**4. Discussion**

Mygdonia Basin is a typical Mediterranean agricultural highly negative basin in terms of water balance. This study aimed to summarize and assess potential adaptation measures to reverse the unsustainable water managemen<sup>t</sup> as a combination of different strategies, which were formed by taking into account both the hydrology of the basin; socioeconomic conditions; environmental parameters; and several international, national, regional and local policies. Sustainable strategies for the restoration of the water bodies in Mygdonia Basin for the 2020–2050 and 2050–2080 periods were tested as adaptation solutions. In addition, the economic effects on the farmers' incomes were estimated for each of the proposed strategies.

It was confirmed that in cases of drained water basins, such as Mygdonia Basin, the efficacy of measures that will only reduce/limit the use of water does not provide a sustainable solution to the problem.

Of all the combined strategies, the most effective one that could guarantee the restoration of both the aquifer and the lakes and assure the sustainability of the water system is the drastic suspension of the agricultural sector. Concurrently, the expansion of alternative competitive economic activities that are capable of maintaining the income of the inhabitants and ensuring the sustainability and protection of water resources was proposed. More specifically, the implementation of a fallow land measure, as well as the promotion of rain-fed or low-water-intensive crops, in combination with the promotion of drip irrigation systems, was found to be the ideal solution for sustainable water managemen<sup>t</sup> and development in the area under study.

Highly water-stressed hydrological basins, such as Mygdonia Basin, which are also found in other Mediterranean countries, can only be restored if there are drastic reductions in economic water-consuming activities, such as agriculture, or a shift to other new economic activities that are compatible with the new climate conditions.

Generally, the new ominous climate context calls for a new approach. The development of a new "social calculus" that would enable the water community to not only meet present crises but also consider the meaning of our actions in the context of long-range plans could be feasible and sustainable in the future. The change in perception of how water

should be treated in all uses is the key to sustainable water management. In the case of farmers, irrigation efficiency is most of the time synonymous with maximizing net revenue rather than saving water. Even in cases of limited supplies, water-saving is not a priority for most farmers. Although innovative irrigation technologies are at the forefront of the solution in saving water in agriculture, labor and other inputs to ge<sup>t</sup> better economic gains are the main concern of farmers who make irrigation decisions by relying mostly on their practical experience. The selection of crops used to be related to subsidies coming from the EU, which resulted in the depletion of water resources in many basins with water problems, as water-intensive consuming crops were chosen (cotton, rice, etc.). In such cases, the development of local irrigation advisory services, education and training programs are important and should be considered by the relevant authorities. Farmers generally lack adequate assistance to develop and adopt better approaches and need better technical advice.

Adaptation goes beyond traditional coordination between agencies, interactions between water uses and planning approaches that consider all possible strategies and impacts. It is an integral part of a region's social and economic development. It refers to a norm-shifting change in managemen<sup>t</sup> and policy that is mainly focused on demand managemen<sup>t</sup> although strategies for adaptation that entail both water supply and water demand management.

The following directions are central for effective adaptation to climate change in water management.

### *Change the "Orientation" of the Hydraulic Engineering Projects*

Until recently, large infrastructure (dams and reservoirs) were designed and constructed to store excess seasonal water for future use under the condition that the availability of water resources is almost constant over time. Now that we are experiencing a deep change in the pattern of the hydrological cycle with the more frequent occurrence of extreme events and a severe decrease in water reserves, this option can no longer satisfy water demand and competing needs. Adaptive managemen<sup>t</sup> with regard to hydraulic engineering projects means managing the consequences of extreme events, i.e., the frequent interchange of the period of droughts and floods. More specifically, groundwater recharge managemen<sup>t</sup> and managed aquifer recharge (MAR) [72–74] are among the most effective engineering techniques. The constant decrease in precipitation and runoff requires a new orientation of water storage engineering projects that will manage the new water deficits. These techniques include the use of treated wastewater for aquifer storage [73–76]. Furthermore, changes in the hydrology of a basin in relation to changes in social values may result in new uses for reservoir storage, which may have greater economic or social value. Of course, high uncertainty in future projections for water availability poses a threat to the accuracy of projections.

Moreover, the adoption of an integrated approach is required to manage the consequences of natural disasters (fires, droughts and floods) in terms of providing proactive measures to prevent disasters and shield natural systems, such as through fire protection, control of forest fires, erosion prevention and flood control projects.

Given that interventions in existing infrastructure to enhance water resources have limited potential, due to climate projections that predict a decrease in rainfall, the only effective and sustainable way out is to adopt demand managemen<sup>t</sup> methods and measures. Demand managemen<sup>t</sup> measures consist of a grea<sup>t</sup> array of techniques and tools (engineering, economic, environmental, institutional and social). Demand managemen<sup>t</sup> may be applied through the implementation of strict standards in terms of water use and appropriate legislation to limit and control illegal drilling. In Mediterranean countries, such as France, Portugal, Italy and Spain, they have implemented different tax systems on agricultural water abstractions to recover the costs of the regulation, storage and managemen<sup>t</sup> of basin-level water services with various levels of cost recovery in accordance with the provision in the Water Framework Directive. Meanwhile, incentives, such as tax reduction, would encourage water saving in all uses. Technical interventions to reduce losses in irriga-

tion networks and water efficiency advantages through education and training campaigns on farms are among the options. Economic instruments, such as water metering and water pricing, are critical but very difficult to be implemented, first, because there is a high initial cost for metering that needs to be subsided by the authorities and, second, because the appropriate pricing policy needs detailed analysis that takes into account socioeconomic constraints, among others, which, for the moment in Greece, is still in the early stage. Educating water users, giving access to data and strengthening the cooperation between academia and industry are also important elements for successful demand management.

All the measures are location- and case-specific since adaptation is more effective at the local level. In the areas most vulnerable to climate change, emphasis is given to socioeconomic development and robust agricultural management. Sometimes it is wise to make a combination of adopting traditional techniques of water storage (cisterns) and traditional cultivations, which are already well known to farmers, with the use of modern technology to achieve water conservation. Moreover, the choice of crops and crop pattern in the case of irrigated agriculture should be compatible with the climatic conditions of the area and the land (soil). More efficient irrigation systems, shifts toward less water-intensive or more drought-tolerant crops, application of deficit irrigation schemes, land reclamation and land managemen<sup>t</sup> for carbon sequestration [77–80] may reduce water needs for agriculture and increase water-use efficiency [27,75]. The yearly water withdrawal for irrigation in the Mediterranean region amounts to ~223 km<sup>3</sup> [81], but there is a grea<sup>t</sup> water saving potential through the implementation of efficient irrigation systems [82–84]. The rebound effect should be mentioned though, as the water-saving effect of efficient irrigation systems may be counterbalanced by the expansion of irrigated areas [63,85,86].
