Use of water-retention additives to improve performance of green roof substrates

Abstract

Green roofs provide an opportunity to make our cities more liveable by reducing the impact of urban stormwater runoff through the combined effects of substrates (growing media) absorbing rainfall and plants using water. Stormwater retention is determined by substrate s ability to absorb and store water (water holding capacity; WHC) and supply it to plants (plant available water; PAW). As green roof substrates are largely mineral-based with minimal organic matter, water-retention additives might provide improved stormwater and plant performance. We evaluated the effects of adding biochar, silicates and hydrogels on WHC, PAW, permanent wilting point and bulk density of a scoria-based green roo..