The runoff retention effectiveness of 10 extensive green roof (EGR) modules (100 mm substrate planted Sedum lineare Thunb.) were analyzed in Beijing for 22 rainfall events (2.4–46.4 mm) from 1 July to 30 September 2017. Differences between minimum inter-event dry periods, module scales, substrate hydraulic conductivity and depths, drainage layer types and rainfall characteristics were examined to study their correlation to the retention performance of EGRs. In general, EGRs with lower substrate hydraulic conductivity, deeper substrate and lower rainfall depth had higher runoff retention performance. By comparsion, no siginificant correlation was found between rainfall duration, prior dry period, average rainfall intensity, drainage layer type and EGR runoff retention rate. Analyses of variance (ANOVA) and Tukey tests supported these results. Low or moderate rainfall (25 mm) definitely affects the EGR retention performance of the next rainfall event.

Ship canals, which play a crucial role in facilitating transport, exert significant and long-term impacts on wetland ecosystems. For social and economic development, numerous countries have put forward plans for ship canals. This paper reviews the literature on the ecological effect of ship canals on wetland ecosystems, identifies research gaps, and suggests future research directions. Ship canals typically involve high construction intensity, usually including river regulation, ship locks, and water diversion for navigation. The ecological effects of ship canals on wetlands refer to changing wetland hydrological processes, degrading water quality, eliminating wetland botany, disturbing wetland animals, and increasing ecological threats. The cumulative impact can either alter the trend of ecological succession or degrade biodiversity. Thus, there is a need for further research to elucidate the mechanisms by which canals affect wetland ecosystems, enhance the practices for wetland protection associated with canals, and develop a robust evaluation system for green canal projects.