Investigations on water-permeability, load capacity and vegetation of different kinds of gravel turf

Surface sealing affects the natural functions of the soil, effectively impairing natural water circulation. Interference with hydrological cycles reduces and impairs the soil¿s drainage capacity, water permeability and water absorption potential, which in turn leads to greater risks of flooding and flood damage, because it prevents seepage and strains the sewage water systems. As a further consequence, the lack of seepage water lowers the groundwater tables, which cannot be enriched and renewed any more Gravel turf offers a multi-use surface for efforts to return urban surfaces to a more near-natural state. It represents an inexpensive technology to consolidate low-traffic areas (e.g. parking spaces, emergency access roads) as well as camp sites, picnic areas, exhibition centres, etc. A gravel turf surface provides an excellent alternative of high ecological value to conventional consolidation methods (especially asphalt), as it does not seal the surface. It is an open system, enabling transfer of oxygen and water between the soil and the atmosphere, permitting the natural water circulation of seepage and evaporation. In absorbing surface water, it relieves the burden on the sewage system and may even foster groundwater enrichment. A vegetation layer of resistant grasses and herbs allows water purification and buffering of harmful substances like petrol and oil before they enter the groundwater. Furthermore, evaporation influences the microclimatic conditions, increases humidity and lowers temperatures. The urban landscape becomes enriched with more green spaces and habitats. The project aims to improve the interaction of opposite parameters which make the construction and functionality of gravel turf difficult: water permeability to seep away even heavy rainfalls, water absorption capacity to allow the growth and survival of a vegetation cover and sufficient load bearing capacity to permit its use in traffic areas, so that it can withstand high traffic loads and multiple uses such as emergency access roads, parking lots, exhibition sites, cycle paths, etc. The object is a highly biodiverse vegetation which is resistant and has an excellent load-bearing capacity to provide good long-term usage, maintain a high ecological value and enhance the esthetical value of townscapes. By means of the results of the project precise recommendations for the successful installation of gravel turf will be compiled and thus its ranges of application will be extended.