Gabardine

(Groundwater Artificial recharge Based on Alternative sources of wateR: aDvanced  INtegrated technologies and managEment).

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.

Strategic objectives :

· Explore the viability of supplementing existing water resources in semi-arid areas with alternative sources of water that could be exploited in the context of an integrated water resources management approach. Such alternative water sources are surface water surpluses generated during rainy seasons (runoff water, flashfloods etc.), treated effluent that is continuously produced in urban areas, surpluses of desalinated water, that are expected in periods of low water demand or high water availability (from natural resources) and exploitation of saline water bodies that could be used for adequate agricultural practices or used a raw material for low-cost desalination. Obviously, the exploitation of such type of water sources precludes the availability of seasonal and long-term storage of large quantities of water.

· Consider aquifers as the primal facility for the storage of these alternatives water sources and investigate techniques for their artificial recharge and injection of the produced alternative water, including a monitoring of water quality and purification by natural attenuation and filtration processes.

· Evaluate and quantify the potential impact of degrading factors, such as climate change, changes in the quality of water, salt water etc on the global quality and usability of the resource, by developing tools for risk mapping, for modeling and for monitoring, and to propose measures for preventing or minimizing, mitigating, their impact.

Research strategy :

Development of an integrative methodology for: 1) the evaluation of aquifer water budgets as a basis for the determination of hydrologic deficits; 2) mapping of areas according to groundwater quality and vulnerability to contamination factors; 3) areas potentially suitablefor seasonal and long-term storage; 4) Delineation and characterization of replenishment areas to groundwater aquifers, using state-of-the-art remote sensing, aerial and satellite imaging, incorporating them into a GIS system and for the identification of propitious areas for artificial replenishment.

Development of technologies for the storage of waters of various qualities and the assessment of the impact on the aquifer overall groundwater quality and the expected quality of the water to be produced in existing and planned well fields, including the aspects of recovery efficiency and water losses. The role of the unsaturated zone, which in many semi-arid areas is rather thick (~20 m) as a filtration medium will be investigated.

Field tests of water injection through wells and infiltration ponds, using the cleaning capabilities of the unsaturated zone will be preformed.

· Study the feasibility of improving the quality of the water prior to artificial recharge, such desalination and or ultra-filtration of effluent and waters of quality lower than the one in the aquifer.

· Investigate the impact of large scale artificial recharge of water of various qualities and mixing effects, with the help of sophisticated computational models for the simulation of groundwater flow and solute transport in regional aquifers.

· Investigate and quantify the mechanisms of climate change effects on precipitation patterns and aquifer natural replenishment, and to assess their impacts on the quality and availability of scarce groundwater resources.

· Develop a methodology for evaluating, in a physically-based way, the vulnerability of the aquifer to stress factors such as climate change, injection and storage of waters of various qualities in the aquifer, salinization processes and salt water intrusion, in order to optimize the management of the resource and land use planning in the area.

· Define future water demand scenarios and operational alternatives measures to meet the needs, such as amplification of the storage capacity in the aquifers, artificial recharge, utilization of saline groundwater, coastal collectors, etc.

· Application of the suggested schemes to three test sites of major importance: Thessaloniki area (Greece), the southern part of the coastal aquifer in Israel and Palestine, the Algarve aquifer in Portugal and the Llobregat Bay aquifer in Spain. In all these sites severe water supply problems exist, due to over-exploitation, and therefore, artificial recharge may prove to be a viable solution.

· Development of a dissemination and knowledge base platforms so that the results of the project will be made available also to other institutions/authorities in the European space.

· Performing an evaluation of the socio-economic impact of the suggested solution on the respective communities.