Ecological Engineering Approaches to Improve Hydraulic Properties of Infiltration Basins Designed for Groundwater Recharge

Infiltration systems are increasingly used in urban areas for groundwater recharge. The reduction of sediment permeability by physical and/or biological processes is a major problem in management of infiltration systems often requiring expensive engineering operations for hydraulic performance maintenance. To reduce these costs and for the sake of sustainable development, we proposed to evaluate the ability of ecological engineering approaches to reduce the biological clogging of infiltration basins. A 36-day field-scale experiment using enclosures was performed to test the influences of abiotic (light reduction by shading) and biotic (introduction of the macrophyte <i>Vallisneria spiralis</i> (L.) or the gastropod <i>Viviparus viviparus</i> (Linnaeus, 1758)) treatments to limit benthic biofilm biomass and to maintain or even increase hydraulic performances. We coupled biological characterization of sediment (algal biomass, bacterial abundance, total organic carbon, total nitrogen, microbial enzymatic activity, photosynthetic activity, and photosystem II efficiency) with hydraulic conductivity measurements to assess the effects of treatments on sediment permeability. The grazer <i>Viviparus viviparus</i> significantly reduced benthic biofilm biomass and enhanced hydraulic conductivity. The other treatments did not produce significant changes in hydraulic conductivity although <i>Vallisneria spiralis</i> affected photosynthetic activity of biofilm. Finally, our results obtained with <i>Viviparus viviparus</i> are promising for the development of ecological engineering solutions to prevent biological fouling in infiltration systems

Data_FWB.xlsx

   We focused on the macrophyte communities living in particular freshwater ecosystems i.e. the ponds of the Iles Kerguelen, in the sub-Antarctic region. This model of freshwater ecosystem is especially abiotically constrained (cold climate), and its plant communities are remarkably species-poor, simplifying the study of plant-plant interactions. Specifically, we measured several abiotic variables of the ponds as well as species spatial patterns, interspecific interactions using the Log Response Ratio metric, and the functional composition of the community using aerial, root and clonal traits. We also determined the biomass of the whole macrophyte community.</p