shanghai was taken as the research area and the river ecological restoration effect was evaluated. Based on the combination of analytic hierarchy process and entropy weight methods, referring to relevant studies and field investigations, the evaluation index system was established by optimizing and selecting relevant indicators such as water quality, sediment, and bank protection. The results showed high nitrate content of (3.055±2.863) mg/L, which was significantly correlated with chlorophyll a (r=0.36, P<0.05), was an important potential risk factor for blooms in the gate-controlled plain river network. The aeration mode could be further optimized to create a suitable anoxic microenvironment and enhance total nitrogen removal by coupling sulfur and iron elements, in combination with the existing sluice pump engineering live water smooth flow technology. The sediment of river channel was mainly polluted by nutrient salt with the endogenous nitrogen content of (2 171.99±1 664.40) mg/kg. The existing submerged plant species were relatively simple, which was easy to produce filamentous algal blooms. The species of submerged plants could be increased, and the rational allocation could reduce the nutrient salt pollution of the sediment and enhance the stability of the aquatic ecosystem with submerged plants as the core. The purification and interception ability of rainwater runoff pollution by the slurry concrete rigid bank revetment was seriously insufficient. Therefore, the river channel could be properly widened, the ecological transformation of the bank revetment could be carried out, and reasonable filler matrix and vegetation allocation could be selected to strengthen the interception function of the bank revetment on non-point source pollution.