Relevance of xenobiotics in artificial recharge with alternative sources of water (GABARDINE, EU)

This project is part of the from Göttingen coordinated EU project „Groundwater Artificial recharge based on alternative sources of water: Advanced integrated technologies and management (GABARDINE)”



Groundwater resources are the source of freshwater in many arid and semi-arid areas of the globe and particularly around the Mediterranean basin. Many are under extreme stresses and hydrologic deficits as the demand for freshwater by all the sectors (urban, agricultural and industrial) is steadily increasing, a combined result of population growth, industrial and agricultural development and improvement of living standards. Often water demands can be met only by practicing over-pumping, or pumping above the safe yield (the amount of water from rainfall that replenishes the aquifer). This practice usually disturbs the hydrologic equilibrium within the aquifer.
In many of these aquifers, there is a delicate coexistence between freshwater bodies and ancient saline or brackish ones. Any change in this fragile equilibrium can induce a migration and spreading of the brackish waters that may endanger substantial portions of the aquifer as persistent, sustainable sources of freshwater. Problems of this kind are encountered in many countries of the Mediterranean basin, Spain, Portugal, Greece, Italy, Palestine, Israel, and others, with various degrees of acuity. This situation is further aggravated by the impact of the global climate change on the precipitation patterns (spatial and temporal distribution), that are the major source of replenishment of aquifers and one of the key factors in their viability as sustainable and renewable water sources. In semi-arid areas, aquifers are replenished during relatively short rainy seasons, mainly between December and March. The precipitation regime, which is characterized by extreme fluctuations with regard to long-term annual average, will deeply affect their natural replenishment and subsequently their viability as renewable and sustainable freshwater reservoirs.
The impacts of hydrologic deficits, which are already felt today, have been translated into water supply shortages during dry seasons and water quality degradation (mainly steady increases in the salinity concentration). In order to solve this problem, alternative resources of water will be required in the near future. Desalination is obviously one of them. However, the desalination cost is still very high and prohibitive for agriculture (assuming no subsidies) and cannot be considered as a sole solution. Therefore, there is a great need to explore the availability of alternatives sources of water, of cost lower than desalination that could be exploited with the help of adequate and judicious planning. Since water demand and production do not always exactly balance, the expected alternative water volume will have to be stored. Surface storage would result in important losses by evaporation and leakage, while this water would be very sensitive to any type of contamination. Also, surface storage requires substantial areas, which in densely populated areas are not available. The alternative is underground storage by artificial recharge. Storage in underground reservoirs has an additional value of filtration (through the flow in the unsaturated zone), which can greatly improve the quality of the injected water.

For a sustainable water management concept it is important to understand the risk possessed by xenobiotics when using surface run-off or treated effluent as alternative sources of water.
One test site within Gabardine Thessaloniki (Greece) was especially selected and build to study the efficiency of xenobiotics removal by underground (saturated and unsaturated conditions) passage in a large scale field environment. By changing the operation scheme and considering water management aspects the optimum operation practise is to be established allowing for a safe removal/control of priority xenobiotics.

The site specific xenobiotics as well as their temporal change are investigated and their transport in the subsurface is monitored. The field investigation are accomplished by lab experiments under controlled conditions with field soil. Numerical modelling supports the process understanding.

For more information please contact tlicha@gwdg.de