EFFECTS OF ARTIFICIAL STORMWATER INFILTRATION ON URBAN GROUNDWATER ECOSYSTEMS

Abstract

Urban groundwater is commonly recharged artificially by stormwater runoff. This paper focuses on the effects of artificial stormwater infiltration on groundwater ecosystems using data from a specific study site. It is demonstrated that at this site artificial stormwater infiltration increased local fluxes of organic matter into the groundwater ecosystems. An insufficient residence time of stormwater in the vadose zone resulted in organic matter reaching the water table and subsequent oxygen consumption. The invertebrate assemblages in the underlying urban groundwater system were enhanced, probably because organic matter enrichment stimulated microbial production. Thus, urban groundwater biodiversity was higher under stormwater infiltration basins for shallow water-table conditions. Furthermore, groundwater biodiversity peaked at the water table, and decreased with depth. Invertebrate assemblage composition showed a vertical shift with depth below the water table, thereby suggesting that competition processes occur among taxa. This work highlights interesting ecological issues in groundwater and provides several recommendations for urban stormwater management.