Managed aquifer recharge in Austria as central element of integrated water resources management

Hans Kupfersberger, Joanneum Research Forschungsgesellschaft, Elisabethstr. 16, A-8010 Graz, Austria, hans.kupfersberger@joanneum.at
During the last 5 years the artificial groundwater recharge system of the municipal works Graz, Austria, which is in operation for almost 30 years, has been thoroughly examined. About 180 l/s of high quality water from pristine creeks (i.e. no pre-treatment necessary) are infiltrated at two sites via sand and lawn basins and infiltration trenches to sustain the extraction of approximately 400 l/s for drinking water supply. The investigations included (i) field experiments and laboratory analyses to improve the trade off between infiltration rate and elimination capacities of the sand filter basins’ top layer, (ii) numerical groundwater modelling to compute the recovery rate of the recharged water, the composition of the origin of the pumped water, the transient capture zones of the withdrawal wells and the optimization of recharge and withdrawal coordination and (iii) development of an online monitoring setup combined with a decision support system to guarantee reliable functioning of the entire structure. Additionally, the depreciation, maintenance and operation costs of the managed aquifer recharge system have been evaluated. It turned out that next to personal and housing infrastructure expenditures the maintenance costs of the water intakes at the creeks and of the preservation measures within the protection areas around the production wells are the most relevant cost items. Overall, total costs of artificial groundwater recharge amount to 0,15 €/m³ excluding pumping and distribution costs compared to a water price of about 1,5 €/m³ charged to consumers. Thus, also in predominantly humid regions managed aquifer recharge represents a viable and sustainable solution to overcome local shortages of drinking water supply which is expected to increase due to projected climate change impacts. Currently, the implications of building a hydro power plant adjacent to the recharge site are evaluated emphasizing the need for innovative solutions given only limited land resources.